[Paleopsych] Hormones of the Hypothalamus

[Steve Hovland]

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hypothalamus.html
The hypothalamus is a region of the brain. It secretes a number of 
hormones.
Thyrotropin-releasing hormone (TRH)
Gonadotropin-releasing hormone (GnRH)
Growth hormone-releasing hormone <Hypothalamus.html> (GHRH)
Corticotropin-releasing hormone <Hypothalamus.html> (CRH)
Somatostatin <Hypothalamus.html>
Dopamine <Hypothalamus.html>
All of these are released into the blood, travel immediately to the 
anterior lobe of the pituitary <../P/Pituitary.html>, where they exert 
their effects.
All of them are released in periodic spurts. In fact, replacement hormone 
therapy with these hormones does not work unless the replacements are also 
given in spurts.
Two other hypothalamic hormones:
Antidiuretic hormone <Hypothalamus.html> (ADH) and
Oxytocin <Hypothalamus.html>
travel in neurons <../N/N.html> to the posterior lobe of the pituitary 
where they are released into the circulation.
Link to diagram of the endocrine glands <../E/Endocrines.gif> (92K)	
Thyrotropin-releasing hormone (TRH)
TRH is a tripeptide (GluHisPro).
When it reaches the anterior lobe of the pituitary it stimulates the 
release there of
thyroid-stimulating hormone <../P/Pituitary.html> (TSH)
prolactin <../P/Pituitary.html> (PRL)
Gonadotropin-releasing hormone (GnRH)
GnRH is a peptide of 10 amino acids. Its secretion at the onset of puberty 
triggers sexual development.
Primary Effects	Secondary Effects	
FSH <../P/Pituitary.html> and LH <../P/Pituitary.html> Up 	estrogen and 
progesterone Up (in females)	
	testosterone Up (in males)	

After puberty, a hyposecretion of GnRH may result from
intense physical training
anorexia nervosa
Synthetic agonists <../A/A.html> of GnRH are used to treat
inherited or acquired deficiencies of GnRH secretion.
prostate cancer. In this case, high levels of the GnRH agonist
reduces the number of GnRH receptors in the pituitary, which
reduces its secretion of FSH and LH, which
reduces the secretion of testosterone, which
reduces the stimulation of the cells of the prostate.
Growth hormone-releasing hormone (GHRH)
GHRH is a mixture of two peptides, one containing 40 amino acids, the other 
44.
As its name indicates, GHRH stimulates cells in the anterior lobe of the 
pituitary to secrete growth hormone <../P/Pituitary.html> (GH).
Corticotropin-releasing hormone (CRH)
CRH is a peptide of 41 amino acids.
As its name indicates, its acts on cells in the anterior lobe of the 
pituitary to release adrenocorticotropic hormone <../P/Pituitary.html> 
(ACTH)
CRH is also synthesized by the placenta and seems to determine the duration 
of pregnancy.
Description of the mechanism. <../S/SexHormones.html>	
It may also play a role in keeping the T cells of the mother from mounting 
an immune attack against the fetus. [Discussion 
<../S/Sexual_Reproduction.html>]
Somatostatin
Somatostatin is a mixture of two peptides, one of 14 amino acids, the other 
of 28.
Somatostatin acts on the anterior lobe of the pituitary to
inhibit the release of growth hormone <../P/Pituitary.html> (GH)
inhibit the release of thyroid-stimulating hormone <../P/Pituitary.html> 
(TSH)
Somatostatin is also secreted by cells in the pancreas <../P/Pancreas.html> 
and in the intestine <../G/GutHormones.html> where it inhibits the 
secretion of a variety of other hormones.
Dopamine
Dopamine is a derivative of the amino acid tyrosine <../T/Tyr_phe.gif>. Its 
principal function in the hypothalamus is to inhibit the release of 
prolactin <../P/Pituitary.html> (PRL) from the anterior lobe of the 
pituitary.
Antidiuretic hormone (ADH) and Oxytocin
These peptides are released from the posterior lobe of the pituitary and 
are described in the page devoted to the pituitary.