Protective Therapies for Monomethylhydrazine: Comparison of Pyridoxine and Physical Restraint in the Monkey

Abstract : This study compared convulsive and related pre-convulsive responses to monomethylhydrazine (MMH) in three groups of chaired rhesus monkeys. One group served as a control and the other two as experimental groups to evaluate the influence on these measures of arm restraint and pyridoxine, respectively. Control animals displayed emesis, pre-ictal responses and generalized seizures within the first 75 min post-MMH-injection. Pyridoxine treated animals showed emesis but no pre-ictal or ictal behavior during this period, while arm restrained animals showed no emesis, pre-ictal or ictal behavior. Control animals exhibited a criterion of three generalized seizures, after which chemotherapy was administered within the first 100 min post-MMH-injection. Neither pyridoxine treated nor arm restraint animals showed any generalized seizures during a standard 240 min observation period, although both groups eventually displayed emesis and pre-ictal responses. The protective effects of pyridoxine were interpreted within the context of established neurochemical influences of the hydrazines on synthesis of the inhibitory neurotransmitter, gamma aminobutyric acid.