Increase of cerebral phosphocreatine in normal rats after intracerebroventricular administration of creatine

Intracerebroventricular (ICV) administration of creatine increased cerebral phosphocreatine in normal rats by 67%, the highest increase so far reporte d in an in vivo model. We used osmotic minipumps (Alzet, Pale Alto, CA, USA ) to administer creatine, 0.5 mM, to the lateral ventricle at the rate of 1 0 mul/h for 3 days. Brain phosphocreatine in saline-treated controls was 33 +/- 17 muM/g protein (mean +/- SD, N = 9). In creatine-treated rats (0.5 m M for 3 days) such content was 55 +/- 17 muM/g protein (mean +/- SD, N = 7) . This difference is statistically significant (p = 0.02, t-test). The incr ease we found in cerebral phosphocreatine is of an order of magnitude compa rable to the increase previously found in in vitro experiments, and may be effective in protecting brain tissue from ischemic damage.