Kumar Ujendra
Faculty of Pharmaceutical Sciences, Division of Pharmacology and Toxicology, University of British Columbia, Vancouver, Canada.
J Comp Neurol. 2007 Sep 10;504(2):185-205. doi: 10.1002/cne.21444.
The hypothalamus is a major site of somatostatin (SST) production and action. SST is synthesized in several hypothalamic nuclei and involved in a variety of functions. Using SST receptor (SSTR)-specific antibodies, we localized SSTR subtypes in the rat hypothalamus. In addition, we also demonstrated SSTRs colocalization with SST, NADPH-diaphorase (NADPH-d), and tyrosine hydroxylase (TH). SSTR1 is strongly localized in neurons in all major hypothalamic nuclei as well as in nerve fibers in the zona externa of the median eminence and the ependyma of the third ventricle. SSTR2 is also well expressed in most regions but with a relatively lower abundance in comparison to SSTR1. In contrast, SSTR3 is localized primarily in the paraventricular nucleus, dorsomedial hypothalamic nucleus, arcuate nucleus, and median eminence. SSTR4-like immunoreactivity is mainly confined to the arcuate nucleus, ventromedial hypothalamic nucleus, median eminence, and ependymal cells of third ventricle, with the rare SSTR4-positive neuron in the paraventricular nucleus. SSTR5 is the least expressed subtype occurring only in few cells in the inner layer of the median eminence. Overall, SSTR1 is the predominant subtype, followed by SSTR2, 4, 3, and 5. Combined immunofluorescence, immunocytochemistry, and histochemistry were used to demonstrate SSTRs colocalization with SST, TH, and NADPH-d. SSTRs colocalization with SST, TH, and NADPH-d displays in a region and receptor specificity. Colocalization of SST and NADPH-d with SSTRs in hypothalamic regions was similar, suggesting that SST and NADPH-d producing cells are same. In contrast, TH was selectively coexpressed with SSTRs in the hypothalamus in a receptor-specific manner. Taken together, these data suggest that SSTRs may interact with NADPH-d and TH to exert a physiological role in concert within the hypothalamus.
下丘脑是生长抑素（SST）产生和发挥作用的主要部位。SST在下丘脑的多个核团中合成，并参与多种功能。我们使用SST受体（SSTR）特异性抗体，对大鼠下丘脑的SSTR亚型进行了定位。此外，我们还证实了SSTR与SST、还原型辅酶Ⅱ黄递酶（NADPH-d）和酪氨酸羟化酶（TH）的共定位。SSTR1在所有主要下丘脑核团的神经元以及正中隆起外侧区的神经纤维和第三脑室室管膜中均有强烈定位。SSTR2在大多数区域也有良好表达，但与SSTR1相比丰度相对较低。相比之下，SSTR3主要定位于室旁核、下丘脑背内侧核、弓状核和正中隆起。SSTR4样免疫反应主要局限于弓状核、下丘脑腹内侧核、正中隆起和第三脑室的室管膜细胞，室旁核中罕见SSTR4阳性神经元。SSTR5是表达最少的亚型，仅在正中隆起内层的少数细胞中出现。总体而言，SSTR1是主要亚型，其次是SSTR2、4、3和5。联合免疫荧光、免疫细胞化学和组织化学方法用于证实SSTR与SST、TH和NADPH-d的共定位。SSTR与SST、TH和NADPH-d的共定位表现出区域和受体特异性。下丘脑区域中SST和NADPH-d与SSTR的共定位情况相似，表明产生SST和NADPH-d的细胞相同。相比之下，TH在下丘脑中以受体特异性方式与SSTR选择性共表达。综上所述，这些数据表明SSTR可能与NADPH-d和TH相互作用，在下丘脑中协同发挥生理作用。
