FGF23 and obesity due to melanocortin 4 receptor deficiency: AT increases Klotho and decreases FGF23 in Zucker rats (Obese+AT compared to CTL-Obese and Obese+AT+L-NAME; p < 0.0001), thus combating the imbalance in the Klotho/FGF23 axis caused by obesity (CTL-Obese, Obese+AT, and Obese+AT+L-NAME compared to CTL-Lean; p < 0.0001), but under a low concentration of NO−, AT amplifies this lack of control (Obese+AT+L-NAME compared to CTL-Obese; p < 0.0001).