TCDD DECREASES BRAIN INOSITOL CONCENTRATIONS IN THE RAT

A single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) reduced si gnificantly brain regional inositol levels in both the most TCDD-susce ptible (Long-Evans; LD(50) 9.8 mu g/kg and the most TCDD-resistant (Ha n/Wistar; LD(50) > 7200 mu g/kg) rat strain. The decrease emerged earl ier in Long-Evans rats but was similar in magnitude al 8 days in both strains. There were some inconsistent and largely dose-independent cha nges in inositol-1- and inositol-4-monophosphate concentrations at 2 d ays. On day 8, a tendency towards reduced levels was seen especially i n H/W rats. We conclude that TCDD reduces brain inositol levels presum ably by inhibiting its synthesis by way of substrate deficit (hypoglyc emia), but this effect does not appear to be causally related to the l ethal action of TCDD.