降钙素作用于刺鼠相关蛋白神经元调控能量平衡的研究

Calcitonin acts on agouti-related peptide neurons to regulate energy balance

目的探讨降钙素通过刺鼠相关蛋白(AgRP)神经元发挥调控能量平衡的作用。方法将12周龄普通食物喂养雄性C57BL/6小鼠分为自由进食组和禁食24 h组,6周龄雄性C57BL/6小鼠分为普通食物组和高脂食物组(喂养3个月),每组3只,采用免疫荧光染色法检测脑组织切片降钙素受体(Calcr)的表达。12只6周龄雄性C57BL/6小鼠通过高脂食物喂养6个月构建高脂食物喂养小鼠模型,侧脑室置管后将小鼠分为生理盐水侧脑室注射组(侧脑室注射1μl生理盐水)和鲑鱼降钙素(sCT)侧脑室注射组[侧脑室注射1μl sCT(1μg/μl)],每组6只,测定各组小鼠注射后24 h的体重和进食量,并采用Oxymax/CLAMS代谢笼测定小鼠的氧气消耗量、二氧化碳生成量和能量消耗。将12周龄普通食物喂养雄性C57BL/6小鼠分为生理盐水腹腔注射组(腹腔注射,10 ml/kg)和sCT腹腔注射组(腹腔注射,150μg/kg),每组3只,采用免疫荧光染色法检测脑组织切片AgRP、c-Fos、磷酸化信号转导子和转录激活子3(pStat3)的表达。采用独立样本t检验比较组间差异。结果与自由进食组相比,禁食24 h组弓状核Calcr表达明显下降(P<0.05)。与普通食物组相比,高脂食物组下丘脑弓状核Calcr表达明显下降(P<0.05)。与生理盐水侧脑室注射组相比,sCT侧脑室注射组体重和进食量明显减少(P<0.05),而氧气消耗量、二氧化碳生成量及能量消耗明显升高(P<0.05)。与生理盐水腹腔注射组相比,sCT腹腔注射组弓状核AgRP和c-Fos的共染明显减少,室旁核AgRP表达明显减少而室旁核c-Fos表达明显增多,弓状核pStat3表达明显增多(P<0.05)。结论弓状核Calcr与能量平衡密切相关。降钙素可通过Stat3通路抑制AgRP表达,抑制AgRP神经元活性,进而抑制食欲、促进能量消耗。

Objective To investigate whether calcitonin can regulate energy balance via agouti-related peptide(AgRP)neurons.Methods The 12-week-old male C57BL/6 mice fed normal chow diet were divided into free-feeding group and 24-h fasting group,while 6-week-old male C57BL/6 mice were divided into normal chow diet group and high-fat diet group fed for 3 months,with three mice in each group,and the expression of calcitonin receptor(Calcr)in brain sections was detected by immunofluorescence staining.Twelve 6-week-old male C57BL/6 mice were fed with high-fat diet for 6 months to establish a high-fat diet-fed mouse model.After lateral ventricular cannulation,the mice were divided into saline lateral ventricular injection group(lateral ventricular injection of 1μl saline)and salmon calcitonin(sCT)lateral ventricular injection group[lateral ventricular injection of 1μl sCT(1μg/μl)],with six mice in each group.Body weight and food intake were measured for 24 hours after injection.Oxygen consumption,carbon dioxide production and energy expenditure were measured after injection by Oxymax/CLAMS indirect calorimetry system.The 12-week-old normal chow diet-fed male C57BL/6 mice were divided into saline intraperitoneal injection group(intraperitoneal injection,10 ml/kg)and sCT intraperitoneal injection group(intraperitoneal injection,150μg/kg),with three mice in each group,and the expression of AgRP,c-Fos,phosphorylated signal transducer and transcriptional activator 3(pStat3)in brain sections was detected by immunofluorescence staining.Independent-samples t test was used for comparison between two groups.Results Compared with free-feeding group,Calcr expression in the arcuate nucleus was significantly decreased in 24-h fasting group(P<0.05);compared with normal chow diet group,Calcr expression in the hypothalamic arcuate nucleus was significantly decreased in high-fat diet group(P<0.05).Compared with saline lateral ventricular injection group,body weight and food intake were significantly reduced in sCT lateral ventricular injection group(P<0.05),while oxygen consumption,carbon dioxide production and energy expenditure were significantly increased in sCT lateral ventricular injection group(P<0.05).Compared with saline intraperitoneal injection group,double immunofluorescence staining of AgRP and c-Fos in the arcuate nucleus was significantly decreased,AgRP expression in the paraventricular nucleus was significantly decreased,and c-Fos expression in the paraventricular nucleus was significantly increased in sCT intraperitoneal injection group(P<0.05).Compared with saline intraperitoneal injection group,the expression of pStat3 in the arcuate nucleus was significantly increased in sCT intraperitoneal injection group(P<0.05).Conclusions Calcr in the arcuate nucleus is closely related to energy balance.Calcitonin can inhibit the expression of AgRP and the activity of AgRP neurons via Stat3 pathway,which in turn suppresses appetite and promotes energy expenditure.