Abstract
The rhythmic pulsatile nature of gonadotropic hormone section first noted in the ovariectomized rhesus monkey (Dierschke et al., 1970) has since been described in every mammal studied in this regard (Pohl and Knobil, 1982). The original supposition that each gonadotropin pulse is the consequence of a pulse of GnRH released by the hypothalamus into the pituitary portal circulation has been amply confirmed (Carmel et al., 1976; Clarke and Cummins, 1982). These findings have given rise to the concept of a neuronal construct in the central nervous system which is responsible for the rhythmic activation of GnRH cells and the release of the neuropeptide from their terminals. While this system has been variously referred to as an oscillator or pulse generator for descriptive convenience, its cellular nature remains unknown. In the rhesus monkey, using conventional neuroendocrinological techniques, the pulse generator has been localized to the mediobasal hypothalamus (MBH) (Krey et al., 1975), and more specifically, to the area of the arcuate nucleus (Plant et al., 1978). An effort to detect the electrophysical basis of pulse generator activity was initiated in the late 1970’s and was based on the supposition that each bolus of GnRH released into the pituitary portal circulation must be the consequence of the synchronous firing of a large number of GnRH cells and that the approach most likely to detect their action potentials was the application of multiunit recording techniques as utilized earlier for the study of the macrocellular system in the rhesus monkey by Hayward and his colleagues (Hayward, 1977). Our initial approach utilizing single tungsten electrodes acutely placed in the region of the arcuate nucleus of anesthetized rhesus monkeys, while largely unsuccessful, occasionally yielded evidence of astonishing increases in multiunit electrical activity (MUA) coupled with pulses of LH as measured in the peripheral circulation (Dufy et al., 1979; Knobil, 1981). We assumed that the rarity of successful electrode placements were attributable to the sparsity of the active units in the hypothalamus and changed our strategy to the stereotaxic bilateral implantation of chronic multiple electrode arrays which blanketed the MBH (Wilson et al., 1984). This new approach yielded predictable results from one or more electrodes in most animals and permitted the systematic study of the pulse generator by direct, electrophysiological observation.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Carmel, P. W., Araki, S., and Ferin, M., 1976, Pituitary stalk portal blood collection in rhesus monkeys: evidence for pulsatile release of GnRH, Endocrinology, 99:243.
Clarke, I. J., and Cummins, J. T., 1982, The temporal relationship between gonadotropic releasing hormone (GnRH) and luteinizing hormone (LH) secretion in ovariectomized ewes, Endocrinology, 11:1737.
Dierschke, D. J., Bhattacharya, A. N., Atkinson, L. E., and Knobil, E., 1970, Circhoral oscillations of plasma LH levels in the ovariectomized rhesus monkey, Endocrinology, 87:850.
Dufy, B., Dufy-Barbe, L., Vincent, J. D., and Knobil, E., 1979, Etude electrophysiologique des. neurones hypothalamiques et regulation gonadotrope chez le singe rhesus, Journal de Physiologie, 75:105.
Hayward, J. N., 1977, Functional and morphological aspects of hypothalamic neurons, Physiol. Rev., 57:574.
Kaufman, J. M., Kesner, J. S., Wilson, R. C., and Knobil, E., 1985, Electro-physiologic manifestation of “LHRH pulse generator” activity in the rhesus monkey: influence of α-adrenergic and dopaminergic blocking agents, Endocrinology, 1164:1327.
Kesner, J. S., Kaufman, J. M., Wilson, R. C., Kuroda, G., and Knobil, E., 1986a, The effect of morphine on the electrophysiological activity of the hypothalamic luteinizing hormone releasing hormone pulse generator in the rhesus monkey, Neuroendocrinology, 43:686.
Kesner, J. S., Kaufman, J. M., Wilson, R. C., and Knobil, E., 1986b, On the short-loop feedback regulation of the hypothalamic luteinizing hormone releasing hormone “pulse generator” in the rhesus monkey, Neuroendocrinology, 42:109.
Kesner, J. S., Wilson, R. C., Kaufman, J. M., Hotchkiss, J., and Knobil, E., 1986c, Unphysiological responses of the LHRH pulse generator to physiological estrogen inputs in the absence of the ovary, Proc. Ann. Mtg. Endocrine Soc., Abstract.
Knobil, E., 1981, Patterns of hypophysiotropic signals and gonadotropin secretion in the rhesus monkey, Biol. Reprod., 24:44.
Krey, L. C., Butler, W. R., and Knobil, E., 1975, Surgical disconnection of the medial basal hypothalamus and pituitary function in the rhesus monkey. I. Gonadotropin secretion, Endocrinology, 96:1073.
Plant, T. M., and Krey, L. C., Moossy, J., McCormack, J. T., Hess, D. L., and Knobil, E., 1978, The arcuate nucleus and the control of gonadotropin and prolactin secretion in the female rhesus monkey (Macaca mulatta), Endocrinology, 102:52.
Pohl, C. R., and Knobil, E., 1982, The role of the central nervous system in the control of ovarian function in higher primates, Ann. Rev. Physiol., 44:583.
Silverman, A. J., Antunes, J. L., Abrams, G. M., Nilaver, G., Thau, R., Robinson, J. A., Ferin, M., Krey, L. C., 1982, The luteinizing hormone-releasing hormone pathways in rhesus (Macaca mulatta) and pigtailed (Macaca nemestrina) monkeys: new observations on thick unembedded sections, J. Comp. Neurol., 211:309.
Silverman, A. J., Wilson, R. C., Kesner, J. S., and Knobil, E., Hypothalamic localization of multiunit electrical activity associated with pulsatile LH release in the rhesus monkey, Neuroendocrinology, in press.
Van Vugt, D. A., Bakst, G., Dyrenfurth, I., and Ferin, M., 1983, Naloxone stimulation of luteinizing hormone secretion in the female monkey: influence of endocrine and experimental conditions, Endocrinology, 113:1858.
Veldhuis, J. D., Rogol, A. D., Samojlik, E., and Ertel, N. H., 1984, Role of endogenous opiates in the expression of negative feedback actions of estrogens and androgens on pulsatile properties of luteinizing hormone secretion in man, J. Clin. Invest., 74:47.
Wilson, R. C., Kesner, J. S., Kaufman, J. M., Uemura, T., Akema, T., and Knobil, E., 1984, Central electrophysiologic correlates of luteinizing hormone secretion in the rhesus monkey, Neuroendocrinology, 39:256.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1987 Springer Science+Business Media New York
About this chapter
Cite this chapter
Knobil, E. (1987). The Electrophysiology of the Hypothalamic Gonadotropic Hormone Releasing Hormone (GnRH) Pulse Generator in the Rhesus Monkey. In: Leung, P.C.K., Armstrong, D.T., Ruf, K.B., Moger, W.H., Friesen, H.G. (eds) Endocrinology and Physiology of Reproduction. Springer, Boston, MA. https://doi.org/10.1007/978-1-4899-1971-7_3
Download citation
DOI: https://doi.org/10.1007/978-1-4899-1971-7_3
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4899-1973-1
Online ISBN: 978-1-4899-1971-7
eBook Packages: Springer Book Archive