Effects of long-term replacement therapy of compound nylestriol tablet or low-dose 17beta-estradiol on synapse in OVX rat hippocumpal formation

Objective To investigate the effects of long-term replacement therapy of compound nylestriol tablet or low-dose 17beta-estradiol on synaptic structure in hippocampal formation. Methods Fifty seven-month-old female Sprague-Dawley rats were randomly divided into five groups:normal control,SHAM,OVX,OVX plus 17beta-estradiol (OVX/ERT),and OVX plus compound nylestriol tablet (OVX/NL). The sections were doubly stained with uranyl acetate and lead curate for transmission electron microscopy to evaluate synaptic structure of hippocampal formation. Results Under transmission electron microscopy, the neurons of OVX rats were found to have a trend of degrading and aging. The numberical density, surface density and volume density of synapse in hippocampal formation in OVX rats were markedly reduced while the synaptic ribbon area in hippocampal formation in OVX rats was increased significantly. Conclusions Long-term estrogen deficiency (OVX) can result in a loss of synapses and change of synaptic structure. Replacement therapy of compound nylestriol tablet or low-dose 17beta-estradiol can equally maintain the normal integrity of ultrastructure and synaptic plasticity in OVX rat hippocampal formation.