Sim L J, Selley D E, Tsai K P, Morris M
Department of Physiology and Pharmacology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC 27157.
Brain Res. 1994 Aug 8;653(1-2):155-60. doi: 10.1016/0006-8993(94)90384-0.
Immediate-early genes, such as c-fos, couple extracellular signals to genetic changes in the cell. We have previously demonstrated that depolarization with 50 mM KCl increases Fos immunoreactivity in hypothalamic tyrosine hydroxylase (TH) and oxytocin immunoreactive (-ir) neurons in primary culture. This Fos activation occurs within 1.5-2 h in TH-ir cells. In the present study, we examined the effects of depolarization, glutamate receptor activation and adenylyl cyclase stimulation on Fos-ir to determine the possible mechanism(s) of Fos activation in TH-ir neurons. Hypothalamic cultures were treated with KCl, glutamate or forskolin, and Fos and TH were visualized immunocytochemically. Forskolin increased the percentage of Fos/TH-ir neurons in a dose-dependent manner, with a maximal stimulation of 53.4 +/- 4.5% Fos/TH-ir neurons at 30 microM forskolin. The dose-response curve for glutamate was steep, with a maximal stimulation of 24.8 +/- 2.1% Fos-ir neurons at 100 microM. 50 mM KCl resulted in 50.0 +/- 0.8% Fos/TH-ir neurons. Pretreatment with verapamil decreased KCl induced Fos-ir by 57%, glutamate by 65% and forskolin by 39%. Combined drug administration demonstrated significant additivity between forskolin and glutamate, and forskolin and KCl, however, no significant additivity was found with KCl and glutamate. The results are discussed in terms of cAMP and calcium mediation of the Fos response to these stimuli.
即刻早期基因，如c-fos，可将细胞外信号与细胞内的基因变化联系起来。我们之前已经证明，用50 mM氯化钾进行去极化可增加原代培养的下丘脑酪氨酸羟化酶（TH）和催产素免疫反应性（-ir）神经元中的Fos免疫反应性。这种Fos激活在TH-ir细胞中1.5 - 2小时内发生。在本研究中，我们研究了去极化、谷氨酸受体激活和腺苷酸环化酶刺激对Fos-ir的影响，以确定TH-ir神经元中Fos激活的可能机制。用氯化钾、谷氨酸或福斯高林处理下丘脑培养物，并通过免疫细胞化学方法观察Fos和TH。福斯高林以剂量依赖的方式增加Fos/TH-ir神经元的百分比，在30 microM福斯高林时最大刺激为53.4 +/- 4.5%的Fos/TH-ir神经元。谷氨酸的剂量反应曲线较陡，在100 microM时最大刺激为24.8 +/- 2.1%的Fos-ir神经元。50 mM氯化钾导致50.0 +/- 0.8%的Fos/TH-ir神经元。用维拉帕米预处理可使氯化钾诱导的Fos-ir降低57%，谷氨酸诱导的降低65%，福斯高林诱导的降低39%。联合给药显示福斯高林与谷氨酸、福斯高林与氯化钾之间有显著的相加作用，然而，氯化钾与谷氨酸之间未发现显著的相加作用。将根据cAMP和钙对这些刺激的Fos反应的介导作用来讨论结果。
