ABSTRACT
The aim of this research was to investigate the effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats. We hypothesized that plasma glucose might be decreased in the exercised group during heavy (more intense) exercise. Twenty-four 10-week-old male Wistar rats were randomly assigned to sedentary and exercised groups. The prescription of endurance exercise training intensity was determined as 60% of the maximum intensity reached at the incremental speed test. The animals were trained by running on a motorized treadmill, five days/week for a total period of 67 weeks. Plasma glucose during the constant speed test in the exercised group at 20 m/min was reduced at the 14th, 21st and 28th min compared to the sedentary group, as well at 25 m/min at the 21st and 28th min. Plasma glucose during the incremental speed test was decreased in the exercised group at the moment of exhaustion (48th min) compared to the sedentary group (27th min). Endurance training positively modulates the mitochondrial activity and capacity of substrate oxidation in muscle and liver. Thus, in contrast to other studies on high load of exercise, the effects of endurance training on the decrease of plasma glucose during constant and incremental speed tests was significantly higher in exercised than in sedentary rats and associated with improved muscle and hepatic oxidative capacity, constituting an important non-pharmacological intervention tool for the prevention of insulin resistance, including type 2 diabetes mellitus.
Subject(s)
Animals , Male , Rats , Blood Glucose/metabolism , Liver/metabolism , Muscle, Skeletal/metabolism , Physical Conditioning, Animal , Physical Endurance/physiology , Acetyl-CoA Carboxylase/metabolism , Cytochromes c/metabolism , Exercise Test , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Protein Kinases/metabolism , Rats, WistarABSTRACT
The LH-RH analog-LH-RH-A (des-Gly10, [D-Trp6]-LH-RH ethylamide) was administerd in pharmacological doses (20 µg/Kg, sc) to adult male cats for 15 days and its effect on testis and adrenal function was determined. Dayly adminitration of the analog promoted a 3-fold increase in plasma testosterone levels after 7 days, indicating stimulatory effect of LH-RH-A (mean ñ SD for 6 treated cats, 1.88 ñ 0.35 vs 0.51 ñ 0.08ng/ml for 6 control cats). After 15 days the LH-RH-A-treated group exhibited a similar plasma testosterone concentration as the control group (mean ñ SD, 0.96 ñ 0.35 ng/ml vs 0.88 ñ 0.39 ng/ml, respectively), similar testicular and adrenal weights and no significant differences in the spermatogenic process. However, semiquantitative analysis of the zona fasciculata of the adrenals from the LH-RH-A treated group showed a significant accumulation of a substance not stained by hematoxylin-eosin or Schiff periodic acid (mean ñ SD of index of accumulation was 3.50 ñ 0.4 for treated cats vs 2.20 ñ 0.3 for control cats). The present results show that pharmacological doses of LH-RH-A have an effect on the adrenal cortex of cats without modifying spermatogenesis or plasma testosterone levels