A.: Neuroplastic adaptations to exercise: neuronal remodeling in cardiorespiratory and locomotor areas

First published August 25, 2005; doi:10.1152/japplphysiol.00693.2005.— Neuronal activity has been shown to be attenuated in cardiorespiratory and locomotor centers of the brain in response to a single bout of exercise in trained (TR) vs. untrained (UN) animals, but the mechanisms remain ob-scure. Based on this finding, dendritic branching patterns of seven brain areas associated with cardiorespiratory and locomotor activity were examined in TR and UN animals. Twenty-eight male Sprague-Dawley rats were kept in individual cages and divided into TR and UN. TR were provided with a running wheel and exercised spontaneously. After 85 or 120 days, exercise training indexes were obtained, including maximal oxygen consumption, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was removed and processed according to a modified Golgi-Cox procedure. Impregnated neurons from seven brain areas were examined in coronal sections: the periaqueductal gray, posterior hypothalamic area, nu-cleus of the tractus solitarius, rostral ventrolateral medulla, cuneiform nu