Mathiasen J R, Larson E R, Ariano M A, Sladek C D
Department of Physiology, Finch University of Health Sciences, Chicago Medical School, Illinois 60064-3095, USA.
Am J Physiol. 1996 Feb;270(2 Pt 2):R404-12. doi: 10.1152/ajpregu.1996.270.2.R404.
We have exposed primary dispersed hypothalamic cultures from 14-day-old fetal Sprague-Dawley rats to substances known to either elevate adenosine 3',5'-cyclic monophosphate (cAMP) levels or increase vasopressin (VP) secretion. The levels of VP in the medium collected from the cultures were determined by radioimmunoassay, and the number of neurophysin (NP)-positive cells after immunohistochemistry was counted. cAMP-elevating agents, 3-isobutyl-1-methylxanthine (200 microM) and forskolin (25 microM), in combination (I-F) maintained NP synthesis and VP secretion in 19-day cultures. I-F replacement by K+ (28 mM), isoproterenol (10 microM), glutamate (10 microM), or bicuculline (10 microM) during the last week of culture resulted in maintenance of NP expression and transient stimulation of VP secretion, but these agents did not induce NP expression independently of I-F treatment. In contrast, exposure to the dopamine D1 agonist SKF-38393 (10 microM) significantly increased NP expression independently and after replacement of I-F. Dopamine D1A receptors were detected by immunofluorescence on NP-expressing cells, providing a morphological basis for this response. These results suggest a role for D1A receptors in the regulation of VP gene expression.
我们将来自14日龄胎儿Sprague-Dawley大鼠的原代分散下丘脑培养物暴露于已知能提高3',5'-环磷酸腺苷（cAMP）水平或增加血管加压素（VP）分泌的物质中。通过放射免疫测定法测定从培养物中收集的培养基中VP的水平，并对免疫组织化学后神经垂体素（NP）阳性细胞的数量进行计数。提高cAMP的试剂，3-异丁基-1-甲基黄嘌呤（200微摩尔）和毛喉素（25微摩尔），联合使用（I-F）在19天的培养中维持NP合成和VP分泌。在培养的最后一周用钾离子（28毫摩尔）、异丙肾上腺素（10微摩尔）、谷氨酸（10微摩尔）或荷包牡丹碱（10微摩尔）替代I-F，导致NP表达维持和VP分泌的短暂刺激，但这些试剂在没有I-F处理的情况下不会独立诱导NP表达。相比之下，暴露于多巴胺D1激动剂SKF-38393（10微摩尔）在独立以及替代I-F后均显著增加NP表达。通过免疫荧光在表达NP的细胞上检测到多巴胺D1A受体，为这种反应提供了形态学基础。这些结果表明D1A受体在VP基因表达的调节中起作用。
