Distinct physiological characteristics and altered glucagon signaling in GHRH knockout mice: Implications for longevity

Our previous research has demonstrated that mice lacking functional growth hormone-releasing hormone (GHRH) exhibit distinct physiological characteristics, including an extended lifespan, a preference for lipid utilization during rest, mild hypoglycemia, and heightened insulin sensitivity. They also show a further increase in lifespan when subjected to caloric restriction. These findings suggest a unique response to fasting, which motivated our current study on the response to glucagon, a key hormone released from the pancreas during fasting that regulates glucose levels, energy expenditure, and metabolism. Our study investigated the effects of an acute glucagon challenge on female GHRH knockout mice and revealed that they exhibit reduced glucose production, likely due to suppressed gluconeogenesis. However, these mice showed an increase in energy expenditure. We also observed alterations in pancreatic islet architecture, with smaller islets and a reduction of insulin-producing beta cells but no changes in glucagon-producing alpha cells. Additionally, the analysis of hepatic glucagon signaling showed a decrease in glucagon receptor expression and phosphorylated CREB. In conclusion, our findings suggest that the unique metabolic phenotype observed in these long-lived mice may be partly explained by changes in glucagon signaling. Further exploration of this pathway may lead to new insights into the regulation of longevity in mammals.     

组织透明化三维显示全包埋耳皮肤神经血管网（英文）

目的 结合组织学染色技术和组织透明化策略研究耳部皮肤中神经纤维和血管的空间对应关系。方法 将耳廓前面和后面的皮肤从其中间软骨仔细剥离，然后直接分别用蛋白基因产物9.5 (PGP 9.5)和鬼笔环肽对耳部皮肤的神经纤维和血管进行免疫荧光染色并进行组织透明化处理。随后，以全包埋方式将耳皮肤组织裱贴在载玻片上用于荧光显微镜和共聚焦显微镜观察。结果 本研究显示PGP 9.5阳性神经纤维伴随鬼笔环肽标记的血管一道从耳廓的基部走行到其外围区域形成耳廓的神经血管网。在传统的免疫荧光染色技术基础上，后续的组织透明化技术可以更好地展示耳部皮肤中神经纤维和血管的形态学细节。结论 从方法学的角度来看，组织透明化技术增进了耳部皮肤中免疫荧光标记的可视性，它可能成为有效的技术手段用于解析正常和病理状态下耳部神经血管网的空间结构。