Effects of synaptic plasticity regulated by 17 beta-estradiol on learning and memory in rats with Alzheimer's disease

Objective To investigate whether estrogen modulates learning and memory and long-term potentiation (LTP) in the hippocampus of rats with Alzheimer's disease (AD). Methods The rats were divided into ovariectomy (OVX) and estrogen replacement therapy (ERT) groups. Rats in the ERT group received OVX, followed by ERT, while rats in the OVX group received only OVX. The rat model of AD was established by injection of 1 mu L (10 mu g/mu L) amyloid-beta peptide 1-40(A beta(1-40)) into the hippocampus. The learning and memory ability and LTP were determined by Morris water maze and electrophysiological method, respectively. Results The escape latency in Morris water maze significantly decreased in ERT group compared with that in OVX group (P < 0.05). Besides, rats in ERT group exhibited a significant enhancement of the magnitude of LTP at 30 min after high-frequency stimulation (HFS), compared with that in OVX group (P < 0.01). Conclusion ERT can attenuate the cognitive deficits in the rat model of AD, and estrogen can regulate LTP and synaptic remodeling in AD rats.