Proton MRS of oral creatine supplementation in rats. Cerebral metabolite concentrations and ischemic challenge

Proton magnetic resonance spectroscopy (MRS) was employed to determine the concentrations of N-acetylaspartate (NAA), total creatine (tCr), choline-co ntaining compounds (Cho), myo-inositol (Ins), glucose (Glc), and lactate (L ac) in rat brain before and after 10 days of oral supplementation of 2.6 g Cr-monohydrate per kg body weight per day. Measurements were performed both in vitro (n = 16) and in vivo (n = 6), The neuroprotective potential of or al Cr was assessed by dynamically monitoring brain Glc and Lac in response to transient global ischemia (12 min). In comparison to controls the in vit ro concentrations of Cr (13.1 +/- 9.3%) and Ins (12.7 +/- 14.0%) were signi ficantly increased in Cr-fed rats. Under in vivo conditions, the data revea led trends for elevated tCr (4.7%) and Ins (10.6%) which were enhanced in t he concentration ratios of tCr:Cho (10.2%) and Ins:Cho (17.8%). Together wi th an increased Glc level (27.3%), the observation of a statistically signi ficant decrease of brain Lac (-38.5 +/- 19.3%) in Cr-fed rats may reflect a shift of the energy metabolism from non-oxidative toward oxidative glycoly sis. One hour after global ischemia most of the metabolic differences betwe en Cr-fed rats and controls were retained. The increased Glc level (44.4 +/ - 33.3%) reached statistical significance, but the accumulation of Lac and its time course during ischemia and early reperfusion showed no differences between Cr-fed rats and controls. Copyright (C) 1999 John Wiley & Sons, Lt d.