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.

SummaryThe acute effects of dihydrocapsaicin (DHC) and capsaicin (CAP) on the number of white blood cells (WBCs), neutrophils, eosinophils, basophils, monocytes, lymphocytes, T lymphocytes, B lymphocytes and NK cells, and serum corticosterone levels were studied in rats. Male 7-wk-old SD rats were divided into DHC (3.0 mg/kg BW), CAP (3.0 mg/ kg BW) and control (CON) groups. The number of total WBCs was 1.30-1.42 times significantly higher in the DHC group than in the CON group at 6-12 h. The number of neutrophils was 1.62 times significantly higher in the DHC group than in the CON group at 12 h. The number of total WBCs and neutrophils, however, showed no significant changes between the CAP and CON groups. The number of lymphocytes was 0.61 and 0.70 times significantly lower in the DHC and CAP groups than in the CON group at 3 h. The number of T lymphocytes and B lymphocytes was 0.74 and 0.54 times lower in the DHC group than in the CON group, respectively. CAP, however, did not significantly change the number of T lymphocytes or B lymphocytes. No significant changes in the number of NK cells were observed among the three groups. CAP and DHC did not change the number of monocytes, eosinophils or basophils. No significant changes of the serum corticosterone levels were observed among the three groups. In conclusion, capsaicinoids decreased the number of acquired immunity cells, and increased the number of total WBCs and neutrophils without changing the number of monocytes, eosinophils or basophils. The magnitidue of these effects was relatively higher in DHC than in CAP.

Summary Zinc is known to play an important role for immune-functions. However, the effects of zinc-deficiency on the immune response system from the point of view of the distribution changes of the number of total white blood cells (WBCs) are still primarily unknown. Therefore, the effects of zinc-deficiency on the number of total WBCs, neutrophil, eosinophil, basophil, monocyte and lymphocytes (T lymphocyte, B lymphocyte and NK cell) were studied in rats. The weaned male rats were randomly divided into the zinc deficient diet (ZDD: 0.7 mg zinc/kg diet) group and the control diet (CON: 34.8 mg zinc/kg diet) group, and were pair-fed for 4 wk. The number of lymphocyte subsets, visceral organ weights, serum zinc, corticosterone and IL-6 concentrations were also determined. Zinc-deficiency increased duration-dependently the number of total white blood cells, granulocytes (neutrophil, eosinophil and basophil) and monocytes in 2-4 wk without changing the number of lymphocytes, T lymphocytes, B lymphocytes or NK cells. The relative weights of thymus and adrenals were 0.63 times ( p Ͻ 0.01) lower and 1.60 times ( p Ͻ 0.001) higher in ZDD group than in CON group, respectively. Zinc-deficiency increased serum corticosterone concentration to 1.48 times ( p Ͻ 0.05) without changing serum IL-6 concentration, as compared with those of CON group. From these results, zinc-deficiency increases markedly the number of granulocytes and monocytes without changing the number of lymphocytes, T lymphocytes, B lymphocytes or NK cells. These results also suggest that zinc-deficiency induces stress responses and the responses may have in part participated in increased actions of the number of granulocytes and monocytes during zinc-deficiency, and induce thymus atrophy and adrenal hypertrophy.

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.

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