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样多肽7(INSL7)或松弛蛋白3的生理功能，它属于胰岛素超家族。1.第一年，我们用大鼠揭示了INSL7在中枢神经系统中的表达分布。它主要表达在脑干的限制性区域，即位于第四脑室附近的脑桥灰质的疑核(NI)。它仅在神经元中表达，而不在神经胶质细胞中表达，INSL7阳性神经元向前脑向上投射轴突。在隔核、海马体和下丘脑等边缘系统可见致密的INSL7纤维。超微结构检查显示，INSL7弥漫分布于神经细胞周围。在轴突终末，它被包含在突触附近的致密核小泡中。INSL7被强烈地提示它像多肽神经递质一样被分泌到突触间隙。2.第二年，我们研究了这种多肽的功能。获得了INSL7和CRF 1型受体的共表达。由于CRF在大脑中是众所周知的应激反应肽，我们检测了侧脑室注射CRF和束缚应激后c-Fos的表达。两种实验均显示在CRF注射或束缚应激后，NI内c-Fos蛋白INSL7神经元立即被诱导。此外，我们还证实了束缚应激后NI中INSL7mRNA的表达增加。这些结果表明，INSL7参与了脑内应激反应的调节。我们在参考文献1和参考文献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.