Early change and adaptation in the social behaviour or rats given methyl mercury in the diet
Silverman, A.P.; Banham, P.B.; Extance, K.; Williams, H.
Neurotoxicology 2(2): 269-281
1981
ISSN/ISBN: 0161-813X PMID: 7198756 Document Number: 176751
Rats were fed diets containing methyl mercury dicyandiamide (MMD) at concentrations of 1.5, 7.5 or 75 ppm and observations made of their social and exploratory behavior and of gross neurotoxicity (ataxia). Hg concentration in the blood was monitored. MMD at 75 ppm (50 ppm Hg) for 24 days caused ataxia with a sudden onset at 21-27 days. Social behavior was reduced at 16-17 days. In 2 experiments at 7.5 ppm MMD, activity was increased in observations of social behavior after 2-17 days and treated rats found water in an unfamiliar cage sooner than controls. No difference from controls was apparent from then until increased activity re-appeared after 9 mo. of the diet or after 7 days recovery from 31 or 45 days diet. Ataxia was not observed after 7.5 ppm MMD for up to 47 wk or in 14 wk recovery. No consistent effect was observed at 1.5 ppm MMD for 31-45 days MMD had a behavioral effect in rats independent of gross neurotoxicity; its details were consistent with a hyperresponsiveness to stimuli. Tolerance occurred to this effect at a time when blood Hg concentration was still rising but the tolerance was subject to overload.