Uwe Pschorn

Preincubation with Creatine Enhances Levels of Creatine Phosphate and Prevents Anoxic Damage in Rat Hippocampal Slices

Abstract: We have investigated the relationship between energy metabolism, NMDA‐receptor antagonism, and anoxic damage in vitro. Anoxic damage was assessed by measuring protein synthesis, defined as the incorporation of [14C]lysine into perchloric acid‐insoluble tissue extracts. The concentrations of energy metabolites were measured by ion‐exchange HPLC. Anoxia caused an inhibition of protein synthesis, a reduction in phosphocreatine and adenosine triphosphate, and extensive neuronal damage. The reduction of protein synthesis depended on the duration of anoxia and the time allowed for recovery. Preincubation with the creatine dose‐dependently (0.03–3 mmol/L) increased baseline levels of phosphocreatine, reduced the anoxia‐induced decline in phosphocreatine and adenosine triphosphate, prevented the impairment of protein synthesis, and reduced neuronal death. Incubation with (R,S)‐3‐guanidinobutyric acid, a synthetic analogue of creatine that cannot be phosphorylated, did not prevent the anoxia‐induced impairment of protein synthesis and did not enhance the levels of phosphocreatine and adenosine triphosphate. Incubation with a combination of both creatine and the noncompetitive NMDA antagonist MK‐801 provided complete protection. These results indicate that energy status is a major factor controlling anoxic damage in the rat hippocampal slice.

Broad-spectrum cation channel inhibition by LOE 908 MS reduces infarct volume in vivo and postmortem in focal cerebral ischemia in the rat

Cation channels conduct calcium, sodium and potassium, cations that are likely deleterious in the evolution of focal ischemic injury. We studied the effects of a novel, broad-spectrum inhibitor of several cation channels, LOE 908 MS, on acute ischemic lesion development with diffusion-weighted magnetic resonance imaging (DWI) and on cerebral perfusion with perfusion imaging (PI) in vivo and on cerebral infarct size using 2,3,5-triphenyltetrazolium chloride (TTC) staining postmortem. A total of 18 male Sprague-Dawley rats underwent 90 min of middle cerebral artery occlusion (MCAO) and were randomly and blindly assigned to either LOE 908 MS or vehicle starting 30 min after inducing focal ischemia and continuing for 4 h. Whole-brain DWI and multislice PI were done before initiation of treatment and repeated frequently for the next 3.5 h. DWI-derived lesion volume at 4 h showed a significant difference in favor of the drug treated group (P=0.03), whereas PI-derived perfusion deficit volumes did not significantly differ between the groups. The postmortem infarct volume at 24 h was significantly attenuated in the treated group in comparison to controls (P=0.0001) and neurological score was significantly better in the treated group (P<0.02). Blocking several distinct cation channels with LOE 908 MS significantly reduced infarct size and improved neurological outcome without observable adverse effects in this focal ischemia model.

The influence of repeated doses, route and time of administration on the neuroprotective effects of BIII 277 CL in a rat model of focal cerebral ischemia

OBJECTIVE We investigated the influence of dose, route and time of administration on the neuroprotective effects of the noncompetitive N-methyl-D-aspartic acid antagonist BIII 277 CL ([2R-[2alpha, 3(R*), 6alpha]]-1,2,3,4,5,6-hexahydro-3-(2-methoxy-propyl)-6,11,11-trimethyl-2,6-methao-3-benzazocin-9-ol hydrochloride). METHODS Focal cerebral ischemia was induced in isoflurane-anaesthetized Fischer rats by permanent occlusion of the left middle cerebral artery. Rats were treated with BIII 277 CL three times at doses of 1 and 3 mg/kg intraperitoneally (IP) (5 to 10 minutes and 4 and 24 hours after occlusion) or twice with 0.1, 0.3, and 1.0 mg/kg subcutaneously (SC) (5 to 10 minutes and 3 hours after occlusion) or twice with 1 mg/kg SC (30 minutes and 3 hours 30 minutes; 1 and 4 hours; 2 and 5 hours; or 4 and 7 hours after occlusion). Other rats received (+)MK-801 (dizocilpine) three times at doses of 0.3, 1.0, and 3.0 mg/kg IP (5 to 10 minutes and 4 and 24 hours after occlusion). Control rats received an equal volume of saline. Infarct volume was determined 48 hours after occlusion by standard histological techniques. RESULTS IP administration of BIII 277 CL caused a dose-dependent reduction of infarct volume (1 mg/kg, 13%; 3 mg/kg, 25%). (+)MK-801 had similar effects (0.3 mg/kg, 13%; 1.0 mg/kg, 21%; 3 mg/kg, 27%). BIII 277 CL also dose-dependently reduced the infarct volume after SC administration (0.1 mg/kg, 14%; 0.3 mg/kg, 30%; 1.0 mg/kg, 28%). Furthermore, significant neuroprotective effects of BIII 277 CL were observed even when initial treatment was delayed up to 1 hour after occlusion (30 minutes, 28%; 1 hour, 23%; 2 hours, 5%; 4 hours, 4%). CONCLUSIONS These results indicate that BIII 277 CL shows significant neuroprotective effects at doses as low as 0.1 mg/kg SC. The effects after IP administration are comparable with those of (+)MK-801, and significant effects were observed even when the BIII 277 CL was first administered up to 1 hour after the beginning of ischemia.