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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.

Prolonged inactivity is known to induce changes in responses of many physiological defense systems such as the hypothalamo-hypophyseal-adrenocortical axis, the sympathetic nervous system, and immuno-responsive systems. However, effects of various types of inactivity on immuno-responsive systems are still unknown. Therefore, the effects of two types of inactivity (immobilization: IMM and whole body suspension: WBS) on the number of white blood cells were studied in rats. Rats were divided into the control group and each inactivity group to compare the number of total white blood cells, lymphocytes, monocyte, neutrophil, eosinophil, and basophil during the experimental periods. Both IMM and WBS were maintained for 11 days. IMM markedly increased the number of total white blood cells, monocyte, neutrophil, and eosinophil in the 1st to 10th day. However, the number of total white blood cells, monocyte, neutrophil, and eosinophil during the experiment of WBS were characterized by the presence of a lag phase followed by the significant increased actions. IMM did not change the number of basophil during the experimental period. However, WBS increased the number of basophil in the 1st to 8th day to 2.8-4.8 times, compared with the values of the control. Both IMM and WBS did not change the number of lymphocytes. From these results, WBS increases the number of natural immunity cells without changing acquired immunity cells, and there are different responses in the number of total white blood cells, monocyte, neutrophil, eosinophil, and basophil between IMM and WBS.

Abstract. Clenbuterol [CLE: 4-amino-α(t-butyl-amino)methyl-3,5-dichlorobenzyl alcohol] is well known as a potent β 2 -adrenergic agonist and non-steroidal anabolic drug, and thus it is generally used for sports doping and asthma therapy. Although the functions of immune cells such as white blood cells (WBCs) have shown to be modulated through β 2 -adrenoceptors, the effects of CLE on immune-responsive systems have not been elucidated systematically. Therefore, the effects of CLE on the number of WBCs were studied in rats. Male adult rats were divided into CLE-administered group and the control group to compare the number of total WBCs, neutrophils, monocytes, lymphocytes, eosinophils, and basophils. The administration (dose = 1.0 mg ⋅ kg −1 body weight ⋅ day −1 , s.c.) of CLE was maintained for 30 days. CLE did not change the number of total WBCs during the experimental period. However, CLE increased significantly the number of neutrophils and monocytes, while CLE decreased drastically the number of lymphocytes and eosinophils. There was no significant change in the number of basophils between both groups. These results suggest that the administration of CLE induces drastic redistribution of WBCs in circulation without changing the number of total WBCs, and these responses of WBCs during the administration of CLE are sustained for at least 30 days.

Endurance training and ingestion of green tea extract (GTE), composed mainly of tea catechins (TC), are well known to enhance fat metabolism. However, their synergistic effects remain to be fully elucidated. We tested the hypothesis that endurance training supplemented with GTE would further accelerate whole-body fat utilization during exercise, compared with training alone, in humans. Twelve healthy male subjects [peak oxygen consumption (VO2peak), 50.7 ± 1.3 (SEM) mL/kg/min] were divided into two groups: GTE and placebo (PLA) groups. Subjects in both groups performed a cycle ergometer exercise at 60% of VO2peak for 60 min/day, 3 days/week, and daily ingested 572.8 or 0 mg TC in GTE and PLA groups for 10 weeks, respectively. Before and after training, respiratory gas exchange was measured during 90-min exercise at pre-training ∼55% of VO2peak. After training, the average respiratory exchange ratio during exercise remained unchanged in the PLA group (post-training: 0.834 ± 0.008 vs pre-training: 0.841 ± 0.004), whereas it was lower in the GTE group (post-training: 0.816 ± 0.006 vs pre-training: 0.844 ± 0.005, P<0.05). These results suggest that habitual GTE ingestion, in combination with moderate-intense exercise, was beneficial to increase the proportion of whole-body fat utilization during exercise.