Adaptive effects of the β2-agonist clenbuterol on expression of β2-adrenoceptor mRNA in rat fast-twitch fiber-rich muscles

Abstract

Administration of the beta(2)-agonist clenbuterol has been shown to reduce the expression of beta(2)-adrenoceptor (AR) mRNA in fast-twitch fiber-rich (extensor digitorum longus, EDL) muscle without changing that in slow-twitch fiber-rich (soleus, SOL) muscle in rats. However, the regulatory mechanism for muscle fiber type-dependent down-regulation of the expression of beta(2)-AR mRNA induced by clenbuterol is still unclear. Therefore, mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels in fast-twitch fiber-rich (EDL and plantaris, PLA) and slow-twitch fiber-rich (SOL) muscles in clenbuterol-administered (1.0 mg/kg body weight/day for 10 days, subcutaneous) rats was studied by real-time reverse transcription-polymerase chain reaction. Administration of clenbuterol significantly reduced expression of beta(2)-AR mRNA in EDL and PLA muscles without changing that in SOL muscle. Administration of clenbuterol also significantly reduced the mRNA expression of transcriptional regulatory factor (glucocorticoid receptor) and mRNA stabilizing factor (Hu antigen R) in EDL and PLA muscles without changing those in SOL muscle. These results suggest that muscle fiber type-dependent effects of clenbuterol on expression of beta(2)-AR mRNA are closely related to the down-regulation of mRNA expression of transcriptional and post-transcriptional regulatory factors for beta(2)-AR mRNA levels.

Casted-immobilization downregulates glucocorticoid receptor expression in rat slow-twitch soleus muscle

“…e l s e v i e r . c o m / l o c a t e / l i f e s c i e plasticity via maintenance of muscle protein synthesis and degradation (Hinkle et al, 2002;Lynch and Ryall, 2008;Sato et al, 2008Sato et al, , 2010. Furthermore, several studies have demonstrated that glucocorticoids and the GR complex activate the transcription of the β 2 -AR gene through interaction with glucocorticoid response elements (GREs) in its promoter region (Cornett et al, 1998), leading to an upregulation of β 2 -AR expression (Hadcock and Malbon, 1988;Mak et al, 1995).…”

“…Synthesized cDNA was added to a Power SYBR Green PCR Master Mix (Applied Biosystems) with 200 nM PCR primers (forward and reverse). The primer oligonucleotide sequences used for real-time quantitative PCR were as follows (Sato et al, 2010(Sato et al, , 2011: GR, 5′-TAC CAC AGC TCA CCC CTA CC-3′ (forward), 5′-AGC AGG GTC ATT TGG TCA TC-3′ (reverse); β 2 -AR, 5′-GAG CCA CAC GGG AAT GAC A-3′ (forward), 5′-CCA GGA CGA TAA CCG ACA TGA-3′ (reverse); 18S rRNA, 5′-GTG CAT GGC CGT TCT TAG TTG-3′ (forward), 5′-AGC ATG CCG AGA GTC TCG TT-3′ (reverse). Amplification was performed using an ABI PRISM 7000 Sequence Detection System (Applied Biosystems).…”

Synthesized glucocorticoid, dexamethasone regulates the expressions of .BETA.2-adrenoceptor and glucocorticoid receptor mRNAs but not proteins in slow-twitch soleus muscle of rats

“…In real-time quantitative PCR, synthesized cDNA was added to a power SYBR green PCR master mix (Applied Biosystems) containing 200 nM PCR primer (forward and reverse). The primer oligonucleotide sequences used for real-time quantitative PCR are described previously (Sato et al, 2010). Amplification was performed using an ABI PRISM 7000 Sepuence Detection System (Applied Biosystems).…”

“…We reported that administration of β 2 -agonist, clenbuterol (CLE: 4-amino-α (t-butylamino) methyl-3, 5-dichlorobenzyl alcohol), one of doping drugs, increased the weight of EDL muscle without changing that of SOL muscle (Sato et al, 2008). Further, administration of CLE decreased the density of β 2 -AR in fast-twitch muscles (Huang et al, 2000) and decreased the expression of β 2 -AR mRNA in EDL muscle without changing that in SOL muscle (Sato et al, 2008(Sato et al, , 2010. On the contrary, Cornett et al (1998) reported that glucocorticoids increased the transcription of β 2 -AR by acting toward glucocorticoid response elements (GREs) on β 2 -AR gene via glucocorticoid receptor (GR) using HepG2 cells in vitro.…”

Age-related effects of fasting on ketone body production during lipolysis in rats

“…Therefore, fasting of the 3-, 8-, and 32-week-old rats was maintained for 2, 5, and 12 days, respectively. The animals were housed individually in stainless-steel cages at a controlled temperature (23-26°C) and a relative humidity of 45-60% with light-dark cycles [0700-1900 hours (light) and 1900-0700 hours (dark)] [21][22][23]. Animal chow (CE-2 cubic type; CLEA Japan, Tokyo, Japan) and once-boiled tap water were provided to the rats ad libitum.…”