Alex Lee: “Effect of creatine supplementation on AGAT expression and metabolic intermediates in GAMT-deficient mice”
SHORT SUMMARY
In this study, we used wild-type and GAMT knockout mice to study how treating them with creatine affected the levels of creatine and guanidinoacetate within their organs as well as how this treatment affects AGAT expression. We observed that the knockout mice that were given creatine had increased levels of creatine in all organs and reduced levels of guanidinoacetate in all organs except the liver. Furthermore, treating the GAMT knockout mice with creatine resulted in significant reductions in AGAT protein levels and activity. Our research confirms that creatine administration lowers guanidinoacetate in GAMT deficiency via reduced AGAT expression.
ABSTRACT
We carried a multidimensional study to examine the effect of creatine supplementation on arginine-derived guanidino compounds, AGAT expression and AGAT activity in creatine-deficient mouse model. Adult wildtype, heterozygous and GAMT-deficient mice were kept either on creatine-free, 2% or 4% creatine supplemented mouse chow for 10 weeks. Mouse urine and blood were collected at the beginning and the end of the trial; mouse tissues were harvested at the end of the study. An appropriate age matching non-treatment mouse group was used as a control for tissue analysis. In urine, plasma and selected tissues LCMSMS analysis demonstrated varied effect of creatine supplementation on creatine and guanidino acetate (GAA) levels. Wildtype mice showed increase of creatine in urine, plasma, kidneys and liver and there was no change in brain, heart and muscle. Mutant mice on the other hand showed increase of creatine in urine, plasma and all organs. Further, creatine supplementation led to decrease of GAA in urine, plasma and all organs of wildtype mice. Mutant mice also showed reduction of GAA in their organs, except liver. Western blot analysis revealed marked decrease in AGAT gene expression in kidneys, brain and liver following creatine supplementation. Since the creatine effect on AGAT mRNA in liver was inconclusive, we measured AGAT enzyme activity and could confirm reduced AGAT activity. In conclusion, we can demonstrate the efficacy of creatine on reduction of GAA in mice. The mechanism by which creatine reduces GAA is the noticeable inhibitory effect of creatine on AGAT expression.