Physiological analysis of the role of PACAP using transgenic and knockout mice

本研究利用本实验室新培育的PACAP基因敲除小鼠(PACAP^&lt；-/-&gt；)、胰腺高表达PACAP的转基因小鼠(PACAP-TG)和PACAP(PAC_1)受体外显子2靶向的小鼠(PAC_1^&lt；-/-&gt；)，研究了内源性PACAP在中枢和外周神经系统中的生理和病理生理作用。通过这些体内诱变研究，我们获得了以下结果。精神运动功能(1)PACAP^&lt；-/-&gt；；小鼠在旷野表现出过度活跃和爆炸性跳跃行为，探索性行为增加，焦虑减少。这些异常行为可被抗精神病药物和SSRI改善。(2)PACAP小鼠表现出明显的脉冲前抑制声惊厥反应的损害。这些结果提供了PACAP在精神运动行为调节中发挥先前未知的作用的证据，并表明PACAP小鼠的表型在一定程度上类似于人类的sc…更多的精神分裂症和/或注意力缺陷/多动障碍(ADHD)。海马区功能PACAP^&lt；-/-&gt；小鼠和PAC_1^&lt；-/-&gt；小鼠表现出海马长时程增强(LTP)的损害。此外，行为学研究还揭示了海马区依赖联想学习的缺陷，暗示PACAP能神经元参与了高级脑功能的调节。疼痛传递神经病理性和炎症性疼痛模型中的痛觉过敏和痛觉过敏在PACAP^&lt；-/-&gt；小鼠中显著减少。PACAP^&lt；-/-&gt；小鼠视交叉上核(SCN)中光诱导的时相重置和c-Fos表达减弱，凸显了PACAP在体内对昼夜节律性光携带的作用。血糖和胰岛素稳态(1)转基因PACAP改善链脲佐菌素诱导的糖尿病。值得注意的是，在链脲佐菌素治疗的PACAP-TG小鼠中，5-溴-2-脱氧尿苷(BrdU)阳性的β细胞增加。(2)我们将PACAP-TG小鼠与致死的黄色kka^y小鼠杂交，这是一种肥胖-糖尿病的遗传模型。Kka^y小鼠表现出明显的高血糖，并伴有代偿性高胰岛素血症和胰岛增生；然而，在携带PACAP转基因的kka^y小鼠中，高胰岛素血症和胰岛增生都显著受到抑制。本研究结果表明，PACAP对I型糖尿病和肥胖相关(II型)糖尿病具有保护作用，并可能参与了β细胞的新生。这是首次报道PACAP在体内对胰岛增殖和β细胞新生的作用，为与PACAP信号通路相关的药物治疗糖尿病提供了可能性。较少

This study examined the physiological and pathophysiological roles of endogenous PACAP in the central and peripheral nervous system using PACAP gene knockout (PACAP^<-/->) mice, transgenic mice overexpressing PACAP in the pancreas (PACAP-Tg), and PACAP (PAC_1) receptor exon 2-targeted (PAC_1^<-/->) mice which were recently generated in this laboratory. Through these in vivo mutagenesis studies, we obtained the following results.1. Psychomotor function(1) PACAP^<-/-> mice exhibited hyperactive and explosive jumping behaviors in an open field, and increased exploratory behavior and less anxiety. These aberrant behaviors are ameliorated by the antipsychotic drug and SSRI.(2) PACAP^<-/-> mice exhibited a significant impairment of prepulse inhibition of the acoustic startle response.These results provide evidence that PACAP plays a previously uncharacterized role in the regulation of psychomotor behaviors and suggest that the phenotype of PACAP^<-/-> mice in part resembles those in human sc … More hizophrenia and/or attention deficit/hyperactivity disorder (ADHD).2. Hippocampal functionPACAP^<-/-> mice and PAC_1^<-/-> mice showed an impairment of hippocampal long-term potentiation (LTP). In addition, the behavioral study revealed a deficit in hippocampus-dependent associative learning, implicating PACAP-ergic neurons in regulation of higher brain functions.3. Pain transmissionAllodynia and hyperalgesia in the neuropathic and inflammatory pain models were significantly reduced in PACAP^<-/-> mice.4. Circadian rhythmThe light-induced phase resetting and c-Fos expression in the suprachiasmatic nucleus (SCN) were attenuated in PACAP^<-/-> mice, highlighting the in vivo role of PACAP in circadian photoentrainment.5. Glucose and insulin homeostasis(1) The PACAP transgene ameliorated streptozotocin-induced diabetes in PACAP-Tg mice. Notably, an increase in 5-bromo-2-deoxyuridine (BrdU)-positive β cells in the streptozotocin-treated PACAP-Tg mice was observed.(2) We crossed PACAP-Tg and lethal yellow KKA^y mice, a genetic model for obesity-diabetes. KKA^y mice showed marked hyperglycemia associated with compensatory hyperinsulinaemia and islet hyperplasia; however, both hyperinsulinemia and islet hyperplasia were significantly suppressed in KKA^y mice carrying the PACAP transgene.The present data suggest a protective role for PACAP against type I diabetes as well as obesity-associated (type II) diabetes, and the possible involvement of PACAP in the β cell neogenesis. This is the first report suggesting in vivo roles of PACAP on islet hyperplasia and β cell neogenesis, providing the possibility that drugs associated with PACAP-signaling pathways might be of therapeutic value for the treatment of diabetes. Less