ZOO 4910 Lecture Notes - Lecture 15: Pituitary Gland, Hypothalamus, Testicle
2 May 2018
School
Department
Course
Professor
Arnold Berthold and the history of endocrinology
•
Hormone synthesis is highly conserved
•
Input, integration, and output
•
Types of cycles and their mechanisms
•
How to investigate behavioural endocrinology
•
Outline:
Capons (castrated roosters) = hens
!
Observed: sexually dimorphic behaviour and appearance
○
Hypothesis: intact testes are required for the development
of "male" characteristics
○
Arnold Berthold: first formal endocrine experiment in 1849
•
Group 1: castrated rooster --> caponization
○
Group 2: castrated rooster with testes re-implanted -->
normal male development
○
Group 3: castrated rooster with transplanted testes -->
normal male development
○
Berthold's Classic Experiment:
•
Testes can be transplanted
○
Transplanted testes are functional
○
Not a neuronal process (all nerves were severed when testes
transplanted)
○
Revised hypothesis: testes secrete a "blood borne product"
= hormones
○
Determined that…
•
Historical roots of behavioural endocrinology:
Testosterone --> ARs
!
Estradiol --> ERs
!
Glucocorticoids (cortisol/corticosterone) --> GRs
!
Hormone --> Receptor:
○
Hormones -organic chemical messengers produced and released
by endocrine glands into the bloodstream
•
Hypothalamus
○
Pituitary gland
○
Parathyroid gand
○
Kidney
○
Pineal gland
○
Thyroid gland
○
Thymus
○
Adrenal gland
○
Pancreas
○
Testes/ovary
○
Endocrine glands -highly conserved among vertebrae taxa in
form and function
•
*see slide
○
Steroid hormone biosynthesis:
•
The Endocrine System:
Stress exposure during development decreases song quality and
HVC size
•
Neuroprotective mechanism to counter stress-induced
damage?
○
DHEA plays a unique role in the songbird brain during stress
exposure
•
Control
!
CORT only
!
DHEA only
!
CORT + DHEA
!
4 groups of adult male song sparrows in non-breeding
condition were treated with physiological steroid doses or 4
weeks
○
Decreased with corticosterone
!
Increased with DHEA
!
No significant change with both
!
Determined brain region volume, mature neuron number
and newborn cells
○
Study:
•
Avian Song Control System:
Output: behaviour
!
Integration: CNS / endocrine glands
○
Input: physical environment + social environment
•
Testosterone levels increase in breeding stage (decreases in
molt)
○
Avian brain contains endrogen and estrogen receptors
•
Large gonads --> high concentrations of circulating
hormones --> enlarged song control nuclei in
brain --> song behaviour
!
Breeding:
○
Regressed gonads --> low concentrations of
circulating hormones --> smaller song control nuclei
in brain --> no song behaviour
!
Non-breeding:
○
Control of bird song:
•
Endocrine Control of Behaviour:
Food availability
○
Foraging effort
○
Ambient temperature
○
Predator pressure
○
Food quality
○
Food quantity
○
Reproduction is a function of:
•
Capital Breeding -using stored energy to reproduce
(gestation occurs when food abundance is low)
1.
Income Breeding -relying on energy availability (usually
will occur later in the year when food abundance is high)
2.
Two reproductive strategies (see slide):
•
Yolk: nutrients from wintering sites and breeding
sites
!
Albumen: nutrients from breeding sites
!
Ex. Eggs of arctic breeding eiders (exogenous and
endogenous nutrients)
○
Migratory birds combine these strategies
•
Increased melatonin during short days inhibits
gonadotropins
○
Longer days releases inhibition by melatonin
○
*see slide for mechanism
○
Daily rhythms may be influenced by melatonin (high at night)
and cortisol (peaks in the morning)
•
Environmentally triggered
!
E.g. seasonal allergies
!
Cycles analogous to type I&II rhythms, but phase
transitions are dependent on environmental stimuli
!
Type III -exogenous
○
Product of circannual clocks
!
E.g. ground squirrel body weight
!
Cycles analogous to type I rhythms, but not
dependent on photoperiod (likely genetic)
!
*even under constant day length, physiological
processes cycle
!
Type II -endogenous
○
*see slide
□
As days get shorter, transition out of
reproductive condition
□
Despite short days, start to become
reproductively active
!
They are then insensitive to day length
□
E.g. small mammals or avian reproduction
!
Type I -mixed input (endogenous/exogenous)
○
Types of Rhythms:
•
Evolution of Seasonal Rhythms
11/10/17
Remove hormone --> behaviour abolished1.
Restore hormone --> behaviour reinstated2.
Hormone concentration --> covaries with behavioural intensity 3.
To confirm a hormone-behaviour relationship, three experimental
conditions should be met:
Different selection pressures modify the hormonal mechanisms of
behaviour
•
Parental care
○
Immune suppression
○
Cost of testosterone
•
Alternative hormonal mechanisms
•
Endocrine control of behaviour has many shared mechanisms across
species, but:
Ex. Territorial behaviour coincide with high testosterone levels in
sparrows
Long-term, irreversible
○
During critical periods of development
○
Permanent effects on adult physiology and behaviour
○
Hormonal environment (in utero) affects adult
behaviour
!
Male between 2 females in utero: increased parental
care, decreased aggression
!
Male between 2 other males in utero: increase
aggression, decrease parental care
!
Delayed puberty
□
High parental care and "choosy"
□
All females in utero:
!
Mature earlier
□
More accepting of strange males
□
Female between two males in utero:
!
Ex. Do steroids make men more aggressive?
○
Organizational Effects1.
Short term, reversible
○
Acute effects of hormones
○
Maintains behaviours in adulthood
○
Oxytocin injection and optical stimulation of
oxytocin neurons stimulated maternal behaviour in
rats (specifically neurons in the left auditory cortex)
!
Optical stimulation (so brain thinks its
receiving oxytocin) is higher than
injected with oxytocin
!
Saline solution (control) causes virgin to
slowly increase pup retrieval behaviour
over time
!
Virgins injected with oxytocin start to engage
in pup retrieval behaviour
□
*usually a isolated pup will be brought back to the
den by a dam (not a naïve virgin)
!
Muscimol infusion reduced retrieval behaviour
of experienced moms
□
Note: muscimol is an antagonist to oxytocin
receptors
□
Auditory cortex (left):
!
Ex. Oxytocin exposure triggers maternal behaviour in
mammals
○
Open prairie habitat
□
monogamous, biparental
□
Live in family groups
□
Prairie vole:
!
Rocky mountain habitat
□
Promiscuous, uniparental
□
Solitary territories
□
Montane vole:
!
Prairie vole prefers partner (montane prefers
neutral)
□
Mating:
!
Many AVP receptors in nucleus
accumbens and ventral pallidum (area of
brain involved in addiction)
!
Prairie: long-term pair bond (life long
romance)
□
No AVP receptors in nuclear accumbens
!
Montane: no pair bound
□
Increased levels of vasopression:
!
If AVP receptor is blocked in Prairie voles,
they do not prefer spending time with their
partner vs. stranger
□
If AVP is injected, one can enhance partner
preference (increase intensity)
□
Manipulating AVP receptor activity:
!
Using transgenic techniques, the AVP gene is
inserted
□
This caused the vole to prefer their partner
rather than a stranger --> pair bond behaviour
□
Transgenic Montane Vole:
!
Higher: homerange, extrapair, intrusion
rate, male visits
!
EPF: males roam and mate with additional
females
□
IPF: males stay closer to home and are more
faithful
□
*due to RSC-V1aR (higher in IPF)
!
IPF: higher for HI vs LO
!
EPF: higher for LO (very
low for HI)
!
Relative fitness differs when
broken down between IPF and EPF
with HI and LO
◊
Overall, the relative fitness is similar
within populations with high RSC-V1aR
(HI) and low RSC-V1aR (LO)
!
*balancing selection = variation in
social/mating behaviour
□
Sexual fidelity trade-offs promote regulatory
variation in the prairie vole brain
!
Ex. Vole partner preference
○
Activational Effects2.
Mechanisms for Hormone Action:
Hormones influence behaviour BUT the outcomes of a behaviour
can influence hormone production
•
Ex. salivary testosterone levels increased in the winning
team following the game and decreased in the losing team
○
Simulated territorial intrusion induces aggressive behaviour BUT
testosterone levels increase after the challenge has ceased and
remain elevated
•
California mice win in aggressive actions --> hormones
increase so it can win again
○
White-footed mice has increased win with aggressive
action if given testosterone (vs. saline) --> sets up "winning
streak"
○
"The Winner Effect":
•
Porn viewership went way done
○
Fans of winning team: increase porn watching after game
○
Losing team: smaller increase in porn watching after game
○
Testosterone levels in men:
•
Behavioural Control of Hormones: "the challenge hypothesis"
11/15/17
Topic: Sexchange & Fisticuffs in Fish, and the Ecophysiology of Stress
The brain not only controls behaviour; behaviour can also affect
the brain
•
Harems
!
Males act aggressively to females
!
Aggressive social environment inhibits aggressive
behaviour in females
!
Protogynous fish:
○
Protogyny: sex change from female to male
•
Largest: alpha males
!
Large: older females
!
Small: younger females
!
Has 3 morphs:
○
The largest female will then have a function
transformation to male (within days)
!
If the alpha male is removed from a population, the largest
female displays male behaviour (within hours)
○
*also known to change from male to female
○
*see slide
!
Note: steroid synthesis occurs in the gonads and the
brain
!
Testosterone can be converted into 11-ketotestosterone via
11beta-HSD (--> male physiology and behaviour) and
estradiol via aromatase (--> female physiology and
behavior)
○
Low aromatase activity so T --> KT which
drives aggression and courtship
□
Dominant Male
!
High aromatase activity so T-->E2
□
Large & Small Female
!
Normally:
○
Results in male gonads --> functional
alpha male (results in courtship)
!
Low aromatase activity (decreases rapidly) so
T--> KT causes male behaviour with high
aggression
□
Brain aromatase activity decreases
!
Gonad aromatase activity does not differ
□
Large Female:
!
With dominant male removed:
○
Ex. Blue Banded Goby:
•
Neurosteroids and Behaviour
Output: behaviour, physiology, phenotypic plasticity
!
Integration: CNS/endocrine glands
○
Input: physical and social environments
•
*see slide
○
Adrenal cortex in mammals/birds
!
--> glucocorticoids such as cortisol (provides
negative feedback to anterior pituitary and
hypothalamus)
Interrenal tissue in amphibians and fish
!
Highly conserved across vertebrates
○
Corticosterone: birds, rats
!
Cortisol: primates, fish, mammals
--> mobilize energy stores to fuel fight or flight
response
!
Glucocorticoids: stress hormone
○
Mobilize energy stores to fuel fight or flight
response
□
Increased heart rate
□
Inhibited reproduction
□
Inhibited digestion
□
Increased analgesia
□
Acute stress response (short-term adaptive)
!
Fatigue
□
Hypertension
□
Impotence, anovulation
□
Peptic ulcers
□
Depression
□
Chronic stress response (long-term costly)
!
Traditional Dichotomous Outcomes:
○
HPA Axis:
•
Thermal stress hides upstrike in inflammation when
rodents are fed high-cholesterol diet
!
Atherosclerosis effects from western diet were
not detected because mice at low temperatures
have high inflammation
□
Masks experimental outcome:
!
Ex. Chilly cages may skew disease studies in lab mice
○
Designing Physiological Studies:
•
Presence of predators have an impact
!
Higher in tadpoles
□
Higher in juveniles
□
No significant difference in stressed juveniles
(already at maximum stress level --> harder to
respond to additional stresses)
□
Whole-body glucocorticoid levels increases with
predatory biomass
!
Trunk length was smaller in individuals
exposed to predators or with CORT
--> higher probability of survival in presence of
predators
□
Tail height was higher in individuals exposed to
predators or with CORT
!
by changing swimming behaviour + less for
predator to grab
□
Cost: lower reproductive output (but have
higher survival when young = trade-off)
□
short and wide tail with predators -higher fitness
!
Ex. Phenotypic plasticity in amphibian tadpoles
○
High reproductive
success
–
Energetically
expensive
–
Shorter lifespan
–
Territorial:
!
Always have high testosterone
◊
Yes -high CORT & No -low CORT
!
Stress:
□
Males with blue-orange phenotypes (--> directional
selection)
!
No reproductive
success
–
Moderate lifespan
–
Nomadic:
!
Low testosterone
◊
Yes -high CORT
!
Moderate reproductive
success
–
Moderate lifespan
–
Sedentary satellite
!
High testosterone
◊
No -low CORT
!
Stress:
□
Males with orange phenotypes (--> disruptive
selection)
!
Ex. Tree lizards -relative plasticity
○
Adaptive Stress-mediated Responses:
•
*see slide
!
Epigenetics: heritable changes in gene expression and
phenotype that are independent of DNA sequence
○
Female and germ line forming embryo directly
experienced stressor
□
F0: non-pregnant female exposed to stressor
!
F1: directly experienced stressor as germ line
!
F2 & F3: never directly experienced stressor
!
Example 1:
○
Pregnant female embryo and embryos germ
line directly experienced stressor
□
F0: pregnant female exposed to stressor
!
F1: directly experienced stressor as embryo
!
F2: directly experiences stressor as germ line
!
F3: never directly experienced stressor
!
Example 2:
○
Shut off stress response quickly
□
Less anxious
□
Low maternal glucocorticoids (high GR expression):
!
Hyper-responsive to stress exposure
□
Anxiety behaviour
□
High maternal glucocorticoids (low GR expression):
!
*therefore GR expression as fetus = adult stress
phenotype
!
Prenatal stress in rodents: lasting effect in offspring
○
High GR expression
!
Lower peak cortisol, quick stress
shutdown
!
Low anxiety behaviour
!
High maternal behaviour
!
F1 offspring:
□
Control (no prenatal stress) --> high maternal
behaviour
!
Low GR expression
!
Hyper-responsive to stress
!
Anxious as adults
!
Low maternal behaviour
!
F1 offspring:
□
Prenatal stress --> low maternal behaviour
!
Early life stress --> mother's stress phenotype --> maternal
behaviour
○
*see stress-induced changes in maternal gut could
negatively impact offspring for life
○
High natal philopatry
!
Ecology well described
!
Maternal behaviour
!
Density = stress
!
Fitness
!
Kluane Red Squirrel Project (Yukon)
○
Early Life Effects:
•
Ecophysiology of Stress:
Behavioural Neuroendocrinology
Wednesday,+ November+ 8,+2017
12:30+PM
Arnold Berthold and the history of endocrinology
•
Hormone synthesis is highly conserved
•
Input, integration, and output
•
Types of cycles and their mechanisms
•
How to investigate behavioural endocrinology
•
Outline:
Capons (castrated roosters) = hens
!
Observed: sexually dimorphic behaviour and appearance
○
Hypothesis: intact testes are required for the development
of "male" characteristics
○
Arnold Berthold: first formal endocrine experiment in 1849
•
Group 1: castrated rooster --> caponization
○
Group 2: castrated rooster with testes re-implanted -->
normal male development
○
Group 3: castrated rooster with transplanted testes -->
normal male development
○
Berthold's Classic Experiment:
•
Testes can be transplanted
○
Transplanted testes are functional
○
Not a neuronal process (all nerves were severed when testes
transplanted)
○
Revised hypothesis: testes secrete a "blood borne product"
= hormones
○
Determined that…
•
Historical roots of behavioural endocrinology:
Testosterone --> ARs
!
Estradiol --> ERs
!
Glucocorticoids (cortisol/corticosterone) --> GRs
!
Hormone --> Receptor:
○
Hormones -organic chemical messengers produced and released
by endocrine glands into the bloodstream
•
Hypothalamus
○
Pituitary gland
○
Parathyroid gand
○
Kidney
○
Pineal gland
○
Thyroid gland
○
Thymus
○
Adrenal gland
○
Pancreas
○
Testes/ovary
○
Endocrine glands -highly conserved among vertebrae taxa in
form and function
•
*see slide
○
Steroid hormone biosynthesis:
•
The Endocrine System:
Stress exposure during development decreases song quality and
HVC size
•
Neuroprotective mechanism to counter stress-induced
damage?
○
DHEA plays a unique role in the songbird brain during stress
exposure
•
Control
!
CORT only
!
DHEA only
!
CORT + DHEA
!
4 groups of adult male song sparrows in non-breeding
condition were treated with physiological steroid doses or 4
weeks
○
Decreased with corticosterone
!
Increased with DHEA
!
No significant change with both
!
Determined brain region volume, mature neuron number
and newborn cells
○
Study:
•
Avian Song Control System:
Output: behaviour
!
Integration: CNS / endocrine glands
○
Input: physical environment + social environment
•
Testosterone levels increase in breeding stage (decreases in
molt)
○
Avian brain contains endrogen and estrogen receptors
•
Large gonads --> high concentrations of circulating
hormones --> enlarged song control nuclei in
brain --> song behaviour
!
Breeding:
○
Regressed gonads --> low concentrations of
circulating hormones --> smaller song control nuclei
in brain --> no song behaviour
!
Non-breeding:
○
Control of bird song:
•
Endocrine Control of Behaviour:
Food availability
○
Foraging effort
○
Ambient temperature
○
Predator pressure
○
Food quality
○
Food quantity
○
Reproduction is a function of:
•
Capital Breeding -using stored energy to reproduce
(gestation occurs when food abundance is low)
1.
Income Breeding -relying on energy availability (usually
will occur later in the year when food abundance is high)
2.
Two reproductive strategies (see slide):
•
Yolk: nutrients from wintering sites and breeding
sites
!
Albumen: nutrients from breeding sites
!
Ex. Eggs of arctic breeding eiders (exogenous and
endogenous nutrients)
○
Migratory birds combine these strategies
•
Increased melatonin during short days inhibits
gonadotropins
○
Longer days releases inhibition by melatonin
○
*see slide for mechanism
○
Daily rhythms may be influenced by melatonin (high at night)
and cortisol (peaks in the morning)
•
Environmentally triggered
!
E.g. seasonal allergies
!
Cycles analogous to type I&II rhythms, but phase
transitions are dependent on environmental stimuli
!
Type III -exogenous
○
Product of circannual clocks
!
E.g. ground squirrel body weight
!
Cycles analogous to type I rhythms, but not
dependent on photoperiod (likely genetic)
!
*even under constant day length, physiological
processes cycle
!
Type II -endogenous
○
*see slide
□
As days get shorter, transition out of
reproductive condition
□
Despite short days, start to become
reproductively active
!
They are then insensitive to day length
□
E.g. small mammals or avian reproduction
!
Type I -mixed input (endogenous/exogenous)
○
Types of Rhythms:
•
Evolution of Seasonal Rhythms
11/10/17
Remove hormone --> behaviour abolished1.
Restore hormone --> behaviour reinstated2.
Hormone concentration --> covaries with behavioural intensity 3.
To confirm a hormone-behaviour relationship, three experimental
conditions should be met:
Different selection pressures modify the hormonal mechanisms of
behaviour
•
Parental care
○
Immune suppression
○
Cost of testosterone
•
Alternative hormonal mechanisms
•
Endocrine control of behaviour has many shared mechanisms across
species, but:
Ex. Territorial behaviour coincide with high testosterone levels in
sparrows
Long-term, irreversible
○
During critical periods of development
○
Permanent effects on adult physiology and behaviour
○
Hormonal environment (in utero) affects adult
behaviour
!
Male between 2 females in utero: increased parental
care, decreased aggression
!
Male between 2 other males in utero: increase
aggression, decrease parental care
!
Delayed puberty
□
High parental care and "choosy"
□
All females in utero:
!
Mature earlier
□
More accepting of strange males
□
Female between two males in utero:
!
Ex. Do steroids make men more aggressive?
○
Organizational Effects1.
Short term, reversible
○
Acute effects of hormones
○
Maintains behaviours in adulthood
○
Oxytocin injection and optical stimulation of
oxytocin neurons stimulated maternal behaviour in
rats (specifically neurons in the left auditory cortex)
!
Optical stimulation (so brain thinks its
receiving oxytocin) is higher than
injected with oxytocin
!
Saline solution (control) causes virgin to
slowly increase pup retrieval behaviour
over time
!
Virgins injected with oxytocin start to engage
in pup retrieval behaviour
□
*usually a isolated pup will be brought back to the
den by a dam (not a naïve virgin)
!
Muscimol infusion reduced retrieval behaviour
of experienced moms
□
Note: muscimol is an antagonist to oxytocin
receptors
□
Auditory cortex (left):
!
Ex. Oxytocin exposure triggers maternal behaviour in
mammals
○
Open prairie habitat
□
monogamous, biparental
□
Live in family groups
□
Prairie vole:
!
Rocky mountain habitat
□
Promiscuous, uniparental
□
Solitary territories
□
Montane vole:
!
Prairie vole prefers partner (montane prefers
neutral)
□
Mating:
!
Many AVP receptors in nucleus
accumbens and ventral pallidum (area of
brain involved in addiction)
!
Prairie: long-term pair bond (life long
romance)
□
No AVP receptors in nuclear accumbens
!
Montane: no pair bound
□
Increased levels of vasopression:
!
If AVP receptor is blocked in Prairie voles,
they do not prefer spending time with their
partner vs. stranger
□
If AVP is injected, one can enhance partner
preference (increase intensity)
□
Manipulating AVP receptor activity:
!
Using transgenic techniques, the AVP gene is
inserted
□
This caused the vole to prefer their partner
rather than a stranger --> pair bond behaviour
□
Transgenic Montane Vole:
!
Higher: homerange, extrapair, intrusion
rate, male visits
!
EPF: males roam and mate with additional
females
□
IPF: males stay closer to home and are more
faithful
□
*due to RSC-V1aR (higher in IPF)
!
IPF: higher for HI vs LO
!
EPF: higher for LO (very
low for HI)
!
Relative fitness differs when
broken down between IPF and EPF
with HI and LO
◊
Overall, the relative fitness is similar
within populations with high RSC-V1aR
(HI) and low RSC-V1aR (LO)
!
*balancing selection = variation in
social/mating behaviour
□
Sexual fidelity trade-offs promote regulatory
variation in the prairie vole brain
!
Ex. Vole partner preference
○
Activational Effects2.
Mechanisms for Hormone Action:
Hormones influence behaviour BUT the outcomes of a behaviour
can influence hormone production
•
Ex. salivary testosterone levels increased in the winning
team following the game and decreased in the losing team
○
Simulated territorial intrusion induces aggressive behaviour BUT
testosterone levels increase after the challenge has ceased and
remain elevated
•
California mice win in aggressive actions --> hormones
increase so it can win again
○
White-footed mice has increased win with aggressive
action if given testosterone (vs. saline) --> sets up "winning
streak"
○
"The Winner Effect":
•
Porn viewership went way done
○
Fans of winning team: increase porn watching after game
○
Losing team: smaller increase in porn watching after game
○
Testosterone levels in men:
•
Behavioural Control of Hormones: "the challenge hypothesis"
11/15/17
Topic: Sexchange & Fisticuffs in Fish, and the Ecophysiology of Stress
The brain not only controls behaviour; behaviour can also affect
the brain
•
Harems
!
Males act aggressively to females
!
Aggressive social environment inhibits aggressive
behaviour in females
!
Protogynous fish:
○
Protogyny: sex change from female to male
•
Largest: alpha males
!
Large: older females
!
Small: younger females
!
Has 3 morphs:
○
The largest female will then have a function
transformation to male (within days)
!
If the alpha male is removed from a population, the largest
female displays male behaviour (within hours)
○
*also known to change from male to female
○
*see slide
!
Note: steroid synthesis occurs in the gonads and the
brain
!
Testosterone can be converted into 11-ketotestosterone via
11beta-HSD (--> male physiology and behaviour) and
estradiol via aromatase (--> female physiology and
behavior)
○
Low aromatase activity so T --> KT which
drives aggression and courtship
□
Dominant Male
!
High aromatase activity so T-->E2
□
Large & Small Female
!
Normally:
○
Results in male gonads --> functional
alpha male (results in courtship)
!
Low aromatase activity (decreases rapidly) so
T--> KT causes male behaviour with high
aggression
□
Brain aromatase activity decreases
!
Gonad aromatase activity does not differ
□
Large Female:
!
With dominant male removed:
○
Ex. Blue Banded Goby:
•
Neurosteroids and Behaviour
Output: behaviour, physiology, phenotypic plasticity
!
Integration: CNS/endocrine glands
○
Input: physical and social environments
•
*see slide
○
Adrenal cortex in mammals/birds
!
--> glucocorticoids such as cortisol (provides
negative feedback to anterior pituitary and
hypothalamus)
Interrenal tissue in amphibians and fish
!
Highly conserved across vertebrates
○
Corticosterone: birds, rats
!
Cortisol: primates, fish, mammals
--> mobilize energy stores to fuel fight or flight
response
!
Glucocorticoids: stress hormone
○
Mobilize energy stores to fuel fight or flight
response
□
Increased heart rate
□
Inhibited reproduction
□
Inhibited digestion
□
Increased analgesia
□
Acute stress response (short-term adaptive)
!
Fatigue
□
Hypertension
□
Impotence, anovulation
□
Peptic ulcers
□
Depression
□
Chronic stress response (long-term costly)
!
Traditional Dichotomous Outcomes:
○
HPA Axis:
•
Thermal stress hides upstrike in inflammation when
rodents are fed high-cholesterol diet
!
Atherosclerosis effects from western diet were
not detected because mice at low temperatures
have high inflammation
□
Masks experimental outcome:
!
Ex. Chilly cages may skew disease studies in lab mice
○
Designing Physiological Studies:
•
Presence of predators have an impact
!
Higher in tadpoles
□
Higher in juveniles
□
No significant difference in stressed juveniles
(already at maximum stress level --> harder to
respond to additional stresses)
□
Whole-body glucocorticoid levels increases with
predatory biomass
!
Trunk length was smaller in individuals
exposed to predators or with CORT
--> higher probability of survival in presence of
predators
□
Tail height was higher in individuals exposed to
predators or with CORT
!
by changing swimming behaviour + less for
predator to grab
□
Cost: lower reproductive output (but have
higher survival when young = trade-off)
□
short and wide tail with predators -higher fitness
!
Ex. Phenotypic plasticity in amphibian tadpoles
○
High reproductive
success
–
Energetically
expensive
–
Shorter lifespan
–
Territorial:
!
Always have high testosterone
◊
Yes -high CORT & No -low CORT
!
Stress:
□
Males with blue-orange phenotypes (--> directional
selection)
!
No reproductive
success
–
Moderate lifespan
–
Nomadic:
!
Low testosterone
◊
Yes -high CORT
!
Moderate reproductive
success
–
Moderate lifespan
–
Sedentary satellite
!
High testosterone
◊
No -low CORT
!
Stress:
□
Males with orange phenotypes (--> disruptive
selection)
!
Ex. Tree lizards -relative plasticity
○
Adaptive Stress-mediated Responses:
•
*see slide
!
Epigenetics: heritable changes in gene expression and
phenotype that are independent of DNA sequence
○
Female and germ line forming embryo directly
experienced stressor
□
F0: non-pregnant female exposed to stressor
!
F1: directly experienced stressor as germ line
!
F2 & F3: never directly experienced stressor
!
Example 1:
○
Pregnant female embryo and embryos germ
line directly experienced stressor
□
F0: pregnant female exposed to stressor
!
F1: directly experienced stressor as embryo
!
F2: directly experiences stressor as germ line
!
F3: never directly experienced stressor
!
Example 2:
○
Shut off stress response quickly
□
Less anxious
□
Low maternal glucocorticoids (high GR expression):
!
Hyper-responsive to stress exposure
□
Anxiety behaviour
□
High maternal glucocorticoids (low GR expression):
!
*therefore GR expression as fetus = adult stress
phenotype
!
Prenatal stress in rodents: lasting effect in offspring
○
High GR expression
!
Lower peak cortisol, quick stress
shutdown
!
Low anxiety behaviour
!
High maternal behaviour
!
F1 offspring:
□
Control (no prenatal stress) --> high maternal
behaviour
!
Low GR expression
!
Hyper-responsive to stress
!
Anxious as adults
!
Low maternal behaviour
!
F1 offspring:
□
Prenatal stress --> low maternal behaviour
!
Early life stress --> mother's stress phenotype --> maternal
behaviour
○
*see stress-induced changes in maternal gut could
negatively impact offspring for life
○
High natal philopatry
!
Ecology well described
!
Maternal behaviour
!
Density = stress
!
Fitness
!
Kluane Red Squirrel Project (Yukon)
○
Early Life Effects:
•
Ecophysiology of Stress:
Behavioural Neuroendocrinology
Wednesday,+ November+ 8,+2017 12:30+PM
Arnold Berthold and the history of endocrinology
•
Hormone synthesis is highly conserved
•
Input, integration, and output
•
Types of cycles and their mechanisms
•
How to investigate behavioural endocrinology
•
Outline:
Capons (castrated roosters) = hens
!
Observed: sexually dimorphic behaviour and appearance
○
Hypothesis: intact testes are required for the development
of "male" characteristics
○
Arnold Berthold: first formal endocrine experiment in 1849
•
Group 1: castrated rooster --> caponization
○
Group 2: castrated rooster with testes re-implanted -->
normal male development
○
Group 3: castrated rooster with transplanted testes -->
normal male development
○
Berthold's Classic Experiment:
•
Testes can be transplanted
○
Transplanted testes are functional
○
Not a neuronal process (all nerves were severed when testes
transplanted)
○
Revised hypothesis: testes secrete a "blood borne product"
= hormones
○
Determined that…
•
Historical roots of behavioural endocrinology:
Testosterone --> ARs
!
Estradiol --> ERs
!
Glucocorticoids (cortisol/corticosterone) --> GRs
!
Hormone --> Receptor:
○
Hormones -organic chemical messengers produced and released
by endocrine glands into the bloodstream
•
Hypothalamus
○
Pituitary gland
○
Parathyroid gand
○
Kidney
○
Pineal gland
○
Thyroid gland
○
Thymus
○
Adrenal gland
○
Pancreas
○
Testes/ovary
○
Endocrine glands -highly conserved among vertebrae taxa in
form and function
•
*see slide
○
Steroid hormone biosynthesis:
•
The Endocrine System:
Stress exposure during development decreases song quality and
HVC size
•
Neuroprotective mechanism to counter stress-induced
damage?
○
DHEA plays a unique role in the songbird brain during stress
exposure
•
Control
!
CORT only
!
DHEA only
!
CORT + DHEA
!
4 groups of adult male song sparrows in non-breeding
condition were treated with physiological steroid doses or 4
weeks
○
Decreased with corticosterone
!
Increased with DHEA
!
No significant change with both
!
Determined brain region volume, mature neuron number
and newborn cells
○
Study:
•
Avian Song Control System:
Output: behaviour
!
Integration: CNS / endocrine glands
○
Input: physical environment + social environment
•
Testosterone levels increase in breeding stage (decreases in
molt)
○
Avian brain contains endrogen and estrogen receptors
•
Large gonads --> high concentrations of circulating
hormones --> enlarged song control nuclei in
brain --> song behaviour
!
Breeding:
○
Regressed gonads --> low concentrations of
circulating hormones --> smaller song control nuclei
in brain --> no song behaviour
!
Non-breeding:
○
Control of bird song:
•
Endocrine Control of Behaviour:
Food availability
○
Foraging effort
○
Ambient temperature
○
Predator pressure
○
Food quality
○
Food quantity
○
Reproduction is a function of:
•
Capital Breeding -using stored energy to reproduce
(gestation occurs when food abundance is low)
1.
Income Breeding -relying on energy availability (usually
will occur later in the year when food abundance is high)
2.
Two reproductive strategies (see slide):
•
Yolk: nutrients from wintering sites and breeding
sites
!
Albumen: nutrients from breeding sites
!
Ex. Eggs of arctic breeding eiders (exogenous and
endogenous nutrients)
○
Migratory birds combine these strategies
•
Increased melatonin during short days inhibits
gonadotropins
○
Longer days releases inhibition by melatonin
○
*see slide for mechanism
○
Daily rhythms may be influenced by melatonin (high at night)
and cortisol (peaks in the morning)
•
Environmentally triggered
!
E.g. seasonal allergies
!
Cycles analogous to type I&II rhythms, but phase
transitions are dependent on environmental stimuli
!
Type III -exogenous
○
Product of circannual clocks
!
E.g. ground squirrel body weight
!
Cycles analogous to type I rhythms, but not
dependent on photoperiod (likely genetic)
!
*even under constant day length, physiological
processes cycle
!
Type II -endogenous
○
*see slide
□
As days get shorter, transition out of
reproductive condition
□
Despite short days, start to become
reproductively active
!
They are then insensitive to day length
□
E.g. small mammals or avian reproduction
!
Type I -mixed input (endogenous/exogenous)
○
Types of Rhythms:
•
Evolution of Seasonal Rhythms
11/10/17
Remove hormone --> behaviour abolished1.
Restore hormone --> behaviour reinstated2.
Hormone concentration --> covaries with behavioural intensity 3.
To confirm a hormone-behaviour relationship, three experimental
conditions should be met:
Different selection pressures modify the hormonal mechanisms of
behaviour
•
Parental care
○
Immune suppression
○
Cost of testosterone
•
Alternative hormonal mechanisms
•
Endocrine control of behaviour has many shared mechanisms across
species, but:
Ex. Territorial behaviour coincide with high testosterone levels in
sparrows
Long-term, irreversible
○
During critical periods of development
○
Permanent effects on adult physiology and behaviour
○
Hormonal environment (in utero) affects adult
behaviour
!
Male between 2 females in utero: increased parental
care, decreased aggression
!
Male between 2 other males in utero: increase
aggression, decrease parental care
!
Delayed puberty
□
High parental care and "choosy"
□
All females in utero:
!
Mature earlier
□
More accepting of strange males
□
Female between two males in utero:
!
Ex. Do steroids make men more aggressive?
○
Organizational Effects1.
Short term, reversible
○
Acute effects of hormones
○
Maintains behaviours in adulthood
○
Oxytocin injection and optical stimulation of
oxytocin neurons stimulated maternal behaviour in
rats (specifically neurons in the left auditory cortex)
!
Optical stimulation (so brain thinks its
receiving oxytocin) is higher than
injected with oxytocin
!
Saline solution (control) causes virgin to
slowly increase pup retrieval behaviour
over time
!
Virgins injected with oxytocin start to engage
in pup retrieval behaviour
□
*usually a isolated pup will be brought back to the
den by a dam (not a naïve virgin)
!
Muscimol infusion reduced retrieval behaviour
of experienced moms
□
Note: muscimol is an antagonist to oxytocin
receptors
□
Auditory cortex (left):
!
Ex. Oxytocin exposure triggers maternal behaviour in
mammals
○
Open prairie habitat
□
monogamous, biparental
□
Live in family groups
□
Prairie vole:
!
Rocky mountain habitat
□
Promiscuous, uniparental
□
Solitary territories
□
Montane vole:
!
Prairie vole prefers partner (montane prefers
neutral)
□
Mating:
!
Many AVP receptors in nucleus
accumbens and ventral pallidum (area of
brain involved in addiction)
!
Prairie: long-term pair bond (life long
romance)
□
No AVP receptors in nuclear accumbens
!
Montane: no pair bound
□
Increased levels of vasopression:
!
If AVP receptor is blocked in Prairie voles,
they do not prefer spending time with their
partner vs. stranger
□
If AVP is injected, one can enhance partner
preference (increase intensity)
□
Manipulating AVP receptor activity:
!
Using transgenic techniques, the AVP gene is
inserted
□
This caused the vole to prefer their partner
rather than a stranger --> pair bond behaviour
□
Transgenic Montane Vole:
!
Higher: homerange, extrapair, intrusion
rate, male visits
!
EPF: males roam and mate with additional
females
□
IPF: males stay closer to home and are more
faithful
□
*due to RSC-V1aR (higher in IPF)
!
IPF: higher for HI vs LO
!
EPF: higher for LO (very
low for HI)
!
Relative fitness differs when
broken down between IPF and EPF
with HI and LO
◊
Overall, the relative fitness is similar
within populations with high RSC-V1aR
(HI) and low RSC-V1aR (LO)
!
*balancing selection = variation in
social/mating behaviour
□
Sexual fidelity trade-offs promote regulatory
variation in the prairie vole brain
!
Ex. Vole partner preference
○
Activational Effects2.
Mechanisms for Hormone Action:
Hormones influence behaviour BUT the outcomes of a behaviour
can influence hormone production
•
Ex. salivary testosterone levels increased in the winning
team following the game and decreased in the losing team
○
Simulated territorial intrusion induces aggressive behaviour BUT
testosterone levels increase after the challenge has ceased and
remain elevated
•
California mice win in aggressive actions --> hormones
increase so it can win again
○
White-footed mice has increased win with aggressive
action if given testosterone (vs. saline) --> sets up "winning
streak"
○
"The Winner Effect":
•
Porn viewership went way done
○
Fans of winning team: increase porn watching after game
○
Losing team: smaller increase in porn watching after game
○
Testosterone levels in men:
•
Behavioural Control of Hormones: "the challenge hypothesis"
11/15/17
Topic: Sexchange & Fisticuffs in Fish, and the Ecophysiology of Stress
The brain not only controls behaviour; behaviour can also affect
the brain
•
Harems
!
Males act aggressively to females
!
Aggressive social environment inhibits aggressive
behaviour in females
!
Protogynous fish:
○
Protogyny: sex change from female to male
•
Largest: alpha males
!
Large: older females
!
Small: younger females
!
Has 3 morphs:
○
The largest female will then have a function
transformation to male (within days)
!
If the alpha male is removed from a population, the largest
female displays male behaviour (within hours)
○
*also known to change from male to female
○
*see slide
!
Note: steroid synthesis occurs in the gonads and the
brain
!
Testosterone can be converted into 11-ketotestosterone via
11beta-HSD (--> male physiology and behaviour) and
estradiol via aromatase (--> female physiology and
behavior)
○
Low aromatase activity so T --> KT which
drives aggression and courtship
□
Dominant Male
!
High aromatase activity so T-->E2
□
Large & Small Female
!
Normally:
○
Results in male gonads --> functional
alpha male (results in courtship)
!
Low aromatase activity (decreases rapidly) so
T--> KT causes male behaviour with high
aggression
□
Brain aromatase activity decreases
!
Gonad aromatase activity does not differ
□
Large Female:
!
With dominant male removed:
○
Ex. Blue Banded Goby:
•
Neurosteroids and Behaviour
Output: behaviour, physiology, phenotypic plasticity
!
Integration: CNS/endocrine glands
○
Input: physical and social environments
•
*see slide
○
Adrenal cortex in mammals/birds
!
--> glucocorticoids such as cortisol (provides
negative feedback to anterior pituitary and
hypothalamus)
Interrenal tissue in amphibians and fish
!
Highly conserved across vertebrates
○
Corticosterone: birds, rats
!
Cortisol: primates, fish, mammals
--> mobilize energy stores to fuel fight or flight
response
!
Glucocorticoids: stress hormone
○
Mobilize energy stores to fuel fight or flight
response
□
Increased heart rate
□
Inhibited reproduction
□
Inhibited digestion
□
Increased analgesia
□
Acute stress response (short-term adaptive)
!
Fatigue
□
Hypertension
□
Impotence, anovulation
□
Peptic ulcers
□
Depression
□
Chronic stress response (long-term costly)
!
Traditional Dichotomous Outcomes:
○
HPA Axis:
•
Thermal stress hides upstrike in inflammation when
rodents are fed high-cholesterol diet
!
Atherosclerosis effects from western diet were
not detected because mice at low temperatures
have high inflammation
□
Masks experimental outcome:
!
Ex. Chilly cages may skew disease studies in lab mice
○
Designing Physiological Studies:
•
Presence of predators have an impact
!
Higher in tadpoles
□
Higher in juveniles
□
No significant difference in stressed juveniles
(already at maximum stress level --> harder to
respond to additional stresses)
□
Whole-body glucocorticoid levels increases with
predatory biomass
!
Trunk length was smaller in individuals
exposed to predators or with CORT
--> higher probability of survival in presence of
predators
□
Tail height was higher in individuals exposed to
predators or with CORT
!
by changing swimming behaviour + less for
predator to grab
□
Cost: lower reproductive output (but have
higher survival when young = trade-off)
□
short and wide tail with predators -higher fitness
!
Ex. Phenotypic plasticity in amphibian tadpoles
○
High reproductive
success
–
Energetically
expensive
–
Shorter lifespan
–
Territorial:
!
Always have high testosterone
◊
Yes -high CORT & No -low CORT
!
Stress:
□
Males with blue-orange phenotypes (--> directional
selection)
!
No reproductive
success
–
Moderate lifespan
–
Nomadic:
!
Low testosterone
◊
Yes -high CORT
!
Moderate reproductive
success
–
Moderate lifespan
–
Sedentary satellite
!
High testosterone
◊
No -low CORT
!
Stress:
□
Males with orange phenotypes (--> disruptive
selection)
!
Ex. Tree lizards -relative plasticity
○
Adaptive Stress-mediated Responses:
•
*see slide
!
Epigenetics: heritable changes in gene expression and
phenotype that are independent of DNA sequence
○
Female and germ line forming embryo directly
experienced stressor
□
F0: non-pregnant female exposed to stressor
!
F1: directly experienced stressor as germ line
!
F2 & F3: never directly experienced stressor
!
Example 1:
○
Pregnant female embryo and embryos germ
line directly experienced stressor
□
F0: pregnant female exposed to stressor
!
F1: directly experienced stressor as embryo
!
F2: directly experiences stressor as germ line
!
F3: never directly experienced stressor
!
Example 2:
○
Shut off stress response quickly
□
Less anxious
□
Low maternal glucocorticoids (high GR expression):
!
Hyper-responsive to stress exposure
□
Anxiety behaviour
□
High maternal glucocorticoids (low GR expression):
!
*therefore GR expression as fetus = adult stress
phenotype
!
Prenatal stress in rodents: lasting effect in offspring
○
High GR expression
!
Lower peak cortisol, quick stress
shutdown
!
Low anxiety behaviour
!
High maternal behaviour
!
F1 offspring:
□
Control (no prenatal stress) --> high maternal
behaviour
!
Low GR expression
!
Hyper-responsive to stress
!
Anxious as adults
!
Low maternal behaviour
!
F1 offspring:
□
Prenatal stress --> low maternal behaviour
!
Early life stress --> mother's stress phenotype --> maternal
behaviour
○
*see stress-induced changes in maternal gut could
negatively impact offspring for life
○
High natal philopatry
!
Ecology well described
!
Maternal behaviour
!
Density = stress
!
Fitness
!
Kluane Red Squirrel Project (Yukon)
○
Early Life Effects:
•
Ecophysiology of Stress:
Behavioural Neuroendocrinology
Wednesday,+ November+ 8,+2017 12:30+PM
