Exaggerated response to (+)amphetamine in geriatric bergils

Young adult (6--8 months) and old (greater than 24 months) gerbils were compared with respect to locomotor activity, body temperature and toxicity to (+)amphetamine given intraperitoneally. Old gerbils showed greater locomotor activity to 5.6 mg/kg, greater hyperthermia to 10.0 mg/kg, and lower LD50 (young adult 34.0 +/- 7 mg/kG vs. old 17.6 +/- 2.8 mg/kg) than young adults. These differences were not related to increased drug levels in whole blood or brain nor to diminished clearance of the drug from these sites. No age-related difference could be found in the ability to regulate body temperature in the face of extreme environmental temperatures nor could a difference be detected in the hypothermic response to the dopaminergic agonist apomorphine in doses of 5.6 mg/kg i.p.