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We tested the hypothesis that there are sex differences in hindlimb unloading-induced activation of the forkhead box subfamily O3a (FoxO3a) signaling pathway in rat soleus muscle. Age-matched male and female Wistar rats were subjected to hindlimb unloading, and the soleus muscle was removed before or 1 or 7 days after unloading. Female rats showed greater percent changes in relative soleus muscle weight than males. FoxO3a phosphorylation was lower in females than in males and was associated with higher levels of protein ubiquitination 7 days after unloading. Heat shock protein 72 (Hsp72) levels were lower in female rats and increased in males during unloading. Female rats showed slightly higher myostatin levels, which showed a non-significant decline in male rats following unloading. Thus, males and females show different responses to the FoxO3a/ubiquitin-proteasome pathway following hindlimb unloading in rat soleus muscle, which may be associated with differences in Hsp72 expression and myostatin signaling. Keywords: Sex difference, Soleus muscle, Forkhead box O, Heat shock protein 72, Myostatin, Hindlimb unloading, Author(s): Toshinori Yoshihara[sup.1], Toshiharu Natsume[sup.1], Takamasa Tsuzuki[sup.1,2], Shuo-wen Chang[sup.1], Ryo Kakigi[sup.3], Takao Sugiura[sup.4] and Hisashi Naito[sup.1] Introduction Males and females exhibit marked physiological differences, including body composition [1], hormone concentration [...]

Heat shock proteins (Hsps) have a critical role in maintaining cellular homeostasis and in protecting cells from a range of acute and chronic stressful conditions. Treadmill running exercise results in increased Hsp72 and Hsp25 levels in various tissues and heat production during exercise has been shown to be the main factor for the increased levels of Hsp72 in myocardium. Since the adrenal gland plays a vital role in general response to stress, regulation of Hsps in adrenal glands following stressful events seems to be critical for controlling the whole-body stress response appropriately. This study tested the hypothesis of whether elevation of temperature is solely responsible for exercise-induced adrenal Hsp72 and Hsp25 expression. Female Sprague-Dawley rats (3 months old) were randomly assigned to either a sedentary control group or one of two treadmill-running groups: a cold exercise group run in a cold room at 4 [degrees]C (CE), and a warm exercise group run at 25 [degrees]C temperature (WE). Animals were run 60 min a day at 30 m min.sup.-1 speed for 4 consecutive days following adaptation to treadmill exercise. Exercise resulted in a significant elevation of body temperature only in the WE group (p < 0.05). Adrenal Hsp72 and Hsp25 levels were significantly higher in the WE group compare to the other groups (p < 0.05). These data demonstrated that exercise-related elevations of body temperature could be the only factor for the inductions of adrenal Hsp72 and Hsp25 expression. Keywords: Hsp72, Hsp25, Cold exercise, Adrenal, Treadmill running, Author(s): Senay Akin[sup.1], Hisashi Naito[sup.2], Yuji Ogura[sup.2], Noriko Ichinoseki-Sekine[sup.2], Mitsutoshi Kurosaka[sup.2], Ryo Kakigi[sup.2] and Haydar A. Demirel[sup.1] Introduction Sustaining of homeostasis from molecular to physiological level is important for survival [...]

Extended periods of skeletal muscle disuse results in muscle atrophy and weakness. Currently, no therapeutic treatment is available for the prevention of this problem. Nonetheless, growing evidence suggests that prevention of disuse-induced oxidative stress in inactive muscle fibers can delay inactivity-induced muscle wasting. Therefore, this study tested the hypothesis that dietary supplementation with the antioxidant astaxanthin would protect against disuse muscle atrophy, in part, by prevention of myonuclear apoptosis. Wistar rats (8 weeks old) were divided into control (CT, n = 9), hindlimb unloading (HU, n = 9), and hindlimb unloading with astaxanthin (HU + AX, n = 9) groups. Following 2 weeks of dietary supplementation, rats in the HU and HU + AX groups were exposed to unloading for 7 days. Seven-day unloading resulted in reduced soleus muscle weight and myofiber cross-sectional area (CSA) by ~30 and ~47 %, respectively. Nonetheless, relative muscle weights and CSA of the soleus muscle in the HU + AX group were significantly greater than those of the HU group. Moreover, astaxanthin prevented disuse-induced increase in the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive nuclei. We conclude that astaxanthin supplementation prior to and during hindlimb unloading attenuates soleus muscle atrophy, in part, by suppressing myonuclear apoptosis. Keywords: Antioxidant, Apoptosis, Disuse muscle atrophy, Protein degradation, Author(s): Toshinori Yoshihara[sup.1], Yuki Yamamoto[sup.2], Tsubasa Shibaguchi[sup.3], Nobuyuki Miyaji[sup.4], Ryo Kakigi[sup.5], Hisashi Naito[sup.1], Katsumasa Goto[sup.6], Daijiro Ohmori[sup.7], Toshitada Yoshioka[sup.8] and Takao Sugiura[sup.9] Introduction It is well established that prolonged skeletal [...]