Journal of Sport and Exercise Physiology

Journal of Sport and Exercise Physiology

The effects of forced training, voluntary training, and playing in an enriched environment on hippocampal orexin A expression in pre-pubertal male rats

Document Type : Original Article

Authors
Fatemeh Arabtaheri Zade 1
Behrouz Abdoli 1
Rana Fayazmilani 2
Narges Norouzi 3
1 Department of Cognitive, Behavioral and Technology in Sports, Faculty of Sports Sciences and Health, Shahid Beheshti University, Tehran, Iran
2 Department of Biological Sciences in Sport, Faculty of Sports Sciences and Health, Shahid Beheshti University, Tehran, Iran
3 Faculty of Sport Sciences, Al Zahra University, Tehran, Iran
10.48308/joeppa.2025.240281.1371
Abstract
Background and Purpose: Environmental factors can play a role in learning and cognitive development during childhood and adolescence, when the brain is still developing. A variety of physical activities and environmental interactions can also help regulate the orexinergic pathway in the brain, which in turn affects stress responses, food intake, and energy intake. Orexin A is a key neuropeptide that plays a crucial role in various behavioral outcomes. This neuropeptide directly affects both central and peripheral pathways of the hypothalamic-pituitary-adrenal axis. During brain development, the impact of environmental factors and lifestyle on cognitive and emotional development becomes more apparent. For example, environments that provide diverse stimuli and challenging activities can help strengthen the orexinergic system, thereby improving mental functions. The main aim of the present study was to compare the effect of an enriched environment and forced and voluntary training methods on the function of orexinergic system, followed by evaluating anxiety responses in immature male rats.
Materials and Methods: In the present study, 60 immature male rats aged 12 days were selected and randomly divided into 4 groups of 15: forced training, voluntary training, play in an enriched environment, and control. After familiarization and performing the maximum speed test (25 days old; weight, 43.51±7 g) all rats followed the respected protocol for 3 weeks. Rats in the forced exercise group performed endurance running on a treadmill, three times a day, and 6 days a week. In the voluntary group, rats had unlimited access to a running wheel. For playing in an enriched environment, a large cage containing different enriched stimuli (toys, running wheel, and ladder) was provided. Finally, hippocampal tissue from several rats was isolated for biochemical evaluation. Brain levels of orexin A were measured using the Western blot technique. Thereafter, to determine the motor activity the remaining groups were evaluated in an open field behavioral test. One-way ANOVA followed by a Bonferroni post-hoc test was used to assess differences between groups.
Results: Data analysis showed a significant between-group differences for orexin A of the hippocampus of immature rats. Post-hoc analysis revealed a significant difference between the forced training group and the control group (P=0.022). In the open field behavioral test, a significant difference was seen between the groups. The results showed that the level of anxiety in the training groups was higher in the control group than the other groups, while between-group comparisons showed higher anxiety levels in the forced training group in comparison to the voluntary training and enriched environment groups. However, no significant between-group differences were seen for general motor activity.
Conclusions: It is concluded that physical activity and environmental factors lead to an increase in orexin A levels, and that forced training had a significant effect, too. Generally, exercise and physical activity led to an increase in orexin A, through affecting the HPA axis, which might result in an anxiety-like behavior in immature rats.
Keywords
Forced and voluntary training
Enriched environment
Orexinergic system
Hippocampus
Pre-pubertal
Subjects
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  • Receive Date 04 June 2025
  • Revise Date 11 July 2025
  • Accept Date 03 August 2025
  • First Publish Date 03 August 2025
  • Publish Date 22 June 2026