p,p'-DDT-induced neurotoxic syndrome: experimental myoclonus.

p,p'-DDT (100 to 600 mg per kilogram orally) produced spontaneous and stimulus-sensitive myoclonus in mice and rats. Drugs that enhance brain serotonergic activity reduced p,p'-DDT-induced myoclonus, and serotonin antagonists invariably aggravated this syndrome. p,p'-DDT-treated rats had increased concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in seven regional areas, but serotonin was increased only in the midbrain and cerebellum. We postulate that p,p'-DDT-induced myoclonus may be causally related to blockage of serotonin receptors or inhibition of serotonin release into the synapse, resulting in functional deficiency of this neurotransmiter at the receptor site.