Vesicular glutamate transporter 1 (VGLUT1)-mediated glutamate release and membrane GluA1 activation is involved in the rapid antidepressant-like effects of scopolamine in mice

Abstract

Emerging data have identified certain drugs such as scopolamine as rapidly acting antidepressants for major depressive disorder (MDD) that increase glutamate release and induce neurotrophic factors through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) activation in rodent models. However, little research has addressed the direct mechanisms of scopolamine on AMPAR activation or vesicular glutamate transporter 1 (VGLUT1)-mediated glutamate release in the prefrontal cortex (PFC) of mice. Herein, using a chronic unpredictable stress (CUS) paradigm, acute treatment with scopolamine rapidly reversed stress-induced depression-like behaviors in mice. Our results showed that CUS-induced depression-like behaviors, accompanied by a decrease in membrane AMPAR subunit 1 (GluA1), phosphorylated GluA1 Ser845 (pGluA1 Ser845), brain-derived neurotrophic factor (BDNF) and VGF (non-acronymic) and an increase in bicaudal C homolog 1 gene (BICC1) in the PFC of mice, and these biochemical and behavioral abnormalities were ameliorated by acute scopolamine treatments. However, pharmacological block of AMPAR by NBQX infusion into the PFC significantly abolished these effects of scopolamine. In addition, knock down of VGLUT1 by lentiviral-mediated RNA interference in the PFC of mice was sufficient to induce depression-like phenotype, to decrease extracellular glutamate accumulation and to cause similar molecular changes with CUS in mice. Remarkably, VGLUT1 knockdown alleviated the rapid antidepressant-like actions of scopolamine and the effects of scopolamine on membrane GluA1-mediated BDNF, VGF and BICC1 changes. Altogether, our findings suggest that VGLUT1-mediated glutamate release and membrane GluA1 activation may play a critical role in the rapid-acting antidepressant-like effects of scopolamine in mice.