Tolón R M, Sánchez-Franco F, López Fernández J, Lorenzo M J, Vázquez G F, Cacicedo L
Servicio de Endocrinología, Hospital Ramón y Cajal, Madrid, Spain.
Brain Res Mol Brain Res. 1996 Jan;35(1-2):103-10. doi: 10.1016/0169-328x(95)00188-x.
The stimulatory effect of veratridine (VTD) depolarization upon somatostatin mRNA (SS mRNA) levels in primary cultures of fetal cerebrocortical cells was analyzed. Depolarizing stimuli, such as 100 microM VTD exposure for 30 min, elicited an increase in immunoreactive somatostatin (IR-SS) release to the media without affecting SS mRNA levels. These levels increased when exposure to depolarization stimuli was prolonged up to 3 or more hours. At this time, veratridine acted as a secretagogue, stimulating somatostatin secretion, but was also effective in stimulating somatostatin mRNA levels. These changes were blunted by the Na+ channel blockade tetrodotoxin (TTX), and partially abolished by the Ca2+ channel antagonist, verapamil (VPM). To study whether VTD may affect mRNA stability we determine the rate of disappearance of SS mRNA after inhibition of transcription by actinomycin D and demonstrated that VTD stimulation did not stabilize the SS mRNA. These results indicate that the induction of SS mRNA expression by VTD involves the modulation of Ca2+ and Na+ channels. The time course study confirmed that the VTD-induced SS mRNA accumulation is time-dependent, and requires a prolonged exposure to stimulate SS gene expression. VTD stimulation does not modify the SS mRNA rate of degradation.
分析了藜芦碱（VTD）去极化对胎儿大脑皮质细胞原代培养物中生长抑素mRNA（SS mRNA）水平的刺激作用。去极化刺激，如暴露于100 microM VTD 30分钟，会使免疫反应性生长抑素（IR-SS）释放到培养基中增加，而不影响SS mRNA水平。当暴露于去极化刺激的时间延长至3小时或更长时间时，这些水平会升高。此时，藜芦碱起到促分泌素的作用，刺激生长抑素分泌，但也能有效刺激生长抑素mRNA水平。这些变化被钠通道阻滞剂河豚毒素（TTX）减弱，并被钙通道拮抗剂维拉帕米（VPM）部分消除。为了研究VTD是否可能影响mRNA稳定性，我们在放线菌素D抑制转录后测定了SS mRNA的消失速率，并证明VTD刺激并未使SS mRNA稳定。这些结果表明，VTD诱导的SS mRNA表达涉及钙通道和钠通道的调节。时间进程研究证实，VTD诱导的SS mRNA积累是时间依赖性的，并且需要长时间暴露以刺激SS基因表达。VTD刺激不会改变SS mRNA的降解速率。
