Cannabis administered during pregnancy: First- and second-generation effects in rats

A literature review of the consequences of prenatal marihuana exposure. An emerging theme of a deficiency in aspects of executive function

In spite of marihuana being the most widely used illegal drug among women of reproductive age, there is a relative paucity of literature dealing with the neurobehavioral consequences in offspring--particularly the longer-term effects. However, there is a degree of consistency in the limited data, both across cross-sectional reports and longitudinally, where offspring have been followed for a number of years. Two cohort studies fall into the latter category; one involving a low-risk sample and, the other, a high-risk sample. Global IQ is not impacted by prenatal marihuana exposure but aspects of executive function (EF)--in particular, attentional behavior and visual analysis/hypothesis testing--appear to be negatively associated with in utero cannabis exposure in children beyond the toddler stage. This hypothesized influence of prenatal marihuana on EF is examined and discussed relative to effects (or lack of effects) across different ages in the offspring, cannabinoid receptors, and the extant general marihuana and prefrontal literature.

Behavioural consequences of maternal exposure to natural cannabinoids in rats

Cannabis sativa preparations (hashish, marijuana) are the most widely used illicit drugs during pregnancy in Western countries. The possible long-term consequences for the child of in utero exposure to cannabis derivatives are still poorly understood. Animal models of perinatal cannabinoid exposure provide a useful tool for examining the developmental effects of cannabinoids. Behavioral consequences of maternal exposure to either cannabis preparations or to its main psychoactive component, delta 9-tetrahydrocannabinol (THC) in rat models are reviewed in this paper. Maternal exposure to cannabinoids resulted in alteration in the pattern of ontogeny of spontaneous locomotor and exploratory behavior in the offspring. Adult animals exposed during gestational and lactational periods exhibited persistent alterations in the behavioral response to novelty, social interactions, sexual orientation and sexual behavior. They also showed a lack of habituation and reactivity to different illumination conditions. Adult offspring of both sexes also displayed a characteristic increase in spontaneous and water-induced grooming behavior. Some of the effects were dependent on the sex of the animals being studied, and the dose of cannabinoid administered to the mother during gestational and lactational periods. Maternal exposure to low doses of THC sensitized the adult offspring of both sexes to the reinforcing effects of morphine, as measured in a conditioned place preference paradigm. The existence of sexual dimorphisms on the developmental effects of cannabinoids, the role of sex steroids, glucocorticoids, and pituitary hormones, the possible participation of cortical projecting monoaminergic systems, and the mediation of the recently described cannabinoid receptors are also analyzed. The information obtained in animal studies is compared to the few data available on the long-term behavioral and cognitive effects on in utero exposure to cannabis in humans.

Effects of low doses of alcohol on delta-9-tetrahydrocannabinol's effects in pregnant rats

Pregnant rats were intubated with 50 mg/kg of delta-9-tetrahydrocannabinol (THC) or with THC plus alcohol to determine if a low dose of alcohol (1 g/kg) would significantly increase blood levels of THC. On the basis of this study, a second study was conducted in which pregnant rats were intubated with THC (50, 25 or 0 mg/kg) plus alcohol (2, 1 or 0 g/kg) from gestation day six to parturition. THC reduced birth weights but did not significantly affect litter size or passive avoidance learning. Alcohol did not have a significant effect on offspring birth weight nor did it interact with THC to affect offspring.

Marihuana: much ado about THC

The availability of delta 1-THC, the major psychoactive component of marihuana, in pure form offered an opportunity for better understanding of the mechanism of action of this drug. Two decades after the isolation of delta 1-THC its mode of action is still obscure despite the enormous amount of research invested in it. Studying cannabis content as a whole offers a different approach for better understanding of this ancient weed and its effects.