GH1 and obesity due to melanocortin 4 receptor deficiency: Taken together, these results suggest that impairment of T4-to-T3 conversion in PIT and BAT by decreased D1 and D2 activities respectively in response to exercise could be involved in the genesis of obesity in E2 deficient rats trough (i) decreasing GH release by PIT and/or (ii) reducing BAT metabolism.