Khan I A, Joy K P
Centre of Advanced Study in Zoology, Banaras Hindu University, Varanasi, India.
J Pineal Res. 1990;8(3):277-87. doi: 10.1111/j.1600-079x.1990.tb00687.x.
In Channa punctatus, day-night variations in hypothalamic 5-HT (serotonin) and monoamine oxidase (MAO) activity were noticed in preparatory but not other phases (prespawning and postspawning) of the annual reproductive cycle. Hypothalamic MAO, 5-HT, and norepinephrine (NE) activity was found to be high in the prespawning phase and low in the postspawning phase. Dopamine (DA) activity, on the other hand, was high in the postspawning season and low in the prespawning phase. Pinealectomy caused season-dependent effects on hypothalamic monoaminergic activity, with a significant increase in serotonergic activity and a significant reduction in MAO activity at midscotophase during the preparatory phase (March) but not in the prespawning (May-June) or postspawning (September) phases. Hypothalamic catecholaminergic (CA) activity was not influenced by pinealectomy during any of the seasons. To determine whether or not the photoperiodic influences on daily variations of 5-HT and MAO in the preparatory phase are mediated via pineal and/or lateral eyes, fish were pinealectomized and/or blinded in January, when there is no rhythm, and sacrificed in February, when a day-night variation normally sets in. The day-night difference in 5-HT content and activity and MAO activity was not abolished by pinealectomy or blinding alone; but the combination (pinealectomy + blinding) obliterated the daily variation only in 5-HT content and in MAO activity. However, pinealectomy and blinding, alone or in combination, caused a significant elevation of 5-HT activity (not its level) and a significant decrease in MAO activity at midscotophase, with the combination having an additive effect. Hypothalamic CA content or activity was not affected by these regimes. The results show that photoperiodic influence on the daily pattern of 5-HT and MAO activity is mediated through and by the interaction of the pineal and lateral eyes.
在斑鳢中，下丘脑5-羟色胺（血清素）和单胺氧化酶（MAO）活性的昼夜变化在年度繁殖周期的准备阶段被观察到，而在其他阶段（产卵前和产卵后）则未观察到。发现下丘脑MAO、5-羟色胺和去甲肾上腺素（NE）活性在产卵前阶段较高，而在产卵后阶段较低。另一方面，多巴胺（DA）活性在产卵后季节较高，而在产卵前阶段较低。松果体切除对下丘脑单胺能活性产生季节依赖性影响，在准备阶段（3月）的午夜黑暗期，血清素能活性显著增加，MAO活性显著降低，但在产卵前（5 - 6月）或产卵后（9月）阶段则没有这种情况。在任何季节，松果体切除都不会影响下丘脑儿茶酚胺能（CA）活性。为了确定光周期对准备阶段5-羟色胺和MAO每日变化的影响是否通过松果体和/或侧眼介导，在1月（此时没有节律）对鱼进行松果体切除和/或致盲，并在2月（此时昼夜变化通常开始）将其处死。单独的松果体切除或致盲并没有消除5-羟色胺含量和活性以及MAO活性的昼夜差异；但联合处理（松果体切除 + 致盲）仅消除了5-羟色胺含量和MAO活性的每日变化。然而，单独或联合的松果体切除和致盲在午夜黑暗期导致5-羟色胺活性（而非其水平）显著升高，MAO活性显著降低，联合处理具有累加效应。这些处理方式均未影响下丘脑CA含量或活性。结果表明，光周期对5-羟色胺和MAO活性每日模式的影响是通过松果体和侧眼的相互作用介导的。
