DIFFERENTIAL-EFFECTS OF PRENATAL PROTEIN-MALNUTRITION AND PRENATAL COCAINE ON A TEST OF HOMING BEHAVIOR IN RAT PUPS

The effects of prenatal cocaine exposure and protein malnutrition on o rientation to home nest material was assessed in rat pups. Sprague-Daw ley darns were fed a dib of low protein content (6% casein), an isocal oric diet of adequate protein content (25% casein, control), or a labo ratory chow diet prior to mating and throughout pregnancy. Within each diet group, rats received either cocaine injections (30 mg/kg IP 2 ti mes per week prior to mating and then 30 mg/kg SC daily from day 3 to 18 of pregnancy) or saline injections. All litters were fostered on th e day of birth to control mothers fed an adequate diet. On postnatal d ays 7, 9, and 11, a single pup from each litter (n = 11-15 per treatme nt) was tested repeatedly in a clean test cage for the rapidity of app roach, and level of attraction to their own home (nest) bedding compar ed with fresh bedding. Prenatal malnutrition and prenatal cocaine expo sure each gave rise to independent effects on performance, based upon factor analysis. Prenatal malnutrition, but not prenatal cocaine, incr eased the time taken for rat pups to approach their nest bedding, redu ced the time spent on this bedding, decreased the number of entries in to the sector containing the home bedding and reduced pup weight. Pren atal cocaine, but not prenatal malnutrition, produced a reduction in a ctivity, but had no effect on pup weight. The lower activity level was most pronounced on postnatal day 7. Surprisingly, interactive effects of prenatal cocaine and prenatal malnutrition were not observed on an y behavior examined. Nevertheless, the co-existence of drug addiction and malnutrition in human populations raises the possibility that some of the effects generally attributed to drug exposure may, in fact, be due to malnutrition.