Nizielski S E, Levine A S, Morley J E, Hall K A, Gosnell B A
Physiol Behav. 1986;37(1):5-9. doi: 10.1016/0031-9384(86)90375-6.
Opioids are well recognized to modulate ingestive behaviors in a variety of species. To study the potential role of opioids in the alteration of ingestive behaviors that occur prior to hibernation, we have administered opiate agonists and the antagonist, naloxone, to the 13-lined ground squirrel (Spermophilus tridecemlineatus) during periods when they were hyperphagic and hypophagic. Naloxone consistently reduced feeding during both phases of the feeding cycle. Hypophagic animals, however, were 10 times more sensitive to the effects of naloxone. The effect of the opiate agonists (morphine and butorphanol, 1 and 10 mg/kg) on feeding also varied between seasons. The low dose of morphine produced a slight, but significant increase in feeding at one hour in hyperphagic animals, while the high doses tended to decrease feeding. When administered to hypophagic animals, feeding was decreased by both doses of each agonist. Immunoreactive (IR)-dynorphin levels in the cortex, hypothalamus and striatum were higher during the hypophagic phase compared with the hyperphagic phase. These data indicate that the 13-lined ground squirrel possesses an opiate sensitive feeding system which is affected by season.
阿片类药物在多种物种中调节摄食行为已得到广泛认可。为了研究阿片类药物在冬眠前发生的摄食行为改变中的潜在作用，我们在13条纹地松鼠（Spermophilus tridecemlineatus）处于多食和少食阶段时，给它们注射了阿片类激动剂和拮抗剂纳洛酮。纳洛酮在摄食周期的两个阶段均持续减少进食。然而，少食动物对纳洛酮的作用敏感度是多食动物的10倍。阿片类激动剂（吗啡和布托啡诺，1毫克/千克和10毫克/千克）对摄食的影响在不同季节也有所不同。低剂量吗啡在多食动物中于1小时时使进食量略有但显著增加，而高剂量则倾向于减少进食。当给少食动物注射时，两种激动剂的两种剂量均使进食量减少。与多食阶段相比，少食阶段皮质、下丘脑和纹状体中免疫反应性（IR）强啡肽水平更高。这些数据表明，13条纹地松鼠拥有一个受季节影响的阿片类敏感摄食系统。
