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34 terms

Hypothalamus

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Hypthalamic Input
every area of the brain, CSF through tanycytes, through the blood (systemic circulation), cold TRH, diet GHRH, BP
Monoamine Neurotransmitters Derived from Amino Acids
Dopamine, Norepinephrine, Serotonin, Histamine, Epinephrine, Acetylcholine
Amino Acid Neurotransmitters (Hypothalamus)
GABA, Glycine, Glutamic Acid
Where does Hypothalamic Output towards the Adenohypophysis Start
Arcuate Nuclei and Paraventricular Nucleus, where tuberoinfundibular tracts start with parvicellular neurons
Where does Hypothalmic Output towareds the PP Start
magnocellular in SON and PVN, then to PP where it connects with inferior hypophysial artery
Long Loop Feedback
Ultimate target tissues( e.g. goand or thyroid) feedback on pituitary, hypothalamus or CNS
Short Loop Feedback
hormones from pituitary feedback on the hypothalamus
Autoinhibition
Hormones from the pituitary feed back on the pituitary
Negative Regulator of TRH
T4, T3, TSH
Negative Regulator of GHRH
GH, IGF, hypothalmic SST
Negative Regulator of Prolactin
Dopamine
Negative Regulator of GnRH
sex steroids (gonads)
Negative Regulator of CRH
Cortisol (adrenals)
GHRH is expressed where?
Arcuate and Ventromedial nuclei
What sitmulates GH release?
Ghrelin
Where is Ghrelin expressed and What does it do?
Expressed in stomach, small intestine and a few hypothalamic neurons. In addition to GH stimulation Ghrelin also regulates feeding behavior and fat cell activity.
SST regulation
GH and IGF-1 can activate hypothalamic SST expression to negatively regualte GH in a negative feedback loop
SST affects which tissues
brain, endocrine and exocrine pancreas, gastrointestinal tract, pituitary (SST secreting cells)
What does SST inhibit?
TSH, GH release
GnRH is secreted from?
Arcuate Nucleus
PRL secretion increases from
TRH, VIP, GNrH, and oxytocin increase PRL no releasing hormone found yet
What is PIF?, Where from?
Dopamine, arcuate nuclei, cheif inhibitor of PRL release
Control of PIF
seretonin is an inhibitor of dominergic neurons, when they are active the can inhibit DA release cuasing PRL release
Seretonin can be inhibited by
SSRI (Prozac)
Hyperprolactinemia: Sx and cure
breast milk production despite not being pregnant, Bromocriptine- DA agonist
GnRH is released in pulses
less frequent pulses lead to higher relative FSH release, Preferential release due to different FSH and LH gene expression rates, overall higher LH
GnRH is complex
DA from hypothalamic neurons stimulate GnRH, Met-enkephalin inhibts DA, Labled estrogen accumulates in Hypothalamic neurons that secrete GnRH
What regulates ACTH
CRH (AVP also does to some extent)
Where is the Corticotropin Releasing Hormone expressed?
Paraventricular Nucleus, expressed in parvicellular neurons in the PVN
Contol of CRH secretion
Atropine (acetycholine receptor antagonist) inhibits CRH
Glucocorticoids negitely regulate
CRH
As stress increases...
more POMC and ACTH secretion, stress induced catecholamine (epi and Nepi), Catecholamines from axons innervating the PVN axons induce CRH secretion
Mech. of Action of Releasing Hormones
all of them use PLC to increase calcium and cuase ion gating that elicitys ap's in the target cells. exception is GHRH and SST which regualate AC-cAMP
Perfusion Chamber
Technique for analyzing the effects of a hypothalamic hormone on a culture of pituitary cells