SEROTONIN RECEPTORS: CHARACTERIZATION & ONTOGENY

5-羟色胺(5-HT)是肠道中的一种神经递质 神经系统(ENS)。肠神经5-羟色胺受体的两种类型 已鉴定为5-HT1P和5-HT3。5-HT1P受体是 5-羟色胺受体拮抗剂包括N-羟色胺 Acetyl-5-hydroxytryptophyl-5-hydroxytryptophan酰胺(5-HTP-DP)和 BRL 24924。在发育过程中，5-HT1P受体在 5-羟色胺能神经元的出现。5-HT3受体不是 5-羟色胺受体拮抗剂包括ICS 205- 930、BRL 43694(格拉司琼)和GR 65630。既不是 5-HT3在肠壁的分布及个体发育 受体之前已经被研究过了。现建议： 小鼠肠道5-HT3受体的放射配基研究 结合技术，使用肠液的快速过滤 用~3H-格拉司琼和~3H-GR 65630作细胞膜和放射自显影。 特定绑定将被定义为被ICS 205-930取代的绑定。 5-HT3受体的位置将在成人和 胎儿肠道和它们出现在个体发育中的时间将是 与5-HT1P受体相关。有选择地销毁 5，7-二羟色胺(5，7-DHT)能突起 被用来探索它们对发育，成熟， 以及5-HT1P受体的维持。5-羟色胺本身的能力 影响5-HT1P受体发育的因素将另行探讨。 5-羟色胺的作用将通过检测5-HT1P受体来研究 在特定拮抗剂存在下的发育和成熟 色氨酸抑制5-羟色胺耗竭后 羟基酶。实验将用胎儿肠道的外植体进行 在器官类型组织培养中生长和体内发育 后肠，5-HT1P受体在前3周发育 生活的一部分。6-羟基多巴胺(6-OHDA)化学交感神经切除术 诱导5-HT1P受体快速上调。的影响 现在将确定5-HT3受体上的6-OHDA。此外, 将进行研究以确定6-OHDA是否对 肠神经5-羟色胺受体是由去甲肾上腺素丢失引起的 (Ne)，并具体涉及销毁 5-羟色胺能神经元的去甲肾上腺素能神经支配。这些 实验将利用酪氨酸羟化酶抑制来耗尽 BE与细胞色素的定量细胞化学显示 用氧化酶活性评价交感神经切断对强直性神经的影响 5-羟色胺能神经元的活动。最后，由于两种血清素能 神经元和5-HT1P受体已经存在，而肠道 包含神经元的增殖前体，其中包含 血管活性肠肽与降钙素基因相关 肽(CGRP)免疫反应性存在的可能性 5-羟色胺能神经元可能影响神经营养因子的表型表达 这些发育较晚的神经元。这种可能性将通过以下方式进行测试 5，7-二羟色胺或5-羟色胺1P慢性抑制作用的测定 和/或5-HT3受体在生日和最终数量 VIP和CGRP免疫反应阳性神经元。这些因素的影响 早期发育神经肽Y免疫反应性的治疗 神经元也将作为对照进行检查。最后，如果效果 AR发现，将进行研究以确定是否会受到影响 神经元实际上接受5-羟色胺能突触。这些实验 将增进对先天性心脏病发病机制的认识 肠神经肌肉发育缺陷将是重要的 在评估精神活性药物的安全性时， 妊娠期5-羟色胺受体的5-羟色胺能神经元。

5-hydroxytryptamine (5-HT) is a neurotransmitter in the enteric nervous system (ENS). Two types of enteric neural 5-HT receptor have been identified, 5-HT1P and 5-HT3. The 5-HT1P receptor is labeled by 3H-5-HT; antagonists at 5-HT1P receptors include N- acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP) and BRL 24924. During developments 5-HT1P receptors arise after the appearance of serotonergic neurons. 5-HT3 receptors are not labeled by 3H-5-HT; antagonists at 5-HT3 receptors include ICS 205- 930, BRL 43694 (granisetron) and GR 65630. Neither the distribution in the wall of the bowel, nor the ontogeny of 5-HT3 receptors have previously been studied. It is now proposed to study enteric 5-HT3 receptors in the murine gut by radioligand binding techniques, using both rapid filtration of enteric membranes and radioautography with 3H-granisetron and 3H-GR 65630. Specific binding will be defined as that displaced by ICS 205-930. The location of 5-HT3 receptors will be determined in the adult and fetal bowel and the timing of their appearance in ontogeny will be related to that of 5-HT1P receptors. Selective destruction of serotonergic neurites with 5,7-dihydroxytryptamine (5,7-DHT) will be used to explore their influence on the development, maturation, and maintenance of 5-HT1P receptors. The ability of 5-HT itself to affect 5-HT1P receptor development will be separately explored. The role of 5-HT will be studied by examining 5-HT1P receptor development and maturation in the presence of specific antagonists and after depletion of 5-HT by inhibition of tryptophan hydroxylase. Experiments will be done with explants of fetal gut grown in organotypic tissue culture and in vivo with developing hindgut, in which 5-HT1P receptors develop during the first 3 weeks of life. Chemical sympathectomy with 6-hydroxydopamine (6-OHDA) induces a rapid upregulation of 5-HT1P receptors. The effect of 6-OHDA on 5-HT3 receptors will now be ascertained. In addition, studies will be done to determine whether the effect of 6-OHDA on enteric neural 5-HT receptors is due to loss of norepinephrine (NE), and is specifically related to destruction of the noradrenergic innervation of serotonergic neurons. These experiments will utilize tyrosine hydroxylase inhibition to deplete BE and the quantitative cytochemical demonstration of cytochrome oxidase activity to evaluate effect of sympathectomy on the tonic activity of serotonergic neurons. Finally, since both serotonergic neurons and 5-HT1P receptors are already present while the gut contains the proliferating precursors of neurons that contain vasoactive intestinal polypeptide (VIP) and calcitonin gene related peptide (CGRP) immunoreactivity the possibility exists that serotonergic neurons may influence the phenotypic expression of these late-developing neurons. This possibility will be tested by determining the effects of 5,7-DHT or chronic inhibition of 5-HT1P and/or 5-HT3 receptors on the birthdays and ultimate numbers of VIP- and CGRP-immunoreactive neurons. The effect of these treatments on the earlier-developing neuropeptide Y-immunoreactive neurons will also be examined as a control. Finally, if effects ar found, studies will be done to determine whether affected neurons actually receive serotonergic synapses. These experiments will enhance understanding of the pathogenesis of congenital defects of enteric neuromuscular development and will be important in evaluating the safety of psychoactive drugs that affect serotonergic neurons of 5-HT receptors in pregnancy.