DEVELOPMENT OF SPATIAL NAVIGATION FOLLOWING PRENATAL COCAINE AND MALNUTRITION IN RATS - LACK OF ADDITIVE EFFECTS

The effects of prenatal cocaine exposure and protein malnutrition on t he development of spatial navigation were assessed in rats. Sprague-Da wley dams were fed a low-protein (6% casein), adequate protein (25% ca sein), or a laboratory chow diet prior to mating and throughout pregna ncy. Within each diet group, rats received either cocaine injections ( 30 mg/kg IP two times per week prior to mating and then 30 mg/kg SC da ily from day 3 to 18 of pregnancy) or saline injections. All litters w ere fostered on the day of birth to saline-injected mothers fed either the 25% casein diet or the chow diet. Gestation length was decreased by prenatal cocaine exposure whereas litter size was reduced by prenat al malnutrition. On postnatal days 21, 25, 30, or 70, rats were tested for their ability to locate a submerged platform in a Morris water ma ze. In well-nourished rats, prenatal cocaine increased the mean distan ce swum during acquisition over days 21-30, a difference that was abol ished in rats with prenatal malnutrition. Ln the absence of drug expos ure (saline groups), prenatal malnutrition was itself associated with longer swim paths. Neither prenatal insult affected the accuracy of th e spatial navigation at these ages, as determined by their search patt ern when the platform was removed. On postnatal day 25, rats raised on the chow diet exhibited superior performance to that of rats raised o n the 25% casein diet, but by day 30 these two well-nourished groups w ere comparable. At day 70, prenatal cocaine impaired spatial performan ce on the first session, in well-nourished rats only. Thus, these resu lts provide no support for the hypothesis that prenatal cocaine and pr otein malnutrition combine to produce a greater effect on behavioral d evelopment than either insult alone. (C) 1997 Elsevier Science Inc.