Galantamine in rheumatoid arthritis: A cross talk of parasympathetic and sympathetic system regulates synovium-derived microRNAs and related pathogenic pathways.

Abstract The acetylcholinesterase inhibitor, galantamine, has shown therapeutic effect in rat model of rheumatoid arthritis. Hence, the current study aims at determining the mode of action of galantamine by examining different synovium-derived microRNAs (miRs) and their related pathogenic pathways. The study also focuses on how parasympathetic and sympathetic pathways in the synovial tissue could affect the mode of action and anti-arthritic effect of galantamine. Chemical sympathectomy was initiated in 12 adjuvant arthritic rats by exposure to 6-hydroxydopamine (6-OHDA; 2 × 50 mg/kg) on day 9 after adjuvant injection and again (2 × 100 mg/kg) one week later. Six rats were treated with galantamine (2.5 mg/kg/day) to explore the influence of sympathetic impairment on galantamine effect. Another twelve additional adjuvant arthritic rats were exposed to the selective α7 nicotinic acetylcholine receptor blocker methylcaconitine citrate (MLA; 5.6 mg/kg/day), 15 min before galantamine treatment. As control, six adjuvant arthritic rats were treated with galantamine alone. Treatment proceeded for 5 days, from day 14 till day 18 post-adjuvant injection. Different miRs and their related pathogenic pathways were examined. Tyrosine hydroxylase (TH) expression was also measured in joint tissue. Galantamine affected the expression of the different miRs and their related parameters. Both, 6-OHDA and MLA, interrupted the anti-inflammatory/anti-arthritic effect of galantamine to different extent. Additionally, TH expression in the synovium was affected by galantamine, suggesting a novel pathogenic target in the treatment of rheumatoid arthritis.