Wang G, Lim A T
Cell Biology Unit, Mental Health Research Institute of Victoria, Royal Park Hospital, Australia.
Endocrinology. 1996 Jan;137(1):379-82. doi: 10.1210/endo.137.1.8536639.
We describe here long term primary cultures of adult rat hypothalamic cells, a novel system which we have exploited to examine the effect of glucocorticoids on adult ANF neurons in vitro. ANF neurons with and without neurite outgrowths were identified by immunocytochemistry and by in situ hybridization studies, in which pro-ANF mRNA signals were localised in cultured cells. Dexamethasone (DM) augmented the abundance of pro-ANF mRNA signals in a dose-related manner with ED50 of 5 x 10(-12)M and Emax of 10(-10)M. This stimulation effect was mimicked by corticosterone but not by deoxycorticosterone. Similarly, activation of the adenylyl cyclase-cAMP system with forskolin, 8-brom-cAMP or 3-isobutyl-1-methylxanthine (IBMX), also markedly elevated the level of pro-ANF mRNA abundance. Interestingly, whereas forskolin-induced stimulation was reversed by Rp-cAMP, a cAMP antagonist, the augmentation induced by DM alone or by DM and forskolin together, was similarly suppressed by the chemical. We therefore conclude that (i) adult ANF neurons are capable of regenerating neurite outgrowths in vitro, (ii) cAMP dependent pathways play a fundamental role in regulating the expression of pro-ANF mRNA, and (iii) the stimulatory effect of glucocorticoids is indirect and mediated, at least in part, through modulating the activity of cAMP dependent pathways.
我们在此描述成年大鼠下丘脑细胞的长期原代培养，这是一种新型系统，我们利用该系统在体外研究糖皮质激素对成年心房钠尿肽（ANF）神经元的影响。通过免疫细胞化学和原位杂交研究鉴定有无神经突生长的ANF神经元，其中前体ANF mRNA信号定位于培养细胞中。地塞米松（DM）以剂量相关方式增加前体ANF mRNA信号的丰度，ED50为5×10（-12）M，Emax为10（-10）M。这种刺激作用被皮质酮模拟，但不被脱氧皮质酮模拟。同样，用福斯可林、8-溴-cAMP或3-异丁基-1-甲基黄嘌呤（IBMX）激活腺苷酸环化酶-cAMP系统，也显著提高前体ANF mRNA丰度水平。有趣的是，虽然福斯可林诱导的刺激被cAMP拮抗剂Rp-cAMP逆转，但单独由DM或由DM和福斯可林共同诱导的增加，同样被该化学物质抑制。因此，我们得出结论：（i）成年ANF神经元在体外能够再生神经突生长；（ii）cAMP依赖性途径在调节前体ANF mRNA的表达中起基本作用；（iii）糖皮质激素的刺激作用是间接的，至少部分是通过调节cAMP依赖性途径的活性介导的。
