Physical exercise ameliorates memory impairment in rat pups with maternal lipopolysaccharide-induced cerebral palsy

Abstract

Maternal lipopolysaccharide (LPS) exposure increases the incidence of cerebral palsy (CP). In the present study, we investigated the effects of treadmill exercise on memory in relation to the expression of brain-derived neurotrophic factor (BDNF) and serotonin (5-hydroxytryptamine, 5-HT) in the brain using rat pups of a maternal LPS-induced cerebral palsy model. There were two groups of pregnant rats, an LPS-injection group and a control group. During pregnancy, the rats in the LPS-injection group received a 1 mL intracervical injection of 0.15 mg/kg LPS. After birth, the neonatal rats were divided into three groups: a control group, an LPS-injection group, and a LPS-injection and exercise group. Five weeks after birth, the rat pups in the LPS-injection and exercise group were forced to run on a motorized treadmill for 30 min per day, five times per week for 4 weeks. Rat pups in the maternal LPS injection group showed decreased memory with suppressed BDNF expression, its receptor tyrosine kinase B (TrkB), 5-HT, and its synthesis enzyme tryptophan hydroxylase (TPH). Rat pups in the maternal LPS injection group that exercised showed alleviated memory impairment with enhanced expression of BDNF, TrkB, 5-HT, and TPH. We suggest that treadmill exercise increases 5-HT synthesis in the dorsal raphe, which, in turn, enhances BDNF expression in the hippocampus, resulting in the restoration of memory function. Treadmill exercise may be a useful strategy to mitigate neurodegenerative disorders in offspring that have been induced with an LPS injection during pregnancy.