Kawano H, Masuko S
Department of Anatomy, Saga Medical School, Nabeshima 5-1-1, 849-8501, Saga, Japan.
Neuroscience. 2000;98(3):555-65. doi: 10.1016/s0306-4522(00)00134-2.
The nucleus preopticus medianus is known to be situated in a key site in pathways regulating the paraventricular hypothalamic nucleus. To investigate the innervation pattern to nucleus preopticus medianus neurons by afferent fibers containing beta-endorphin, adrenocorticotrophic hormone and neuropeptide Y, a retrograde tracing method was combined with immunohistochemistry for these peptides in the rat. In the first experiment with injection of a retrograde tracer in the nucleus preopticus medianus, retrogradely labeled neurons were found in many regions throughout the brain. Among these, the arcuate hypothalamic nucleus contained a number of retrogradely labeled neurons showing immunoreactivity to the neuropeptides examined. About 20%, 20% and 40% of retrogradely labeled arcuate hypothalamic nucleus neurons showed beta-endorphin, adrenocorticotrophic hormone and neuropeptide Y immunoreactivity, respectively. About 18% and 57% of retrogradely labeled neurons in the nucleus tractus solitarius and ventrolateral medulla, respectively, were immunoreactive to neuropeptide Y. There were many more neuropeptide Y-immunoreactive projections to the nucleus preopticus medianus from the arcuate hypothalamic nucleus than those from the medulla. None of the retrogradely labeled neurons in the medulla showed immunoreactivity to beta-endorphin or adrenocorticotrophic hormone. In the second experiment with injection of a retrograde tracer in the paraventricular hypothalamic nucleus, electron microscopic observation revealed that retrogradely labeled neurons in the nucleus preopticus medianus were in synaptic contact with beta-endorphin-, adrenocorticotrophic hormone- and neuropeptide Y-immunoreactive axon terminals. The present finding indicates that nucleus preopticus medianus neurons projecting to the paraventricular hypothalamic nucleus are innervated by beta-endorphin-, adrenocorticotrophic hormone- and neuropeptide Y-containing arcuate hypothalamic nucleus neurons in addition to being innervated by neuropeptide Y-containing catecholaminergic medullary neurons which have been reported in our previous study.
已知视前正中核位于调节下丘脑室旁核的通路中的关键部位。为了研究含β-内啡肽、促肾上腺皮质激素和神经肽Y的传入纤维对视前正中核神经元的支配模式，在大鼠中将逆行追踪法与这些肽的免疫组织化学相结合。在第一个实验中，将逆行示踪剂注射到视前正中核，在整个大脑的许多区域发现了逆行标记的神经元。其中，下丘脑弓状核含有许多对所检测神经肽呈免疫反应性的逆行标记神经元。分别约20%、20%和40%的下丘脑弓状核逆行标记神经元显示β-内啡肽、促肾上腺皮质激素和神经肽Y免疫反应性。孤束核和延髓腹外侧分别约18%和57%的逆行标记神经元对神经肽Y呈免疫反应性。从下丘脑弓状核到视前正中核的神经肽Y免疫反应性投射比从延髓的投射要多得多。延髓中没有逆行标记的神经元显示对β-内啡肽或促肾上腺皮质激素的免疫反应性。在第二个实验中，将逆行示踪剂注射到下丘脑室旁核，电子显微镜观察显示，视前正中核中逆行标记的神经元与β-内啡肽、促肾上腺皮质激素和神经肽Y免疫反应性轴突终末形成突触联系。目前的发现表明，投射到下丘脑室旁核的视前正中核神经元除了接受我们先前研究中报道的含神经肽Y的儿茶酚胺能延髓神经元的支配外，还接受含β-内啡肽、促肾上腺皮质激素和神经肽Y的下丘脑弓状核神经元的支配。
