Abstract: Objective To investigate the effects of estrogen on brain derived neurotrophic factor (BDNF) and neuropeptide Y (NPY) levels in cerebellar cortex of ovariectomized rats. Methods 24 female Wistar rats were randomly divided into three groups: intact (INT) group, ovariectomized (OVX) group, and OVX+estrogen 0.5 mg/kg every day group (E group). Radioimmunoassay (RIA) was used to measure the estrogen content in plasma, and the levels of BDNF and NPY were measured with Immunohistochemistry. Results Compared with the INT group, the plasma estrogen level significantly reduced in OVX group (P<0.001). However, the plasma estrogen level was higher in the E group than that in the OVX group (P<0.001). The BDNF and NPY presented in the Purkinje cell layer,and BDNF also distributed in the molecular layer and granular layer. Compared with that in the INT group, BDNF and NPY positive cells markedly decreased in OVX group, with slight cytosol staining in the cerebellar cortex (P<0.001). The BDNF and NPY positive neurons increased in E group compared with that in the OVX group (P<0.001). Conclusion Estrogen can increase the BDNF and NPY levels in cerebellar cortex of female rats, which may protect the structure and function of cerebellar neurons.

Key words: estrogen, cerebellar cortex, ovariectomy, brain derived neurotrophic factor (BDNF), neuropeptide Y (NPY), rats