The effect of nutrition on the neural mechanisms potentially involved in melatonin-stimulated LH secretion in female Mediterranean goats.
The effect of nutrition on the neural mechanisms potentially involved in melatonin-stimulated LH secretion in female Mediterranean goats.
复制标题
DOI：
10.1530/joe-11-0225
复制
发表时间：
2011-12
期刊：
影响因子：
--
通讯作者：
L. Zarazaga;I. Celi;J. Guzmán;B. Malpaux
中科院分区：
文献类型：
--
作者：
L. Zarazaga;I. Celi;J. Guzmán;B. Malpaux
本研究探讨了内源性阿片、多巴胺、肾上腺素和兴奋性氨基酸系统中哪些神经机制参与褪黑素植入刺激LH分泌以及营养水平对它们的调节。雌性山羊被分配到两个实验组，分别接受1.1（H组; n=24）或0.7（L组; n=24）倍的营养维持需求。每组中的一半在长时间的白天后植入褪黑激素。每周测量两次血浆LH浓度。在褪黑激素植入前一天以及第30天和第45天再次评估静脉注射纳洛酮、匹莫齐特、赛庚啶和N-甲基-d，l-天冬氨酸（NMDA）对LH分泌的影响。除了多巴胺能系统外，所有系统的功能都明显受到营养水平、褪黑激素植入和植入后时间的影响。植入后30天，纳洛酮可增加LH浓度，与营养水平无关（P<0.05），与植入褪黑素的H山羊的NMDA相似（HM; P<0.01）。在第45天，纳洛酮增加了HM动物中的LH浓度（P<0.05），与非植入H（HC）和HM动物中的赛庚啶相似（P<0.01）。45 d时，NMDA使各亚组LH浓度均升高（P<0.01）。这些结果提供了证据，不同的神经系统对LH分泌的影响，通过营养水平和褪黑素植入修改。内源性阿片类物质似乎是最强烈的参与抑制LH分泌的褪黑激素植入后30和45天。然而，多巴胺能机制似乎受营养水平的影响最大。
This research examines which neural mechanisms among the endogenous opioid, dopaminergic, serotonergic and excitatory amino acid systems are involved in the stimulation of LH secretion by melatonin implantation and their modulation by nutritional level. Female goats were distributed to two experimental groups that received either 1.1 (group H; n=24) or 0.7 (group L; n=24) times their nutritional maintenance requirements. Half of each group was implanted with melatonin after a long-day period. Plasma LH concentrations were measured twice per week. The effects of i.v. injections of naloxone, pimozide, cyproheptadine and N-methyl-d,l-aspartate (NMDA) on LH secretion were assessed the day before melatonin implantation and again on days 30 and 45. The functioning of all but the dopaminergic systems was clearly modified by the level of nutrition, melatonin implantation and time elapsed since implantation. Thirty days after implantation, naloxone increased LH concentrations irrespective of the level of nutrition (P<0.05), similar to NMDA in the melatonin-implanted H goats (HM; P<0.01). On day 45, naloxone increased LH concentrations in the HM animals (P<0.05), similar to cyproheptadine in both the non-implanted H (HC) and the HM animals (P<0.01). Finally, at 45 days, NMDA increased the LH concentration in all subgroups (P<0.01). These results provide evidence that the effects of different neural systems on LH secretion are modified by nutritional level and melatonin implantation. Endogenous opioids seem to be most strongly involved in the inhibition of LH secretion on days 30 and 45 after melatonin implantation. However, the serotonergic mechanism appears to be most influenced by nutritional level.