雌性大鼠下丘脑5-羟色胺1A和2A受体亚型的定位分布

本研究应用免疫细胞化学技术观察了雌性成年SD大鼠下丘脑内5-HT1A受体亚型(5-HT1AR)和5-HT2AR免疫阳性结构的分布。结果显示:5-HT1AR免疫阳性神经元在视前区大细胞核、视前室周核、视上核和下丘脑外侧前核等核团内密集分布。在内侧视前核、外侧视前区、下丘脑室周核、下丘脑外侧区、背内侧核、腹内侧核、结节核、结节乳头体核、乳头体内侧核和乳头体外侧核等结构内也有较多的分布;而在正中视前核、视交叉上核、下丘脑室旁核、下丘脑背侧核、弓状核、乳头体上核和乳头体前核等部位有散在的分布。与5-HT1AR不同,5-HT2AR免疫阳性反应产物主要见于纤维和终末,阳性胞体少且染色淡。5-HT2AR阳性胞体见于下丘脑室旁核、视上核、腹内侧核、结节核、视前内侧区、外侧区、外侧前核、下丘脑背内侧核等处。另外,在视前区前内侧视前核、视交叉上核背侧和外侧可见围绕血管分布、密集成团簇状、带有大小不同膨体的阳性神经纤维缠结。本文结果提示5-HT1AR阳性结构广泛地分布于大鼠下丘脑,而5-HT2AR在下丘脑分布较为局限。二者不同的分布特点,提示它们可能介导5-HT在下丘脑的不同生理功能。

LOCALIZATION OF 5-HT1A AND 5-HT2A RECEPTOR SUBTYPES IN THE NORMAL FEMALE RAT HYPOTHALAMUS

In the present study, immunohistochemical staining technique was used to observe the distribution pattern of serotonin 1A receptor subtype (5-HT1AR) and 5-HT2AR immunoreactivity in the rat hypothalamus. The results showed that intensely and densely stained 5-HTiAR immunoreactive neurons were observed in magnocellular nucleus of preoptic area, preoptic periventricular nucleus, supraoptic nucleus and lateroanterior hypothalamic nucleus. Considerably weaker immunoreactivity was detected in medial preoptic nucleus, lateral preoptic area, periventricular hypothalamic nucleus, lateral hypothalamic area, dor-somedial hypothalamic nucleus, ventromedial hypothalamic nucleus, tuber cinereum, tuberomammillary nucleus, medial mam-millary nucleus and lateral mammillary nucleus. Very weak immunoreactivity was found in the median preopitc nucleus, suprachiasmatic nucleus, paraventricular hypothalamic nucleus, dorsal hypothalamic nucleus, arcuate nucleus, posterior hypothalamic area, supramammillary nucleus and premammillary nucleus. 5-HT2AR immunohistochemically stained products were mainly observed in the fibers and terminals. 5-HT2AR immunoreactive cell bodies were mainly present in paraventricular hypothalamic nucleus, supraoptic nucleus, ventromedial hypothalamic nucleus and tuber cinereum, medial preoptic area, lateralhypothalamic area, lateroanterior hypothalamic nucleus and dorsomedial hypothalamic nucleus. The present results indicate that 5-HT1AR immunoreactive structures are widely distributed in the rat hypothalamus, whereas 5-H2AR immunoreactivity is more restricted. The different distribution patterns of 5-HT1A R and 5-HT2AR suggest their different roles in mediating the physiological functions of 5-HT in the hypothalamus.