BIOCHEMICAL EFFECTS OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN (TCDD) ANDRELATED-COMPOUNDS ON THE CENTRAL-NERVOUS-SYSTEM

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related compounds are a n important class of environmental contaminants which induce several t ypes of biochemical alterations, Their effects have been most thorough ly characterized in the liver, especially regarding the Ah receptor-me diated induction of xenobiotic metabolizing enzymes. The behavioral si gns exhibited by animals exposed to TCDD (progressive anorexia and bod y weight loss) suggest a role for the central nervous system (CNS) in TCDD toxicity. At lethal doses, TCDD affects the metabolism of seroton in, a neurotransmitter able to modulate food intake in the brain, This effect is associated with an elevated concentration of free tryptopha n in the plasma, There does not appear to be any major changes in cate cholaminergic neurotransmitter systems in TCDD-treated rats, Cytochrom e P-450 related enzyme activities are induced by TCDD in the brain. As is the case in the liver, this induction does not correlate with susc eptibility to TCDD lethality in rats. The involvement of the CNS in TC DD toxicity is still obscure, Elucidation of this role as well as the mechanism of TCDD-induced wasting may well advance our understanding o f the regulation of food intake and body weight