Effects of prenatal cocaine exposure on postnatal growth patterns of male Wistar rats

The purpose of this study was to investigate basic parameters regarding the postnatal effects of prenatal exposure to cocaine. Timed-pregnant Wistar rats were injected SC with 60 mg/kg body weight/day of cocaine from gestational day 8 to 22. Control females were nonmanipulated and given food ad lib; saline females received saline injections and pair-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 adjustment of the logistic and Gompertz models to the body weights of the offspring 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 significant differences in the estimated adult weight were found among the experimental groups. The allometric relationship between forebrain and body weight is described by two postnatal growth phases with a first phase of rapid growth between PND 14 and 30 and a decelerating phase between PND 30 and 90. This relationship was not different among the experimental groups; however, the cocaine and pair-fed offspring showed a constant deficit in the forebrain weight as compared with the control and saline off-spring. 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 groups. The low weight of the cerebellum until PND 30 in cocaine or pair-fed offspring is subsequently compensated by sustaining the high early relative growth between PND 30 and 90. These effects of prenatal cocaine exposure on growth patterns are not different from those detected 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 exposure on body and brain weights, suggesting a possible technique for further evaluation of the developmental processes of the central nervous system.