J. Tonkiss et al., DEVELOPMENT OF SPATIAL NAVIGATION FOLLOWING PRENATAL COCAINE AND MALNUTRITION IN RATS - LACK OF ADDITIVE EFFECTS, Neurotoxicology and teratology, 19(5), 1997, pp. 363-372
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.