rTMS Ameliorates Prenatal Stress–Induced Cognitive Deficits in Male-Offspring Rats Associated With BDNF/TrkB Signaling Pathway

BACKGROUND: Growing evidences suggest that brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) plays a key role in the regulation of hippocampal synaptic plasticity in a prenatal stress (PNS) rat model. Repetitive transcranial magnetic stimulation (rTMS) is currently being acknowledged to affect attention and memory in both preclinical and clinical studies, although the mechanism is still unclear. OBJECTIVE: The current study aimed to explore whether a whole brain rTMS (5 Hz, 14 days) could ameliorate cognitive dysfunction-induced PNS in male offspring, and examine if the positive effect of rTMS was associated with the BDNF/TrkB signaling in the hippocampus. METHODS: The rats were randomly divided into 5 groups: CON, PNS, PNS + rTMS, PNS + rTMS + DMSO (dimethyl sulfoxide), and PNS + rTMS + K252a. Spatial cognition was evaluated by using Morris water maze test. Following behavioral assessment, both paired-pulse facilitation and long-term potentiation were recorded from Schaffer collaterals to CA1 region in the hippocampus. Synaptic, apoptotic, and BDNF/TrkB signaling proteins were measured by Western blot. RESULTS: PNS-exposed offspring exhibited cognitive deficits, long-term potentiation inhibition in the hippocampus, the decrease of synaptic and BDNF/TrkB signaling proteins expression, apoptosis, and reduced number of cells in the CA1 region. Five-hertz rTMS significantly alleviated the PNS-induced abnormalities. However, the effect of rTMS was antagonized by intracerebroventricular infusion of K252a (a TrkB inhibitor). CONCLUSIONS: The findings suggest that 5-Hz rTMS significantly improves the impairment of spatial cognition and hippocampal synaptic plasticity, which is possibly associated with the activation of BDNF/TrkB signaling.