Mice were fed with standard chow and treated for 3 days with saline (VEH); fed with standard chow and treated for 3 days with 1 μg g−1 of murine recombinant leptin (LEP); fed with a MHF diet for 8 weeks, then treated for 3 days with saline (MHF); fed with a MHF diet for 8 weeks, then treated for 3 days with 1 μg g−1 of murine recombinant leptin (MHF + LEP). Data are expressed as density of blue dots and are means ±s.e.m.; numbers within each column indicate the number of animals used for the determination. VMH, one-way ANOVA: A, F1,3 = 3.6764, P = 0.0254. *P < 0.05 versus VEH by Newman–Keuls test; B, F1,3 = 1.1757, P = 0.331. DMH, one-way ANOVA: A, F1,3 = 6.1503, P = 0.025. *P < 0.05 versus VEH and LEP by Newman–Keuls test; B, F1,3 = 1.5731, P = 0.21.