CHANGES IN THE EXERCISE ACTIVATION OF DIENCEPHALIC AND BRAINSTEM CARDIORESPIRATORY AREAS AFTER TRAINING

Abstract

The involvement of several areas of the CNS in the control of cardiovascular responses to exercise has been demonstrated. There are, however, virtually no data directly investigating potential changes in the activation of cardiorespiratory areas in the CNS in response to regular exercise. PURPOSE: To determine whether regular spontaneous exercise changes the pattern and extent of activation of areas in the CNS involved in cardiorespiratory control in response to a single bout of exercise. METHODS: Rats which spontaneously trained on running wheels for 80–100 days were compared to rats that were not provided an opportunity to exercise. After an initial familiarization period of one week both groups were tested on a motorized running wheel for 45 min at a speed of 4.9 m/min after 5 min of familiarization. Following the single bout of exercise rats were sacrificed after a 1h recovery period, perfused and their brains removed. Selected brain regions including the hypothalamic and mesencephalic locomotor regions, and the ventrolateral medulla were studied using c-Fos-like immunocytochemistry. RESULTS: A single bout of exercise evoked significantly less activation as indicated by Fos labeling in the posterior (caudal) hypothalamic area, periaqueductal grey, nucleus of the tractus solitarius and the rostral ventrolateral medulla of trained rats when compared to sedentary rats. CONCLUSIONS: These results are consistent with the concept that the nervous system changes its activity after exercise training. These changes may also be related to perceived exertion. Supported by NIH HL 06296 and HL 374000 and the National Science Foundation