Marek P, Yirmiya R, Liebeskind J C
Department of Psychology, University of California, Los Angeles 90024.
Brain Res. 1991 Feb 8;541(1):154-6. doi: 10.1016/0006-8993(91)91090-n.
The effect of naloxone on periaqueductal gray matter (PAG) stimulation-produced analgesia (SPA) was examined in pentobarbital anesthetized Swiss-Webster mice. Electrodes were placed either in dorsolateral or ventrolateral PAG, and SPA threshold was assessed using the hind paw-flick test (paw withdrawal from radiant heat). SPA threshold did not differ between dorsal and ventral PAG, and naloxone equally attenuated SPA from both areas. SPA threshold for the paw contralateral to the stimulation site was half that for the ipsilateral paw. Elevation of SPA threshold by naloxone was greater for the contralateral than ipsilateral paw. Exposure to analgesic neck pinch prior to SPA almost completely abolished the antinociceptive effect of contralateral PAG stimulation without affecting SPA on the ipsilateral paw. This effect of pinch was itself reversed by prior naloxone administration. We suggest that the substrate of opioid mediated SPA from PAG in the mouse has principally a contralateral organization.
在戊巴比妥麻醉的瑞士韦伯斯特小鼠中，研究了纳洛酮对导水管周围灰质（PAG）刺激产生的镇痛作用（SPA）的影响。将电极置于背外侧或腹外侧PAG，使用后爪轻弹试验（爪子从辐射热中撤回）评估SPA阈值。背侧和腹侧PAG的SPA阈值没有差异，纳洛酮同样减弱了这两个区域的SPA。刺激部位对侧爪子的SPA阈值是同侧爪子的一半。纳洛酮对侧爪子的SPA阈值升高幅度大于同侧爪子。在SPA之前进行镇痛性颈部挤压几乎完全消除了对侧PAG刺激的抗伤害感受作用，而不影响同侧爪子的SPA。这种挤压效应本身可被预先给予的纳洛酮逆转。我们认为，小鼠中阿片类药物介导PAG的SPA的底物主要具有对侧组织。
