PDF(Pubmed)
Abstract：
Gonadotropin-releasing hormone (GnRH)-synthesizing neurons orchestrate reproduction centrally. Early studies have proposed the contribution of acetylcholine (ACh) to hypothalamic control of reproduction, although the causal mechanisms have not been clarified. Here, we report that in vivo pharmacogenetic activation of the cholinergic system increased the secretion of luteinizing hormone (LH) in orchidectomized mice. 3DISCO immunocytochemistry and electron microscopy revealed the innervation of GnRH neurons by cholinergic axons. Retrograde viral labeling initiated from GnRH-Cre neurons identified the medial septum and the diagonal band of Broca as exclusive sites of origin for cholinergic afferents of GnRH neurons. In acute brain slices, ACh and carbachol evoked a biphasic effect on the firing rate in GnRH neurons, first increasing and then diminishing it. In the presence of tetrodotoxin, carbachol induced an inward current, followed by a decline in the frequency of miniature postsynaptic currents (mPSCs), indicating a direct influence on GnRH cells. RT-PCR and whole-cell patch-clamp studies revealed that GnRH neurons expressed both nicotinic (α4β2, α3β4, and α7) and muscarinic (M1-M5) AChRs. The nicotinic AChRs contributed to the nicotine-elicited inward current and the rise in firing rate. Muscarine via M1 and M3 receptors increased, while via M2 and M4 reduced the frequency of both mPSCs and firing. Optogenetic activation of channelrhodopsin-2-tagged cholinergic axons modified GnRH neuronal activity and evoked cotransmission of ACh and GABA from a subpopulation of boutons. These findings confirm that the central cholinergic system regulates GnRH neurons and activates the pituitary-gonadal axis via ACh and ACh/GABA neurotransmissions in male mice.
摘要：
GnRH合成神经元集中协调生殖。早期研究提出了乙酰胆碱（ACh）对下丘脑控制生殖的贡献，虽然因果机制尚未明确。这里,我们报道，胆碱能系统的体内药物遗传激活增加了睾丸切除小鼠黄体生成素（LH）的分泌。3DISCO免疫细胞化学和电子显微镜显示胆碱能轴突对GnRH神经元的神经支配。从GnRH-Cre神经元开始的逆行病毒标记将Broca的内侧隔膜和对角线带鉴定为GnRH神经元胆碱能传入的唯一起源位点。在急性脑切片中，ACh和ACh受体（AChR）激动剂卡巴胆碱对GnRH神经元的放电率产生双相作用，首先增加，然后减少。在河豚毒素的存在下,卡巴胆碱诱导内向电流，随后是mPSC频率的下降，表明对GnRH细胞的直接影响。RT-PCR和全细胞膜片钳研究表明，GnRH神经元同时表达烟碱（α4β2，α3β4和α7）和毒蕈碱（M1-M5）ACh受体。烟碱AChR有助于尼古丁引起的内向电流和激发率的升高。毒蕈碱通过M1和M3受体增加，而通过M2和M4降低了微型突触后电流（mPSC）和放电的频率。通道视紫红质2标记的胆碱能轴突的光遗传激活修饰了GnRH神经元活性，并诱发了来自boutons亚群的ACh和GABA的共同传递。这些发现证实，在雄性小鼠中，中枢胆碱能系统极大地调节GnRH神经元并通过ACh和ACh/GABA神经传递激活HPG轴。意义声明胆碱能药物影响生殖集中，尽管确切的神经元靶标和调节机制仍不确定。我们发现，体内胆碱能系统的药物遗传激活会引起雄性小鼠LH释放增加。该研究还确定了小鼠前脑中神经支配促性腺激素释放激素（GnRH）神经元的胆碱能细胞群，生殖的主要下丘脑调节器。我们还确定了参与神经元信息传递的烟碱和毒蕈碱受体的亚型，并探索了它们的配体如何影响GnRH神经元的电生理活性。发现胆碱能神经元的子集共同传递GABA，该GABA通过GABA-A受体激发GnRH细胞。这些发现表明了一部小说，GnRH系统的胆碱能调节激活成年雄性小鼠的垂体-性腺轴。
