Finally, although with less potential for clinical translation, one study using human fetal brain tissue was reviewed. DiNieri and colleagues [115] examined the effects of prenatal cannabis exposure in postmortem human fetal subjects and in rats prenatally exposed to cannabis. In the fetal subjects, in situ hybridization histochemistry was used to measure expression of DRD1, DRD2, PENK, and PDYN in the nucleus accumbens (NAc) in cannabis-exposed cases and controls. Cannabis exposure was confirmed by maternal self-report and/or urine THC and/or fetal meconium THC. Of the four genes studied, only DRD2 expression was significantly correlated with cannabis exposure, with decreased expression levels detected. In the rat model, increased 2meH3K9 and decreased 3meH3K4 and RNA polymerase II expression were found at the DRD2 locus, as well as decreased DRD2 expression.
