Michael C. Riddell

Learn More
Adaptations of the hypothalamic-pituitary-adrenal (HPA) axis to voluntary exercise in rodents are not clear, because most investigations use forced-exercise protocols, which are associated with psychological stress. In the present study, we examined the effects of voluntary wheel running on the circadian corticosterone (Cort) rhythm as well as HPA axis(More)
Diabetes is associated with increased basal hypothalamo-pituitary-adrenal (HPA) activity and impaired stress responsiveness. Previously, we demonstrated that the HPA response to hypoglycemia is significantly impaired in diabetic rats. In this study our goals were to 1) differentiate between the effects of hyperinsulinemia and those of hypoglycemia per se,(More)
The effects of exercise training on hypothalamo-pituitary-adrenal (HPA) function are unclear. We investigated whether pituitary-adrenal adaptation during exercise training is mediated by changes in neuropeptide and corticosteroid receptor gene expression in the brain and pituitary. Sprague-Dawley rats were subject to either daily swimming (DS) or sham(More)
Glucocorticoids (GCs) are potent pharmacological agents used to treat a number of immune conditions. GCs are also naturally occurring steroid hormones (e.g. cortisol, corticosterone) produced in response to stressful conditions that are thought to increase the preference for calorie dense 'comfort' foods. If chronically elevated, GCs can contribute to the(More)
OBJECTIVE Type 1 diabetes leads to impairments in growth, function, and regenerative capacity of skeletal muscle; however, the underlying mechanisms have not been clearly defined. RESEARCH DESIGN AND METHODS With the use of Ins2(WT/C96Y) mice (model of adolescent-onset type 1 diabetes), muscle regeneration was characterized in terms of muscle mass,(More)
Recently, we established that hypothalamo-pituitary-adrenal (HPA) and counterregulatory responses to insulin-induced hypoglycemia were impaired in uncontrolled streptozotocin (STZ)-diabetic (65 mg/kg) rats and insulin treatment restored most of these responses. In the current study, we used phloridzin to determine whether the restoration of blood glucose(More)
OBJECTIVEdIn type 1 diabetes, small studies have found that resistance exercise (weight lifting) reduces HbA 1c. In the current study, we examined the acute impacts of resistance exercise on glycemia during exercise and in the subsequent 24 h compared with aerobic exercise and no exercise. RESEARCH DESIGN AND METHODSdTwelve physically active individuals(More)
OBJECTIVE To determine the effects of exercise order on acute glycemic responses in individuals with type 1 diabetes performing both aerobic and resistance exercise in the same session. RESEARCH DESIGN AND METHODS Twelve physically active individuals with type 1 diabetes (HbA(1c) 7.1 ± 1.0%) performed aerobic exercise (45 min of running at 60%(More)
BACKGROUND Systemic elevations in PAI-1 suppress the fibrinolytic pathway leading to poor collagen remodelling and delayed regeneration of tibialis anterior (TA) muscles in type-1 diabetic Akita mice. However, how impaired collagen remodelling was specifically attenuating regeneration in Akita mice remained unknown. Furthermore, given intrinsic differences(More)
Although exercise is a common and potent activator of the hypothalamic-pituitary adrenal (HPA) axis, the effects of exercise on the acute stress response are not well understood. Here, we investigated the effects of short- (2 wk) and long-term (8 wk) voluntary wheel running on adrenal sensitivity to ACTH stimulation and the acute stress response to(More)