下丘脑外侧区-伏隔核orexin通路对大鼠胃动力及奖赏性摄食的作用

Effects of LHA-NAc orexinergic pathway on gastric motility and reward feeding in rats

目的:探讨从下丘脑外侧区(LHA)到伏隔核(NAc)的orexin通路对胃动力及奖赏性摄食的调控作用。方法:(1)随机选取48只大鼠,按照随机数字表法分为6组,每组8只,分别为生理盐水组(NS组)、1μg orexin-A组、5μg orexin-A组、10μg orexin-A组、20μg orexin受体拮抗剂(SB334867)组、20μg SB334867+5μg orexin-A组,采用大鼠NAc核团埋置套管注射orexin-A及SB334867的方法,观察大鼠胃收缩的频率和幅度;(2)随机选取32只大鼠,按照随机数字表法分为4组,每组8只,分别为:生理盐水+假刺激组(NS+SS组)、生理盐水+电刺激组(NS+ES组)、SB334867(20μg)+假刺激组(SB334867+SS组)、SB334867(20μg)+电刺激组(SB334867+ES组),采用电刺激大鼠LHA及大鼠NAc注射SB334867的方法,观察大鼠胃收缩的频率和幅度;(3)随机选取32只大鼠,按照随机数字表法分为4组,每组8只,分别为NS组、orexin-A(5μg)组(orexin-A组)、SB334867(20μg)组(SB334867组)、orexin-A(5μg)+SB334867(20μg)组(orexin-A+SB334867组),采用大鼠NAc核团埋置套管注射orexin-A及SB334867的方法,观察大鼠与摄食行为有关的条件性位置偏爱(conditioned place preference,CPP)或者胃功能(比如胃排空或者胃分泌);(4)随机选取32只大鼠,按照随机数字表法分为4组,每组8只,分为生理盐水+假刺激组(NS+SS组)、生理盐水+电刺激组(NS+ES组)、SB334867(20μg)+假刺激组(SB334867+SS组)、SB334867(20μg)+电刺激组(SB334867+ES组),采用电刺激大鼠LHA及大鼠NAc注射SB334867的方法,观察大鼠与摄食行为有关的CPP或者胃功能(比如胃排空或者胃分泌)。结果:(1)胃收缩活动记录结果显示,NAc微量注射orexin-A和电刺激LHA均显著增加了大鼠胃收缩的幅度和频率,并且这种作用可被NAc预注射SB334867阻断[给予orexin-A后10 min:10μg orexin-A组(60.78±5.67)%,NS组(7.35±1.08)%;t=26.18,P<0.05]。(2)胃排空实验结果显示,NAc微量注射orexin-A以及电刺激LHA均可使胃排空的速度显著升高,SB334867预处理可阻断该作用[电刺激LHA:NS+SS组(71.18±17.78)%,NS+ES组(132.23±31.18)%;t=4.81,P<0.05]。(3)胃分泌实验结果显示,NAc微量注射orexin-A和电刺激LHA均可使胃酸分泌量显著增多,且这种作用可被NAc中预注射SB334867阻断[给予orexin-A后90 min:orexin-A组(100.18±23.23),NS组(39.23±7.69);t=7.05,P<0.05]。(4)CPP实验结果显示,NAc微量注射orexin-A或电刺激LHA后,大鼠在放置巧克力的隔间里时间更久,而这种现象可被NAc中SB334867预处理阻断[电刺激LHA:NS+SS组(36.23±6.23)%,NS+ES组(53.36±6.66)%;t=5.31,P<0.05]。结论:从LHA到NAc存在orexin神经通路,这条通路可能对胃功能和奖赏性摄食具有调节作用。

Objective:To investigate the regulation of orexinergic pathway from the lateral hypothalamic area(LHA)to the nucleus accumbens(NAc)on gastric function and reward feeding.Methods:(1)Forty-eight rats were randomly selected and divided into six groups:normal saline(NS)group,1μg orexin-A group,5μg orexin-A group,10μg orexin-A group,20μg orexin receptor antagonist(SB334867)group,20μg SB334867+5μg orexin-A group with eight in each group according to the random number table.The gastric motility of rats was observed by injecting orexin-A and SB334867 into NAc.(2)Thirty-two rats were randomly selected and divided into four groups according to the random number table,with eight in each group.They were divided into NS+sham stimulation(SS)group,NS+electrical stimulation(ES)group,SB334867(20μg)+SS group,and SB334867(20μg)+ES group.The gastric motility of rats were observed by electro-stimulation of rat LHA and rat NAc injection of SB334867.(3)In order to observe the feeding-behavior related conditioned place preference(CPP)and gastric function(such as gastric emptying and gastric secretion),thirty-two rats were randomly divided into four groups with eight in each group by using the method of NAc injection of orexin-A and SB334867 according to the random number table:NS group,orexin-A(5μg),SB334867(20μg),SB334867(20μg)+orexin-A(5μg).(4)Thirty-two rats were randomly selected in accordance with the random number table and divided into four groups with eight in each group:NS+SS group,NS+ES group,SB334867(20μg)+SS group,SB334867(20μg)+ES group,using electro-stimulation of rat LHA and rat NAc injection of SB334867,observing the feeding-behavior related CPP and gastric function(such as gastric emptying and gastric secretion).Results:(1)In the gastric motility experiment,both the NAc microinjection of orexin-A and electrical stimulation of the LHA significantly increased the amplitudes and frequencies of gastric contraction in rats,and these effects could be blocked by the pre-administration of SB334867(10 min after administration of orexin-A:10μg orexin-A group(60.78±5.67)%vs NS group(7.35±1.08)%;t=26.18,P<0.05).(2)The results of gastric emptying showed that the rates of gastric emptying were significantly increased by the NAc microinjection of orexin-A and electrical stimulation of LHA,which were blocked by the SB334867 pretreatment(after electrical stimulation of LHA:NS+SS group(71.18±17.78)%vs NS+ES group(132.23±31.18)%;t=4.81,P<0.05).(3)Orexin-A microinjection in the NAc and electrical stimulation of the LHA significantly increased gastric acid secretion,and these effects could be blocked by pre-injection of SB334867 in NAc(90 minutes after administration of orexin-A:orexin-A group(100.18±23.23)vs NS group(39.23±7.69);t=7.05,P<0.05)in the gastric secretion experiment.(4)The results of CPP showed that the rats were kept in the chocolate compartment for a longer time after the NAc microinjection of orexin-A and electrical stimulation of the LHA,which could be blocked by the SB334867 pretreatment in NAc(after LHA was electrically stimulated:NS+SS group(36.23±6.23)%vs NS+ES group(53.36±6.66)%;t=5.31,P<0.05).Conclusion:There is an orexinergic pathway from LHA to NAc that may regulate gastric function and food reward.