EFFECTS OF PRENATAL COCAINE EXPOSURE ON POSTNATAL-GROWTH PATTERNS OF MALE WISTAR RATS

The purpose of this study was to investigate basic parameters regardin g the postnatal effects of prenatal exposure to cocaine. Timed-pregnan t Wistar rats were injected SC with 60 mg/kg body weight/day of cocain e from gestational day 8 to 22. Control females were nonmanipulated an d given food ad lib; saline females received saline injections and pai r-fed received saline and were nutritionally controlled to the cocaine -treated rats. Litters were restricted to 8 pups, weighed every other day until postnatal day (PND) 30 and every week from PND 30 to PND 90. The rats were perfused at PND 14, 30, and 90. The adequacy of adjustm ent of the logistic and Gompertz models to the body weights of the off spring was tested for the whole experimental period. The results from the Gompertz curve showed a higher growth rate and less time to reach 37% of expected mature body mass for the offspring of cocaine and pair -fed dams as compared with that of control and saline dams. No signifi cant differences in the estimated adult weight were found among the ex perimental groups. The allometric relationship between forebrain and b ody weight is described by two postnatal growth phases with a first ph ase of rapid growth between PND 14 and 30 and a decelerating phase bet ween PND 30 and 90. This relationship was not different among the expe rimental groups; however, the cocaine and pair-fed offspring showed a constant deficit in the forebrain weight as compared with the control and saline offspring. An analogous two- phase allometric relationship was found between cerebellum and body weight in the control and saline groups in contrast with a single phase for the cocaine and pair-fed g roups. The low weight of the cerebellum until PND 30 in cocaine or pai r-fed offspring is subsequently compensated by sustaining the high ear ly relative growth between PND 30 and 90. These effects of prenatal co caine exposure on growth patterns are not different from those detecte d in the offspring of pair-fed dams, suggesting effects on food intake rather than a direct drug effect. This longitudinal data analysis is of considerable value in the assessment of the effects of drug exposur e on body and brain weights, suggesting a possible technique for furth er evaluation of the developmental processes of the central nervous sy stem.