Dissociation between behavioral and physiological indices of organomercurial ingestion

Rats allowed to behaviorally regulate intake of methyl mercuric chloride (MMC) contained in a palatable sucrose solution exhibited markedly different manifestations of toxicosis depending on concentration of the adulterant. A dose level of 25 g/liter of MMC in a 5% sucrose solution was initially ingested but was then rejected prior to the appearance of any neurological or physiological damage. The rejection was shown to be based on the sucrose taste stimulus. At a lower MMC concentration of 5 g/liter, the solution was vigorously consumed through the appearance of profound signs of organic mercury toxicosis including weight loss, ataxia, postural abnormalities, neural degeneration, and renal failure. These results demonstrate a dissociation between the behavioral and pathophysiological toxicity induced by organic mercury.