下丘脑Ghrelin 通过β-内啡肽抑制去卵巢大鼠促黄体生成激素的脉冲分泌。
Hypothalamic Ghrelin suppresses pulsatile secretion of luteinizing hormone via beta-endorphin in ovariectomized rats.
机构信息
Department of Obstetrics and Gynecology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan. r-ogata @ pop21.odn.ne.jp
出版信息
Neuroendocrinology. 2009;90(4):364-70. doi: 10.1159/000257421. Epub 2009 Nov 6.
OBJECTIVES
Ghrelin, an endogenous growth hormone secretagogue, is a known accelerator of feeding behavior and suppresses pulsatile secretion of luteinizing hormone (LH) in ovariectomized rats. However, the mechanisms underlying this action remain unclear. We examined the effects of naloxone (NAL), a specific opioid antagonist, on the suppression of pulsatile LH secretion by ghrelin to determine whether beta-endorphin (beta-END) is involved in this suppressive effect.
METHODS
Ghrelin was administered intracerebroventricularly, and NAL was injected intravenously in ovariectomized rats; then, serum LH concentrations were measured by radioimmunoassay in blood samples drawn every 6 min for 2 h to analyze pulsatile secretion.
RESULTS
Administration of ghrelin significantly reduced mean LH concentration and pulse frequency. Coadministration of NAL with ghrelin significantly restored mean LH concentration and pulse frequency.
CONCLUSION
Suppressive effect of intracerebroventricular injection of ghrelin on pulsatile LH secretion was mediated by beta-END, suggesting that hypothalamic ghrelin suppressed pulsatile gonadotropin-releasing hormone secretion via beta-END in female rats.
目的
Ghrelin 是一种内源性生长激素促分泌素，已知它能加速摄食行为，并抑制去卵巢大鼠黄体生成素（LH）的脉冲式分泌。然而，其作用机制尚不清楚。我们研究了纳洛酮（NAL），一种特定的阿片受体拮抗剂，对 Ghrelin 抑制 LH 脉冲式分泌的影响，以确定β-内啡肽（β-END）是否参与这种抑制作用。
方法
Ghrelin 经脑室内给药，NAL 经静脉内给药，于 2 小时内每隔 6 分钟采集一次血样，通过放射免疫法测定血清 LH 浓度，以分析脉冲式分泌。
结果
Ghrelin 的给药显著降低了平均 LH 浓度和脉冲频率。Ghrelin 与 NAL 共同给药显著恢复了平均 LH 浓度和脉冲频率。
结论
Ghrelin 经脑室内注射对 LH 脉冲式分泌的抑制作用是通过β-END 介导的，这表明下丘脑 Ghrelin 通过β-END 抑制雌性大鼠促性腺激素释放激素的脉冲式分泌。
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