Vizi E S, Tóth I E, Szalay K S, Windisch K, Orsó E, Szabó D, Vinson G P
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
J Endocrinol. 1992 Dec;135(3):551-61. doi: 10.1677/joe.0.1350551.
The effect of supramaximal electric field stimulation on [3H]noradrenaline (NA) release and hormone production by rat adrenal capsule-glomerulosa preparations was studied using a microvolume perfusion system. A substantial proportion (about 20%) of nerve endings (varicosities) were observed close to zona glomerulosa cells, and about half of them appeared to be catecholaminergic, as judged by the chromaffin reaction of the synaptic vesicles studied at electron microscopic level. In tissue, preloaded with [3H]NA, the release of NA in response to electrical stimulation was frequency-dependent. Reserpinization, calcium removal or inhibition of Na+ influx by tetrodotoxin completely blocked NA release by field stimulation, indicating that the release resulted from axonal activity and is of vesicular origin. Neither the alpha 2-adrenoceptor agonist xylazine nor the muscarine-receptor agonist oxotremorine affected the stimulation-evoked release of [3H]NA, suggesting that, in contrast with other neurones present in the central nervous system or in the peripheral autonomic nervous system but like those in the median eminence, these axon terminals contained few presynaptic modulatory receptors. The NA (10.20 +/- 1.79 (S.E.M.) micrograms/g, n = 9), adrenaline (24.38 +/- 5.50 micrograms/g, n = 9) and dopamine (0.35 +/- 0.09 micrograms/g, n = 6) contents of the preparations were high, as determined by high-performance liquid chromatography. Our observations that the release and content of NA is high, and that a substantial proportion of catecholaminergic axon terminals lie in close proximity to zona glomerulosa cells (median value of the distance 300 nm) or to smooth muscle cells of the vessels, suggest that NA released from local adrenergic neurones without being presynaptically modulated may play an important role in fine-tuning both steroid production and/or blood flow through the gland, itself a powerful modulator of the adrenocortical response. This local modulating effect of NA may be especially significant when sympathetic activity is enhanced.
使用微量灌注系统研究了超强电场刺激对大鼠肾上腺被膜 - 肾小球制备物中[3H]去甲肾上腺素（NA）释放和激素产生的影响。在电子显微镜水平下，通过对突触小泡的嗜铬反应判断，观察到相当比例（约20%）的神经末梢（曲张体）靠近肾小球细胞，其中约一半似乎是儿茶酚胺能的。在预先加载[3H]NA的组织中，电刺激引起的NA释放具有频率依赖性。利血平化、去除钙或用河豚毒素抑制Na+内流完全阻断了电场刺激引起的NA释放，表明这种释放是由轴突活动引起的，且起源于囊泡。α2 - 肾上腺素能受体激动剂赛拉嗪和毒蕈碱受体激动剂氧化震颤素均不影响刺激诱发的[3H]NA释放，这表明与中枢神经系统或外周自主神经系统中的其他神经元不同，但与正中隆起中的神经元相似，这些轴突终末几乎不含突触前调节受体。通过高效液相色谱法测定，制备物中的NA（10.20±1.79（标准误）μg/g，n = 9）、肾上腺素（24.38±5.50μg/g，n = 9）和多巴胺（
