The effect of surgical isolation or ablation of the medial basal hypothalamus on serum prolactin levels in male rats.

Complete isolation of ablation of the medial basal hypothalamus (MBH) was performed in adult male rats, and non-stress prolactin levels were measured by radioimmunoassay in blood collected by decapitation at 24h, 2 weeks and 6 weeks following surgery. 24 h after surgery, medial hypothalamic ablation (MHA) markedly elevated prolactin levels compared to those of intact control rats; prolactin levels subsequently declined to normal resting values 2 to 6 weeks following surgery. Circulating prolactin levels following hypothalamic isolation were not different from those of controls at either acute or chronic sampling intervals. These data suggest that chronic isolation or destruction of the MBH does not alter basal prolactin secretion in male rats, provided that circadian and stress-induced variations in control animals are properly considered.