生长激素促分泌素受体(GHSR)1a是ghrelin唯一的分子鉴定受体,介导ghrelin对饮食的相关影响,体重,血糖控制,在其他人中。先前已经通过几种神经解剖学技术评估了GHSR在脑内的表达模式。然而,这些技术的固有局限性以及缺乏可靠的抗GHSR抗体和鉴定含GHSR的神经元的报告啮齿动物模型,阻止了对生长素释放肽反应性神经元进行更全面的功能表征.在这里,我们系统地表征了最近报道的GHSR报告小鼠中由Ghsr启动子控制的增强绿色荧光蛋白(eGFP)转基因的脑表达。通过原位杂交组织化学将eGFP在冠状脑切片中的表达与在相同切片中检测到的GHSRmRNA表达进行比较。在几个区域检测到eGFP免疫反应性,包括前额叶皮层,岛叶皮层,嗅觉灯泡,杏仁核,海马体,显示无或低GHSRmRNA表达。相比之下,eGFP在几个中脑区域和几个下丘脑核中表达低,尤其是弓形核,其中健壮的GHSRmRNA表达已得到充分表征。eGFP在几个脑干核中的表达显示出具有GHSRmRNA标记的高至中等程度的共定位。对eGFP标记的海马细胞的进一步定量PCR和电生理分析证实了eGFP在含GHSR的海马细胞中的忠实表达,ghrelin反应神经元。总之,GHSR-eGFP报告小鼠模型可能是研究GHSR功能的有用工具,特别是在脑干和海马内;然而,它代表了下丘脑和中脑核内的GHSR表达。
Growth hormone secretagogue receptor (GHSR) 1a is the only molecularly identified receptor for ghrelin, mediating ghrelin-related effects on eating, body weight, and blood glucose control, among others. The expression pattern of GHSR within the brain has been assessed previously by several neuroanatomical techniques. However, inherent limitations to these techniques and the lack of reliable anti-GHSR antibodies and reporter rodent models that identify GHSR-containing neurons have prevented a more comprehensive functional characterization of ghrelin-responsive neurons. Here we have systematically characterized the brain expression of an enhanced green fluorescence protein (eGFP) transgene controlled by the Ghsr promoter in a recently reported GHSR reporter mouse. Expression of eGFP in coronal brain sections was compared with GHSR mRNA expression detected in the same sections by in situ hybridization histochemistry. eGFP immunoreactivity was detected in several areas, including the prefrontal cortex, insular cortex, olfactory bulb, amygdala, and hippocampus, which showed no or low GHSR mRNA expression. In contrast, eGFP expression was low in several midbrain regions and in several hypothalamic nuclei, particularly the arcuate nucleus, where robust GHSR mRNA expression has been well-characterized. eGFP expression in several brainstem nuclei showed high to moderate degrees of colocalization with GHSR mRNA labeling. Further quantitative PCR and electrophysiological analyses of eGFP-labeled hippocampal cells confirmed faithful expression of eGFP within GHSR-containing, ghrelin-responsive neurons. In summary, the GHSR-eGFP reporter mouse model may be a useful tool for studying GHSR function, particularly within the brainstem and hippocampus; however, it underrepresents GHSR expression in nuclei within the hypothalamus and midbrain.