Prolactin secretion is stimulated by: March 2005

Ans. A: TRH The system of increased production is a positive feedback cycle. This is one of the few instances in the body where positive feedback is normal. Pituitary prolactin secretion is regulated by neuroendocrine neurons in the hypothalamus, the most impoant ones being the neurosecretory tuberoinfundibulum (TIDA) neurons of the arcuate nucleus, which secrete dopamine to act on the dopamine-2 receptors of lactotrophs, causing inhibition of prolactin secretion. Thyrotropin-releasing factor (thyrotropin-releasing hormone) has a stimulatory effect on prolactin release. Vasoactive intestinal peptide and peptide histidine isoleucine also help to regulate prolactin secretion in humans.