Treadmill exercise restores memory and hippocampal synaptic plasticity impairments in ovalbumin-sensitized juvenile rats: Involvement of brain-derived neurotrophic factor (BDNF)

Studies demonstrate that asthma, especially during childhood, affects the functions of the brain including learning and memory. Exercise is well known for its neuroprotective functions and for its beneficial effects on asthma. We aimed to assess the effects of exercise on cognitive function, synaptic plasticity, and hippocampal brain-derived neurotrophic factor (BDNF) levels in ovalbumin (OVA) sensitized juvenile rats. Rats were sensitized by intraperitoneal administration and inhaled OVA. Animals were subjected to treadmill running exercise during the OVA-challenged period. T-helper type 2 (Th2) cytokine [interleukin (IL)-4], Th1 cytokine (INF-gamma) levels, and INF-gamma/IL-4 (Th1/Th2) ratio in bronchoalveolar lavage fluid (BALF), and tracheal response to methacholine and OVA were measured. Further, memory behaviors and BDNF levels were measured in the hippocampus as well as long-term potentiation (LTP) was assessed by recording field excitatory postsynaptic potentials (fEPSPs) in the hippocampus. The levels of IL-4 and TGF-beta were decreased but INF-gamma level and INF-gamma/IL-4 ratio increased in the BALF due to exercise in the OVA-sensitized animals. In addition, exercise improved OVA-sensitization induced cognitive impairments, increased BDNF levels, and enhanced hippocampal LTP in OVA-sensitized rats. Exercise is not only effective in the alleviation of airway inflammation by restoring Th1/Th2 cytokines balance, but also is a candidate for improvement of memory and synaptic plasticity deficits partially through increasing the levels of hippocampal BDNF in OVA-sensitized rats.