Exercise training-induced changes in anterior pituitary gonadotrope of the female rat.

Chronic exercise training may alter the hypothalamic-pituitary-ovarian axis by affecting gonadotropin secretion and structural indexes of the anterior pituitary gonadotropes. Young female Harlan Sprague-Dawley rats were randomly assigned to either a 12-wk intensive treadmill-running program (n = 16) or to a sedentary untrained group [untrained-proestrus (UTP), n = 16]. After training for 3 mo, animals were killed on proestrous morning, and individual pituitary glands were enzymatically dispersed into single-cell suspensions.

Endurance training increases arterial wall thickness in rats.

We tested whether endurance training altered the morphology of systemic arteries. Female Sprague-Dawley rats (8 wk, 120 g) were either treadmill run for 16 wk (up to 3 h/day, 5-10% grade, 35 m/min) or used as caged controls (n = 7/group). At 24-h post-running bout, rats were anesthetized (ether) and decapitated.

Effect of training on insulin secretion from single pancreatic beta cells.

The objective of this study was to determine whether insulin secretion from single pancreatic beta cells is reduced by endurance training. Male Sprague Dawley rats either trained (T, N = 9) for 11 wk on a rodent treadmill, remained sedentary, and were fed ad libitum (S, N = 8) or remained sedentary and were food restricted (pair fed, PF, N = 8) so that final body weights were similar to T. After training, T had significantly higher red gastrocnemius muscle citrate synthase activity compared with S and PF.

Changes in insulin response to glucose after exercise training in partially pancreatectomized rats.

The effects of exercise training on glucose-stimulated insulin secretion (GSIS) were studied in male Sprague-Dawley rats made mildly to severely diabetic by partial pancreatectomy. Exercise trained (10 wk treadmill; T) and untrained (Unt) rats were grouped according to posttraining fed-state hyperglycemia as follows: T less than 200 and Unt less than 200 (glucose concn less than 200 mg/dl), T 200-300 and Unt 200-300 (glucose concn 200-300 mg/dl), and T greater than 300 and Unt greater than 300 (glucose concn greater than 300 mg/dl). After exercise training, hyperglycemic glucose clamps were performed in awake rats by elevation of arterial blood glucose concentration 126 mg/dl above fasting basal levels for 90 min.

Kinetic parameters for plasma beta-endorphin in lean and obese Zucker rats.

To determine plasma clearance kinetics for beta-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data.