Bado A, Rozé C, Lewin M J, Dubrasquet M
INSERM U10, Hôpital Bichat, Paris, France.
Peptides. 1989 Sep-Oct;10(5):967-71. doi: 10.1016/0196-9781(89)90177-0.
In this report, we investigated the role of exogenous and endogenous enkephalins on food intake in the cat, using, respectively, exogenous [D-Ala2-Met5]-enkephalin (DAME) and acetorphan (Ac) in order to inhibit the degradation of endogenous enkephalins. In addition, the selective peripheral antagonist naltrexone methylbromide (NTxMB) and the nonselective antagonist naloxone (Nx) were used in an attempt to discriminate central and peripheral opioid receptors. In 18-hours food-deprived animals, Ac (5 mg/kg IV) increased milk intake during sham feeding (+18%, p less than 0.05), but did not modify it in feeding conditions. Nx (1 mg/kg SC) reduced milk intake in sham-feeding experiments (-67%, p less than 0.01) more than in milk-feeding conditions (-30%, p less than 0.01). NTxMB (1 mg/kg SC) did not modify milk intake in sham-feeding but decreased it in feeding experiments. In nonfasted animals, Ac did not modify food intake. IV infusion of DAME (50 micrograms/kg) resulted in a reduction of daily food intake (-32%, p less than 0.01). Nx (1 mg/kg SC) decreased the earlier 30 min intake followed by reduction of daily intake (-30%, p less than 0.01). NTxMB (1 and 4 mg/kg SC) increased the 30-min intake dose dependently, without significant change in daily intake. In conclusion, Ac increases food intake in sham-feeding conditions, suggesting that endogenous enkephalins are likely to be involved in the stimulation of food intake. The effects of Nx and NTxMB furthermore suggest both a central activation, and a peripheral inhibition of food intake by opiates when food is allowed to proceed normally through the digestive tract.
在本报告中，我们分别使用外源性[D - Ala2 - Met5] - 脑啡肽（DAME）和醋托芬（Ac）来抑制内源性脑啡肽的降解，研究了外源性和内源性脑啡肽对猫食物摄入量的作用。此外，使用选择性外周拮抗剂甲基溴化纳曲酮（NTxMB）和非选择性拮抗剂纳洛酮（Nx）来区分中枢和外周阿片受体。在禁食18小时的动物中，Ac（5毫克/千克静脉注射）在假饲期间增加了牛奶摄入量（增加18%，p小于0.05），但在进食条件下未改变牛奶摄入量。Nx（1毫克/千克皮下注射）在假饲实验中比在牛奶喂养条件下更能减少牛奶摄入量（分别减少67%，p小于0.01和30%，p小于0.01）。NTxMB（1毫克/千克皮下注射）在假饲时未改变牛奶摄入量，但在进食实验中使其减少。在未禁食的动物中，Ac未改变食物摄入量。静脉注射DAME（50微克/千克）导致每日食物摄入量减少（减少32%，p小于0.01）。Nx（1毫克/千克皮下注射）减少了最初30分钟的摄入量，随后每日摄入量也减少（减少30%，p小于0.01）。NTxMB（1和4毫克/千克皮下注射）剂量依赖性地增加了30分钟的摄入量，每日摄入量无显著变化。总之，Ac在假饲条件下增加食物摄入量，表明内源性脑啡肽可能参与食物摄入的刺激。此外，Nx和NTxMB的作用表明，当食物正常通过消化道时，阿片类药物对食物摄入既有中枢激活作用，也有外周抑制作用。
