Sexual dimorphism in the growth response of entire and gonadectomized rats to clenbuterol

Abstract

This study compared the anabolic effects of clenbuterol in male and female rats and determined the relative contribution of testicular and ovarian hormones to any observed gender difference. Seventy-two 12-wk-old rats were used in a 2 x 2 x 2 factorial design in which animals were either male or female, entire or gonadectomized at 3 wk of age, and fed either a control diet or a diet containing 4 mg clenbuterol/kg feed for 8 days. Compared with entire male rats, entire females gained 64% less weight, had lighter carcasses (-36%) and gastrocnemius muscles (-62%), and had higher plasma concentrations of the catabolic hormone corticosterone (P < 0.05). Castration had a negative effect on growth in male rats, and ovariectomy had a positive effect in females, but there was still a gender difference in body weight between gonadectomized males and females, which amounted to 34% of the gender difference observed in intact rats. The density of beta 2-adrenoceptors in skeletal muscle was not different between males and females, nor was it affected by gonadectomy. Clenbuterol increased both weight gain and gastrocnemius muscle weight, with the latter response in entire and castrated male rats (+ 1.31 and + 1.17 g) being more than double that seen in entire and ovariectomized females (+ 0.58 and + 0.55 g). The downregulation response of beta 2-adrenoceptors in this muscle was remarkably consistent in all treated groups (-50% to -53%).(ABSTRACT TRUNCATED AT 250 WORDS)

Castration differentially alters basal and leucine-stimulated tissue protein synthesis in skeletal muscle and adipose tissue

“…Castration also decreased the weight of the heart and kidney, and such changes have been reported previously (9,10,51). The castration-induced atrophy in these two tissues is not mediated by an altered rate of protein synthesis either under basal conditions or in response to leucine stimulation.…”

Albuterol and Exercise Effects on Ankle Extensor Strength during 40 Days of Unloading

“…The current drug/body mass covariate accounted for the variance in relative b 2 agonist doses consumed by ALB-dosed subjects. Yet ALB-W still incurred the most favorable strength changes, in disagreement with prior results ( 32 ). Administration of the b 2 agonist clenbuterol led to greater muscle in both intact and castrated male rats vs. their female counterparts ( 32 ).…”

“…Yet ALB-W still incurred the most favorable strength changes, in disagreement with prior results ( 32 ). Administration of the b 2 agonist clenbuterol led to greater muscle in both intact and castrated male rats vs. their female counterparts ( 32 ). Genderrelated differences among current and prior results may be due to subject ages, the type of b 2 agonist given, and drug dosages.…”

“…Data were compared with a 2 (gender) 3 2 (treatment) 3 4 (time) MANCOVA, with day 0 AEXT strength measurements and a drug/body mass ratio as covariates. Results: [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], as well as CAP and EAP days 11-20 and 21-30 showed the following signifi cant results: ALB-W . ALB-M, PLA-M .…”

A comparison of the development of renal hypertension in male and female rats

“…Although males and females were weightmatched initially, it was not possible to provide weightmatched male and female 2K1C rats over the entire experimental period, since intact female 2K1C rats exhibit only a small weight gain, which is characteristic of growth in female rats in general [14][15][16][17][18]. However, there was no significant difference in BWs between the groups at the time of clipping when previous studies have shown that increased renin release can be detected as soon as 1-2 days after clipping [19].…”