Stimulatory role for medial preoptic/anterior hypothalamic area neurones in growth hormone and prolactin secretion. A kainic acid study.

The role of preoptic/anterior hypothalamic area (PO/AHA) neurones in the regulation of basal patterns of growth hormone (GH) and prolactin (Prl) secretion was investigated in unanesthetized male rats prepared with chronic indwelling venous cannulae. PO/AHA injections of the neurotoxin kainic acid (KA) substantially reduced both GH and Prl secretion. Histological examination of tissue sections indicated that KA treatment had produced extensive neuronal loss and gliosis in the medial (m) but not the periventricular (p) PO/AHA. These findings suggest that m-PO/AHA neurones are facilitatory to the basal secretion of both GH and Prl. It is proposed that GH-facilitatory m-PO/AHA neurones provide an inhibitory input to the GH release-inhibiting factor neurones which are known to reside in the p-PO/AHA. Prl-facilitatory m-PO/AHA neurones may secrete, or stimulate the secretion of a Prl releasing factor.