Martynhak Bruno Jacson, Kanazawa Luiz Kae Sales, Messias do Nascimento Guilherme, Andreatini Roberto
Departamento de Farmacologia, Universidade Federal do Paraná Cel. Francisco H. dos Santos, Centro Politécnico, Curitiba, Paraná 81530-900, Brazil.
Departamento de Farmacologia, Universidade Federal do Paraná Cel. Francisco H. dos Santos, Centro Politécnico, Curitiba, Paraná 81530-900, Brazil.
Neurosci Lett. 2015 Feb 19;588:7-11. doi: 10.1016/j.neulet.2014.12.042. Epub 2014 Dec 26.
Circadian rhythm disruptions are often observed in depressed patients, and changes in the light/dark cycle promote depressive-like behavior in animal models. Prolonged exposure to constant light (LL) is known to lead to arrhythmicity of circadian locomotor activity and depressive-like behavior in rats. Interestingly, neonatal exposure to LL prevents both arrhythmicity and depressive behavior in adulthood. Arrhythmic rats under LL conditions that cohabitate with a rhythmic rat exhibit improvement in circadian rhythms. We tested whether such cohabitation also protects against LL-induced depressive-like behavior. Wistar rats were assigned to conditions of either neonatal constant light (neonatal-LL) on postnatal days 10-22 or a regular light/dark cycle (neonatal-LD). On day 45, the animals were assigned to three possible pair combinations. After a baseline sucrose preference test, half of the pairs were placed under LL conditions. Weekly sucrose preference tests were conducted to evaluate depressive-like behavior. The animals were isolated by an aluminum wall on the test day. At week 2 of LL, sucrose preference was reduced in neonatal-LD/neonatal-LD pairs of animals. At week 5, neonatal-LD/neonatal-LD pairs exhibited anhedonic-like behavior, but the pairs with at least one neonatal-LL rat did not. The LL cycle was returned to an LD cycle, and the neonatal-LD/neonatal-LD pairs exhibited a restoration of sucrose preference 2 weeks later. We conclude that social interaction can prevent depressive-like behavior induced by circadian rhythm disruption as long as one of the animals is more prone to present a strong rhythm.
在抑郁症患者中经常观察到昼夜节律紊乱，而光/暗周期的变化会在动物模型中引发类似抑郁的行为。已知长时间暴露于持续光照（LL）会导致大鼠昼夜运动活动节律紊乱和出现类似抑郁的行为。有趣的是，新生大鼠暴露于LL可预防成年后的节律紊乱和抑郁行为。在LL条件下与节律正常的大鼠同居的节律紊乱大鼠，其昼夜节律会有所改善。我们测试了这种同居是否也能预防LL诱导的类似抑郁的行为。将Wistar大鼠分为两组，一组在出生后第10 - 22天处于新生持续光照（新生-LL）条件下，另一组处于正常光/暗周期（新生-LD）条件下。在第45天，将动物分配到三种可能的配对组合中。在进行基线蔗糖偏好测试后，一半的配对被置于LL条件下。每周进行蔗糖偏好测试以评估类似抑郁的行为。测试当天用铝壁将动物隔开。在LL条件下的第2周，新生-LD/新生-LD配对的动物蔗糖偏好降低。在第5周，新生-LD/新生-LD配对的动物表现出快感缺失样行为，但至少有一只新生-LL大鼠的配对则没有。将LL周期恢复为LD周期后，新生-LD/新生-LD配对的动物在2周后蔗糖偏好恢复。我们得出结论，只要其中一只动物更容易呈现强烈的节律，社交互动就可以预防昼夜节律紊乱诱导的类似抑郁的行为。
