Neuroprotective potential of Ganaxolone and allopregnanolone against Aβ deposits in APPswe transfected SH-SY5Y cells

Background: Alzheimer's disease (AD) is a neurological disease characterised pathologically by loss of synapses and neurones, accumulation of amyloid-beta (Aβ) deposits and formation of neurofibrillary tangles. This results in progressive cognitive impairment as people age. Ganaxolone, a synthetic analogue of allopregnanolone, has shown a protective effect on gliosis associated with demyelination. However, its effect on Aβ deposits and neuronal loss associated with AD is still unknown. Additionally, its effect on liver x receptors (LXR) has not yet been reported. In this study, we investigated the effect of Ganaxolone on Aβ toxicity in receptor-dependent manner, and studied the downstream processes involved. Methods: The APPswe plasmid was transfected into the SH-SY5Y neuroblastoma cell line to establish a cell model of Alzheimer's disease. Cells were treated with graded concentration of Ganaxolone for 24 h followed by ThT binding assay and Congo red staining to monitor the effect of Ganaxolone and allopregnanolone on in vitro amyloid formation. Aβ 40 and 42 levels were assessed by ELISA, immunofluorescence and western blot. After treatment, changes in LXR gene expression and associated downstream signaling molecules were confirmed by RT-PCR and Western blotting. Results: Treatment with Ganaxolone and Allopregnanolone increased LXR expression and the associated downstream target, reducing ROS and Aβ 40/42 expression. The results indicate that the cytoprotection conferred by Ganaxolone and Allopregnanolone on APPswe transfected SH-SY5Y cells is mediated by its ability to up-regulate the expression of LXR and downstream signaling pathway. Hereby, we propose that Ganaxolone may be a tractable drug for treatment of AD.