神经递质对大鼠中基底部下丘脑免疫反应性促甲状腺激素释放激素体外释放的影响。

Effect of neurotransmitters on the in vitro release of immunoreactive thyrotropin-releasing hormone from rat mediobasal hypothalamus.

作者信息

Joseph-Bravo P, Charli J L, Palacios J M, Kordon C

出版信息

Endocrinology. 1979 Mar;104(3):801-6. doi: 10.1210/endo-104-3-801.

Abstract

The in vitro release of TRH from hypothalamic fragments or purified nerve endings (synaptosomes) has been evaluated after incubation for 10 min in the presence of various concentrations of K+ or neurotransmitters. Release of the hormone from fragments but not from synaptosomes was enhanced in the presence of 56 mM K+ in a Ca++ -dependent manner. Neurotransmitter effects were thus tested on the fragments. Addition of histamine (10 (-7)-10(-5) M) induced a significant increase over the basal release of TRH. A comparable effect was obtained with dimaprit (10(-5) M), a highly specific agonist of histamine H2 receptors; conversely, the response to histamine was blocked by the addition of a H2 (metiamide; 10(-6) M) but not of a H1 (mepyramine; 10(-6) M) antagonist to the incubation medium. Dopamine (10(-7) M) slightly inhibited the release of TRH, but antagonists of dopamine receptors (10(-7)-10(-6) M fluphenazine or 10(-6) M alpha-flupentixol) exhibited an inhibitory effect by themselves, so that specific receptors involved in mediating dopamine actions could not be further characterized. In contrast, noradrenalin, serotonin gamma-aminobutyric acid and acetylcholine (tested at concentration of 10(-7) M) did not alter the basal release of the tripeptide.

摘要

在存在不同浓度的钾离子（K⁺）或神经递质的情况下，将下丘脑片段或纯化的神经末梢（突触体）孵育10分钟后，对促甲状腺激素释放激素（TRH）的体外释放进行了评估。在56 mM K⁺存在下，片段中激素的释放（而非突触体中的释放）以钙离子（Ca²⁺）依赖的方式增强。因此，对片段进行了神经递质作用的测试。添加组胺（10⁻⁷ - 10⁻⁵ M）导致TRH基础释放量显著增加。组胺H2受体的高度特异性激动剂二甲双胍（10⁻⁵ M）也获得了类似的效果；相反，向孵育培养基中添加H2拮抗剂（甲硫咪特；10⁻⁶ M）可阻断对组胺的反应，而添加H1拮抗剂（甲氧苄二胺；10⁻⁶ M）则无此作用。多巴胺（10⁻⁷ M）对TRH的释放略有抑制作用，但多巴胺受体拮抗剂（10⁻⁷ - 10⁻⁶ M氟奋乃静或10⁻⁶ M α-氟哌噻吨）自身就表现出抑制作用，因此无法进一步确定介导多巴胺作用的特定受体。相比之下，去甲肾上腺素、5-羟色胺、γ-氨基丁酸和乙酰胆碱（浓度为10⁻⁷ M时进行测试）并未改变三肽的基础释放量。