Salidroside ameliorates cognitive impairment in a D-galactose-induced rat model of Alzheimer's disease

The purpose of the present study was to investigate possible preventive effects of salidroside (sal) on a rat model of Alzheimer's disease and to explore its possible mechanism. Sub-acute aging was induced in male SD rats by subcutaneous injection of D-gal (120 mg/kg) for 42 days, and the rats were treated with sal (20, 40 mg/kg) or normal saline for 28 days after 14 days of D-gal injection. Morris water maze (MWM) test and step-down passive avoidance test were conducted to evaluate the cognitive function of the rats. The levels of inflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 beta (IL-1 beta) in hippocampus were assayed by enzyme-linked immunosorbent assay (ELISA) to assess the anti-inflammatory effect of sal. Further, we estimated the expression levels of thioredoxin (Trx), thioredoxin interacting protein (Txnip/vitamin D3 up-regulated protein/thioredoxin binding protein-2), Bax, Bcl-2, caspase-9 and related-proteins of nuclear factor kappa B (NF-kappa B) signaling pathway by western blot assay. It showed that administration of sal significantly attenuated all the D-gal-induced changes in the hippocampus, including cognitive impairment and neuroinflammation. These analytical results provides evidence that sal can improve cognitive capacity by inhibiting neuroinflammation and affecting apoptosis-related proteins in hippocampus. (C) 2015 Elsevier B.V. All rights reserved.