Resumen de Changes in Adipopnectin, Leptin, and Fat Mass after Clenbuterol Treatment in Horses
Kenneth H. McKeever, Karyn Malinowski, Charles F. kearns
Introduction: Adipose tissue plays complex role(s) in metabolic and endocrine control. To date, little work has been done in the horse regarding adipocytokines.
Purpose: This study was conducted to determine whether therapeutic levels of chronic [beta]-agonist administration, exercise, or both could alter their concentrations.
Methods: A total of 23 standard-bred mares were divided into four experimental groups: clenbuterol (2.4 [mu]g[middle dot]kg-1 bw twice daily for 8 wk) plus exercise (8 wk, 20 min[middle dot]d-1 at 50% [latin capital V with dot above]O2max; CLENEX; N = 6), clenbuterol only (CLEN; N = 6), exercise only (EX; N = 5), and control (CON; N = 6). Rump fat thickness was measured using B-mode ultrasound and percent body fat (%fat) was calculated. Plasma adiponectin and leptin concentrations were measured using radioimmunoassay (RIA). In the absence of purified equine adiponectin or leptin, results were expressed as human equivalents of immunoreactive adipocytokines.
Results: The change in plasma immunoreactive (ir)-adiponectin HE concentration was negatively correlated (r = -0.520; P = 0.01) to the change in fat mass and positively correlated (r = 0.446; P = 0.03) to the change in fat-free mass. The change in plasma ir-leptin HE concentration was positively correlated (r = 0.550; P = 0.02) to the change in fat mass and negatively correlated (r = -0.473; P < 0.05) to the change in fat-free mass.
Conclusion: These data demonstrate that a chronic clenbuterol administration alters the concentrations of the adipocytokines adiponectin and leptin in horses. These changes may play a role in previously reported repartitioning effects of clenbuterol.
