Chronic treatment with protriptyline (10, 20 mg/kg) for 2 weeks reduced norepinephrine transporter (NET) expression, determined by 3H-nisoxetine binding (a) and SDS–PAGE/immunoblotting (b), and reduced immobility time in the forced-swim test (c). All measures were determined 2 days after the end of the chronic treatment period, except one group (10 mg/kg per day with 1 day washout). Data shown are means ± SEM of 5–8 rats per group. *p < 0.05, ***p < 0.001 vs control.