(Sisk and Foster 2004; Spear 2000). Puberty refers to gonadal maturation, while adolescence refers to a gradual period of maturation of social and cognitive behaviors (Powell 2006; Sisk and Foster 2004). The precise timing of adolescence in rodents is difficult to determine as there is no specific event signaling the beginning and end of this developmental period and the boundaries vary depending on genetic differences, gender, nutrition, and other environmental periods (Spear 2007). In rats, a conservative estimate of adolescence spans the period between postnatal days (PD) 28 and 42 (Spear 2007), but some harbingers of female adolescent development can begin as early as PD 20 and continue through PD 55 in males (Spear 2000, 2007). Studies investigating the effect of ethanol in adolescent rats have used the period between PD 28 and 60 (Smith 2003), while in mice, adolescence has been characterized as the period from PD 22 to 60 (Laviola et al. 2003).
