mouse dentate gyrus (Taliaz et al., 2010). BDNF is required for enriched environment-induced increases in cell proliferation in adult mice (Rossi et al., 2006). Vascular endothelial growth factor (VEGF) administration also increases cell proliferation in the dentate gyrus of the adult rat (Jin et al., 2002). VEGF is required for running-induced increases in cell proliferation and differentiation of new neurons in adult mice (Fabel et al., 2003), and for enriched environment-induced cell proliferation and differentiation and survival of new neurons in adult rats (Cao et al., 2004). Chronic stress decreases VEGF expression (Heine et al., 2005), so VEGF is another good potential factor in mitigating adult neurogenesis. Insulin-like growth factor 1 (IGF-1) administration increases cell proliferation in the dentate gyrus of the adult rat (Aberg et al., 2001), mediates positive neural changes in the brain following exercise (Carro et al., 2000), and is increased following antidepressant treatment (Khawaja et al., 2004), which is known to stimulate cell proliferation. Therefore, IGF-1 may also be a factor in the paradoxical effects of rewarding experiences on adult neurogenesis, although no direct evidence has supported this yet. No studies have yet examined the roles of BDNF, VEGF, or IGF-1 in sexual experience.
