Abstract
Summary
Responsiveness to synthetic LHRH, as measured by increments in plasma LH following its sc injection, was evaluated in castrated rats with median eminence lesions and compared to that in sham-operated controls and controls with intact brains. Median eminence lesions in castrates were followed by a decline in plasma LH to approximately 30% of control values at 1, 7, and 14 days postlesions. This was associated with an increase in responsiveness to LHRH at 1 day, followed by a return to normal responsiveness at 7 and 14 days postlesions. Even though plasma LH was lowered in the animals with lesions, pituitary LH was little changed, which indicates that these lesions, although effective to inhibit LH release, were probably incomplete.
It is concluded that LH release is inhibited by lesions in the median eminence in the face of normal or even increased responsiveness to LHRH. The cause of the increased responsiveness to LHRH which appeared at 1 day after lesions remains to be elucidated.
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