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Lecture 12

Psychology 2220A/B Lecture Notes - Lecture 12: Gonad, Dihydrotestosterone, B Cell

Course Code
Scott Mac Dougall- Shackleton

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• Hormones and Behaviour
– Endocrine System
– Classes of Hormones
– Control of Hormones
– Sexual Differentiation
Aromitization and Neural Sex Differences
– Levels of Sexual Determination
– Hormones and Stress
• “Secretory blood-borne product”
• Internal chemical messengers
An organic chemical messenger released from endocrine cells that travels through the blood
system to interact with cells at some distance away and causes a biological response
• Molecules that have effects on cells (like NT)
• Can have effects on distant tissues due to blood transportation
• Important parts: Chemical messenger, travels through blood*, endogenous compound, released
from endocrine cells*, interact with target cells at some distance away *
Endocrine Glands
• Ductless glands
• Exocrine glands have ducts
– E.g. sweat glands, mammary glands, scent glands
Chemical Communication
• Endocrine
– Secreting cell --> Blood vessel --> Target cell
Target Cells
• Hormones require receptors to have actions
Endocrine vs. Nervous
Released from endocrine gland
Released from presynaptic neuron
Travels through blood
Travels across synaptic cleft
Received at distant target organ
Received at postsynaptic neuron
Psych 2220A Lecture 12
• Released from neurons (neurosecretory cells)
• Travel through blood
• Received at distant target organ
• Not hormones; not produced by an endocrine gland. Produced by neurosecretory cells
Chemical messengers
• Hormones
• Neurohormones
• Neurotransmitters
• The same molecule may act as more than one type, depending on nature of secretory cell
Adrenaline aka epinephrine; released by the adrenal medulla
Hormone Action
• Hormone action via 2 main processes
• Water soluble hormones (e.g. peptides)
– Cannot cross cell membranes on their own; bind to receptors on the external part of the cells
• Fat soluble hormones (e.g. steroids)
– Liophilic; trouble getting transported in blood plasma. No problem going through cell
Water Soluble Hormones
• Cannot cross cell membranes
• Bind to membrane receptors
• Initiate 2nd messenger system within cell
– Pretty much like a neurotransmitter binding to a metabotropic receptor!
Fat Soluble Hormones
• E.g. steroid hormones
• Freely cross cell membrane
• Bind to intracellular receptors
• Steroid-receptor complex modifies cell
Act as transcription factors (change gene transcription)
• Need protein to help dissolve so they can go through the blood; at the target tissue they can go
through. Float in cytoplasm waiting to bind to receptor. Steroid and receptor bind to form
complex (acts as transcription factor). Enter cell and bind to promotor regions to effect the
transcription of genes
Hormones and Behaviour
• How can hormones affect behaviour?
• Hormone receptors found on – effector organs (e.g. muscles)
– Sensory organs
– The central nervous system!
• Main target for most hormones are the brain. Hormones MODIFY how the nervous system is
Psych 2220A Lecture 12
working (neuromodulator)
• Hormones modulate behaviour by affecting how the nervous system works *
• Hormones do not directly cause a behaviour
• For a behavior to occur you need a functioning CNS leading to a potential change in behavior
• Hormones change the probability or intensity of a behaviour in the appropriate context
• How can hormones affect behaviour?
1 - Development long term effects (organizational effects)
2 - Short term change in adulthood (activational effects) --> Activate behavior happening now
Organizational effects
• Example: urinary posture in dogs
• Sex difference in posture (male lifts leg)
Adult castration does not make male urinate like female
– Early testosterone treatment induces females to urinate like males
• Hormone effects during early stage of development. Later in the life the hormone doesn't need
to be there as the change has already taken place. Eventually don't "need" the hormones around
• Hormones can alter the development of the nervous system, effector organs, and sensory
system *
Activational Effects
• Short term changes in behaviour
• Neurons can have hormone receptors
• Hormones induce change in activity of nervous system
– Mammals: suckling leads to oxytocin release which leads to milk letdown (released from the
pituitary gland)
– Stress response, stress hormones released in minutes
• Rodents: sexual behavior is hormone dependent. Male won't mount female unless he has
circulating testosterone. To exhibit behavior he needs to be exposed to testosterone in early
development. Treat female with testosterone? She won't mount. BOTH activational and
Classes of Hormones
• Peptide/ protein hormones
– Direct product of gene transcription. Water soluble (growth hormone, comes through
expression of gene)
• Steroid hormones
– Lipid soluble; derivative of cholesterol. Gene for enzyme to take cholesterol to testosterone, no
gene for testosterone
• Monoamines
• Lipid-based hormones (but don’t affect behaviour directly in vertebrates
• Usually only one class produced by any given gland *
Psych 2220A Lecture 12