Drugs

Selegiline hydrochloride (FP Pharmaceutical Co., Osaka, Japan) was dissolved in saline and administered by single or repeated (daily for 3 days) subcutaneous (s.c.) injections at a dose of 1–10 mg/kg, which was the effective dose and treatment in PD and/or depression rodent models (Fredriksson et al., 1999; Shimazu et al., 2005). Rasagiline mesylate (Sigma-Aldrich, St. Louis, MO, USA) was dissolved in saline and administered in a single s.c. injection at a dose of 1 or 10 mg/kg in order to compare the antidepressant effects between these two MAO-B inhibitors (Finberg and Youdim, 2002; Youdim and Tipton, 2002). Pramipexole dihydrochloride (Sigma-Aldrich) was dissolved in saline and administered in a single s.c. injection at a dose of 1 mg/kg which was reported to be the effective dose and treatment in PD and/or depression rodent models (Maj et al., 1997; Siuciak and Fujiwara, 2004; Kitagawa et al., 2009; Bonito-Oliva et al., 2014). A noradrenergic and specific serotonergic antidepressant (NaSSA), mirtazapine (Sigma-Aldrich) was suspended in 0.2% Tween 80 solution and injected intraperitoneally (i.p.) at a dose of 1 mg/kg daily for 7 days, based on our preparatory experiments of the previous study (Lopatina et al., 2014). All drugs or saline were administered to mice in a volume of 10 mL/kg. Mice were subjected to behavioral tests 1 h after the last injection of selegiline, rasagiline, pramipexole or saline, or 30 min after the last injection of mirtazapine.