Oral administration of marijuana produces alterations in serotonin 5-hydroxytryptamine receptor 3A gene (HTR3A) and electrolyte imbalances in brain of male Wistar rats

The gene expression of serotonin 5-hydroxytryptamine receptor 3A (receptor 3A:HTR3A) as well as the concentration of electrolytes in male Wistar rats after administration of graded doses of marijuana extract was investigated. Twelve groups (3 control and 9 test groups) of 6 animals each were daily exposed to 12.5, 25 and 50 mg/kg b.w doses of petroleum ether extract of marijuana for 4, 8 and 12 weeks. The expressions of the gene were obtained using reverse transcriptase-polymerase chain reaction (RT-PCR) while electrolytes concentrations were determined. An upregulation of over 90% was observed in the expression of HTR3A after exposure to the highest dose throughout the exposure period. There was significant increase in the plasma potassium concentration at all doses while there was a decrease in the brain only at 50 mg/kg dose throughout the exposure period. Sodium concentration in the brain was not affected by the doses over the period of exposure but plasma concentration decreased significantly. All the doses of marijuana extract significantly increased calcium concentration in the brain after prolonged exposure but the plasma concentration remained unchanged. This suggests that different doses of marijuana extract alter the expression of serotonin receptor and electrolyte concentrations over a period of time with possible neurological consequences.