Histological and Biochemical Alterations in the Superior Colliculus and Lateral Geniculate Nucleus of Juvenile Rats Following Prenatal Exposure to Marijuana Smoke.

Introduction: Prenatal exposure to Marijuana (MJN) has been associated with various brain deficits. The main activity in marijuana, Δ9-Tetrahydrocannabinol (THC), crosses the placenta and affects fetal brain development. Despite this, marijuana remains a commonly abused substance among pregnant women. The current study examined the histological and biochemical changes in the Superior Colliculus (SC) and Lateral Geniculate Nucleus (LGN) in rat brains prenatally exposed to marijuana.

Methods: Four groups of pregnant rats (n=5 rats/group) were exposed to the smoke of 10 g/kg marijuana at various days during their gestational period, with a group (control), i.e., not exposed. After parturition, the litters from each group were sacrificed by cervical dislocation on postnatal days 7, 14, and 21; the superior colliculi and lateral geniculate nuclei were excised. Tissue sections were prepared for histological studies using Haematoxylin and Eosin stains. Biochemical studies were performed on alkaline phosphatase, acid phosphatase, lactate dehydrogenase, and glucose-6-phosphate dehydrogenase activity levels. The histological and biochemical analyses of tissues were performed.

Results: Prenatal exposure to marijuana resulted in spontaneous abortion and affected neuronal morphology in the SC and LGN of the progeny. Furthermore, the levels of enzyme activities were altered following maternal exposure to MJN.

Conclusion: These data suggested that histological changes in the SC and LGN were associated with oxidative damage.

Highlights: Prenatal exposure to marijuana smoke in early gestation induced spontaneous abortion.Prenatal exposure to marijuana smoke-induced damage to the visual pathway in the progeny.Prenatal exposure to marijuana-induced histological changes in juvenile rats' superior colliculus and lateral geniculate nucleus.Prenatal exposure to marijuana smoke resulted in biochemical alterations in juvenile rats' superior colliculus and lateral geniculate nucleus.

Plain Language Summary: Marijuana is the most widely used psychoactive substance in the western world, consumed for recreational, medicinal, and spiritual purposes. Although marijuana consumption by pregnant women has been linked with neurodevelopmental consequences, little is known of its effect on the visual pathway of the progeny. We examined juvenile rats using the rat model, the effect of prenatal exposure to marijuana smoke on the superior colliculus and lateral geniculate body (regions of the brain involved in visual information processing). Our result reveals that marijuana use in early gestation induces spontaneous abortion. Also, prenatal exposure to marijuana smoke produced histological changes in the brain mentioned above regions involved in visual information of the progeny. Our findings also include biochemical alterations in these regions. Hence, we highlight the damaging effects of marijuana smoke on the developing brain, specifically the superior colliculus and lateral geniculate nucleus, i.e., involved in visual information processing, of juvenile rats following prenatal exposure.