Schwartz D D, Malik K U
University of Tennessee, Department of Pharmacology, College of Medicine, Memphis 38163.
Neuroscience. 1993 Jan;52(1):107-13. doi: 10.1016/0306-4522(93)90186-j.
The purpose of this study was to determine whether a decrease in cyclic AMP accumulation mediates the inhibition of norepinephrine release in response to alpha-2 adrenergic receptor activation in cultured rat superior cervical ganglion cells. Superior cervical ganglia from neonatal rats were dissociated and cultured on collagen-coated plastic strips. Neurotransmitter release was assessed by measuring the fractional overflow of tritium in superfused cells prelabeled with [3H]norepinephrine. Intracellular cyclic AMP accumulation was measured using radioimmunoassay. Electrical field stimulation at 1 Hz, 30 pulses, 1 ms duration at 20 min intervals produced an increase in the fractional overflow of tritium that was composed predominantly of intact [3H]norepinephrine. The alpha-2 adrenergic receptor agonist UK-14,304 dose-dependently attenuated the increase in fractional tritium overflow elicited by electrical field stimulation. The adenylyl cyclase activator, forskolin, increased cyclic AMP accumulation in superior cervical ganglion cells and UK-14,304 dose-dependently inhibited forskolin-stimulated cyclic AMP accumulation. UK-14,304 had no effect on basal cyclic AMP accumulation or cyclic AMP accumulation during electrical field stimulation. Forskolin (1-10 microM) or the non-hydrolysable cAMP analog, 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (1-100 microM), slightly increased basal and dose-dependently potentiated the increase in fractional tritium overflow in response to electrical stimulation. Despite enhancement by forskolin and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate of fractional tritium overflow caused by electrical field stimulation, UK-14304 (1-10 microM) reduced release to a similar degree as that observed in the absence of forskolin or 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是确定环磷酸腺苷（cAMP）积累的减少是否介导了培养的大鼠颈上神经节细胞中去甲肾上腺素释放的抑制，该抑制是对α-2肾上腺素能受体激活的反应。新生大鼠的颈上神经节被解离并培养在胶原包被的塑料条上。通过测量预先用[3H]去甲肾上腺素标记的灌流细胞中氚的分数溢出量来评估神经递质的释放。使用放射免疫测定法测量细胞内cAMP的积累。以1Hz、30个脉冲、持续时间1ms、间隔20分钟进行电场刺激，可使氚的分数溢出量增加，其主要由完整的[3H]去甲肾上腺素组成。α-2肾上腺素能受体激动剂UK-14,304剂量依赖性地减弱了电场刺激引起的氚分数溢出量的增加。腺苷酸环化酶激活剂福斯高林增加了颈上神经节细胞中cAMP的积累，UK-14,304剂量依赖性地抑制了福斯高林刺激的cAMP积累。UK-14,304对基础cAMP积累或电场刺激期间的cAMP积累没有影响。福斯高林（1至-10 microM）或不可水解的cAMP类似物8-（4-氯苯硫基）腺苷3',5'-环一磷酸（1至-100 microM）略微增加了基础值，并剂量依赖性地增强了电场刺激后氚分数溢出量的增加。尽管福斯高林和8-（4-氯苯硫基）腺苷3',5'-环一磷酸增强了电场刺激引起的氚分数溢出量，但UK-（1至-（10 microM）将释放量降低到与未使用福斯高林或8-（4-氯苯硫基）腺苷3',5'-环一磷酸时观察到的相似程度。（摘要截短于250字）
