Since cyclodextrin gas chromatography columns became popular for chiral separations, many researchers have noticed high enantiomeric ratios [ER: (+)-enantiomer/(-)-enantiomer] for α-HCH in the brains of wildlife. This investigation used the laboratory rat as a model for these phenomena. Rats were either pretreated with phenobarbital (PB) or left untreated and then dosed with α-HCH. Animals were sacrificed after 1 or 24 h. The ER averaged 0.95 ± 0.01 in blood, 1.29 ± 0.02 in fat, and 0.77 ± 0.004 in liver. ERs in brain ranged from 2.8 ± 0.5 to 13.5 ± 0.4. Both the tissue concentration distribution and the ERs agree well with those previously reported in wildlife. To determine whether high brain ERs were due to enantioselective metabolism or transport through the blood-brain barrier, α-HCH exposed brain and liver tissue slices were compared. Concentrations in the brain slices did not decrease with PB pretreatment but did decrease in the liver slices. Enantiomeric ratios in the brain slices averaged 1.ll ± 0.02 and were 0.76 ± 0.03 in liver slices for the PB pretreated rats. These data indicate that the enantioselective metabolism of α-HCH by the brain is not the mechanism responsible for high ERs in this tissue.
ASJC Scopus subject areas
- Environmental Chemistry