PHY3181 Lecture Notes - Lecture 14: Menopause, Melatonin, Olfactory Bulb
30 Jun 2018
School
Department
Course
Professor
Lecture 21: environmental control of
reproduction
Lecture summary
• Pheromones are chemicals that
animals sense – these may be
important in hums – thought to be
involved in the bond following birth
• Seasonality and daylength:
photoperiod
• Role of estrogen feedback: in seasonal
breeding – the effects of estrogen
negative feedback are vital the
brain becomes highly sensitised to
estrogen
• Neural pathways including kisspeptin
and GnIH
• Day length is important for seasonal
breeders
*************************************
Brain pathways associated with steroid
feedback
• Negative feedback can be mediated
by: kisspeptin – the KnDY cells in the
ARC
• GnIH
• NPY: important in controlling body
weight – also a negative regulator of
reproduction
In any state of undernutrition – body weight
will go down, NPY will increase massively is
the most potent appetite stimulator that we
have to try and restore body weight
• Positive feedback can be mediated by
NA (released by Dopamine beta
hydroxylase cells) and kisspeptin
Summary of kisspeptin
• KnDY cells (arcuate) mediate both
positive and negative feedback
• KISS cells (POA) mediate positive
feedback onlu
• KnDY cells initiate positive feedback
and this effect is facilitated by KISS
cells in the ARC
• KnDY do not project directly to the
GnRH cells
• Effect are indirect either through Kiss-
Kiss or Kiss-? Interaction
• KnDY cells project to the median
eminence but kisspeptin is NOT
secreted into the hypophyseal portal
blood
• Kisspeptin modulate GnRH release at
terminals
Kisspeptin and GnIH are also important in
mediating the effects of season (photoperiod)
and pheromones on reproductive function
*************************************
Pheromones – effect of introduction of an
ewe on the plasma LH levels in rams
• Animals were treated with
testosterone to inhibit their
reproductive axis
• In the presence of an estrous ewe:
increase in LH immediately
(reproductive axis was activated)
• This effect was driven by pheromones
Pheromone – a chemical substance that
affects the behaviour of another animal
Releaser pheromone – they elicit an
immediate response, the response is rapid and
reliable. They are usually linked to sexual
attraction
Primer pheromones – these take longer to get
a response. They can, for example, influence
the development or reproduction physiology,
including menstrual cycles in females, puberty,
and the success or failure of pregnancy. They
can alter hormone levels. In some mammals,
scientists found that females who has become
pregnant and were exposed to primer
pheromones from another male would
spontaneously abort the fetus (these cause
long term reproductive changes)
Document Summary
Gnrh cells: effect are indirect either through kiss- Interaction: kndy cells project to the median eminence but kisspeptin is not secreted into the hypophyseal portal blood, kisspeptin modulate gnrh release at terminals. Kisspeptin and gnih are also important in mediating the effects of season (photoperiod) and pheromones on reproductive function: day length is important for seasonal breeders. Brain pathways associated with steroid feedback: negative feedback can be mediated by: kisspeptin the kndy cells in the. Arc: gnih, npy: important in controlling body weight also a negative regulator of reproduction. Pheromones effect of introduction of an ewe on the plasma lh levels in rams: animals were testosterone reproductive axis to treated inhibit with their. In the presence of an estrous ewe: increase immediately (reproductive axis was activated) Lh in: this effect was driven by pheromones. Pheromone a chemical substance that affects the behaviour of another animal.
