Alavi F K, McCann J P, Sangiah S, Mauromoustakos A
Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078-0353.
Domest Anim Endocrinol. 1991 Jan;8(1):109-15. doi: 10.1016/0739-7240(91)90045-l.
The dose-dependent effects of naloxone on feed intake, and plasma chemicals (insulin, glucose, FFA) purportedly involved in feed intake regulation, were determined in 16-hr fasted sheep that were lean and chronically fed maintenance. Dorset ewes (n = 5) were treated with 0 (saline), 0.3, 1 or 3 mg/kg of naloxone in a generalized randomized block experiment with at least 7 d between successive doses. Feed intakes and plasma insulin, glucose and FFA were determined frequently during 24 hr of ad libitum intake after each naloxone treatment. The 0.3, 1 and 3 mg/kg doses of naloxone reduced (P less than 0.01) the 4-hr feed intake by 30, 40, and 60% respectively, whereas the initial feed intake (10 min) was decreased (P less than 0.05) 45% only by 3 mg/kg naloxone. However, total 24-hr intakes were similar across all doses because intakes between 4 and 24 hr of feeding in sheep treated with 0.3 (839 g), 1.0 (802 g) and 3.0 (1330 g) mg/kg naloxone exceeded (P less than 0.01) that in saline-treated sheep (391 g). Feeding-induced changes in plasma insulin, glucose and FFA concentrations were independent of naloxone treatment, suggesting that endorphinergic control of feed intake may not involve coincidental changes in plasma insulin, glucose and FFA levels which are thought to play a role in systemic regulation of appetite in animals. The endorphinergic regulation of appetite in sheep may involve the central nervous system, rather than peripheral opiate mechanisms that utilize blood-borne signals. Further, the ability of naloxone to suppress appetite in sheep appears inversely related to the duration of fasting or severity of negative energy balance.
在长期维持性饲养且体型偏瘦的16小时禁食绵羊中，研究了纳洛酮对采食量以及据推测参与采食量调节的血浆化学成分（胰岛素、葡萄糖、游离脂肪酸）的剂量依赖性影响。在一项广义随机区组实验中，对多塞特母羊（n = 5）分别给予0（生理盐水）、0.3、1或3 mg/kg的纳洛酮，连续给药之间至少间隔7天。每次纳洛酮治疗后，在24小时自由采食期间频繁测定采食量以及血浆胰岛素、葡萄糖和游离脂肪酸水平。0.3、1和3 mg/kg剂量的纳洛酮分别使4小时采食量降低（P < 0.01）30%、40%和60%，而仅3 mg/kg纳洛酮使初始采食量（10分钟）降低（P < 0.05）45%。然而，所有剂量下的24小时总采食量相似，因为接受0.3（839 g）、1.0（802 g）和3.0（1330 g）mg/kg纳洛酮治疗的绵羊在4至24小时的采食量超过（P < 0.01）生理盐水处理的绵羊（391 g）。采食诱导的血浆胰岛素、葡萄糖和游离脂肪酸浓度变化与纳洛酮治疗无关，这表明内啡肽能对采食量的控制可能不涉及血浆胰岛素、葡萄糖和游离脂肪酸水平的同步变化，而这些物质被认为在动物食欲的全身调节中发挥作用。绵羊食欲的内啡肽能调节可能涉及中枢神经系统，而非利用血源信号的外周阿片机制。此外，纳洛酮抑制绵羊食欲的能力似乎与禁食时间或负能量平衡的严重程度呈负相关。
