Spike After-Potentials of Oxytocin Cells in Lactation

哺乳期催产素细胞的尖峰后电位

• 批准号: 6819324
• 负责人: RYOICHI TERUYAMA
• 金额: $ 7.3万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-06 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6819324
• 关键词: action potentials; calbindin; confocal scanning microscopy; female; immunocytochemistry; laboratory rat; lactation; mammary gland; myoepithelial cell; neurons; oxytocin; single cell analysis; supraoptic nucleus; voltage /patch clamp

DESCRIPTION (provided by applicant): My research interest has been focused on the physiological adaptation of animals to their different reproductive states. The oxytocin (OT) neuron in the supraoptic nucleus (SON) of the hypothalamus is one of the best models to study such adaptation, because the importance of OT during parturition and lactation are well documented. The reports of neuronal activity and morphological responses of OT neurons to lactation are abundant as well. However, the mechanisms underlying the physiological adaptation of OT neurons to lactation are only sparsely discussed. OT neurons in the supraoptic nucleus are known to undergo a remarkable change in neuronal activity in response to the increased hormonal demand that occurs during parturition and lactation. OT neurons display a short, high frequency burst proceeding each milk ejection (Poulain & Wakerley, 1982). The bursting activity is synchronized among all OT neurons (Belin et al., 1984) and results in a bolus release of OT into the blood stream, necessary for uterine contraction or contraction of myoepithelial cells in the mammary glands. This pulsatility is believed to maximize the biological effects of OT and allows the neurons to recover from secretory fatigue (Bicknell, 1988). Because of their significance in controlling hormone secretion, mechanisms involve in the regulation of firing rate and pattern in OT neurons are the subject of great interest. The pattern of electrical activity of neurons generally results from the interaction of intrinsic ionic mechanisms and synaptic activity. The intrinsic membrane properties of OT neuron, the spike after-potentials (after hyperpolarizing potentials (AHP) and depolarization after-potential (DAP)), appear to change in favor of the short bursting activity of OT neuron necessary during parturition and lactation. The ionic conductances mediating these properties are, at least partly, involving in the regulation of the firing rate and pattern that ultimately control the release of hormone. Therefore, this application is to elucidate the mechanisms responsible for the changes in physiological properties of OT neurons in response to lactation. The specific aims of the application are to determine 1) what specific component of spike after-potentials (AHPs and DAP) is altered during lactation; 2) whether the responsive component is responsive to changes in the gonadal steroids.

描述（由申请人提供）：我的研究兴趣集中在动物对不同生殖状态的生理适应上。下丘脑视上核（SON）中的催产素（OT）神经元是研究这种适应的最佳模型之一，因为OT在分娩和哺乳期间的重要性已被充分证明。有关OT神经元对泌乳的神经活性和形态学反应的报道也很丰富。然而，OT神经元对泌乳的生理适应机制却很少被讨论。已知视上核中的OT神经元响应于分娩和哺乳期间发生的增加的激素需求而经历神经元活动的显著变化。OT神经元在每次排乳过程中显示出短而高频率的爆发（Poulain & Wakerley，1982）。爆发活动在所有OT神经元中同步（贝林等人，1984），并导致OT向血流中的快速释放，这是子宫收缩或乳腺中肌上皮细胞收缩所必需的。这种脉动性被认为使OT的生物学效应最大化，并允许神经元从分泌疲劳中恢复（Bicknell，1988）。由于OT神经元在控制激素分泌方面的重要性，其放电频率和放电模式的调节机制一直是研究的热点。神经元的电活动模式通常由内在离子机制和突触活动的相互作用产生。OT神经元的固有膜特性，尖峰后电位（超极化后电位（AHP）和去极化后电位（DAP）），似乎有利于OT神经元在分娩和哺乳期间所需的短爆发活动。介导这些性质的离子电导至少部分地涉及调节放电速率和模式，最终控制激素的释放。因此，本申请旨在阐明哺乳期OT神经元生理特性变化的机制。该应用的具体目的是确定1）尖峰后电位（AHPs和DAP）的哪些特定成分在哺乳期间发生变化; 2）反应成分是否对性腺类固醇的变化有反应。