Tyrosine Hydroxylase Expression in Differentiating Neurons of theRat Arcuate Nucleus: Stimulatory Influence of Serotonin Afferents

[摘要] The influence of serotonin afferents ontyrosine hydroxylase expression in differentiatingneurons of the rat arcuate nucleus was studiedin vivo and in vitro. In the in vivo study, pchlorophenylalanineinhibited serotonin synthesisin fetal brain from the11thto the20thembryonicday. We then used semiquantitative immunocytochemistryto evaluate tyrosine hydroxylaselevels in neurons of the arcuate nucleus infetuses at the21stembryonic day or in offspringat the35thpostnatal day. Serotonin depltionsignificantly decreased the tyrosine hydroxylasecontent in neurons of males and females at the21stembryonic day and in males at the35thpostnatal day. For the in vitro study, embryonicneurons of the arcuate nucleus were coculturedwith embryonic neurons of the raphenucleus, the main source of serotonin innervationof the brain, including the arcuate nucleus.Co-culture of the neurons resulted in a genderspecificincrease of the tyrosine hydroxylaselevel in the neurons of the arcuate nucleus. Inturn, the neurons of the raphe nucleus showedincreased levels .of serotonin in both males andfemales, with no sexual dimorphism. Thus, ourresults suggest a stimulatory, long-lasting effectof serotonin afferents on tyrosine hydroxylaseexpression in the differentiating neurons of therat arcuate nucleus during prenatal ontogenesis.

[学科分类] 精神健康和精神病学