A subset of gonadotropin-releasing hormone neurons in the ovine medial basal hypothalamus is activated during increased pulsatile luteinizing hormone secretion.

GnRH neurons active in the preovulatory LH surge have been identified in several species using the early intermediate gene product, Fos, but the GnRH neurons active during episodic LH secretion remain unknown. In this study, we have used Fos and Fos-related antigens (FRA) to determine whether a subset of GnRH neurons is active when pulsatile LH secretion is acutely stimulated in sheep. In experiment 1, episodic LH secretion was stimulated in five of six ewes by injection of an opioid antagonist to luteal phase ewes. These five ewes had a 6-fold increase in the percentage of GnRH neurons in the medial basal hypothalamus (MBH) expressing Fos/FRA, compared with control ewes that had no LH pulses before death. Fos/FRA expression was not increased in GnRH neurons found in any other area. In experiment 2, episodic LH secretion was induced in rams by introduction of estrous ewes. This treatment increased Fos/FRA expression in MBH GnRH neurons approximately 10-fold compared with control rams. Again, this increase in Fos/FRA expression in GnRH neurons was limited to the MBH. This selective activation of MBH GnRH neurons could reflect the preferential inhibition of these perikarya by endogenous opioid peptides. It also raises the possibility that a subset of GnRH neurons in the MBH may be responsible for episodic GnRH secretion in sheep.

[1]  K. Mogi,et al.  Pulsatile release of luteinizing hormone-releasing hormone (LHRH) in cultured LHRH neurons derived from the embryonic olfactory placode of the rhesus monkey. , 1999, Endocrinology.

[2]  S. Moenter,et al.  Gonadotropin-releasing hormone requirements for ovulation. , 1997, Biology of reproduction.

[3]  T. Funabashi,et al.  Fos Expression by Naloxone in LHRH Neurons ofthe Mediobasal Hypothalamus and Effects of Pentobarbital Sodium in the Proestrous Rat , 1997, Journal of neuroendocrinology.

[4]  M. Lehman,et al.  Regional differences in the distribution of gonadotropin-releasing hormone cells between rapidly growing and growth-restricted prepubertal female sheep. , 1997, Endocrinology.

[5]  J. Witkin,et al.  FOS expression in the gonadotropin-releasing hormone (GnRH) neuron does not increase during the ovarian steroid-induced GnRH surge in the rhesus monkey. , 1994, Endocrinology.

[6]  H. Jansen,et al.  Is Fos expression in GnRH and other neurons during the estradiol-induced LH surge of the ewe associated with neurosecretory or behavioral events? , 1994 .

[7]  R. Goodman,et al.  Effect of anterior hypothalamic deafferentation on the negative feedback of gonadal steroids on luteinizing hormone pulse frequency in the ewe. , 1994, Domestic animal endocrinology.

[8]  M. Lehman,et al.  Fos expression during the estradiol-induced gonadotropin-releasing hormone (GnRH) surge of the ewe: induction in GnRH and other neurons. , 1993, Endocrinology.

[9]  Y. Mori,et al.  Opioid peptidergic control of gonadotropin-releasing hormone pulse generator activity in the ovariectomized goat. , 1993, Neuroendocrinology.

[10]  J. Blaustein,et al.  Expression of Fos-like proteins in gonadotropin-releasing hormone neurons of Syrian hamsters: effects of estrous cycles and metabolic fuels. , 1992, Endocrinology.

[11]  A. Silverman,et al.  FOS expression in gonadotropin-releasing hormone neurons: enhancement by steroid treatment and mating. , 1992, Endocrinology.

[12]  B. Rubin,et al.  Sex difference in the effect of mating on c-fos expression in luteinizing hormone-releasing hormone neurons of the ferret forebrain. , 1992, Endocrinology.

[13]  M. Smith,et al.  Detecting steroidal effects on immediate early gene expression in the hypothalamus , 1992 .

[14]  W. Wetsel,et al.  Intrinsic pulsatile secretory activity of immortalized luteinizing hormone-releasing hormone-secreting neurons. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[15]  R. Wood,et al.  GnRH neurons in the fetal lamb hypothalamus are similar in males and females. , 1992, Neuroendocrinology.

[16]  D. Lunstra,et al.  Effects of sexual experience, season, and mating stimuli on endocrine concentrations in the adult ram , 1992, Hormones and Behavior.

[17]  S. Moenter,et al.  Pattern of gonadotropin-releasing hormone (GnRH) secretion leading up to ovulation in the ewe: existence of a preovulatory GnRH surge. , 1991, Endocrinology.

[18]  R. Goodman,et al.  Endogenous opioid suppression of luteinizing hormone pulse frequency and amplitude in the ewe: hypothalamic sites of action. , 1991, Neuroendocrinology.

[19]  H. Hiruma,et al.  Naloxone increases the frequency of the electrical activity of luteinizing hormone-releasing hormone pulse generator in long-term ovariectomized rats. , 1991, Neuroendocrinology.

[20]  P. Orgeur,et al.  Female effect in sheep. I. The effects of sexual receptivity of females and the sexual experience of rams. , 1991, Reproduction, nutrition, development.

[21]  P. Malven,et al.  Intracerebral immunoneutralization of beta-endorphin and met-enkephalin disinhibits release of pituitary luteinizing hormone in sheep. , 1990, Neuroendocrinology.

[22]  P. Goldsmith,et al.  Location of the Neuroendocrine Gonadotropin‐Releasing Hormone Neurons in the Monkey Hypothalamus by Retrograde Tracing and Immunostaining * , ** , 1990, Journal of neuroendocrinology.

[23]  T. Bliss,et al.  Differential expression of immediate early genes in the hippocampus and spinal cord , 1990, Neuron.

[24]  W. S. Lee,et al.  Luteinizing hormone-releasing hormone neurons express c-fos antigen after steroid activation. , 1990, Endocrinology.

[25]  James I. Morgan,et al.  Stimulus-transcription coupling in neurons: role of cellular immediate-early genes , 1989, Trends in Neurosciences.

[26]  W. P. Chen,et al.  Beta‐endorphin and gonadotropin‐releasing hormone synaptic input to gonadotropin‐releasing hormone neurosecretory cells in the male rat , 1989, The Journal of comparative neurology.

[27]  R. Goodman,et al.  Effects of an opioid antagonist on pulsatile luteinizing hormone secretion in the ewe vary with changes in steroid negative feedback. , 1988, Biology of reproduction.

[28]  M. Lehman,et al.  Ultrastructure and synaptic organization of luteinizing hormone‐releasing hormone (LHRH) neurons in the anestrous ewe , 1988, The Journal of comparative neurology.

[29]  A. Silverman,et al.  Transplanted gonadotropin-releasing hormone neurons promote pulsatile luteinizing hormone secretion in congenitally hypogonadal (hpg) male mice. , 1988, Neuroendocrinology.

[30]  G. Lamming,et al.  Ovarian steroid hormone involvement in endogenous opioid modulation of LH secretion in mature ewes during the breeding and non-breeding seasons. , 1988, Journal of reproduction and fertility.

[31]  P. Goldsmith,et al.  Infundibular gonadotropin-releasing hormone neurons are inhibited by direct opioid and autoregulatory synapses in juvenile monkeys. , 1988, Neuroendocrinology.

[32]  F. Ebling,et al.  Endogenous opioid control of pulsatile LH secretion in rams: modulation by photoperiod and gonadal steroids. , 1987, The Journal of endocrinology.

[33]  S. Wiegand,et al.  Use of cryoprotectant to maintain long-term peptide immunoreactivity and tissue morphology , 1986, Peptides.

[34]  M. Lehman,et al.  Immunocytochemical localization of luteinizing hormone‐releasing hormone (LHRH) pathways in the sheep brain during anestrus and the mid‐luteal phase of the estrous cycle , 1986, The Journal of comparative neurology.

[35]  A. Silverman,et al.  Hypothalamic localization of multiunit electrical activity associated with pulsatile LH release in the rhesus monkey. , 1986, Neuroendocrinology.

[36]  J. Kaufman,et al.  Central electrophysiologic correlates of pulsatile luteinizing hormone secretion in the rhesus monkey. , 1984, Neuroendocrinology.

[37]  K. Pau,et al.  Effect of frontal hypothalamic deafferentation on luteinizing hormone secretion and seasonal breeding in the ewe. , 1982, Biology of reproduction.

[38]  G. E. Huffman,et al.  LHRH pathways in rat brain: ‘Deafferentation’ spares a sub-chiasmatic LHRH projection to the median eminence , 1982, Neuroscience.

[39]  B. Soper,et al.  Hypothalamic and extrahypothalamic mediation of pulsatile discharges of luteinizing hormone in the ovariectomized rat. , 1980, Endocrinology.

[40]  E. Knobil,et al.  Surgical disconnection of the medial basal hypothalamus and pituitary function in the rhesus monkey. I. Gonadotropin secretion. , 1975, Endocrinology.

[41]  C. Sawyer,et al.  Effects of hypothalamic deafferentation on the pulsatile rhythm in plasma concentrations of luteinizing hormone in ovariectomized rats. , 1974, Endocrinology.

[42]  R. Gorski,et al.  Gonadotrophic Hormone Secretion in Female Rats After Partial or Total Interruption of Neural Afferents to the Medial Basal Hypothalamus , 1967 .

[43]  C. Sawyer,et al.  A neurogenic timing factor in control of the ovulatory discharge of luteinizing hormone in the cyclic rat. , 1949, Endocrinology.