Vickers C, Paterson A T
Life Sci. 1986 Jul 7;39(1):47-53. doi: 10.1016/0024-3205(86)90436-4.
The male C57BL/6 mice used in this study were the offspring either of untreated or lead treated (0.1% lead acetate (PbAc) instead of drinking water) parents. Offspring of lead treated parents were reared on 0.1% PbAc until weaning, and also given 0.5% PbAc to drink for 3 weeks prior to testing (Pb2 group). Offspring of untreated parents were either given 0.5% PbAc to drink (Pb1 group) or maintained on tap water throughout (Control group). Control (C) and lead treated mice were subdivided according to single- or group-housing; no confrontation ("unfought") or confrontation with a trained aggressor mouse ("defeated"). All the mice were then given a hot-plate pain test, in which paw-lick and escape latencies were recorded. In untreated mice, latencies were reduced after defeat. This effect was not seen in lead treated animals. Lead treatment increased latencies in most instances relative to the appropriate control group. The paw-lick latencies were less consistently affected than the escape latencies. Escape latencies, with one exception, were longer in the Pb2 group than in the Pb1 group. Treatment with naloxone of single-housed C and Pb2 was without effect, except for Pb2 treated undefeated mice: here, naloxone abolished the analgesic effect of lead treatment. Lead-induced analgesia is discussed in terms of central mechanisms of pain reception.
本研究中使用的雄性C57BL/6小鼠是未处理或经铅处理（用0.1%醋酸铅（PbAc）替代饮用水）的亲代的后代。经铅处理的亲代的后代在0.1% PbAc中饲养至断奶，并在测试前3周给予0.5% PbAc饮用（Pb2组）。未处理亲代的后代要么给予0.5% PbAc饮用（Pb1组），要么全程给予自来水（对照组）。对照组（C）和经铅处理的小鼠根据单笼饲养或群居进行细分；无对抗（“未争斗”）或与经过训练的攻击小鼠对抗（“战败”）。然后对所有小鼠进行热板疼痛测试，记录舔爪潜伏期和逃避潜伏期。在未处理的小鼠中，战败后潜伏期缩短。在经铅处理的动物中未观察到这种效应。在大多数情况下，与相应的对照组相比，铅处理延长了潜伏期。舔爪潜伏期受到的影响不如逃避潜伏期一致。除一个例外，Pb2组的逃避潜伏期比Pb1组长。对单笼饲养的C组和Pb2组用纳洛酮处理无效，但对经Pb2处理的未战败小鼠除外：在此，纳洛酮消除了铅处理的镇痛作用。从疼痛感受的中枢机制方面讨论了铅诱导的镇痛作用。
