Catalpol improves cholinergic function and reduces inflammatory cytokines in the senescent mice induced by d-galactose

The neuroprotective effects of catalpol, an iridoid glycoside isolated from the fresh rehmannia roots, on the cholinergic system and inflammatory cytokines in the senescent mice brain induced by d-galactose were assessed. The results showed that acetylcholinesterase (AChE) activity increased in senescent mice brain and choline acetyltransferase (ChAT) positive neurons, detected by immunohistochemical staining, decreased remarkably in the basal forebrain of senescent mice. Simultaneously, muscarinic acetylcholine receptor M1 (mAChR1) expression declined in senescent mice brain by western blotting method. We also found that the contents of tumor necrosis factor (TNF-α), interleukin-1β (IL-1β) and advanced glycation endproducts (AGEs) increased in senescent mice brain by ELISA method. However, administration of catalpol for 2-weeks significantly reversed the biochemical markers mentioned above. These results suggest that catalpol can exert protective effects on senescent mice brain induced by d-galactose and this effect may be due to its protective effects on cholinergic and immune impairment in mice brain. Thus catalpol is worth testing for further preclinical study aimed for senescence or neurodegenerative diseases such as Alzheimer's disease.