| First Author | da Silva AA | Year | 2018 |
| Journal | Am J Physiol Regul Integr Comp Physiol | Volume | 314 |
| Issue | 4 | Pages | R533-R539 |
| PubMed ID | 29351428 | Mgi Jnum | J:261010 |
| Mgi Id | MGI:6150714 | Doi | 10.1152/ajpregu.00293.2017 |
| Citation | da Silva AA, et al. (2018) Control of appetite, blood glucose, and blood pressure during melanocortin-4 receptor activation in normoglycemic and diabetic NPY-deficient mice. Am J Physiol Regul Integr Comp Physiol 314(4):R533-R539 |
| abstractText | Although central melanocortin 4 receptor (MC4R) blockade abolishes the central nervous system (CNS)-mediated anorexogenic, antidiabetic, and cardiovascular actions of leptin, chronic MC4R stimulation fails to completely mimic the effects of leptin. Because neuropeptide Y (NPY) and MC4R exert opposite effects on cardiovascular and metabolic functions, we tested the role of NPY in offsetting the long-term actions of MC4R activation. Wild-type (WT) and NPY-deficient (NPY(-/-)) mice were implanted with telemetry probes for measuring mean arterial pressure (MAP) and heart rate (HR) 24 h/day. After the mice recovered from surgery and stable baseline measurements, the MC3/4R agonist melanotan II (MTII, 120 mug.kg(-1).day(-1) iv) was infused for 7 days followed by a recovery period. No major differences between groups were observed at baseline except for slightly higher food intake and HR in NPY(-/-) mice (4.3 +/- 0.2 vs. 3.4 +/- 0.2 g/day and 567 +/- 14 vs. 522 +/- 13 beats/min). Chronic MTII infusion reduced food intake in both groups while causing transient increases in MAP and HR only in WT mice (peaks of 11 +/- 3 mmHg and 126 +/- 13 beats/min). To examine whether NPY deficiency would amplify the antidiabetic effects of MC4R activation, diabetes was induced with streptozotocin (STZ) 1 wk before baseline measurements were taken, and the same experimental protocol was followed. In WT and NPY(-/-) mice, STZ-induced diabetes led to similar hyperphagia, hyperglycemia, and weight loss, which were not reversed by chronic MTII treatment. Our results demonstrate that chronic MC4R activation, even in NPY-deficient mice, does not mimic chronic antidiabetic, cardiovascular, or metabolic actions of leptin, and that NPY is not essential for hyperphagia or cardiovascular changes associated with diabetes. |
