The phosphodiesterase type-5 inhibitor, tadalafil, improves depressive symptoms, ameliorates memory impairment, as well as suppresses apoptosis and enhances cell proliferation in the hippocampus of maternal-separated rat pups

Early adverse experiences resulting from maternal separation may lead to neuronal cell death and eventually cause memory impairment. Maternal separation has been used to create a valid animal model of early life stress and a depression-like syndrome. The phosphodiesterase (PDE)-5 inhibitor, tadalafil (Cialis), is a widely prescribed agent for the treatment of erectile dysfunction. In this study, we investigated the effects of tadalafil on apoptosis and cell proliferation in the hippocampal dentate gyrus of rat pups following maternal separation. Specifically, the immobility time in the forced swim test was increased in the maternal-separated rat pups, and tadalafil treatment decreased the immobility time. The rat pups in the maternal separation group had deceased memory function compared to the rat pups in the maternal care group, and tadalafil treatment increased memory function of the rat pups in the maternal separation group. Apoptotic cell death in the hippocampal dentate gyrus was significantly increased in the maternal-separated rat pups, and tadalafil treatment suppressed maternal separation-induced apoptosis. In contrast, cell proliferation in the dentate gyrus was significantly decreased in the maternal-separated rat pups, and taldalafil treatment increased cell proliferation. The present results suggest that tadalafil improves depressive symptoms and alleviates memory impairment by suppressing apoptotic neuronal cell death and enhancing cell proliferation in maternal-separated rat pups. (C) 2010 Elsevier Ireland Ltd. All rights reserved.