Effects of the β2-Agonist Clenbuterol on β1- and β2-Adrenoceptor mRNA Expressions of Rat Skeletal and Left Ventricle Muscles

Abstract

Abstract. The β 2 -agonist clenbuterol [4-amino-α(t-butyl-amino)methyl-3,5-dichlorobenzyl alcohol] is used as a non-steroidal anabolic drug for sports doping. The effects of clenbuterol on the transcriptional process and mRNA stability of β-adrenoceptor (β-AR) in skeletal and cardiac muscles are still unknown. Therefore, we investigated the effects of clenbuterol on β 1 -and β 2 -AR mRNA expressions of fast-twitch fiber-rich extensor digitorum longus (EDL), slow-twitch fiber-rich soleus (SOL), and left ventricle (LV) muscles by real-time RT-PCR. Adult male Sprague Dawley rats were divided into the clenbuterol-administered group and control group. The administration (dose = 1.0 mg / kg body weight / day, s.c.) of clenbuterol was maintained for 10 days. The administration of clenbuterol significantly increased the weight, RNA concentration, and total RNA content of EDL muscle. No effects of clenbuterol on those of SOL and LV muscles, however, were observed. The administration of clenbuterol significantly decreased β 1 -AR mRNA expression of LV muscle. Furthermore, the administration of clenbuterol significantly decreased β 2 -AR mRNA expression of EDL and LV muscles. No effect of clenbuterol on β 2 -AR mRNA expression of SOL muscle, however, was observed. These results suggest that the effects of clenbuterol on β 1 -and β 2 -AR mRNA expressions and muscle hypertrophy depend on muscle fiber types.

Acute and Subacute Effects of Dexamethasone on the Number of White Blood Cells in Rats

“…Experiments were designed to minimize pain and discomfort for the rats. [19][20][21] Both experiments were approved by the Committee on Animal Care Use at Waseda University. Administration of Dexamethasone to Rats --Dexamethasone 21-phosphate (Sigma, St. Louis, MO, U.S.A.) was first dissolved in 0.9% NaCl solution as a vehicle to obtain a final dexamethasone concentration of 0.1%.…”

Subacute Effects of Capsaicinoids on the Distribution of White Blood Cells in Rats

“…Male 6-week-old Sprague Dawley rats (CLEA Japan, Tokyo, Japan) were pre-fed for 4 days to allow adaptation to their new environment. [8][9][10][11][12][13] After the adaptation period, the rats were randomly divided into three groups, DHC (initial BW = 234 ± 2 g, in mean ± standard error of the mean), CAP (initial BW = 233 ± 3 g) and the control (CON: initial BW = 233 ± 2 g) groups. DHC and CAP (each dose = 3.0 mg/kg BW per day) were administered to rats for 10 days.…”

“…This study was performed with least possible pain or discomfort to the rats. [8][9][10][11][12][13] Administrations of DHC and CAP to Rats --DHC and CAP (Sigma, St. Louis, MO, U.S.A.) were prepared in 2% ethanol containing 2% Tween 80 and 0.9% NaCl solution as a vehicle to obtain 0.1% solution. 8) DHC (purity ≥ 95%) and CAP (purity ≥ 90%) were administered to rats via subcutaneous (s.c.) injection from cervical portion of the back for 10 days (9:00-10:00, a.m.).…”

Lowering Effects of Allyl Isothiocyanate on the Number of Lymphocyte and Its Subsets in Rats

“…[14][15][16] Lighting was automatically provided from 8:00 to 20:00. 17) Animal chow (CL-2, CLEA Japan Inc.) and onceboiled tap water were given to the rats ad libitum. 18) After the adaptation periods, the rats were randomly divided into the AITC group and the control group (1st experiment), and, the rats were randomly divided into the AITC group (10 mg/kg body weight per day), AITC group (20 mg/kg body weight per day) and the control group (2nd experiment).…”