Serum levels of prolactin, LH and LH-RH after ablation of the medial basal hypothalamus.

4 weeks after surgical ablation (MHA) of the medial basal hypothalamus (MBH) in adult male rats, serum levels of prolactin, LH, and LH-RH were determined by radioimmunoassay. Blood samples were obtained by jugular venipuncture under ether anesthesia (designated 'stress' samples) and 30 min after the ether stress by rapid decapitation (designated 'resting samples). 30 min after ether, serum levels of prolactin, LH, and LH-RH in MHA rats were comparable to those of intact and sham-operated controls. Among intact and sham-operated rats, ether elicited an initial increased in prolactin but not in LH or LH-RH. In the MHA group, prolactin levels were also acutely increased, although the increment was not as great as in control groups. The data indicate that considerable basal prolactin and LH secretion persists after MHA, and that this continued secretion may be regulated by neurohoromones such as LH-RH which arise from areas outside the MBH.