Orchidectomy and NMDA increase GnRH secretion as measured by push-pull perfusion of rat anterior pituitary

Grattan, David R.; Park, Sung-Keun; Selmanoff, Michael

doi:10.1152/ajpendo.1995.268.4.e685

Cited by 12 publications

(11 citation statements)

References 28 publications

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“…5). Castration has been reported to increase both the frequency and the amplitude of GnRH pulses Grattan et al, 1995) (Fig. 6), to increase the frequency but not the amplitude (Meredith and Levine, 1992), or to have no significant effect on GnRH secretion (Phelps et al, 1992).…”

Section: Do Gnrh Mrna Levels Reflect Gnrh Biosynthesis And/or Releasementioning

confidence: 94%

“…Between 7 and 14 days postcastration there is a further increase in plasma LH concentrations, and then LH secretion remains at this elevated level indefinitely (Badger et aL, 1978;Ellis and Desjardins, 1984;Culler et al, 1988). The initial rise in LH secretion during the first few days after castration is not due to a change in pituitary sensitivity to GnRH in either males (Badger et aL, 1978;Fallest et al, 1989;Grattan et aL, 1995) or females (Higuchi and Kawakami, 1982;Whitehead et aL, 1982;Fallest et aL, 1989). Thus, it seems likely that the initial postcastration rise in LH is mediated by increased amplitude and or frequency of GnRH pulses from the hypothalamus.…”

Section: Testosterone Regulation Of Gnrh Gene Expression In the Malementioning

confidence: 98%

“…In the case of GnRH, levels of the prepropeptide are usually correlated with the cellular levels of GnRH mRNA (Roberts et al, 1989), suggesting that steady-state levels of GnRH mRNA indeed reflect rates of GnRH biosynthesis. Acute stimulation of GnRH release (Grattan et al, 1995) by the excitatory amino acid N-methyl-D-aspartate (NMDA) has been shown to induce a rapid, specific increase in GnRH gene expression Liaw and Barraclough, 1993;Gore and Roberts, 1994), suggesting that changes in GnRH mRNA levels are tightly linked to changes in GnRH release. The situation after steroid treatment, however, is considerably less clear.…”

Section: Do Gnrh Mrna Levels Reflect Gnrh Biosynthesis And/or Releasementioning

confidence: 99%

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Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

et al. 1996

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Gonadotropin-releasing hormone (GnRH), having a highly conserved structure across mammalian species, plays a pivotal role in the control of the neuroendocrine events and the inherent sexual behaviors essential for reproductive function. Recent advances in molecular genetic technology have contributed greatly to the investigation of several aspects of GnRH physiology, particularly steroid hormone and neurotransmitter regulation of GnRH gene expression. Behavioral studies have focused on the actions of GnRH in steroid-sensitive brain regions to understand better its role in the facilitation of mating behavior. To date, however, there are no published reports which directly correlate GnRH gene expression and reproductive behavior. The intent of this article is to review the current understanding of the way in which changes in GnRH gene expression, and modifications of GnRH neuronal activity, may ultimately influence reproductive behavior.

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Section: Do Gnrh Mrna Levels Reflect Gnrh Biosynthesis And/or Releasementioning

confidence: 94%

Section: Testosterone Regulation Of Gnrh Gene Expression In the Malementioning

confidence: 98%

Section: Do Gnrh Mrna Levels Reflect Gnrh Biosynthesis And/or Releasementioning

confidence: 99%

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Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

et al. 1996

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“…The fact that the hypothalamic GnRH release increases after castration indicates that testicular signals exert inhibitory actions on the hypothalamus [36]. Since in experiment II BIC infusion was more effective in increasing serum LH concentration in intact male rats than in castrated male rats, and since castration decreased both the single-cell expression of the glutamic acid decarboxylase (a GABA synthetic enzyme) mRNA [37]and the GABA turnover rate [38]in the MPO of male rats, castration may affect the inhibitory GABAergic tone in the MPO.…”

Section: Discussionmentioning

confidence: 99%

Profiles of in vivo Gamma-Aminobutyric Acid Release in the Medial Preoptic Area of Intact and Castrated Male Rats

Tin-Tin-Win-Shwe¹,

Mitsushima²,

Kimura³

2002

Neuroendocrinology

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We have suggested that gamma-aminobutyric acid (GABA) in the hypothalamus plays a tonic inhibitory role in the control of the luteinizing hormone (LH) release in intact male rats. To assess whether feedback from the testis alters the inhibitory GABAergic tone in the medial preoptic area (MPO) of male rats, an in vivo microdialysis study was performed in gonadally intact (n = 10), castrated (n = 12) and castrated testosterone-primed (n = 10) male rats. The microdialysis samples were collected and sequential blood samples were also obtained at 1-hour intervals. GABA in the dialysate was determined by high-performance liquid chromatography system and serum LH concentration was determined by radioimmunoassay. Episodic GABA release in the MPO was observed in all three groups of male rats, although castrated male rats showed lower GABA release (2.3 ± 0.3 ng/h) than intact and castrated testosterone-primed male rats (4.0 ± 0.5 and 4.6 ± 1.0 ng/h, respectively). Conversely, castrated male rats showed higher serum LH concentration (7.31 ± 0.46 ng/ml) than intact and castrated testosterone-primed male rats (0.71 ± 0.04 and 0.53 ± 0.07 ng/ml, respectively). In addition, intravenous infusion of bicuculline significantly increased serum LH in intact male rats, whereas bicuculline did not alter serum LH concentrations in castrated male rats. These results are consistent with the hypothesis that the feedback of testosterone stimulates GABA release in the region of the GnRH cell bodies and dendrites in male rats.

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“…influenced by numerous factors, such as amino acids, neuropeptides, cytokines and steroid hormones [7][8][9][10][11][12][13][14].…”

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confidence: 99%

The Effects of GABA on Embryonic Gonadotropin-Releasing Hormone Neurons in Rat Hypothalamic Primary Culture

Fujioka

Yamanouchi

Akema

et al. 2007

Journal of Reproduction and Development

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Abstract. Gonadotropin-releasing hormone (GnRH) neurons arise in the olfactory placode, migrate into the preoptic area (POA), and then extend axons to the median eminence during embryogenesis. Little information is available concerning the properties of GnRH neurons during the late gestational period when GnRH neurons reach the POA and form neuronal networks, although many studies have examined such properties during earlier developmental stages or the postnatal period. The present study was performed to elucidate the involvement of γ-aminobutyric acid (GABA), one of the major neurotransmitters modifying GnRH neural activity, in regulation of GnRH gene expression on embryonic day 18.5 (E18.5) using transgenic rats expressing enhanced green fluorescence protein (EGFP) under the control of GnRH promoter. First, using RT-PCR, the mRNA of two isoforms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD), GAD65 and GAD67 was detected in E18.5 embryonic POA-containing tissues. GAD67-positive cells were also demonstrated in close vicinity to GnRH-positive cells by immunohistochemistry, and immunoreactivity for both the GABA-A and GABA-B receptor subunits was detected in GnRH neurons. Next, primary cultures derived from anterior hypothalamic tissue of E18.5 embryos were prepared, and the effects of GABA and its agonists on GnRH promoter activity were evaluated using EGFP expression as a marker. GABA and the GABA-A receptor agonist muscimol, but not the GABA-B receptor agonist baclofen, significantly increased the EGFP-positive/GnRH-positive cell ratio. These results suggest that GABA plays a role in stimulating GnRH gene expression through GABA-A receptors in embryonic GnRH neurons in late gestational stages.

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Orchidectomy and NMDA increase GnRH secretion as measured by push-pull perfusion of rat anterior pituitary

Cited by 12 publications

References 28 publications

Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors

Profiles of in vivo Gamma-Aminobutyric Acid Release in the Medial Preoptic Area of Intact and Castrated Male Rats

The Effects of GABA on Embryonic Gonadotropin-Releasing Hormone Neurons in Rat Hypothalamic Primary Culture

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