Protective effect of xanthohumol against age-related brain damage.

It has been recently shown that xanthohumol, a flavonoid present in hops, possesses antioxidant, anti-inflammatory and chemopreventive properties. However, its role in the aging brain has not been addressed so far. Therefore, this study aimed to investigate the possible neuroprotective activity of xanthohumol against age-related inflammatory and apoptotic brain damage in male senescence-accelerated prone mice (SAMP8). Animals were divided into 4 groups: Untreated young mice, untreated old mice and old mice treated either with 1 mg kg-1 day-1 or 5 mg kg-1 day-1 xanthohumol. Young and old senescence accelerated resistant mice (SAMR1) were used as controls. After 30 days of treatment, animals were sacrificed and their brains were collected and immediately frozen in liquid nitrogen. mRNA (GFAP, TNF-α, IL-1β, AIF, BAD, BAX, XIAP, NAIP and Bcl-2) and protein (GFAP, TNF-α, IL-1β, AIF, BAD, BAX, BDNF, synaptophysin and synapsin) expressions were measured by RT-PCR and Western blotting, respectively. Significant increased levels of pro-inflammatory (TNF-α, IL-1β) and pro-apoptotic (AIF, BAD, BAX) markers were observed in both SAMP8 and SAMR1 old mice compared to young animals (P<.05) and also in SAMP8 untreated old mice compared to SAMR1 (P<.05). These alterations were significantly less evident in animals treated with both doses of xanthohumol (P<.05). Also, a reduced expression of synaptic markers was observed in old mice compared to young ones (P<.05) but it significantly recovered with 5 mg kg-1 day-1 xanthohumol treatment (P<.05). In conclusion, xanthohumol treatment modulated the inflammation and apoptosis of aged brains, exerting a protective effect on damage induced by aging.