Brain Activation Patterns at Exhaustion in Rats That Differ in Inherent Exercise Capacity

Abstract

In order to further understand the genetic basis for variation in inherent (untrained) exercise capacity, we examined the brains of 32 male rats selectively bred for high or low running capacity (HCR and LCR, respectively). The aim was to characterize the activation patterns of brain regions potentially involved in differences in inherent running capacity between HCR and LCR. Using quantitative in situ hybridization techniques, we measured messenger ribonuclease (mRNA) levels of c-Fos, a marker of neuronal activation, in the brains of HCR and LCR rats after a single bout of acute treadmill running (7.5–15 minutes, 15° slope, 10 m/min) or after treadmill running to exhaustion (15–51 minutes, 15° slope, initial velocity 10 m/min). During verification of trait differences, HCR rats ran six times farther and three times longer prior to exhaustion than LCR rats. Running to exhaustion significantly increased c-Fos mRNA activation of several brain areas in HCR, but LCR failed to show significant elevations of c-Fos mRNA at exhaustion in the majority of areas examined compared to acutely run controls. Results from these studies suggest that there are differences in central c-Fos mRNA expression, and potential brain activation patterns, between HCR and LCR rats during treadmill running to exhaustion and these differences could be involved in the variation in inherent running capacity between lines.

The improvement of exercise performance by physical training is related to increased hypothalamic neuronal activation

“…This response is consistent with recent findings that better exercise performance until exhaustion in rats with high running capacity was associated with an increase in c‐Fos mRNA levels in several brain areas, including the PVN. This result suggests that there is a potential difference in brain activation patterns that may contribute to the variation in inherent running capacity between individuals . Consistent with this background, this study found that neuronal activity in the PVN, the MPO and the MnPO directly correlated with the workload performed by the animals during incremental exercise until fatigue, indicating that the increased activation of these sites contributed to the improved physical performance seen in TR rats.…”

Potential Genetic Contributions of the Central Nervous System to a Predisposition to Elite Athletic Traits: State-of-the-Art and Future Perspectives

“…Based on the possibility that inherent (untrained) running capacity reflects inherent exercise-related traits, lines of rodents with higher or lower EC were established by selective breeding [ 6 , 17 ]. An exercise-testing protocol, rather than genetic selection, was created to select rodents with intrinsically higher and lower EC [ 18 , 19 , 20 ].…”

“…In addition to peripheral factors such as musculoskeletal and cardiopulmonary functions, the central nervous system (CNS) plays a pivotal role in athletic performance, as the brain controls the initiation and processing of physical activity [ 6 ], motor skill acquisition [ 7 ], regulation of physical activity [ 8 ], and psychological traits, including motivation to exercise, anxiety, and stress resilience [ 4 , 8 ]. In light of the relationship between the brain and physical activities, extensive studies on the effects of exercise on brain functions have reported that exercise is beneficial to cognitive function, potentially through multifactorial pathways that include improvement of cardiovascular conditions [ 9 ], adult neurogenesis [ 10 , 11 ], and modifications of neurotransmission by muscle-derived bioactive molecules [ 12 , 13 , 14 ].…”

Drag-reducing polymers increase exercise tolerance in an ischemic hind-limb rat model

“…Exhaustion was defined as the third time when a rat could no longer keep pace with the speed of the treadmill belt and remained on an electric shock grid for 2 s rather than running. 15 No rat ceased to exercise because of foot or any other type of injury. The flow chart for experimental protocols is shown in Figure 1.…”