Neurochemistry and Neuropharmacology
Author: Leydi Carolina González Gómez | Email: lcarolina.gonzalez@udea.edu.co
Leydi Carolina González Gómez1°, María Clara Gravielle1°
1° Instituto de Investigaciones Farmacológicas (ININFA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET
The development of tolerance limits prolonged treatments with benzodiazepines. In previous work, we demonstrated that sustained exposure of rat neocortical neurons to diazepam induces selective transcriptional repression of the GABAA receptor α1 subunit gene by a mechanism that depends on the activation of L-type voltage-gated calcium channels (L-VGCC) and the protein kinase A. The present study aimed to further investigate the signaling pathway activated by continuous exposure to benzodiazepines that leads to regulating GABAA receptors. To this end, we treated rat primary cerebrocortical cultures with diazepam for different periods. Our results showed that diazepam exposure significantly increased intracellular calcium concentration (P<0.05, Student`t test). We then demonstrated, using immunocytochemical experiments, that the diazepam-induced reduction in the total levels of the α1 subunit is accompanied by a significant decrease in the surface levels of the subunit which are part of functional receptors (P<0.05, one-way ANOVA and Tukey post hoc test). Finally, we observed that prolonged in vivo administration of diazepam (7 days) in rats induced a significant decrease in mRNA and protein levels of α1 in the cerebral cortex (P<0.05, Student`t test). Taken together, our results suggest that diazepam-induced regulation of GABAA receptor expression is mediated by the stimulation of calcium influx through L-VGCC. This regulatory process was validated by in vivo experiments.