The effects of rosuvastatin and simvastatin plasma and liver cholinesterases in rats

Vlasta Bradamante1, Antonija Vuksic1, Nina Blazevic1, Marinko Bilusic2, Pasko Konjevoda3. 1School of Medicine, University of Zagreb, Zagreb, Department of Pharmacology, 10000, Croatia, 2Polyclinic Bonifarm, Zagreb, 10000, Croatia, 3Rudjer Boskovic Institute, Zagreb, NMR Center, 10000, Croatia

Introduction. Statins have many independent or “pleiotropic” effects beyond cholesterol lowering. Epidemiological reports have demonstrated that statins protect against Alzheimer disease (AD). It’s known that the most striking neurochemical disturbance in AD is a deficiency of acetylcholine. Since acetylcholinesterase (AChE) and plasma cholinesterase (PChE) are involved in cholinergic transmission, cholinesterase inhibitors are used for treatment of AD. According to the some experimental data statins can protect against AD by inhibition of both enzymes. The results of some other nonclinical and clinical studies have shown that statins do not influence the AChE and PChE activities. Our previous results have shown the increase of plasma and liver PChE activity in normolipidemic rats after simvastatin and atorvastatin treatment during 3 weeks. Because of opposite literature data, we decided to investigate the influence of rosuvastatin (ROSU) on plasma and liver PChE activity of normolipidemic rats and to repeat the experiment with simvastatin (SIMV).

Material and Methods. Forthy six male normolipidemic Wistar rats were divided into four control groups and four experimental groups. Two experimental groups were on SIMV treatment (10 and 50 mg/kg/day) and the remaining two groups on ROSU treatment (5 and 10 mg/kg/day). Both agents were given orally for the period of 3 weeks, as well as the saline for the control groups. Animals were sacrificed with ether 24 hours after the last dose. Blood samples were obtained directly from heart and liver tissue was rinsed with saline. The PChE activity in plasma and liver was determined by Ellman’s spectrophotometric method using butyrylthiocholine and acetylthiocholine as substrates. In liver tissue, the PChE assay was carried out with and without ethopropazine hydrochloride. Enzyme activities are expressed as μmol of substrate hydrolysed per min per ml of plasma or g of tissue. Data were analysed by Dunn’s Multiple Comparison Test. Results were considered as significant with p<0.05.

Results. Both doses of ROSU and SIMV increased plasma PChE activity in comparison to control, regardless to used substrate. Both doses of ROSU and SIMV increased significantly (p<0.05) plasma PChE activity vs.control (mean±SD) when butyrythiocholine was used (ROSU 5mg vs control: 0,080±0.0141vs 0.066±0.0064; ROSU 10mg vs control: 0.084±0.0110 vs 0.066±0.0067; SIMV 10mg vs control: 0.069±0.0135 vs 0.057±0.0064; SIMV 50mg vs control: 0.109±0.0145 vs 0.073±0.0105). By using acetythiocholine as substrate the significant increase of plasma PChE activity vs. control was obtained only after administration of higher doses of ROSU and SIMV (ROSU10mg vs control: 0.409±0.027 vs 0.339±0.058; SIMV 50mg vs control: 0.480±0.047 vs. 0.392±0.047). The values of plasma PChE activity obtained with butyrylthiocholine were greater in comparison with the values received using acetylcholine as substrate. This difference was expected, because, in average, 95% of total cholinesterase activity refers to PChE. Both doses of these statins either increased or didn’t influence PChE in rat liver regardless to used substrate.

Conclusion. Our results show that rosuvastatin increases plasma and liver PChE activity in normolipidemic rats and confirm our previous results obtained with simvastatin. Their protective effect against AD is not the consequence of cholinesterase inhibition caused by statins.