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The aim of this study was to clarify the intracellular β2-adrenergic receptor signaling specificity in mouse slow-twitch soleus and fast-twitch tibialis anterior (TA) muscles, resulting from single-dose β2-agonist clenbuterol treatment and acute exercise. At 1, 4, and 24 h after single-dose treatment with clenbuterol or after acute running exercise, the soleus and TA muscles were isolated and subjected to analysis. The phosphorylation of p38 mitogen-activated protein kinase (MAPK) increased after single-dose clenbuterol treatment and acute exercise in the soleus muscle but not in the TA muscle. Although there was no change in the phosphorylation of Akt after acute exercise in either muscle, phosphorylation of Akt in the soleus muscle increased after single-dose clenbuterol treatment, whereas that in the TA muscle remained unchanged. These results suggest that p38 MAPK and Akt pathways play a functional role in the adaptation to clenbuterol treatment and exercise, particularly in slow-twitch muscles.

Splenic marginal zone macrophages expressing macrophage receptor with collagenous structure (MARCO) contribute to the clearance of blood-borne pathogens. We determined a splenic adherent cell fraction abundantly containing cells expressing a higher level of MARCO by flow cytometry, and examined the effects of daily administration of an anabolic dose of β2-agonist clenbuterol on the phagocytic capacity of the cells in mice. After 6 weeks of clenbuterol (1.0 mg/kg body weight/d) or vehicle administration to the mice, splenic adherent cells were isolated. These cells were separated into three cell-size subpopulations. Among them, the small-cell subpopulation contained abundantly the cells with markedly higher levels of MARCO and exhibited more intense phagocytic capacity against Escherichia coli, as compared with the other subpopulations. The phagocytic capacity of the small cells was significantly reduced after clenbuterol administration. These results suggest that the utilization of clenbuterol as doping drug impairs bacterial clearance in the spleen.

The acute effects of oral administration of diallyl disulfide (DADS), the major organosulfur compound of garlic, on plasma glucose and free fatty acid (FFA) concentrations were examined in rats. Male, 10-week-old Sprague-Dawley rats were divided into DADS-free and DADS-administered (dose = 10, 20, and 40 mg/kg body weight [BW]) groups. Plasma samples were prepared from whole blood drawn from the tail vein 0, 1, 2, 4, and 6 hr after administration. The stomachs were isolated, and the contents were measured 8 hr after administration. In DADS-administered groups, plasma glucose concentrations were increased in a dose-dependent manner 1 hr after the administration. The increase was transient, except in groups administered 40 mg/kg BW of DADS, in which plasma glucose levels remained significantly higher than the DADS-free levels throughout the experimental period. Similar patterns were observed in the plasma FFA concentrations, although the significant differences were lower than those observed in the plasma glucose concentrations. The gastric contents were dose-dependently elevated after DADS administration. The increase was significant when 20 or 40 mg/kg BW of DADS was administered. These results suggest that oral administration of DADS can mobilize energy substrates into the blood, although a higher dose of DADS slows gastric emptying.

Folate (vitamin B(9)) plays key roles in cell growth and proliferation through regulating the synthesis and stabilization of DNA and RNA, and its deficiency leads to lymphocytopenia and granulocytopenia. However, precisely how folate deficiency affects the distribution of a variety of white blood cell subsets, including the minor population of basophils, and the cell specificity of the effects remain unclear. Therefore, we examined the effects of a folate-deficient diet on the circulating number of lymphocyte subsets [T-lymphocytes, B-lymphocytes, and natural killer (NK) cells] and granulocyte subsets (neutrophils, eosinophils, and basophils) in rats.Rats were divided into two groups, with one receiving the folate-deficient diet (FAD group) and the other a control diet (CON group). All rats were pair-fed for 8 weeks.Plasma folate level was dramatically lower in the FAD group than in the CON group, and the level of homocysteine in the plasma, a predictor of folate deficiency was significantly higher in the FAD group than in the CON group. The number of T-lymphocytes, B-lymphocytes, and NK cells was significantly lower in the FAD group than in the CON group by 0.73-, 0.49-, and 0.70-fold, respectively, indicating that B-lymphocytes are more sensitive to folate deficiency than the other lymphocyte subsets. As expected, the number of neutrophils and eosinophils was significantly lower in the FAD group than in the CON group. However, the number of basophils, the least common type of granulocyte, showed transiently an increasing tendency in the FAD group as compared with the CON group.These results suggest that folate deficiency induces lymphocytopenia and granulocytopenia in a cell-specific manner.

Diallyl disulfide (DADS) is a major sulfur compound of garlic, and exerts anti-inflammatory, immune-modulatory, and enhancing sympathetic activity effects. However, it still remains unclear how DADS affects the distribution of white blood cell subsets, which is essential to execute effective immune responses and partially regulated by adrenal glucocorticoids. Therefore, we examined the dose-dependent effects of DADS administration on the circulating number of white blood cells (WBCs) and lymphocyte subsets, and plasma corticosterone concentration in rats. Male 10-wk-old Sprague Dawley rats were divided into the DADS-free and DADS-orally administered (dose=10, 20, and 40 mg/kg BW) groups. Blood samples were collected from the tail vein at 0, 1, 2, 4, and 6 h after the administration. DADS administration decreased dose- and time-dependently the circulating number of total WBCs, total lymphocytes, and monocytes. Within the lymphocyte subsets, the circulating number of T-lymphocytes and B-lymphocytes was significantly reduced 4 h after DADS administration in a dose-dependent manner, although that of natural killer (NK) cells was not affected. On the other hand, although DADS administration did not significantly change the circulating number of neutrophils, the circulating number of eosinophils and basophils showed a decreasing tendency after DADS administration. In contrast, plasma corticosterone concentration was increased 2 h after DADS administration in a dose-dependent manner. These results suggest that DADS administration reduces the circulating number of monocytes and lymphocytes, including especially acquired immune cells, via the action of corticosterone, and the effects are induced in a dose-dependent manner.

In this review, we discuss the anabolic and metabolic responses of skeletal muscles to β2-agonists and exercise. β2-agonists increase muscle mass, particularly in fast-twitch muscles. Exercise positively regulates glucose homeostasis, mitochondrial biogenesis, and metabolic enzyme levels in skeletal muscles; whereas treatment with β2-agonists attenuates these beneficial effects. This review also describes the role of β2-adrenergic receptor (β2-AR) signaling molecules, such as cyclic adenosine monophosphate response element-binding protein, mitogen-activated protein kinase, and Akt/protein kinase B, in the response of skeletal muscles to β2-agonist treatment and exercise. For example, β2-agonists and exercise increase the phosphorylation of p38 mitogen-activated protein kinase in slow-twitch muscles. Our interpretation of these findings is that β2-adrenergic receptor signaling plays a functional role in the anabolic and metabolic responses of skeletal muscles to β2-agonists and exercise.

Aims Glucocorticoids bind to the glucocorticoid receptor (GR) and increase catabolism of muscle proteins via the ubiquitin-proteasome pathway. Activation of β 2 -adrenergic receptor (β 2 -AR) in skeletal muscle has been shown to induce muscle hypertrophy by promoting muscle protein synthesis and/or attenuating protein degradation. The aim of this study was to investigate the correlation between disuse-induced muscle atrophy, and expression of GR and β 2 -AR. Methods Rats were subjected to casted-immobilization (knee and foot arthrodesis), a model for muscle disuse, for 10 days. Fast-twitch (extensor digitorum longus: EDL) and slow-twitch (soleus: SOL) muscles were isolated and subsequently used for analysis. The expression of GR and β 2 -AR was analyzed by real-time RT-PCR and western blotting. In addition, we analyzed plasma catecholamine and corticosterone concentrations by ELISA. Key findings Casted-immobilization-induced muscle atrophy was much greater in the SOL muscle than in the EDL muscle. Casted-immobilization decreased the expression of GR mRNA and protein in the SOL muscle but not in the EDL muscle. Although the expression of β 2 -AR protein in the cytosol and membrane-rich fractions was not changed by casted-immobilization in either muscle, casted-immobilization decreased the expression of β 2 -AR mRNA in the SOL muscle. Plasma catecholamine and corticosterone concentrations, however, were largely unaffected by casted-immobilization during the experimental period. Significance This study provides evidence that casted-immobilization-induced muscle disuse downregulates GR expression in slow-twitch muscle. These results suggest that muscle disuse suppresses glucocorticoid signals, such as muscle protein breakdown and transcription of the β 2 -AR gene, via downregulation of GR expression in slow-twitch muscle.

Effects of synthesized glucocorticoid, dexamethasone (DEX, dose = 1.0 mg/kg body weight/day for 10 days) on the expressions of β2-adrenoceptor (AR) and glucocorticoid receptor (GR) were studied in fast-twitch (extensor digitorum longus (EDL)) and slow-twitch fiber-rich (soleus(SOL)) muscles of rats. DEX decreased the expression of β2-AR mRNA in SOL muscle without changing that in EDL muscle. The expression of β2-AR protein in EDL and SOL muscles was not affected by DEX. DEX-induced decreased action of the expression of GR mRNA was much greater in SOL muscle than in EDL muscle. However, there were no differences in the expression of GR protein in EDL and SOL muscles. DEX also decreased mRNA expression of cAMP response element binding protein (CREB, transcription factor of β2-AR mRNA) in SOL muscle, whereas increased that in EDL muscle. Further, DEX tended to increase mRNA expressions of post-transcription factors of β2-AR mRNA in EDL muscle without changing those in SOL muscle. These results demonstrated that the expressions of β2-AR and GR are regulated at mRNA levels but not protein levels by DEX. Further, these results also suggest that DEX-induced decrease in the expression of β2-AR mRNA in slow-twitch fiber-rich SOL muscle is associated with the transcriptional regulations.

The aim of this study was to elucidate whether dietary zinc-deficiency and its recovery play a role in controlling autonomic thermoregulation. We investigated the effects of dietary zinc-deficiency and its recovery on autonomic thermoregulation by measuring the rectal temperature, an index of deep body temperature. The weaned male Sprague Dawley rats were randomly divided into the dietary zinc-deficient diet (0.6 mg zinc/kg diet) group and the control diet (35.2 mg zinc/kg diet) group, and were fed for 4 weeks. In the recovery period, the rats of two groups were fed with the control diet for 3 weeks. The rectal temperature was significantly decreased throughout the period of zinc-deficiency and the hypothermic responses during the experimental period were recovered to the control group levels at least within 1 week in the recovery process from dietary zinc-deficiency. These results suggest that the deep temperature in rats was clearly associated with the dietary zinc intake levels.

We discuss the functional roles ofβ2-adrenergic receptors in skeletal muscle hypertrophy and atrophy as well as the adaptive responses ofβ2-adrenergic receptor expression to anabolic and catabolic conditions.β2-Adrenergic receptor stimulation using anabolic drugs increases muscle mass by promoting muscle protein synthesis and/or attenuating protein degradation. These effects are prevented by the downregulation of the receptor. Endurance training improves oxidative performance partly by increasingβ2-adrenergic receptor density in exercise-recruited slow-twitch muscles. However, excessive stimulation ofβ2-adrenergic receptors negates their beneficial effects. Although the preventive effects ofβ2-adrenergic receptor stimulation on atrophy induced by muscle disuse and catabolic hormones or drugs are observed, these catabolic conditions decreaseβ2-adrenergic receptor expression in slow-twitch muscles. These findings present evidence against the use ofβ2-adrenergic agonists in therapy for muscle wasting and weakness. Thus,β2-adrenergic receptors in the skeletal muscles play an important physiological role in the regulation of protein and energy balance.

The purpose of the present study was to elucidate the effects of dietary zinc-deficient feeding and its recovery on liver cytosolic alcohol dehydrogenase (ADH; alcohol: NAD(+) oxidoreductase, EC1.1.1.1) activities and plasma zinc levels in rats. The weaned male Sprague Dawley rats were randomly divided into the zinc-deficient diet (ZDF: 1.9 mg zinc/kg diet) group and the control diet (53.5 mg zinc/kg diet) group, and were fed for 4 weeks. In the recovery periods, the rats of two groups were fed with the control diet for 3 weeks. Liver cytosolic protein content per body weight in the zinc-deficiency and its recovery period showed no significant changes between both groups. However, zinc-deficiency decreased significantly liver cytosolic ADH specific activity, total liver cytosolic ADH activity and total liver cytosolic ADH activity/body weight by 50%, 76% and 53%, respectively, as compared with the control diet group. Zinc-deficiency also decreased significantly plasma zinc concentration by 84%, as compared with the control diet group. On the contrary, no significant changes in liver cytosolic ADH specific activity, total liver cytosolic ADH activity and total liver cytosolic ADH activity/body weight in the recovery period were observed between both groups. Plasma zinc concentration in the recovery period was almost recovered to the control level. These results suggest that rat liver cytosolic ADH activity was clearly related to dietary zinc intake levels.

Acute single administration effects of ethanol on the distribution of total white blood cells (WBCs), neutrophil, basophil, eosinophil, monocyte and lymphocytes were studied in rats. Acute single administration effects of ethanol on the number of red blood cells (RBCs), hemoglobin concentration and hematocrit were also examined. Male 8-week-old Sprague Dawley rats were randomly divided into the ethanol-administered (ETA) group and the control (CON) group. Two parts of an experiment, 1) 1st experiment : (ethanol dose : 1.0 g/kg body weight), and 2) 2nd experiment : (ethanol dose : 2.0 g/kg body weight) were carried out in rats. The rats were starved to 19:00, and deprived of diet for 12 hr and water for 1 hr before the single administration of ethanol. 1.0 or 2.0 g/kg body weight of ethanol (in 20% (w/w) ethanol) was orally administered to ETA group rats via a stainless stomach tube. In the CON group rats, 0.9% NaCl solution was orally given with the solution volume being equal, in the same manner. Single administration of 1.0 or 2.0 g/kg body weight of ethanol did not change the number of RBCs, hemoglobin concentration and hematocrit. Single administration of 1.0 g/kg body weight of ethanol did not also change the number of WBCs. However, administration of 2.0 g/kg body weight of ethanol increased significantly the number of neutrophil, basophil, monocyte and total WBCs without changing the number of eosinophil and lymphocytes. These results suggest that single administration of 2.0 g/kg body weight of ethanol to rats increased markedly the number of the natural immunity cells without changing the number of acquired cells.

Red peppers are used as a spice for enhancing the palatability of foods. Two major capsaicinoids, dihydrocapsaicin (DHC) and capsaicin (CAP) are responsible for up to 90% of the total pungency of pepper fruits. These capsaicinoids are known to enhance energy metabolism and thermogenesis. However, there is a little information on the effects of capsaicinoids on the lipolysis and carbohydrate metabolism. We studied the effects of DHC and CAP on plasma glucose, free fatty acid (FFA) and glycerol concentrations in rats. Male six-week-old Sprague Dawley rats were divided into the DHC, CAP and control groups. Each capsaicinoid (dose = 3 mg/kg BW/day) was subcutaneously administered to rats for 10 days. DHC increased markedly plasma glucose, FFA and glycerol concentrations on day 1-10 by 14-35%, 61-103% and 108-174%, respectively, as compared with those of the control group. CAP increased relatively plasma glucose concentrations on day 1-3 by 15-17%, as compared with the control group. However, there were no significant differences in plasma glucose concentrations on day 7-10 among three groups. On the contrary, CAP did not change plasma FFA and glycerol concentrations on day 1-3. However, CAP increased markedly plasma FFA and glycerol concentrations on day 7-10 by 54-89% and 92-98%, respectively, as compared with the control group. DHC and CAP did not change the weights of white (perirenal and periepididymal) and brown (interscapular) adipose tissues. In conclusion, the effects of capsaicinoids on plasma glucose, FFA and glycerol concentrations were relatively higher in the DHC than in the CAP, and capsaicinoids did not change the weight of white and brown adipose tissues.

The subacute effects of dihydrocapsaincin (DHC) and capsaicin (CAP) (dose=3 mg/kg body weight per day for 10 days, subcutaueous) on the number and distribution of white blood cells (WBCs) were studied in male adult rats. The administration of DHC and CAP for 10 days decreased significantly the number of total WBCs, lymphocytes and monocyte, and increased significantly the number of the neutrophil and eosinophil without changing the number of basophil. The administration of DHC significantly decreased thymus weight and increased adrenal weight, showing that DHC induced thymus atrophy and adrenal hypertrophy. These results suggest that capsaicinoids induced the decrease of acquired immunity responses and these phenomena may have in part participated in capsaicinoids-induced stress-responses in rats.

The main pungent component of wasabi (Eutrema japonica) is known to be isothiocyanate and its derivatives, volatile substances. Allyl isothiocyanate (AITC) accounts for more than half of isothiocyanate derivatives. However, there is a little information on the effects of AITC on the immune system by analyzing the number of white blood cells (WBCs) over the course of days of AITC administration. In the present study, we studied the effects of AITC (dose=20 mg/kg body weight/day for 10 days, subcutaneous: s.c.) on the number of WBCs (total WBCs, lymphocytes, monocyte, neutrophil, basophil and eosinophil) and plasma corticosterone concentrations in adult male rats. Administration of AITC decreased significantly the number of total WBCs on days 1-4 post s.c. injection by 25-27%. Administration of AITC also decreased the number of lymphocytes on days 1-10 by 21-36% and monocyte on days 1-8 by 28-78%. However, administration of AITC increased the number of neutrophil on days 8-10 by 61-112%. AITC did not change the number of eosinophil and basophil. Plasma corticosterone concentrations during the experimental period were 4.7-8.4 times significantly higher in the AITC group than in the control group, indicating that AITC induced stress-responses. The relative weights of thymus and adrenals per body weight were significantly lower and clearly higher in the AITC group than in the control group, respectively. These results suggest that AITC-mediated stress-responses are at least in part attributable to changes in the number of circulating WBCs.

The purpose of this study was to elucidate the effects of dexamethasone, a synthetic glucocorticoid, on the immune system by analyzing the number of white blood cells (WBCs) over the course of hours and days of dexamethasone administration. Dexamethasone was given as either a single dosage [1.0 mg/kg body weight (BW); subcutaneous injection (s.c.)] or as a daily dosage (1.0 mg/kg BW per day; s.c.) for 10 days for the hourly and daily assessment of changes in the number of white blood cells, respectively. A single administration of dexamethasone markedly decreased the number of total WBCs, as well as the number of lymphocyte, monocyte, neutrophil and eosinophil subsets with a nadir at 8 hr post-injection. The number of these cells recovered to the control levels at 24 hr. The numbers of total WBCs, lymphocytes, monocyte, eosinophil and basophil were reduced by the daily administration of dexamethasone. However, the number of neutrophil was significantly higher at days 2 and 8 after the injection. These results suggest that glucocorticoid-mediated immunosuppressions are at least partly attributable to quantitative changes in the number of circulating WBCs.

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.

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.

The 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 magnitude of these effects was relatively higher in DHC than in CAP.

The aim of the present study was to determine whether the antiobesity effects of tea catechins (TCs) are associated with the expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT). Male Sprague-Dawley rats were fed a high-fat (HF; 35% fat) diet for 5 weeks, then divided into four groups and fed an HF, HF with 0.5% TC (HFTC), normal-fat (NF; 5% fat) or NF with 0.5% TC (NFTC) diet for 8 weeks. At the end of the experimental period, perirenal and epididymal white adipose tissues (WATs) and interscapular BAT were isolated. The NFTC group had significantly lower perirenal WAT weights than the NF group (NF: 12.7+/-0.53 g; NFTC: 10.2+/-0.43 g; P

The β2-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 β1- and β2-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 β1-AR mRNA expression of LV muscle. Furthermore, the administration of clenbuterol significantly decreased β2-AR mRNA expression of EDL and LV muscles. No effect of clenbuterol on β2-AR mRNA expression of SOL muscle, however, was observed. These results suggest that the effects of clenbuterol on β1- and β2-AR mRNA expressions and muscle hypertrophy depend on muscle fiber types. Keywords:: clenbuterol, β-adrenoceptor mRNA, down-regulation, muscle hypertrophy, skeletal and left ventricle muscles

Clenbuterol [CLE: 4-amino-α(t-butyl-amino)methyl-3,5-dichlorobenzyl alcohol] is well known as a potent β2-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 β2-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. Keywords:: β2-agonist, clenbuterol, immune-responsive system, white blood cell, lymphocyte

We discuss the functional roles of β2-adrenergic receptors in skeletal muscle hypertrophy and atrophy, as well as the adaptive responses of β2-adrenergic receptor expression to anabolic and catabolic conditions. Stimulation of the β2-adrenergic receptor using anabolic drugs increases muscle mass by promoting muscle protein synthesis and/or attenuating protein degradation. These effects are prevented by the downregulation of the receptor. Endurance training improves oxidative performance, partly by increasing β2-adrenergic receptor density in exercise-recruited slow-twitch muscles. However, excessive stimulation of β2-adrenergic receptors negates their beneficial effects. Although preventive effects of β2-adrenergic receptor stimulation on atrophy induced by muscle disuse and catabolic hormones or drugs were observed, these catabolic conditions decreased β2-adrenergic receptor expression in slow-twitch muscles. These findings present evidence against the use of β2-adrenergic agonists in therapy for muscle wasting and weakness. Thus, β2-adrenergic receptors in the skeletal muscles play an important physiological role in the regulation of protein and energy balance.

Rat liver cytosolic alcohol dehydrogenase (ADH) is the principal enzyme which catalyzes the oxidation of ethanol. ADH activity is known to be significantly higher in females than in males. However, the precise mechanism of the sex-difference in ADH activity is uncertain. Recently, we have shown that the inhibitory action of androgen and the slight facilitatory actions of progestin and estrogen are involved in the mechanism of sex-difference in adult rat liver ADH activity. In the present study, we studied the difference of the postnatal developmental changes of ADH activity between males and females. ADH activity increased rapidly after birth up to about 12 d of age, and was not different in the two sexes. In female rats, ADH activity peaked at about 30 d of age and then increased gradually to plateau levels. However, the ADH activity of male rats fell markedly between 30 and 45 d old, and the reduced enzyme activity was observed until 104 d old. In conclusion, the ADH activity of male rats fell between 30 and 45 d after birth. At the ages over the turning point, the ADH activity was significantly lower in male than in female rats.

ラットの体重, 血清コレステロールレベルおよび腎臓と精巣周囲の脂肪細胞に及ぼす乾燥ビール酵母 (DY) の影響を明確にするため, 成長期と高齢期のラットを用いて検討した。その結果, 以下の知見を得た。1) 生後23～83日齢の期間自由摂餌下で飼育したラットの体重は, 生後24～100日齢の期間85%制限給餌下で飼育した場合と同様に, DY群が対照より低値を示した。このDYによる体重の変動作用は, 日齢で異なっていた。また, 性差がみられ, DYを多く含むほど大きかった。体重低下の程度と摂餌量または摂水量との間には, 相関がみられなかった。高齢期ラットの体重は, 40日間DY飼料で飼育しても25% DYで徐々に減少する傾向がみられたが, 有意な変化を示さなかった。したがって, DYによる体重の変動作用は成長期ラットで認められるが, 成長が停止した高齢期ラットでは大きな変化がみられない。2) 血清中の総コレステロールとHDL-コレステロールの各濃度は, 成長期ラットではDYによって大きな影響がみられなかったが, 高齢期ラットではDY量に比例して有意に低かった。3) 脂肪細胞の半径と体積は精巣周囲部でDYの含有量に比例して増大したが, 腎臓周囲部ではDYの影響がみられず, 部位差がみられた。25% DY群の場合, 精巣と腎臓周囲の脂肪細胞数は, 対照に比べて54～72%有意に少なかった。

The purpose of this study was to elucidate the effects of the recovery from dietary zinc-deficiency on the number of total white blood cells (WBCs), neutrophils, eosinophils and basophils, and plasma zinc and corticosterone concentrations in weanling male Sprague Dawley rats. Rats (n= 34) of the zinc-deficient diet (0.6 mg zinc/kg diet) and control diet (35.2 mg zinc/kg diet) groups were fed for 4 wk, and then rats of both groups were fed with the control diet for 3 wk. Zinc-deficiency increased duration-dependently and clearly the number of total WBCs, neutrophils and eosinophils, and the increased numbers of these cells recovered to the control levels in week 2 of the recovery. On the other hand, the number of basophils increased by the zinc-deficiency recovered to the control levels in week 1 of the recovery. Zinc-deficiency significantly decreased plasma zinc concentrations by 85%, and markedly increased plasma corticosterone concentrations by 317%, as compared with the control group. In the recovery period, plasma zinc and corticosterone concentrations recovered to the control levels in week 2 of the recovery. These results suggest that zinc-deficiency and its recovery responses in the number of granulocytes and total WBCs are reversible, and their recovery rates depend on the subsets of granulocytes in rats.

The effects of bovine bile (50-400 mg.kg-1 BW) on plasma ethanol levels in male rats (6-8 weeks old) were examined. Bovine bile decreased and delayed the peak of plasma ethanol concentration: a dose response to bovine bile was observed in the concentration and time to maximum concentration of ethanol but no change in disappearance rate. These phenomena were observed in two conditions: 1) oral administration of bovine bile before oral intubation of ethanol (1.0 g.kg-1 BW) and 2) simultaneous oral administration of bovine bile and ethanol. Similar responses were obtained in taurocholic acid. No changes in hepatic alcohol and aldehyde (low Km and high Km) dehydrogenase activities were observed. The remaining rate of ethanol in stomach was significantly higher with administration of bovine bile. A negative correlation between the maximum ethanol concentration and the remaining rate of ethanol in stomach was found. The intestinal absorption rate of ethanol decreased significantly in the presence of bovine bile. These results suggest that the delay of the gastric emptying and/or the decrease of the intestinal absorption rate of ethanol are major mechanisms for the decreasing and delaying effects on plasma ethanol by bovine bile. The present paper also suggests that bile acids such as taurocholic acid may participate in the lowering and delaying actions on the peak of plasma ethanol concentration by bovine bile.

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

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.

The effects of feeding levels and body weight loading on the soleus muscle size and visceral organ sizes in rats were studied by using the whole-body suspension technique. Body suspensions in the free-feeding and chowrestraint conditions were maintained for 18 and 11 days, respectively. The rats were divided into three groups: cage control (CON), body suspended (BS), and BS plus continuous weight-bearing of the hind limbs on the floor of the cage (BSW). In the free-feeding conditions, the body weights of the BS and BSW rats decreased during the first 4 days. The initial loss of weight correlated with a reduced chow intake during this period. In the chow-restraint conditions, however, the body weight of BS and BSW rats decreased with prolongation of the suspension period, indicating that factors other than chow intake participated in the weight decrease. In both feeding conditions, the adrenal weights of the BS and BSW rats were 2 times higher than those of CON rats, suggesting that suspension stress may produce adrenal hypertrophy. The rectal temperatures of BS and BSW rats were also significantly higher than those of CON rats, showing that a higher metabolic state may be induced by suspension. In both feeding conditions, the weights and protein concentrations of soleus muscles of BSW rats were significantly higher than those of BS rats, suggesting that the weight bearing by the soleus muscles during suspension may maintain the size and protein levels of muscles.