IDENTIFICATION OF DIENCEPHALIC AND BRAIN-STEM CARDIORESPIRATORY AREASACTIVATED DURING EXERCISE

The purpose of this study was to identify diencephalic and brainstem s ites active during exercise (EX) in conscious rats running on a treadm ill. Brain areas active during exercise, compared to rest conditions ( non-EX), were identified using immunocytochemical labelling of the pro tein product of the proto-oncogene c-fos. Increased labelling was obse rved in the 'defence area' or 'hypothalamic/subthalamic locomotor regi ons' including the posterior and lateral hypothalamic areas. Increased labelling with EX was found in both colliculi, the periaqueductal gra y matter, the parabrachial complex and the cuneiform nucleus ('mesence phalic locomotor region'). Increased labelling with EX was also found in the medial portion of n. tractus solitarius, and both the rostral a nd caudal ventrolateral medulla. Conspicuous by an absence of labellin g during EX were cells in thalamic areas associated with somatosensory function, although the dorsal column nuclei were also labelled above control. Thus, areas in which labelling was increased during exercise closely correlate with the brain areas which have been implicated in b oth autonomic and somatomotor control. These results from awake, exerc ising rats support those obtained previously in anesthetized animal pr eparations.