Al-Zailaie K A, Kang S W, Youngren O M, Thayananuphat A, Bakken T, Chaiseha Y, Millam J R, Proudman J A, El Halawani M E
Department of Animal Science, University of Minnesota, St Paul, MN, USA.
J Neuroendocrinol. 2006 Jul;18(7):514-25. doi: 10.1111/j.1365-2826.2006.01443.x.
The neural and neurochemical substrates regulating reproduction in birds remain vaguely defined. The findings that electrical stimulation in the medial preoptic area (ES/MPOA) or intracerebroventricular infusion of dopamine (DA) stimulated luteinising hormone (LH) and prolactin (PRL) release in female turkeys, led to the suggestion that ES/MPOA might help to clarify the DA circuitry regulating LH and PRL. We used c-fos mRNA and tyrosine hydroxylase immunoreactivity as measured by double in situ hybridisation/immunocytochemistry (ISH/ICC) to determine which group/subgroup of DA neurones was activated following unilateral ES/MPOA. To establish that the reproductive neuroendocrine system was activated, double ISH/ICC was also conducted on c-fos/gonadotrophin-releasing hormone-I (GnRH-I) and c-fos/vasoactive intestinal peptide (VIP). Changes in circulating LH and PRL were determined by radioimmunoassay. Unilateral ES/MPOA (100 microA, right side) of anaesthetised laying turkeys for 30 min increased circulating LH and PRL levels. It also induced c-fos mRNA expression on the ipsilateral side by all GnRH-I neurones within the septopreoptic region, implying that GnRH-I neurones in this region share similar circuitry. VIP neurones within the nucleus infundibularis were the only VIP group to show c-fos mRNA expression, suggesting their involvement in ES/MPOA induced PRL release. c-fos mRNA expression was also observed in a subgroup of DA neurones in the nucleus mamillaris lateralis (ML). To our knowledge, the present study is the first to show that activation of DAergic cells in the ML is associated with the activation of GnRH-I and VIP neurones and the release of LH and PRL. It is likely that ES/MPOA activated VIP/GnRH-I neurones via activation of DA neurones in the ML, as this was the only DA subgroup that showed c-fos mRNA expression.
调节鸟类繁殖的神经和神经化学底物仍未明确界定。内侧视前区电刺激（ES/MPOA）或脑室内注入多巴胺（DA）可刺激雌性火鸡促黄体生成素（LH）和催乳素（PRL）释放，这一发现表明ES/MPOA可能有助于阐明调节LH和PRL的DA神经回路。我们使用通过双原位杂交/免疫细胞化学（ISH/ICC）测量的c-fos mRNA和酪氨酸羟化酶免疫反应性，来确定单侧ES/MPOA后哪些DA神经元群/亚群被激活。为确定生殖神经内分泌系统是否被激活，还对c-fos/促性腺激素释放激素-I（GnRH-I）和c-fos/血管活性肠肽（VIP）进行了双ISH/ICC检测。通过放射免疫测定法测定循环中的LH和PRL变化。对麻醉的产蛋火鸡进行右侧100微安的单侧ES/MPOA刺激30分钟，可提高循环中的LH和PRL水平。它还诱导隔区视前区内所有GnRH-I神经元在同侧表达c-fos mRNA，这意味着该区域的GnRH-I神经元共享相似的神经回路。漏斗核内的VIP神经元是唯一显示c-fos mRNA表达的VIP神经元群，表明它们参与了ES/MPOA诱导的PRL释放。在外侧乳头体核（ML）的一个DA神经元亚群中也观察到了c-fos mRNA表达。据我们所知，本研究首次表明ML中DA能细胞的激活与GnRH-I和VIP神经元的激活以及LH和PRL的释放有关。ES/MPOA可能通过激活ML中的DA神经元来激活VIP/GnRH-I神经元，因为这是唯一显示c-fos mRNA表达的DA亚群。
