Effect of AMPT and/or AMPH administration on feeding behavior and hypothalamis NPY and MC4R expression. (A) The effect of AMPT and/or AMPH administration on food intake over a 4-day period. The first injection of AMPH (0, 2 and 4 mg/kg; i.p.) was conducted at the end of Day 0. AMPT (40 mg/kg; i.p.) was administered twice a day prior to daily AMPH (4 mg/kg). Each point represents the mean ± SEM of 8 rats. *P < 0.05 vs. the control group. #P < 0.05 vs. the AMPH (2 mg/kg)-treated group on Day 2. (B) The effect of AMPT, AMPH (4 mg/kg) or AMPT/AMPH co-administration on NPY and MC4R expression on Day 1. Results showed Western Blots and the relative densitometric value for the protein products. Inserted photo showed the results of NPY, MC4R, and β-actin expression. Bars were mean ± SEM. N = 6 each group. *P < 0.05 vs. control. AMPT: α-methyl-para-tyrosine.