Advis, Juan P
Juan P. Advis
Department of Animal Sciences
School of Environmental & Biological Sciences
New Brunswick, NJ 08903
Hypothalamic regulation of luteinizing hormone. reproduction physiology
To assess if the hypothalamic median eminence (ME) is a neuroendocrine control site where final hypophysiotropic release leading to the preovulatory surge of Luteinizing Hormone (LH), an obligatory event for reproduction to occur, might be ultimately regulated. We have used two animal models for these studies: hens, showing daily LH preovulatory surges for 15-25 days and ewes, showing an LH preovulatory surge at the end of each follicular phase in a 16-day estrous cycle. In our studies, we have concentrated in assessing the hypothalamic control of LHRH by three of its ME putative inputs: -endorphin (END), dopamine (DA), and neuropeptide Y (NPY). Through our immunocytochemical studies we mapped the hypothalamic distribution of LHRH and these three ME putative inputs, in hens and ewes. On the other hand, in our release studies, we used in vitro incubations of ME tissue and push-pull cannula (PPC) sampling of in vivo neuropeptide release from discrete areas of the ME. In addition to our release studies, we assessed the possibility that enzymatic degradation of LHRH in the ME might be a regulated event of some physiological significance. Furthermore, we recently determined steady-state levels of mRNA and expression of c-fos antigens, in some of these putative inputs to ME-LHRH neuronal terminals. In addition, we have developed an extremely sensitive capillary electrophoresis-based assay, that uses fluorescence microscopy detection of derivatized samples, for the determination of multiple neuropeptides in ME-PPC perfusate samples.