Behavioral alterations induced in rats by a pre- and postnatal exposure to2,4-dichlorophenoxyacetic acid

The purpose of this study was to determine whether the behavioral developme nt pattern was altered by a pre- and postnatal exposure to 2,4-Dichlorophen oxyacetic acid (2,4-D). Pregnant rats were daily orally exposed to 70 mg/kg /day of 2,4-D from gestation day (GD) 16 to postnatal day (PND) 23. After w eaning, the pups were assigned to one of the two subgroups: T1 (fed with un treated diet until PND 90) and T2 (maintained with 2,4-D diet until PND 90) . Effects on offsprings were evaluated with a neurotoxicological test batte ry. Neuromotor reflexes, spontaneous motor activity, serotonin syndrome, ci rcling, and catalepsy were analyzed during Various postnatal ages. 2,4-D ne onatal exposure induced delay of the ontogeny of righting reflex and negati ve geotaxis accompanied by motor abnormalities, stereotypic behaviors (exce ssive grooming and vertical head movements), and hyperactivity in the open field. Adult rats of both sexes (T2 group) showed a diminution of ambulatio n and rearing, while excessive grooming responses were only observed in T2 males. Besides. these animals manifested serotonin syndrome behaviors, cata lepsy, and right-turning preference. Some behaviors were reversible, but ot hers were permanent, and some were only expressed after pharmacological cha llenges. (C) 1999 Elsevier Science Inc. All rights reserved.