CONVERSION TO NEUROCYTE OF CULTURED ADRENAL CHROMAFFIN CELLS AND ITS MOLECULAR PHARMACOLOGICAL STUDY

肾上腺嗜铬细胞是儿茶酚胺神经元的模型，适合于刺激-分泌偶联的研究。因此，本研究采用牛肾上腺嗜铬细胞的培养方法。细胞培养条件本课题的最新研究使用的是培养数天的牛肾上腺嗜铬细胞，长期培养这些细胞是转化为神经细胞所必需的。观察糖皮质激素和神经生长因子对培养的牛肾上腺嗜铬细胞形态的影响。培养2周时，神经生长因子刺激这些细胞形成轴突，而糖皮质激素不能。在肾上腺嗜铬细胞的药理学研究中，分泌刺激引起来源于细胞内池和细胞外间隙的细胞内游离钙离子水平升高，从而刺激儿茶酚胺的分泌和儿茶酚胺的生物合成。刺激后，升高的[Ca~(2+)]i应迅速恢复到静息水平，以对随后的刺激作出反应。缓激肽、PACAP和组胺刺激培养的牛肾上腺嗜铬细胞外流Na~(2+)依赖性钙离子。我们正在研究神经生长因子对这些多肽诱导的细胞内钙外流的影响。

Adrenal chromaffin cells are regarded as a model of catecholamine containing neurons and are suitable for study of stimulus-secretion coupling. In this strdy, therefore, bovine adrenal chromaffin cells in culture were used.Condition of cell cultureBovine adrenal chromaffin cells which are cultured for a few days areused in recent research in this project, long term cultured these cells are necessary to convert to neurocyte. We succeeded these cells culture for several weeks (at least 3 weeks).Morphological studyEffects of glucocorticoids and nerve growth factors on form of cultured bovine adrenal chromaffin cells were investigated. Nerve growth factors stimulate formation of axons on these cells at 2 weeks culture, but glucocorticoids do not. Therefore, the conversion to neurocyte of cultured adrenal chromaffin cells is suggested.Pharmacological studyIn adrenal chromaffin cells, secretory stimulations cause an increase in the intracellular free Ca^<2+> level([Ca^<2+>]i) originating from intracellular pools and extracellular spaces, leading to stimulation of catecholamine secretion and activation of catecholamine biosynthesis. After stimulations, the increased[Ca^<2+>]i)should rapidly return to the resting level for response to a subsequent stimulation. Bradykinin, PACAP and histamine stimulate extracellular Na^+-dependent Ca^<2+> efflux from cultured bovine adrenal chromaffin cells. We are investigating the effects of nerve growth factors on these peptides-induced Ca^<2+> efflux from the cells.