Peri-SCN area dopaminergic neuron lesion induced metabolic syndrome. Animals received an infusion of 6-OHDA (2–4 μg/side) at the peri-SCN area bilaterally. GTTs were performed at 6 h after light onset. Plasma glucose and insulin were monitored before and at 30, 60, 90 and 120 min after glucose (3 g/kg BW, i.p.) was administered. The figure depicts plasma insulin and glucose during a GTT performed at 8 weeks (a, b respectively) and a second GTT performed at 16 weeks (c, d respectively) after lesion (n = 14) or sham lesion (n = 8). The area under the insulin (e) and glucose (f) tolerance test curves and Matsuda insulin sensitivity index during the second GTT (g) at week 16. Data are expressed as mean ± SEM. * P < 0.05 or ** P < 0.01 significant difference between treatment groups (two-way ANOVA with repeated measures with post-hoc Student’s t-test, or unpaired Student’s t-test as appropriate).