Endurance training exerts time-dependent modulation on depressive responses and circadian rhythms of corticosterone and BDNF in the rats with pinealectomy.

Pinealectomy can cause a disturbance in emotional status and circadian rhythms of the endocrine and metabolic functions in the body. Endurance training is considered a part of the complex therapy of dysfunctions driven by changes in circadian dynamics of many physiological indicators. In the present study, we aimed to study the effect of endurance training on depressive behavior induced by pinealectomy in rat. We tested the hypothesis that endurance training can have a beneficial impact on depressive behavior induced by pinealectomy in rat via correction of desynchronized circadian rhythms of corticosterone secretion in plasma and brain-derived neurothrophic factor (BDNF) in the hippocampus. The continuous exercise program attenuated depressive responses characterized by the disrupted diurnal rhythm of home-cage motor activity, anhedonia in the sucrose preference test, decreased grooming in the splash test, and despair-like behavior in the forced swimming test of rats with pinealectomy to values resembling those of sham-treated controls. Parallel to the observed positive effect on the emotional status, exercise training diminished total plasma corticosterone levels and corrected its flattened pattern. While the melatonin deficiency did not affect the fluctuations of the BDNF levels, the exercise program induced a considerable and time-dependent increase in its level. These findings suggest that the antidepressant-like effect of endurance training might be mediated via correction of the disturbed circadian rhythm of corticosterone release and enhancement of hippocampal BDNF levels in rats with pinealectomy. Therefore, this alternative mode might have a potential therapeutic application in a subpopulation of people characterized by a melatonin deficiency.

Exercise performance and muscle contractile properties after creatine monohydrate supplementation in aerobic-anaerobic training rats.

The purpose of this study was to investigate the effects of creatine monohydrate supplementation on exercise performance and contractile variables in aerobic-anaerobic training rats. Twenty 90-day-old male Sprague Dawley rats were divided into two groups - creatine (Cr) and controls (K). The creatine group received creatine monohydrate as a nutritional supplement, whereas the control group was given placebo. Both groups were trained 5 days a week on a treadmill for 20 days in a mixed (aerobic-anaerobic) metabolic working regimen (27 m·min(-1), 15% elevation for 40 min). The exercise performance (sprint-test), contractile properties (m. tibialis anterior), oxidative enzyme activity (SDH, LDH, NADH2) in m. soleus and blood hematological and chemical variables were assessed in the groups at the end of the experiment. It was found out that creatine supplementation improved the exercise performance after 20 days of administration in a dose of 60 mg per day on the background of a mixed (aerobic-anaerobic) exercise training. At the end of the trial the Cr-group demonstrated better values for the variables which characterize the contractile properties of m. tibialis anterior containing predominantly types IIA and IIB muscle fibers. On the other hand, a higher oxidative capacity was found out in m. soleus (type I muscle fibers) as a result of 20-day creatine supplementation. No side effects of creatine monohydrate supplementation were assessed by the hematological and blood biochemical indices measured in this study. Key pointsThe creatine monohydrate supplementation of the rats diet improves their exercise performance after 20 days administration in a dose of 60 mg per day on the background of a mixed (aerobic-anaerobic) exercise training.The creatine supplemented rats demonstrate better contractile properties of m. tibialis anterior which muscle contains predominantly types IIA and IIB muscle fibers.The soleus muscle (type I muscle fibers) demonstrates a higher oxidative capacity as a result of 20-days creatine supplementation.

Effects of nandrolone decanoate on VO2max, running economy, and endurance in rats.

PURPOSE: The aim of the present study was to determine the effects of treatment with an anabolic androgenic steroid (AAS), nandrolone decanoate, on the submaximal running endurance (SRE), maximum oxygen consumption (VO2max), running economy (VO2submax), and blood oxygen carrying capacity of endurance trained rats. METHODS: Forty male Wistar rats were randomly allocated into two groups: a sedentary group and an exercising group training on treadmill for 8 wk. Half of the trained and half of the sedentary rats received weekly either nandrolone decanoate (10 mg x kg(-1)) or placebo (Pl) for the last 6 wk of experiment. SRE and VO2max tests were performed several times for all four groups (N = 10 each).Red blood cells parameters were measured at the end of the experiment. RESULTS: The trained rats had increased their SRE compared with sedentary rats throughout the experiment. At the end of the trial, the trained rats receiving nandrolone decanoate ran 46% longer than trained rats receiving Pl during the SRE test (P < 0.05). At the end of the experiment, trained rats had greater maximal time to exhaustion and higher VO2max than those of the sedentary rats but there were no differences in VO2max, VO2submax, and red blood cells parameters between the trained rats receiving nandrolone decanoate and those receiving Pl. CONCLUSIONS: Nandrolone decanoate has no effect on the SRE, VO2max and VO2submax of untrained rats. AAS treatment combined with submaximal training enhances SRE more than training alone but exerts no additive effects on VO2max, running economy, and oxygen carrying capacity of blood. The results suggest that this improvement in SRE of trained rats is due to the impact of AAS on other factors involved in exercise adaptation.