Department of Anatomy and Histology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria.
Cells Tissues Organs. 2009;190(5):256-85. doi: 10.1159/000209233. Epub 2009 Mar 13.
The efferent projections of the anterior and posterodorsal part of the medial nucleus (MePD) in the mouse were studied by means of anterograde axonal tracing using biotinylated dextran amine. The MePD axons ran mainly via the stria terminalis and to a lesser extent via the ventral amygdalofugal pathway. The projections to the forebrain were broadly distributed and varied from very strong to scant. The most significant connections were destined to the bed nucleus of the stria terminalis in which all parts of the medial division were innervated by MePD neurons. Moderate projections reached the limbic striatum (nucleus accumbens), olfactory tubercle and the lateral septal nucleus. The substantia innominata was also innervated by the MePD, and especially the projection to its ventral portion was substantial. The profuse innervation of the medial preoptic nucleus and medial preoptic area indicated significant involvement of the MePD in sexual behavior. Many hypothalamic nuclei were innervated but to a different extent. The very strong innervation of the ventral premammillary nucleus further indicated the involvement of the MePD in the neuronal circuitry for sexual behavior. Substantial projections also reached the anterior hypothalamus and tuber cinereum, while the connections to the lateral hypothalamus were widespread but showed moderate density. MePD strongly innervated the ventrolateral part of the ventromedial hypothalamic nucleus and moderately its remaining parts. The neurosecretory hypothalamic nuclei and the arcuate nucleus contained only a few MePD terminals. The thalamic innervation was very scant and reached the lateral habenular nucleus and the nuclei of the midline. The mesencephalic connections were moderate to sparse and projected to the mesolimbic dopaminergic groups in the ventral tegmental area, the pars lateralis and the dorsal tier of the substantia nigra pars compacta, the periaqueductal gray and the dorsal raphe nucleus. The present results principally resembled data known in other rodent species; however, the efferents of the MePD often differed in extent and/or topical distribution.
用生物素化葡聚糖胺顺行轴突追踪法研究了小鼠内侧视前核（MePD）的前背侧部和后背侧部的传出投射。MePD 轴突主要通过终纹床核和较小程度地通过腹侧杏仁传出通路上行，投射到前脑的纤维广泛分布，从很强到很少。最重要的连接是到达终纹床核的内侧部分，MePD 神经元向其所有部分都发出投射。中等程度的投射到达边缘纹状体（伏隔核）、嗅结节和外侧隔核。终纹床核也被 MePD 神经支配，特别是其腹侧部分的投射是大量的。内侧视前核和内侧视前区也被 MePD 大量神经支配，表明 MePD 广泛参与性行为。许多下丘脑核被神经支配，但程度不同。腹侧前乳头体核的强烈神经支配进一步表明 MePD 参与了性行为的神经元回路。大量的投射也到达了前下丘脑和灰结节，而与外侧下丘脑的连接是广泛的，但密度适中。MePD 强烈地神经支配腹内侧下丘脑的腹外侧部分，中等程度地神经支配其其余部分。神经分泌下丘脑核和弓状核只含有少数 MePD 末梢。丘脑的神经支配非常稀疏，只到达外侧缰核和中线核。中脑的连接从中等到稀疏，投射到腹侧被盖区的中边缘多巴胺能群、黑质致密部的外侧部和背层、导水管周围灰质和中缝背核。目前的结果主要与其他啮齿动物物种中已知的数据相似；然而，MePD 的传出投射在程度和/或局部分布上往往不同。
