Hypothalamus

Created by kmersch63 

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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

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