Veterinary Physiology-III

GHRH (SOMATOCRININ OR SOMATOTROPIN RELEASING HORMONE)

• GHRH is a hypothalamic peptide hormone containing 44 amino acids.
• It regulates GH release by its intermittent release into the portal pituitary vein.
• Factors that stimulate release of GHRH - estradiol, progesterone, ADH, serotonin, dopamine, a -adrenergics, stress (trauma and fever), deep sleep and exercise.
• Factors that inhibit GHRH release - soma­tomedins, increased levels of glucose and fatty acids, b adrenergics, melatonin and morphines.
• GH exhibits a negative feed back inhibition to GHRH release.
• As a galactopoitic agent GHRH causes 10 to 25 % increase in milk yield, total milk fat, protein and lactose when injected to cow and ewes.