The effects of physical restraint are somewhat complicated to interpret and not as straight-forward as the stress effects of social dominance and predator odor effects on adult neurogenesis. Several studies have suggested that acute restraint lasting two to six hours has no effect on cell proliferation in adult rats (Kee et al., 2002; Pham et al., 2003; Rosenbrock et al., 2005). However, one study showed that three hours of restraint decreases cell proliferation in the adult rat (Bain et al., 2004). The same study showed that an increase in cell proliferation was seen in adult mice after acute restraint. It has been suggested that comparisons among different studies using nonstandardized methodologies of physical restraint are impossible because of the variations in intensity, duration, and frequency of restraint across rodent species and strains (Buynitsky & Mostofsky, 2009).
