Intrahypothalamic Localization of the Nuclei Synthesizing the Gonadotropin Releasing Factors

Effect of Pentobarbital on Serum Levels of LH, FSH and Prolactin in Long-Term Ovariectomized Rats

“…A lack of effect of this barbiturate on FSH release has also been reported by Ajika et al [1972], These authors observed that pentobar bital did not inhibit the increase of FSH secretion induced, in castrated female rats, by ether anesthesia and bleeding. The differential effect of pento barbital on LH and FSH release in castrated female rats, reinforces the hypothesis that the mechanisms controlling the secretion of the 2 gonado tropins may be basically different [Motta et al, 1971;Kalra et al, 1971; N eill and Butcher et a!., 1975;Zanisi and M artini, 1975a, b;Barraclough, 1976a, b, 1977], In the present experiments serum Prl showed a biphasic pattern following pentobarbital treatment, being significantly depressed at 3 and 6 h and again at 48 h. In line with these observations, Ajika et al [1972] have found that castrated female rats given pentobarbital have circulating levels of Prl sig nificantly lower than controls 1-5 h but not 24 h after treatment. Unfortu nately, these authors did not prolong their observations, to check whether at 48 h there was a new fall of serum Prl.…”

Neurosecretory Activity within Suprachiasmatic Neurons of the Female Rabbit Following Castration

“…In conclusion, we feel that these observations serve as discrete morpho logical evidence for the view that at least some of the neurosecretory neurons which secrete LH-releasing hormone (LH-RH) have their soma within the SCH region of the mammal [Tejasen and Everett, 1967;C richton and Schneider, 1969;Motta et a!., 1971], Since the times at which the Type II neurons were observed correlate favorably with known times of LH surges following castration in other mammals, our findings strongly suggest ultrastructural changes associated with the synthesis of the RHs that control gonadotropic activity in the female rabbit. Recently.…”

“…Identical changes were evident, however, within only 19.2 and 31.5% of the neurons closely related spatially to capillaries of the PO and SCH nuclei, respectively, of the female rabbit following coitus [C la tten bu rg et al, 1971, 1972], In the present study, morphological signs of enhanced synthetic activity were evident within a maximum of 15.8% (table I) of all SCH neurons. Whether or not these findings reflect different neuronal responses to the functions previously assigned to these hypothala mic nuclei, e.g., the synthesis of dopamine (DA) and/or the releasing hor mones within arcuate neurons [Zambrano and D e R o bertis, 1968] and GRHs within neurons of the more anterior hypothalamus Motta et al. 1971;C latten bu rg et al, 1971; M o gu ilevsky and C h risto t, 1972], can only be placed in the realm of speculation at the present time.…”

Further Evidence on the Intrahypothalamic Locus for Androgenization of Female Rats

“…Although the arcuate nucleus is a likely prospect because of its suspected role in the regu lation of releasing hormone activity [Flament-D urand and Desclin, 1970;M on a et at., 1971], contiguous stuctures such as the median eminence [Harris, 1955] and the ependymal cells lining the third ventricle [Bleier, 1972] warrant consideration because they have been similarly implicated in related functions.…”