Kreutz M R, Acworth I N, Lehnert H, Wurtman R J
Department of Molecular Neuroendocrinology, Max-Planck-Institute for Experimental Medicine, Göttingen, F.R.G.
Brain Res. 1990 Dec 17;536(1-2):347-52. doi: 10.1016/0006-8993(90)90049-h.
We examined the effects of systemically administered thyrotropin-releasing hormone (TRH) on the release of dopamine (DA), as assessed by brain microdialysis within the corpus striatum of anesthetized rats. A single dose (10 micrograms i.v.) elevated DA levels in brain extracellular fluid (ECF) by 240% above baseline levels after 150 min. Systemic tyrosine ([TME] 20 mg/kg i.v.) also increased DA release (by 190% after 150 min), while combined treatment with both agents was associated with significant potentiation of the DA response (to 640% after 150 min). None of the treatments significantly altered striatal tissue levels of DA or its metabolites. A large dose of TRH (50 micrograms i.v.) significantly increased DA release (by 1150%) whether or not animals had received an active or denatured prolactin (PRL) antiserum prior to the experiment, suggesting that the TRH effect is not mediated by PRL. Although TRH is rapidly metabolized in plasma and penetrates the blood-brain barrier only poorly, our results suggest that even relatively small doses of the hormone can affect striatal dopaminergic neurotransmission.
我们通过对麻醉大鼠纹状体内的脑微透析来评估，研究了全身给予促甲状腺激素释放激素（TRH）对多巴胺（DA）释放的影响。单次静脉注射剂量为10微克时，150分钟后，脑细胞外液（ECF）中的DA水平比基线水平升高了240%。静脉注射系统酪氨酸（[TME] 20毫克/千克）也会增加DA释放（150分钟后增加190%），而两种药物联合治疗会使DA反应显著增强（150分钟后达到640%）。这些治疗均未显著改变纹状体内DA及其代谢物的组织水平。无论动物在实验前是否接受了活性或变性催乳素（PRL）抗血清，大剂量的TRH（静脉注射50微克）均能显著增加DA释放（增加1150%），这表明TRH的作用不是由PRL介导的。尽管TRH在血浆中迅速代谢，且穿透血脑屏障的能力很差，但我们的结果表明，即使是相对小剂量的该激素也能影响纹状体多巴胺能神经传递。
