Effects of dexamethasone on the expression of β1-, β2- and β3-adrenoceptor mRNAs in skeletal and left ventricle muscles in rats

Abstract

Glucocorticoids are known to increase the density and mRNA levels of beta-adrenoceptors (beta-AR) via the glucocorticoid receptor (GR) in many tissues. However, the effects of these changes in the skeletal and cardiac muscles remain relatively unknown. We have investigated the effects of dexamethasone on the expression of the beta(1)-, beta(2)-, and beta(3)-AR mRNAs and GR mRNA in fast-twitch fiber-rich extensor digitorum longus (EDL), slow-twitch fiber-rich soleus (SOL), and left ventricle (LV) muscles by real-time quantitative RT-PCR. Male rats were divided into a dexamethasone group and control group. The weight, RNA concentration, and total RNA content of EDL muscle were 0.76-, 0.85-, and 0.65-fold lower, respectively, in the dexamethasone group than in the control group. The weight, RNA concentration, and total RNA content of SOL muscle were 0.92-, 0.87-, and 0.81-fold lower, respectively, in the dexamethasone group than in the control group; these differences were significant. However, the weight/body weight and total RNA content/body weight of LV muscle were 1.38- and 1.39-fold higher, respectively, in the dexamethasone group than in the control group, respectively; these differences were also significant. Dexamethasone significantly decreased GR mRNA expression in EDL muscle without changing the expression of the beta(1)-, beta(2)-, and beta(3)-AR mRNAs. However, dexamethasone significantly decreased the expressions of beta(2)-AR and GR mRNAs in SOL muscle and significantly increased beta(1)-AR mRNA expression in LV muscle-without changing GR mRNA expression. These results suggest that the effects of dexamethasone on the expression of beta(1)- and beta(2)-AR mRNAs and muscle mass depend on the muscle contractile and/or constructive 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%.…”

“…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%. 21) In the dexamethasonetreated group, dexamethasone was administered at the cervical region of the back via a subcutaneous injection (s.c., 9:00-9:30 a.m.). 21) In the control group, an equivalent volume of dexamethasone-free solution was administered in the same manner.…”

“…21) In the dexamethasonetreated group, dexamethasone was administered at the cervical region of the back via a subcutaneous injection (s.c., 9:00-9:30 a.m.). 21) In the control group, an equivalent volume of dexamethasone-free solution was administered in the same manner. 21) Acute Effects of Dexamethasone on the Numbers of WBCs --After 5 days of prefeeding, the rats were divided into a dexamethasone group [dose = 1.0 mg/kg body weight (BW), n = 9, the initial BW = 284 ± 3 g, mean ± SEM] and control group (n = 8, the initial BW = 286 ± 2 g, mean ± standard error of the mean (SEM)).…”

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

“…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).…”

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

“…Glucocorticoids also increased the expression and activity of the ubiquitin-proteasome pathway that play an important role in the major proteolytic mechanism of muscle atrophy (Bodine et al, 2001;Hasselgren, 1999). Some reports showed that the degree of synthesized glucocorticoid, dexamethasone Synthesized glucocorticoid, dexamethasone regulates the expressions of β 2 -adrenoceptor and glucocorticoid receptor mRNAs but not proteins in slow-twitch soleus muscle of rats (DEX)-induced decrease in muscle weight was higher in fast-twitch fiber-rich (extensor digitorum longus (EDL)) muscle than in slow-twitch fiber-rich (soleus (SOL)) muscle (Kawano et al, 2009;Livingstone et al, 1981).…”