Neuroplastic Adaptations to Exercise Training and Detraining

162 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.Neuronal activity has been shown to be attenuated in cardiorespiratory and locomotor centers (CRLC) of the brain in response to a single bout of exercise in trained (TR) versus untrained (UN) animals, but the mechanisms remain obscure. Dendritic branching patterns of seven brain areas associated with cardiorespiratory and locomotor activity were examined in TR and UN animals during development and early adulthood. Dendritic branching patterns in CRLC of the brain were also studied in response to detraining (70 days of exercise training followed by 50 days of detraining). TR and DTR animals exercised spontaneously using a voluntary running wheel. Following the specified training regimen for each study, a multitude of ET indices 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 (PAG), posterior hypothalamic area (PH), nucleus of the tractus solitarius (NTS), rostral ventrolateral medulla, cuneiform nucleus (CnF), nucleus cuneatus and cerebral cortex. Neurons were traced using a camera lucida technique and analyzed using the Sholl analysis of dendritic branching. Our results show that dendritic fields of neurons in important CRLC of the brain are attenuated with exercise training during development and early adulthood. There were significant differences between TR and UN groups in the PH, PAG, CnF and NTS in the inner rings, outer rings and the total number of intersections per animal. The magnitude of differences in dendritic attenuation was less pronounced in adult TR animals when compared to young TR animals. Our results also show that dendritic attenuation resulting from 70 days of ET in PH, PAG, CnF and NTS is completely reversed with 50 days of detraining. These data clearly indicate that, in addition to more readily measured parameters of cardiorespiratory and locomotor control, the central nervous system undergoes intrinsic changes, which parallel changes in the exercise TR or UN state of the organism.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD