Effects of lindane on spontaneous behavior of rats analyzed by multivariate statistics

The effects of subconvulsant doses (10, 15, 30 mg/kg) of the organochlorine insecticide gamma-hexachlorocyclohexane (lindane) on the spontaneous activity of male Wistar rats were assessed in an automated wheel-shaped activity monitor in 4 hr sessions. Most of the activity variables defined on the raw data showed statistically significant differences among treatment groups. These data can be interpreted as a lindane-induced change in the temporal distribution of the activity. The multivariate statistical technique principal component analysis was used to obtain a composite variable that measured this change. The variable obtained was found to be well correlated with dose levels and brain concentration of lindane and was used to estimate a minimal effective dose (MED) of 1.85 mg/kg and a upper limit for a minimal effective concentration (MEC) in brain of 0.84 micrograms/g by a log-linear regression approach. The results obtained with this approach further support the conclusion that the behavioral effects of lindane can be significant at exposure levels far below its LD50.