Objective To investigate the opioidergic mechanism of the central nucleus of the amygdala (CeA) for regulating sodium appetite in rats.Methods Using the elaborate invasive cerebral cannulation and brain microinjection method,we observed the effects of bilateral intra-CeA injections of DAMGO (a selective μ-opioid receptor agonist) and CTAP (a highly selective μ-opioid receptor antagonist),either alone or in combination,on NaCl solution (0.3 mol/L) and water intake by rats in different models of Na+ ingestion.Results In the two-bottle tests,bilateral injections of DAMGO at 1,2,and 4 nmol into the CeA induced a dose-related increase of NaCl and water intake in rats treated with water deprivation with partial rehydration (WD-PR),and pretreatment with 0.5,1,and 2 nmol CTAP injected into the CeA significantly suppressed DAMGO-induced NaCl and water intake in a dose-dependent manner:in the one-bottle tests,bilateral injections of DAMGO (2 noml) into the CeA had no effect on water intake of the rats.In rats with subcutaneous injection of furosemide (FURO) combined with captopril (CAP) (FURO+CAP),bilateral intra-CeA injections of DAMGO (2 nmol) caused increased NaCl and water intake in the two-bottle tests,but such effects were suppressed by pretreatment with CTAP injection into the CeA;in the one-bottle tests,bilateral intra-CeA injections of DAMGO had no effect on water intake of the rats.Conclusion μ-opioid receptors in the CeA are involved in the excitatory regulation of sodium appetite to mediate sodium intake.μ-opioid receptor antagonists are expected to be targets for developing inhibitors of sodium appetite.%目的 探讨杏仁中央核参与钠欲中枢调控的阿片能机制.方法 应用大脑插管术和脑微量注射法给大鼠双侧杏仁中央核内单独或联合注射选择性μ-阿片受体激动剂DAMGO和选择性μ-阿片受体拮抗剂CTAP,观察不同的摄钠模型大鼠对0.3 mol/LNaCl和水摄入的影响.结果 在“禁水-不完全补水(WD-PR)”摄钠模型大鼠,在双瓶测试中,双侧杏仁中央核内分别注射1、2、4 nmol剂量的DAMGO引起剂量依赖性的0.3 mol/L NaC1和水摄入增加的效应,而双侧杏仁中央核内分别注射0.5、l、2nnol剂量的CTAP则产生剂量依赖性的抑制DAMGO 2 nmol注射到同一部位所引起的0.3 mol/L NaCl和水摄入增加的效应;在单瓶测试中,双侧杏仁中央核内注射DAMGO 2 nmol对水摄入量没有影响.在“皮下联合注射利尿剂呋塞米(FURO)与血管紧张素转换酶抑制剂卡托普利(CAP)”摄钠模型大鼠,双侧杏仁中央核内注射2 nmol剂量的DAMGO引起0.3 mol/L NaCl和水摄入增加,而双侧杏仁中央核内注射1 nmol CTAP阻断μ-阿片受体则降低了DAMGO 2 nmol注射到同一部位所引起的0.3 mol/LNaCl和水摄入增加的效应;在单瓶测试中,双侧杏仁中央核内注射DAMGO 2 nmol对水摄入量没有影响.结论 杏仁中央核μ-阿片受体介导钠盐摄入,参与钠欲的兴奋性调控;μ-阿片受体阻断剂有望成为研发钠欲抑制剂的靶标.
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