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Abstract：
Serotonergic mechanisms hosted by raphe nuclei have important roles in affiliative and agonistic behaviors but the separate roles of the two nuclei are poorly understood. Here we studied the roles of the dorsal (DR) and median raphe region (MRR) in aggression by optogenetically stimulating the two nuclei. Mice received three 3 min-long stimulations, which were separated by non-stimulation periods of 3 min. The stimulation of the MRR decreased aggression in a phasic-like manner. Effects were rapidly expressed during stimulations, and vanished similarly fast when stimulations were halted. No carryover effects were observed in the subsequent three trials performed at 2-day intervals. No effects on social behaviors were observed. By contrast, DR stimulation rapidly and tonically promoted social behaviors: effects were present during both the stimulation and non-stimulation periods of intermittent stimulations. Aggressive behaviors were marginally diminished by acute DR stimulations, but repeated stimulations administered over 8 days considerably decreased aggression even in the absence of concurrent stimulations, indicating the emergence of carryover effects. No such effects were observed in the case of social behaviors. We also investigated stimulation-induced neurotransmitter release in the prefrontal cortex, a major site of aggression control. MRR stimulation rapidly but transiently increased serotonin release, and induced a lasting increase in glutamate levels. DR stimulation had no effect on glutamate, but elicited a lasting increase of serotonin release. Prefrontal serotonin levels remained elevated for at least 2 h subsequent to DR stimulations. The stimulation of both nuclei increased GABA release rapidly and transiently. Thus, differential behavioral effects of the two raphe nuclei were associated with differences in their neurotransmission profiles. These findings reveal a surprisingly strong behavioral task division between the two raphe nuclei, which was associated with a nucleus-specific neurotransmitter release in the prefrontal cortex.
摘要：
由中缝核介导的血清素能机制在辅助和激动行为中具有重要作用，但对两个核的单独作用知之甚少。在这里，我们通过光遗传学刺激两个核来研究背侧（DR）和正中缝区（MRR）在侵略中的作用。小鼠接受了三次3分钟长的刺激，它们被3分钟的非刺激期隔开。MRR的刺激以阶段性的方式降低了攻击性。效应在刺激期间迅速表达，当刺激停止时，同样迅速消失。在随后以2天间隔进行的三项试验中未观察到残留效应。没有观察到对社会行为的影响。相比之下,DR刺激迅速而调音地促进了社会行为：在间歇性刺激的刺激和非刺激期间都存在效应。急性DR刺激使攻击行为略有减少，但是，即使在没有并发刺激的情况下，8天的重复刺激也会大大降低攻击性，表明结转效应的出现。在社会行为的情况下没有观察到这种影响。我们还研究了刺激诱导的前额叶皮层神经递质释放，侵略控制的主要地点。MRR刺激迅速但短暂增加5-羟色胺释放，并导致谷氨酸水平持续增加。DR刺激对谷氨酸没有影响,但导致血清素释放持续增加。在DR刺激后，前额叶5-羟色胺水平至少保持升高2小时。两个细胞核的刺激迅速和短暂地增加了GABA的释放。因此，两个中缝核的不同行为效应与其神经传递谱的差异有关。这些发现揭示了两个中缝核之间惊人的强烈行为任务划分，这与前额叶皮层的核特异性神经递质释放有关。
