Blood flow to brown adipose tissue and norepinephrine-induced calorigenesis in physically trained rats.

Abstract

Cardiac output (CO) and regional blood flow to various tissue were measured by means of ƒÁ-labeled plastic microspheres (15•}3 ƒÊm) injected into the left ventricle during 30-min infusion of l-norepinephrine (NE: 4 ƒÊg/(kg•Emin)) or the same amount of saline (11 ,ƒÊl/min per animal) in rats physically trained by 2-hr swimming in water of 32 (SW-32), 36 (SW-36), and 38•Ž (SW-38) for 10-11 weeks and in control (CT) rats. Body weight and skinfold thickness were significantly less in SW-36 and SW-38 than CT rats. The weights of heart and adrenal glands significantly increased in the trained rats in comparison with CT rats. The average weight of brown adipose tissue (BAT) was significantly greater in SW-32 and significantly less in SW-36 and SW-38 as compared with CT rats. Infusion of NE induced significant increases in oxygen consumption (V02), colonic temperature, heart rate, CO, blood flow to BAT, and mean blood pressure in anesthetized rats. The increases in Vo2 and CO were significantly greater in SW-32 and SW-36 than in CT rats. The increases in blood flow to BAT were significantly greater in SW-32, SW-36, and SW-38 than in CT rats. These results indicate that physical training per se enhances calorigenic response to NE supported by an increased cardiac output and blood flow to the dominant calorigenic tissues such as BAT in rats.

Exercise-induced adaptations to white and brown adipose tissue

“…The training also increased the amount of UCP1 antigen in BAT compared with that of the sedentary controls. Other studies examining the effects of 6-8 weeks of swim training in rodents have reported increased blood flow to BAT (Hirata, 1982), increased mitochondrial activity (Ignacio et al, 2012), and increased type 2 deiodinase (dio2) enzymatic activity and mitochondrial respiration in BAT (Ignacio et al, 2012). Rodents that experienced other exercise modalities, including 6-8 weeks of treadmill training, showed an increase in BAT activity: for example, increased cytochrome oxidase activity (Yoshioka et al, 1989), increased oxygen consumption rates (Yoshioka et al, 1989) and upregulation of BAT-specific gene markers (Yoshioka et al, 1989;Xu et al, 2011Xu et al, , 2012.…”

In-cage sandbox as a ground substitute for farmed blue foxes (Alopex lagopus): Effects on digging activity and welfare

“…hypertrophy is encountered in animals subjected to physical exercise (Östman-Smith 1979;Hirada 1982). Thus although test animals did not move more than controls, possibly they exercised/jumped more intensively, which tended to cause increased heart weight.…”

Exercise regulation of adipose tissue

“…2). Some studies have demonstrated increased BAT activity with exercise, [61][62][63][64][65][66] others showed no change in BAT activity, [67][68][69][70] while a third set of studies reported a decrease in BAT activity with exercise. 32,[71][72][73][74] Exercise increases BAT activity Studies in rats have demonstrated that 6-8 wks of swim training for 2-3 hours per day resulted in increased blood flow to BAT and increased responsiveness to norepinephrine stimulation.…”

“…32,[71][72][73][74] Exercise increases BAT activity Studies in rats have demonstrated that 6-8 wks of swim training for 2-3 hours per day resulted in increased blood flow to BAT and increased responsiveness to norepinephrine stimulation. 63,64 Another study demonstrated that 8 wks of exercise training by swimming significantly increased BAT mitochondrial activity in rats. 61 In this study, rats were subjected to an exercise training protocol where they swam in a thermoneutral (31-33 C), 1 gallon, plastic barrel for up to 75 minutes per day.…”