Vanhatalo S, Soinila S, Kaartinen K, Bäck N
Department of Anatomy, University of Helsinki, Finland.
Brain Res. 1995 Jan 16;669(2):275-84. doi: 10.1016/0006-8993(94)01276-n.
The nerve terminals in the intermediate and posterior lobes of the rat pituitary gland are reported to show colocalization of serotonin and tyrosine hydroxylase. This study examined the extent of this colocalization in the pituitary gland and in the nuclei considered to project to the pituitary. In the intermediate lobe, two types of nerve fibers were encountered, one containing serotonin (5-HT-IR) and tyrosine hydroxylase (TH-IR) immunoreactivities and the other showing 5-HT-IR only. Instead, there was no colocalization in the posterior lobe. In the hypothalamus, colchicine treatment with L-tryptophan and pargyline injections resulted in 5-HT-IR in some neurons in the dorsomedial, periventricular and arcuate nuclei, some of which in the arcuate and periventricular nuclei were also TH-IR. In the raphe nuclei no colocalization of 5-HT-IR and TH-IR was observed. Catecholamine neurotoxin, 6-hydroxydopamine, abolished the 5-HT-IR and dramatically reduced the TH-IR in the intermediate lobe nerve fibers. Both effects were prevented by cocaine, a monoamine uptake inhibitor, but not by fluoxetine, a specific serotonin uptake inhibitor. Serotonin neurotoxin p-chloroamphetamine (PCA) had no effect on intermediate lobe fibers, although it caused complete disappearance of 5-HT-IR from the posterior lobe nerve fibers. This effect was prevented by fluoxetine. Our results indicate, that colocalization of serotonin and TH observed in the intermediate lobe occurs both in the nerve terminals within the lobe and in some nuclei that innervate it. Furthermore, drug treatments suggest that serotonin in the intermediate lobe is localized in catecholaminergic fibers, which do not posses a specific serotonin uptake mechanism.
据报道，大鼠垂体中间叶和后叶的神经末梢显示5-羟色胺和酪氨酸羟化酶共定位。本研究检测了垂体以及被认为向垂体投射的核团中这种共定位的程度。在中间叶，发现了两种神经纤维，一种含有5-羟色胺免疫反应性（5-HT-IR）和酪氨酸羟化酶免疫反应性（TH-IR），另一种仅显示5-HT-IR。相反，后叶没有共定位现象。在丘脑下部，用L-色氨酸进行秋水仙碱处理并注射帕吉林后，在背内侧核、室周核和弓状核的一些神经元中出现了5-HT-IR，其中弓状核和室周核中的一些神经元也有TH-IR。在中缝核中未观察到5-HT-IR和TH-IR的共定位。儿茶酚胺神经毒素6-羟基多巴胺消除了中间叶神经纤维中的5-HT-IR，并显著降低了TH-IR。单胺摄取抑制剂可卡因可防止这两种效应，但特异性5-羟色胺摄取抑制剂氟西汀则不能。5-羟色胺神经毒素对氯苯丙胺（PCA）对中间叶纤维没有影响，尽管它导致后叶神经纤维中的5-HT-IR完全消失。氟西汀可防止这种效应。我们的结果表明，在中间叶观察到的5-羟色胺和TH的共定位既发生在叶内的神经末梢，也发生在支配它的一些核团中。此外，药物处理表明，中间叶中的5-羟色胺定位于儿茶酚胺能纤维中，这些纤维不具有特异性的5-羟色胺摄取机制。
