On the mechanisms of neuroprotection by creatine and phosphocreatine

Abstract

Creatine and phosphocreatine were evaluated for their ability to prevent death of cultured striatal and hippocampal neurons exposed to either glutamate or 3-nitropropionic acid (3NP) and to inhibit the mitochondrial permeability transition in CNS mitochondria. Phosphocreatine (PCr), and to a lesser extent creatine (Cr), but not (5R,10S)-(1)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK801), dose-dependently ameliorated 3NP toxicity when applied simultaneously with the 3NP in Mg 21 -free media. Pretreatment of PCr for 2 or 5 days and Cr for 5 days protected against glutamate excitotoxicity equivalent to that achieved by MK801 post-treatment. The combination of PCr or Cr pretreatment and MK801 post-treatment did not provide additional protection, indicating that both prevented the toxicity attributable to secondary glutamate release. To determine if Cr or PCr directly inhibited the permeability transition, mitochondrial swelling and depolarization were assayed in isolated, puri®ed brain mitochondria. PCr reduced the amount of swelling induced by calcium by 20%. Cr decreased mitochondrial swelling when inhibitors of creatine kinase octamer±dimer transition were present. However, in brain mitochondria prepared from rats fed a diet supplemented with 2% creatine for 2 weeks, the extent of calcium-induced mitochondrial swelling was not altered. Thus, the neuroprotective properties of PCr and Cr may re¯ect enhancement of cytoplasmic high-energy phosphates but not permeability transition inhibition.

Mitochondrial Creatine Kinase Activity Prevents Reactive Oxygen Species Generation

“…decrease in total Cr and PCr concentration, CK activity, and/or Cr transporter content (67,68). In cultured rat neurons, as well as in astrocytes, Cr protected against glutamate, ␤-amyloid, and 3-nitropropionic acid toxicity (18,19,69). Furthermore, reduced neuronal damage and ROS formation were observed when cultures were administered with Cr at least 6 h before 3-hydroxyglutarate treatment (53).…”

“…In support to this view, it has been well documented that creatine (Cr) exerts powerful protective effects in models of Huntington disease, Parkinson disease, amyotrophic lateral sclerosis, as well as in in vitro models of glutamate and ␤-amyloid toxicity (12, 16 -19). Moreover, neuronal ATP depletion is a feature of neurodegenerative diseases and the proposed mechanism for Cr protection has been attributed to a build-up of phosphocreatine (PCr) stores, which increase the efficiency of ATP regeneration (18,19). Hyperglycemia in animal and in vitro models of diabetes is associated with both enhanced production as well as decreased scavenging of ROS, leading to a cellular oxidative stress condition and impaired mitochondrial function, which ultimately leads to O 2 .…”

Creatine Supplementation Improves Dopaminergic Cell Survival and Protects against MPP+ Toxicity in an Organotypic Tissue Culture System

“…Creatine-induced neuroprotection has also been demonstrated in several in adult levels by a quadruple increase in the early postnatal period (20,46,67). Regarding the fact that the early vitro models of neurotoxicity and metabolic insults (15,19,61,92). Therefore, creatine is suggested to have postnatal period corresponds to the days following DIV7 in tissue derived from E14 embryos, the pattern of BBpotential as a therapeutic molecule for the treatment of PD (28,50).…”

“…Creatine supplementation may therefore also be effective in improving the metabolic state of embrycultures in a pilot study (Andres et al, unpublished data). Furthermore, Brustovetsky and coworkers reonic neurons and neuronal precursors and thus constitute a means of improving cell viability and long-term surported creatine concentrations of 3 and 10 mM to exert neuroprotection against an energetic insult in hippocamvival of cells for subsequent transplantation.Organotypic tissue cultures like the free-floating pal and striatal cultures, while lower doses turned out to be ineffective (19). Analyses proved that the concentraroller tubes (FFRT) culture system (89) offer advantages for transplantation by preserving the complex functional tion of the added creatine in the culture medium remained stable over the interval between the medium and structural interaction of the nigral neurons at least partially.…”

Release of Ca 2+ from Mitochondria via the Saturable Mechanisms and the Permeability Transition

“…Recent studies show that low Pi concentrations increase the lag period in some cases (21), and that the anti-apoptotic protein bcl-2 has a similar effect (22). Although creatine and creatine phosphate were thought to inhibit the PT with a neuroprotective action, more recent evidence suggests that their effects are due to enhancement of cytosolic high energy phosphate levels and not to direct actions on the PT (23).…”