Acute effects of posterior hypothalamic lesions on LHRH release in the stalk-median eminence. Representative examples from prepubertal monkeys before and after hypothalamic lesions (L5, A) or sham lesions (S/C1, B) are shown. Mean LHRH levels during the 6 hours in the morning and 6 hours in the evening of the same lesion animal (L5, C) and sham control (S/C1, D) are also shown. Note that in monkey L5 which received lesions, LHRH levels, especially the evening levels, increased dramatically, whereas LHRH levels in monkey S/C1 were not significantly affected by the sham surgery. Small arrows indicate the LHRH peaks identified by PULSAR analysis.