Mudd L M, Raizada M K
Department of Physiology, University of Florida, College of Medicine, Gainesville 32610.
Brain Res. 1990 Jun 25;521(1-2):192-6. doi: 10.1016/0006-8993(90)91542-o.
In this study we used differential culturing techniques to study the effects of phorbol esters on insulin receptors on neuronal and astrocytic glial cells in primary culture from the brain. 12-O-Tetradecanoyl-phorbol-13-acetate (TPA), a potent activator of protein kinase C (PKC), increased [125I]insulin binding in a time- and concentration-dependent manner with a maximally effective dose of 50 nM TPA for 2 h in glial cells. Treatment with TPA did not affect [125I]insulin binding in neuronal cells. The TPA effect on glial [125I]insulin binding was specific as evidenced by the observation that potencies of phorbol ester analogs to increase [125I]insulin binding were similar to their abilities to stimulate PKC. Competitive-inhibition experiments indicated that this effect of TPA was due primarily to an increase in the number of high affinity insulin binding sites on glial cells. Removal of the TPA after pretreatment resulted in a recovery from its effects within 6 h. The increase in glial insulin binding was not accompanied by an increase in insulin-sensitive glucose uptake, suggesting that TPA inactivates the glial cell receptors as it increases their numbers.
在本研究中，我们使用差异培养技术来研究佛波酯对原代培养的脑神经元和星形胶质细胞上胰岛素受体的影响。12-O-十四烷酰佛波醇-13-乙酸酯（TPA）是蛋白激酶C（PKC）的强效激活剂，在胶质细胞中，它以时间和浓度依赖性方式增加[125I]胰岛素结合，最大有效剂量为50 nM TPA，作用2小时。用TPA处理对神经元细胞中的[125I]胰岛素结合没有影响。佛波酯类似物增加[125I]胰岛素结合的效力与其刺激PKC的能力相似，这一观察结果证明TPA对胶质细胞[125I]胰岛素结合的作用是特异性的。竞争性抑制实验表明，TPA的这种作用主要是由于胶质细胞上高亲和力胰岛素结合位点数量增加。预处理后去除TPA导致其作用在6小时内恢复。胶质细胞胰岛素结合增加并未伴随胰岛素敏感性葡萄糖摄取增加，这表明TPA在增加胶质细胞受体数量的同时使其失活。
