Plasma obestatin, estradiol, and liver ATP concentrations in response to endurance exercise training at different durations in male rats

Background: Obestatin is secreted from the stomach and has effects on energy balance and food intake. Objectives: The purpose of the present study was to investigate obestatin, estradiol, and liver ATP responses after 8 weeks of a treadmill exercise running program at different durations. Materials and Methods: 37 male Wistar rats (8 to 10 weeks old, 145 to 160 g) were assigned to control (n = 9) and training (n = 28) groups. After an accommodation period of 3 weeks, the training group was further divided randomly into 30-minute (T30), 60-minute (T60), and 90-minute (T90) groups. Animals ran on a motor-driven treadmill at 20 m/min (0% grade) for various durations 5 days/week for the subsequent 5 weeks and were sacrificed 72 h after the last exercise session. Livers were excised and immediately washed in ice-cold saline and frozen in liquid nitrogen to determine liver ATP concentrations. Plasma was also collected for obestatin, glucose, and estradiol determinations. One-way analyses of variance were used for data analysis. Results: Plasma obestatin concentrations were significantly higher after training in the T90 group compared with the T30 group. Higher and significant resting plasma estradiol levels were observed in the T60 and T90 trained rats when compared with the control group. Changes in plasma glucose and liver ATP concentrations were not significant. Conclusions: It seems that long-duration, high-volume training increases plasma obestatin to a greater degree than short-duration, short-volume training. The results also show that long-term exercise induced an increase in plasma obestatin and was accompanied with a higher level of estradiol. A R T I C L E I N F O Article history: Received: 10 Dec 2010 Revised: 25 Dec 2010 Accepted: 1 Jan 2011