In recent years, cannabis is known to affect the central nervous system and designated as an illegal drug and its possession or use is prohibited in many countries and regions. Δ 9-Tetrahydrocannabinol (THC), the main component of cannabis, acts on CB1 receptors, which are highly expressed in presynaptic terminals in the central nervous system. The prefrontal cortex (PFC) is known to be involved in a cognitive function in a number of studies. However, the role of CB1 receptors in the PFC on cognitive function remains unclear. In this study, we administered ACPA (arachidonylcyclopropylamide), a CB1 receptor agonist, topically to mice PFC and examined the involvement of CB1 receptors in the PFC in cognitive functions.
A guide cannula was placed in the PFC of C57BL/6J mice to locally administer ACPA. After a week’s recovery period from surgery, various behavioral tests were performed.
In object location test evaluating spatial memory, spatial memory impairment was observed when ACPA was administered topically to the PFC at all three stages of memory; acquisition, consolidation, and retrieval. In addition, spatial memory impairment was observed when ACPA was administered locally to the PFC during memory acquisition. This study suggests that CB1 receptors in the PFC are important for the acquisition of spatial memory. Analysis of CB1 receptor in the PFC may reveal the effects of cannabis on the brain and neuronal circuits in PFC memory formation.