A SEXUALLY DIMORPHIC POPULATION OF CRF NEURONS IN THE MEDIAL PREOPTICAREA

THE neuropeptide corticotropin-releasing factor (CRF) is thought to me diate the induction of a constellation of behavioral, endocrine, and a utonomic responses which are important for an animal's adaption to str essful events. We have found that the anteroventral periventricular pr eoptic nucleus (AVPv) and medial preoptic nucleus (MPN) of colchicine- injected female rats contained numerous intensely stained CRF-immunore active neurons. The AVPv/MPN in males contained very few CRF-immunorea ctive neurons per section, even in colchicine-injected animals. This s exually dimorphic population of CRF-immunoreactive neurons in the AVPv may play some role in the sex-related differences in hormonal respons es to stress and/or in the control of female reproductive events.