The purpose of this experiment was to examine the effects of cannabinoids, malnutrition and their possible interaction upon the developing rat fetus. Female Wistar rats were exposed to Cannabis smoke, placebo smoke, or no-smoke while concurrently consuming one of three experimental diets differing in protein concentration (8%, 24%, 64%). Thus, 9 treatment combinations were generated from the experimental design. Treatment was administered 20 days prior to, and throughout gestation.
Maternal variables examined included pre-mating weight gain, gestational weight gain, length of gestation, number of offspring born, stillbirth and post-natal pup death rates. Offspring were examined in terms of weight gain, reflexive ontogeny and physical feature development, general locomotor activity, biochemical assays, open field and water maze performance. Incidental observations were performed on aspects of the mother-infant interaction. A concurrent study was added to further examine the effects on rat offspring of the gestational administration only of cannabinoids coupled with a normal (24% protein) diet.
The results indicate that not only do diet and drug contribute separately to altering selected components of the offspring's post-natal development, but in addition, a synergistic interaction between the low protein diet and cannabinoids was found. Furthermore, the low protein diet was successful in unmasking cannabinoid-related effects which were not observed with the other diets. The high protein diet resulted in reversing some of the Cannabis-related effects such as late maturing physical features and reflexes. Evidence for physiological tolerance in mothers receiving the drug prior to and throughout gestation was observed. In the offspring of these mothers some of the cannabinoid-related effects were attenuated relative to offspring of mothers receiving the drug during gestation only.
It was concluded that in studies examining the prenatal effects of drug administration, consideration must be given to the nutritional status of the mothers.