Analysis of a novel peptide INSL7 in the central nervous system

我们研究了3年前新发现的胰岛素超家族成员胰岛素样肽7（insulin like peptide 7，INSL 7）或松弛素3（relaxin 3）的生理功能。1.第一年，我们用大鼠研究了INSL 7在中枢神经系统的表达分布。它主要表达于脑干的限制性区域，即位于第四脑室附近的脑桥灰质中的未定核（NI）。INSL 7仅在神经元中表达，而在胶质细胞中不表达，并且INSL 7阳性神经元向上投射轴突至前脑。在隔核、海马和下丘脑等边缘系统可见密集的INSL 7纤维。超微结构显示，INSL 7在神经元胞体周围呈弥漫性分布。在轴突终末，它包含在突触附近的致密核心囊泡中。INSL 7被强烈地认为是像肽类神经递质一样分泌到突触间隙。2.第二年，我们对这种肽的功能方面进行了研究。我们获得了INSL 7和CRF 1型受体的共表达。由于CRF是脑内众所周知的应激反应肽，我们检测了侧脑室注射CRF和限制应激后c-Fos的表达。两个实验均显示CRF注射或束缚应激后NI中c-Fos蛋白INSL 7神经元的立即诱导。此外，我们证实了束缚应激后NI中INSL 7 mRNA的表达增加。这些结果表明，INSL 7参与调节大脑中的应激反应。我们在参考文献1和2中发表了上述数据。其他参考文献也使用类似的组织化学技术发表。

We have investigated physiological function of a newly identified peptide 3 years ago called, insulin like peptide 7 (INSL7) or relaxin3 which belongs to the insulin super family.1.First year, we revealed the distribution of INSL7 expression in the central nervous system using rats. It was dominantly expressed in the restricted area in the brainstem, called nucleus incertus (NI) which was located in the pontine gray matter near the fourth ventricle. It was exclusively expressed in the neurons but not glial cells and INSL7 positive neurons project axons to the forebrain ascendingly. Dense INSL7 fibers were observed in the limbic system such as septal nucleus, hippocampus and hypothtalamus. Ultrastructural examination revealed that INSL7 was diffusely distributed in the neueronal perikarya. In the axon terminals, it was included in the dense-cored vesicles near the synapse. INSL7 was strongly suggested that it is excreted into the synaptic space like a peptide neurotransmitter.2.Second year, we pursued the functional aspect of this peptide. We obtained the coexpression of INSL7 and CRF type 1 receptor. As CRF is well known as a stress-responded peptide in the brain, we examined the c-Fos expression after CRF injection in the lateral ventricle and restrained stress. Both experiments showed the immediate induction of c-Fos protein INSL7 neurons in the NI after CRF injection or restrained stress. Moreover, we confirmed INSL7 mRNA expression in the NI was increased after the restrained stress. These results indicate that INSL7 is involved in the regulation of stress response in the brain. We published the data mentioned above in the reference 1 and 2. Other references were also published using similar histochemical techniques.