Brain Control of the Reproductive System

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The purpose of the present research group is to elucidate the location of the pulse generator, which is thought to regulate the pulsatile release of luteinizing hormone (LH) through the pulsatile LH releasing homone (LHRH) release, in the hypothalamus and to make clear the regulatory mechanism of the pulse generator. That oxytocin is released in a pulsatile manner in spite of the continous stimulus to the teat by pups has been well established. Therefore, a search for the location of the LHRH pulse generator is also one of the purposes of this research group.The presence of the LH pulse generator in the medial basal hypothalamus (MBH) in rats and shiba goats has been demonstrated by the following experiments : 1) Complete deafferentation of the hypothalamus in the rat ; 2) Transplantation of the fetal median eminence (EM) into the adult female rat in which the pulsatile LH secretion was blocked by electrolytic lesions made in the anterior part of the arculate nucleus in rats ; 3) In vi … More tro intra-arterial perfusion of the rat's hypothalamus ; 4) Multiple unit activities (MUA) recording from the arcuate nucleus in shiba goats. An attempt was made to record the single unit activity from the LHRH cell projecting its axon to the ME.However, the activity was recorded only from a small number of cells and we can not tell whether the LHRH cells themselves generates the pulsatility. Burst discharges of OT cells in the supra optic and paraventricular nuclei were recorded intermittently in the rat suckled continously by pups.We found several neurones fired synchronously with OT cells in the dorsomedial hypothalamic nucleus. Although these neurones send axons to the supra optic nucleus, no projection of these cells to the posterior lobe of the pituitary is found. Therefore, the possibility exists that these cells transform the continuous impulse emanating from the teat to the intermittent information causing the pulsatile secretion of OT. Relationship between these cells and the LHRH pulse generator is remained unsolved. Less