Bryant H U, Lowy M T, Malven P V, Steele T D, Yim G K
Pharmacol Biochem Behav. 1985 Sep;23(3):391-5. doi: 10.1016/0091-3057(85)90011-5.
Dynorphin is one of the most potent appetite stimulants among the endogenous opioids. In this study, we describe the anorexic effects of 5 days of forced 2% NaCl drinking in rats, a regimen which depletes vasopressin as well as dynorphin in the neurohypophysis. Feeding induced by direct activation of kappa-opioid receptors with ketocyclazocine was unaffected by the NaCl regimen. However, 2% NaCl imbibition reduced 2-deoxy-D-glucose (2-DG) induced feeding by 65% and spontaneous nocturnal feeding by 38%. Feeding subsequent to 24 hour food deprivation was not decreased. Naloxone-resistant hyperphagia induced by insulin and spontaneous daytime feeding were also not reduced. The combination of naloxone (3.0 mg/kg) and the NaCl regimen produced an additional 50% reduction in 2-DG induced feeding and an extra 40% decrease in nocturnal feeding. Naloxone, given with 2% NaCl to food deprived animals, retained its appetite suppressing activity, indicating that the NaCl regimen did not deplete the endogenous opioid which mediates food deprivation hyperphagia. These results demonstrate that 2% NaCl imbibition suppresses certain opioid mediated hyperphagias. However, the failure of 2% NaCl to affect all of the naloxone-sensitive types of feeding and the independence of naloxone-sensitive and NaCl-sensitive components suggests that NaCl drinking does not deplete dynorphin in the brain areas which mediate opiate-sensitive hyperphagias.
强啡肽是内源性阿片类物质中最有效的食欲刺激剂之一。在本研究中，我们描述了大鼠连续5天强制饮用2%氯化钠溶液的厌食作用，该方案会消耗神经垂体中的血管加压素和强啡肽。用酮环佐辛直接激活κ-阿片受体诱导的进食不受氯化钠方案的影响。然而，饮用2%氯化钠溶液使2-脱氧-D-葡萄糖（2-DG）诱导的进食减少了65%，夜间自发进食减少了38%。禁食24小时后的进食并未减少。胰岛素诱导的纳洛酮抵抗性多食和白天自发进食也未减少。纳洛酮（3.0毫克/千克）与氯化钠方案联合使用，使2-DG诱导的进食额外减少了50%，夜间进食额外减少了40%。给禁食动物同时给予纳洛酮和2%氯化钠溶液，纳洛酮仍保留其食欲抑制活性，这表明氯化钠方案并未耗尽介导禁食性多食的内源性阿片类物质。这些结果表明，饮用2%氯化钠溶液可抑制某些阿片类物质介导的多食。然而，2%氯化钠未能影响所有对纳洛酮敏感的进食类型，且纳洛酮敏感成分和氯化钠敏感成分相互独立，这表明饮用氯化钠溶液并不会耗尽介导阿片类物质敏感型多食的脑区中的强啡肽。
