Adipose Tissue, Longissimus Muscle and Anterior Pituitary Growth and Function in Clenbuterol-Fed Heifers

Abstract

The present study was conducted to determine the effects of feeding clenbuterol on adipose tissue and longissimus muscle growth in heifers. For 50 d, 14 heifers were fed either a sucrose-based, clenbuterol supplement or a placebo in which the clenbuterol had been omitted. The heifers were slaughtered in two groups, based on initial weight. Adipose tissue from several anatomical sites and longissimus muscle (depending on slaughter group) were obtained fresh at slaughter. Changes in carcass characteristics elicited by clenbuterol were similar to those reported by others for steers and sheep. Subcutaneous (sc) and intramuscular (im), but not perirenal, adipocytes were smaller and there were more cells per g tissue in the adipose tissue depots of the clenbuterol-fed heifers. Clenbuterol decreased lipogenic enzyme activities, fatty acid-binding protein activity, basal lipolysis and acetate incorporation into glyceride-fatty acids (P less than .05) in sc adipose tissue, but had no effect (P greater than .05) on lipogenesis or lipolysis in im adipose tissue. Clenbuterol elicited a 20% increase in type II myofiber diameters (P less than .05) but had no effect on type I myofiber diameters. In vitro growth hormone release by perifused anterior pituitaries was not affected significantly by long-term in vivo exposure to clenbuterol. These data indicate that a depression in lipogenesis is the mechanism by which clenbuterol decreases subcutaneous fat accretion in cattle.

Effect of dietary cimaterol on performance and carcass traits in bulls and on aspects of digestion in cattle and sheep

“…The improvement of the carcass characteristics and the reduction of the weight of organs are in agreement with the findings previously observed in cattle Williams et al, 1987;Miller et al, 1988;Quirke et al, 1988) and sheep (Thornton et al, 1985;Kim et al, 1989). Reductions of the viscera were reported by Williams et al (1987) and Quirke et al (1988).…”

“…Rumen fermentation characteristics were calculated by analysis of variance in a repeated measures experiment (Snedecor and Cochran, 1980 in Friesian veal calves (Williams et al, 1987) or in crossbred heifers (Miller et al, 1988 (Quirke et al, 1988). Reeds et al (1986) (Stiles et al, 1984).…”

Role of Masseter Muscle β2-Adrenergic Signaling in Regulation of Muscle Activity, Myosin Heavy Chain Transition, and Hypertrophy

“…this study increased the mass of the skeletal and cardiac muscle efficiently without altering the body weight, probably due to the concomitant decrease of fat tissue induced by CB through its lipolytic effect (18,19,26). We also performed electrocardiogram (ECG) recording using a telemetric unit (24,25,27).…”

Effect of salbutamol on innervated and denervated rat soleus muscle

“…Most studies have demonstrated that BAA increase the cross-sectional area of fast muscle fibers (7)(8)(9) while the results of studies of the effects of BAA on slow muscle fibers have not been consistent. Some studies have demonstrated that the cross-sectional area of slow twitch oxidative fibers is not changed by chronic administration of BAA (8,10,11) while others have shown that all fiber types are affected equally (12,13). Recent reports have established that clenbuterol is able to induce changes in fiber type distribution.…”