Differential effects of exercise intensities in hippocampal BDNF, inflammatory cytokines and cell proliferation in rats during the postnatal brain development

Abstract

It has been established that low intensities of exercise produce beneficial effects for the brain, while high intensities can cause some neuronal damage (e.g. exacerbated inflammatory response and cell death). Although these effects are documented in the mature brain, the influence of exercise intensities in the developing brain has been poorly explored. To investigate the impact of exercise intensity in developing rats, we evaluated the hippocampal level of brain derived neurotrophic factor (BDNF), inflammatory cytokines (TNFα, IL6 and IL10) and the occurrence of hippocampal cell degeneration and proliferation at different stages of postnatal brain development of rats submitted to two physical exercise intensities. To this point, male rats were divided into different age groups: P21, P31, P41 and P51. Each age group was submitted to two exercise intensities (low and high) on a treadmill over 10 consecutive days, except the control rats. We verified that the density of proliferating cells was significantly higher in the dentate gyrus of rats submitted to low-intensity exercise from P21 to P30 compared with high-intensity exercise and control rats. A significant increase of proliferative cell density was found in rats submitted to high-intensity exercise from P31 to P40 when compared to low-intensity exercise and control rats. Elevated hippocampal levels of IL6 were detected in rats submitted to high-intensity exercise from P21 to P30 compared to control rats. From P41 to P50 period, higher levels of BDNF, TNFα and IL10 were found in the hippocampal formation of rats submitted to high-intensity exercise in relation to their control rats. Our data show that exercise-induced neuroplastic effects on BDNF levels and cellular proliferation in the hippocampal region are dependent on exercise intensity and developmental period. Thus, exercise intensity is an inflammation-inducing factor and exercise-induced inflammatory response during the postnatal brain development is also related to developmental stage. Our findings indicate that neuroplastic changes induced by exercise in developing rats depend on both age and training intensity.

Correlação dos parâmetros endócrinos e comportamentais em cadelas abandonadas em programa de ressocialização

“…These findings suggest that training kept standardized and higher cortisol levels (BEERDA et al, 1999b;NORMANDO et al, 2009;ASCHBACHER et al, 2013), probably resulting in an anti-inflammatory action and featuring an eustress as described previously (BROOM, 1988;ACCO;PACHALY;BACILA, 1999;KUNZ-EBRECHT et al, 2003;ASCHBACHER et al, 2013). The constancy of salivary IL6 levels in trained animals could also be explained by neuroendocrine mechanisms, which involved proinflammatory (IL6) and anti-inflammatory cytokines (IL10) (DE ALMEIDA et al, 2013;GOMES DA SILVA et al, 2013). Aerobic exercise performed daily in the morning induces an increase of anti-inflammatory cytokines and reduces the pro-inflammatory ones, especially in the hippocampus and cerebellum ).…”

“…Aerobic exercise performed daily in the morning induces an increase of anti-inflammatory cytokines and reduces the pro-inflammatory ones, especially in the hippocampus and cerebellum ). However, low-intensity exercises promote beneficial effects, reducing IL6 and elevating anti-inflammatory cytokines (DE ALMEIDA et al, 2013). Our choice for a training routine showed to be effective as it was daily, low in intensity and affordable.…”

“…Exaggerated hormonal elevations may lead to health problems, as low immune response, psychological and neurogenic disturbances as well as physiological and behavioral alterations (DE ALMEIDA et al, 2013). Higher basal cortisol levels may be considered normal and suitable, since its increase due to challenge exposure will occur.…”

“…should remain low to avoid emotional and systemic disturbances (MEYER; DA SILVA, 1999;CARROLL et al, 2011;DE ALMEIDA et al, 2013;GOMES DA SILVA et al, 2013). Sheltered dogs present behavior pattern similar to that of owned dogs, although interaction with the environment and other dogs were greater.…”

“…It has been reported that cortisol influences learning in dogs under stress (HAUBENHOFER; KIRCHENGAST, 2007;HAVERBEKE et al, 2008). IL6 participates in the first general inflammatory response to any injury (BLACK, 2002), including psychic and immediate source as acute stress (HEINRICH et al, 2003;NAS et al, 2011;IZAWA et al, 2013a), and can interfere with cognitive performance, since it stimulates aggression when acting in the limbic system and amygdala (ARHANT et al, 2010;CARROLL et al, 2011;DE ALMEIDA et al, 2013). However, we should question if these newly housed animals are not even more stressed during training.…”