BDNF and major depressive disorder: A similar effect on GPR39 expression is also observed in the chronic restraint stress model of depression, where mRNA levels decreased for GPR39, BDNF, and CREB; interestingly, changes in behavior, GPR39 expression, and BDNF expression were rescued by 30 mg/kg of zinc and 20 mg/kg of the antidepressant imipramine [110].