Blass E M, Shide D J, Zaw-Mon C, Sorrentino J
Department of Psychology, Cornell University, Ithaca, New York 14853, USA.
Behav Neurosci. 1995 Apr;109(2):342-53. doi: 10.1037//0735-7044.109.2.342.
To determine how rat mothers protect their pups against pain, we applied focal heat (34-51 degrees C) to the ear or shoulder of 10-day-old rats that were isolated, in contact among themselves or with their mother, suckling nonnutritively, or in the hyperextension position normally caused by milk letdown. Relative to isolated rats, contact doubled withdrawal latencies from heat (43 or 45 degrees C) applied to the ear. Suckling quadrupled heat-escape latencies. During hyperextension, rats essentially did not escape from thermal stimulation of up to 48 degrees C. Protection provided by maternal contact, especially suckling, was not mediated by either mu or kappa opioid receptors: neither systemic injections of naltrexone nor norbinaltorphimine reduced heat-escape latencies. Morphine (0.125 and 0.250 mg/kg) added to the effects of contact but multiplied the effects of suckling to produce heat-escape latencies that were upward of 2 min.
为了确定大鼠母亲如何保护幼崽免受疼痛，我们对10日龄的大鼠耳部或肩部施加局部热刺激（34 - 51摄氏度），这些大鼠处于隔离状态、相互接触、与母亲接触、非营养性吸吮或处于通常由乳汁排出引起的过度伸展姿势。相对于隔离的大鼠，接触使施加于耳部的热刺激（43或45摄氏度）的撤回避热潜伏期增加了一倍。吸吮使热逃避潜伏期增加了四倍。在过度伸展期间，大鼠基本上不会逃避高达48摄氏度的热刺激。母体接触，尤其是吸吮所提供的保护，并非由μ或κ阿片受体介导：全身注射纳曲酮或诺宾那托啡都不会降低热逃避潜伏期。吗啡（0.125和0.250毫克/千克）增强了接触的效果，但使吸吮的效果加倍，从而产生超过2分钟的热逃避潜伏期。
