Mechanism Research Of Simvastatin And Cholesterol Regulating Melanin Synthesis

Melanin is a kind of pigment with multiple functions,structures and manifestations.Its abnormal expression in the body will cause a variety of diseases such as senile plaques,freckles and other diseases when melanin is too high.Too low will appear vitiligo,alopecia areata and other diseases.Simvastatin can inhibit HMG-CoA reductase activity and reduce endogenous cholesterol synthesis,which is widely used in clinical treatment of hypercholesterolemia.At the same time,it can also protect melanocytes from H₂O₂-induced oxidative damage by scavenging free radicals production and restoring enzymatic and non-enzymatic antioxidant systems,making it a potential vitiligo treatment drug.Although the drug has been carried out phase II clinical trials,but due to its side effects were forced to terminate.Cholesterol plays an important role in the stability of cell membrane and is also the key substrate for the synthesis of steroid hormones and vitamin D.In addition,studies have found that exogenous cholesterol can increase the pigmentation of epidermal melanocytes and melanoma cells.Although simvastatin and cholesterol have effects on the regulation of melanin,simvastatin can also cause changes in cholesterol content in the treatment of vitiligo.However,the interaction between simvastatin and cholesterol on the regulation of melanin synthesis mechanism remains unclear.Therefore,the study on the interaction mechanism of simvastatin and cholesterol regulating melanin synthesis is of great significance for understanding melanin regulation,which lays the foundation for the treatment of related diseases caused by melanin disorder.In this study,we intend to explore the efficacy of simvastatin and cholesterol in promoting melanin and the interaction between them in the efficacy of melanin from the aspects of morphology,melanin content and pigment-related gene expression through cell and zebrafish experiments.The effects of simvastatin and cholesterol on traditional melanin signaling pathway,Tspo protein and glucocorticoid（GC）were further explored by the mechanism of qRT-PCR and ELISA kits,so as to explore the interaction between simvastatin and cholesterol on the mechanism of melanin-stimulating action;Finally,we analyzed the possible mechanism of simvastatin and cholesterol promoting melanin by metabolomics and verified it.The results showed that both simvastatin and cholesterol could promote the production of melanin in zebrafish.The melanin-stimulating efficacy of the two may be through the JNK and AKT melanin signaling pathways,but it has nothing to do with whether cholesterol is transported into the mitochondria through the Tspo protein to generate steroid hormones.In addition,simvastatin improved the antioxidant activity of zebrafish,and simvastatin and cholesterol did not affect the content of GC in zebrafish and thus the production of melanin,and had no significant effect on the expression of GC-related factors.Subsequently,the study found that the simultaneous administration of simvastatin and cholesterol reduced the promotion of zebrafish melanin compared with the two of them alone.Further studies found that cholesterol could inhibit the activation of AKT signaling pathway,antioxidant activity and promotion of arginine content of simvastatin in zebrafish.Finally,through the analysis of metabonomics differential metabolic pathways,we explored the possible pathways of simvastatin and cholesterol promoting melanin,namely arginine biosynthesis pathway,and verified it.To sum up,we first confirmed that simvastatin and cholesterol promoted melanin in zebrafish.The melanin-stimulating effects of the two may be through the JNK and AKT melanin signaling pathways,but have nothing to do with GC-related factors.In addition,we found that simvastatin and cholesterol at the same time compared with their single administration of zebrafish melanin promotion decreased may be due to cholesterol inhibited the activation of AKT signaling pathway and antioxidant activity of simvastatin and promoted the arginine content in zebrafish.