PHY3181 Lecture Notes - Lecture 15: Hypophyseal Portal System, Hyperactivation, Granulosa Cell
30 Jun 2018
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Lecture 19: Stress and reproduction
GnRH is modulated by the effects of stress on
the HPG axis
Stress is defined as a state of threatened or
perceived as threated homeostasis (anything
that threatens the bodies sense of balance).
• Physiological – nutritional deficiency
(starvation), osmotic challenge
(dehydration, increases ions in the
ECF)
• Psychological – phobias, post-
traumatic stress
• Environmental – thermal, oxidative
stress (exposure to UV light)
Cortex hippocampus = pre-frontal cortex
• Both acute and chronic
• Slower, less visceral
• Activation of the HPA axis release of
cortisol
• Cortisol and other corticosteroids are
released eg glucocorticoids (note that
what is released is species specific)
• This is the intellectual response to
stress
Amygdala (basal alteral nucleus) – processes
fear and anxiety
• Short term response
• The release of adrenaline from the
adrenal gland
o Vasoconstriction
o Increase in HR
Neuroendocrine effectors to stress
Corticotropin releasing hormone (CRH) from
the parvocellular paraventricular nucleus
ACTH in the anterior pituitary cortisol in the
adrenal cortex is released into the circulation
(cortisol is a stress hormone)
CRH and arginine-vasopressin (AVP) from
parvocellular paraventricular nucleus
activation of locus coeruleus and
noradrenergic cell groups in the pons and
medulla adrenaline in the adrenal medulla
(this is the flight and flight response and the
HPA axis are both activated)
• The parvocellular nucleus projects to
the arcuate nucleus to release
hormones into the AP
• Also to the locus coeruleus
activated the sympathetic outflow
AVP and oxytocin (OXY) from the parvocellular
paraventricular nucleus, co-localised with CRH
released into hypophyseal-portal system to
enhance the secretagogue property of CRH
• Vasopressin and oxytocin from the
posterior pituitary to enhance the
properties of CRH – can enhance
secretion and action
The paraventricular nucleus (PVN) in the
hypothalamus – the key region in the brain
that regulates the stress response
• Extensive connections in the
hypothalamus and brain stem (this is
where the fight or flight response is
triggered) – also projections to the AP
and PP to regulate hormones
responsible for metabolism
• Role is autonomic control in the
regulation of metabolism, growth,
reproduction and other autonomic
functions
The paraventricular nucleus is divided into two
• Mangocellular – synthesis AVP and
oxytocin for release in the PP (AVP =
antidiuretic vasoconstrictor peptide),
Document Summary
Gnrh is modulated by the effects of stress on the hpg axis. Stress is defined as a state of threatened or perceived as threated homeostasis (anything that threatens the bodies sense of balance): physiological nutritional deficiency (starvation), challenge (dehydration, increases ions in the. Ecf) osmotic: psychological traumatic stress phobias, post, environmental thermal, oxidative stress (exposure to uv light) Amygdala (basal alteral nucleus) processes fear and anxiety: short term response, the release of adrenaline from the adrenal gland, vasoconstriction. Corticotropin releasing hormone (crh) from the parvocellular paraventricular nucleus . Acth in the anterior pituitary cortisol in the adrenal cortex is released into the circulation (cortisol is a stress hormone) of. Crh and arginine-vasopressin (avp) from parvocellular paraventricular nucleus activation and noradrenergic cell groups in the pons and medulla adrenaline in the adrenal medulla (this is the flight and flight response and the.
