Body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of type 2 diabetic rats

This study examined the effect of changes in body temperature during exercise on signal transduction-related glucose uptake in the skeletal muscle of type 2 diabetic rats. Otsuka Long-Evans Tokushima Fatty rats (25 weeks of age), which have type 2 diabetes, were divided into the following four weight-matched groups; control (CON, n = 6), exercised under warm temperature (WEx, n = 8), exercised under cold temperature (CEx, n = 8), and heat treatment (HT, n = 6). WEx and CEx animals were subjected to running on a treadmill at 20 m/min for 30 min under warm (25°C) or cold (4°C) temperature. HT animals were exposed to single heat treatment (40–41°C for 30 min) in a heat chamber. Rectal and muscle temperatures were measured immediately after exercise and heat treatment, and the gastrocnemius muscle was sampled under anesthesia. Rectal and muscle temperatures increased significantly in rats in the WEx and HT, but not the CEx, groups. The phosphorylation levels of Akt, AS160, and TBC1D1 (Thr590) were significantly higher in the WEx and HT groups than the CON group (p < 0.05). In contrast, the phosphorylation levels of AMP-activated protein kinase, ACC, and TBC1D1 (Ser660) were significantly higher in rats in the WEx and CEx groups than the CON group (p < 0.05) but did not differ significantly between rats in the WEx and CEx groups. Body temperature elevation by heat treatment did not activate the AMPK signaling. Our data suggest that body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of rats with type 2 diabetic rats

Effects of voluntary running exercise on bone histology in type 2 diabetic rats.

The incidence of obesity in children and adolescents, which may lead to type 2 diabetes, is increasing. Exercise is recommended to prevent and improve diabetes. However, little is known about the bone marrow environment at the onset of diabetes in the young, and it is unclear whether exercise training is useful for maintaining bone homeostasis, such as mechanical and histological properties. Thus, this study clarified the histological properties of bone and whether exercise contributes to maintaining bone homeostasis at the onset of type 2 diabetes in rats. Four-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF; n = 21) rats as a diabetic model and Long-Evans Tokushima Otsuka (LETO; n = 18) rats as a control were assigned randomly to four groups: the OLETF sedentary group (O-Sed; n = 11), OLETF exercise group (O-Ex; n = 10), LETO sedentary group (L-Sed; n = 9), and LETO exercise group (L-Ex; n = 9). All rats in the exercise group were allowed free access to a steel running wheel for 20 weeks (5-25 weeks of age). In the glucose tolerance test, blood glucose level was higher in the O-Sed group than that in the L-Sed and L-Ex groups, and was markedly suppressed by the voluntary running exercise of O-Ex rats. The energy to fracture and the two-dimensional bone volume at 25 weeks of age did not differ significantly among the groups, though the maximum breaking force and stiffness were lower in OLETF rats. However, bone marrow fat volume was greater in O-Sed than that in L-Sed and L-Ex rats, and was markedly suppressed by wheel running in the O-Ex rats. Our results indicate that exercise has beneficial effects not only for preventing diabetes but also on normal bone remodeling at an early age

Body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of type 2 diabetic rats.

This study examined the effect of changes in body temperature during exercise on signal transduction-related glucose uptake in the skeletal muscle of type 2 diabetic rats. Otsuka Long-Evans Tokushima Fatty rats (25 weeks of age), which have type 2 diabetes, were divided into the following four weight-matched groups; control (CON, n = 6), exercised under warm temperature (WEx, n = 8), exercised under cold temperature (CEx, n = 8), and heat treatment (HT, n = 6). WEx and CEx animals were subjected to running on a treadmill at 20 m/min for 30 min under warm (25°C) or cold (4°C) temperature. HT animals were exposed to single heat treatment (40-41°C for 30 min) in a heat chamber. Rectal and muscle temperatures were measured immediately after exercise and heat treatment, and the gastrocnemius muscle was sampled under anesthesia. Rectal and muscle temperatures increased significantly in rats in the WEx and HT, but not the CEx, groups. The phosphorylation levels of Akt, AS160, and TBC1D1 (Thr590) were significantly higher in the WEx and HT groups than the CON group (p < 0.05). In contrast, the phosphorylation levels of AMP-activated protein kinase, ACC, and TBC1D1 (Ser660) were significantly higher in rats in the WEx and CEx groups than the CON group (p < 0.05) but did not differ significantly between rats in the WEx and CEx groups. Body temperature elevation by heat treatment did not activate the AMPK signaling. Our data suggest that body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of rats with type 2 diabetic rats

Body weight, food consumption and white adipose tissue weight.

<p>Body weight, food consumption and white adipose tissue weight.</p

Blood analysis related to diabetes.

<p>The blood glucose (A), plasma insulin (B) and serum leptin (C) levels were significantly greater in O-sed rats than in the LETO rats, but it was attenuated by exercise. Serum adiponectin (D) levels were increased by exercise. All values are presented as the mean ± SEM. * <i>p</i><0.05 vs. all; † <i>p</i><0.05 vs. L-Sed; # <i>p</i><0.05 vs. L-Ex.</p

The marrow fat volume at the distal end of the femur as assessed by two-dimensional histomorphometry (A) and a micrograph of marrow fat (B) at 25 weeks of age.

<p>The black arrow indicates bone tissue, and red arrow shows marrow fat in micrograph. All values are presented as the mean ± SEM. * <i>p</i><0.05 vs. all; † <i>p</i><0.05 vs. L-Sed; # <i>p</i><0.05 vs. L-Ex.</p

The bone mechanical properties of the rats at 25 weeks of age.

<p>Maximum breaking force (A) and stiffness (B) were lower in OLETF rats. In contrast, energy to fracture was not different between genotype. All values are presented as the mean ± SEM. * <i>p</i><0.05 vs. all; † <i>p</i><0.05 vs. L-Sed; # <i>p</i><0.05 vs. L-Ex.</p

The bone volume at the distal end of the femur as assessed by two-dimensional histomorphometry at 25 weeks of age.

<p>All values are presented as the mean ± SEM.</p

Restoration of RI-beams from a projectile fragment separator by Laser Ionization gas Catcher -PALIS-

A fragment separator at heavy ion accelerator facilities is a versatile instrument to provide wide variety of radioactive isotope (RI) beams. However, more than 99.99% of precious Rl-ions are simply dumped in the slits or elsewhere in the fragment separator. A novel concept to restore such Rl-ions for parasitic slow Rl-beams is proposed. Installation of a laser ionization gas catcher in the vicinity of the first or second focal point of the fragment separator enables to collect dead isotopes in the slits. The design concept and expected performance are discussed.status: publishe