Various exercise intensities deferentially regulate GAP-43 and CAP-1 expression in the rat hippocampus
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Authors
11- Associate Professor, Department of Physical Education and Sport Sciences, Faculty of Literature and Human Sciences, Lorestan University, Khoramabad, Iran
2Department of Physical Education and Sports Sciences, Faculty of Literature and Human Sciences, Vali E Asr University of Rafsanjan, Rafsanjan, Iran
Abstract
Introduction: Exercise intensity is known to affect neuroplasticity. Although, corticosterone and lactate levels has been linked to neuroplasticity, the effect of different endurance exercise intensity-dependent production of these biochemicals on behaviour of hippocampal growth cone markers remains incompletely explored.
Methodology: Here, we investigated the effects of three different endurance treadmill training episodes on growth associated protein 43 (GAP-43) and adenylate cyclase associated protein 1 (CAP-1) expression in the hippocampus of adult male Wistar rats. This study performed according to health guidelines for animal research and approved by Animal Care Committee of the Lorestan University, according to the NIH Guidelines for the Care and Use of Laboratory Animals (NIH publication, 1996). After 2 weeks for an acclimation period, sixty animals were assigned randomly into four groups: (1) age-matched control (C; n = 15), (2) low- intensity exercise (LIE; n = 15), (3) mild- intensity exercise (MIE; n = 15), (4) high- intensity exercise (HIE; n = 15). Ten rats from each group were used to participate in protein analysis (five rats for immunohistochemistry and five rats for western blot), and the remaining five rats from each group were used for analysis of mRNA expression.
Results: Our findings showed that mild- intensity exercise (MIE) with lactate production slightly greater than the lactate threshold (LT) is the best form of physical activity for elevating GAP-43 without changing CAP-1 expression. Moreover, we find that high-intensity exercise (HIE) with the highest level of corticosterone and lactate production, approximately 2-fold higher than the LT, causes decrease expression in GAP-43, but an increase in expression of CAP-1 within the hippocampus. Like HIE, we further identified the expression patterns for these growth cone markers in low-intensity exercise (LIE) with blood lactate production below LT and corticosterone level similar to MIE.
Discussion: The present findings suggested that in high-intensity exercise condition the negative pattern of hippocampal neuroplasticity depends on both corticosterone and lactate levels, whereas, in low-intensity exercise the most important factor determining this negative pattern is lactate levels. Generally, MIE with lactate levels a little greater than LT is the most beneficial intensity for improving hippocampal neuroplasticity.
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