The serotonergic and cannabinoidergic systems of the Prelimbic cortex: their interactions in memory consolidation

Background and Aim: Endocannabinoid-mediated modulation of many physiological functions requires the participation of the serotonergic system. There is insufficient information about different mechanisms that underlies coupling of the cannabinoid system with the serotonin system in the brain. Methods Adult male Sprague-Dawley rats were bilaterally implanted with chronic cannulae in the PL. Animals were trained in the step-through type passive avoidance task, and tested ۲۴ h after training to measure step-through latency as an index of the IA memory consolidation. All of the drugs injected immediately after a training session to examine the effects of the drugs on memory consolidation. Results: Therefore, we investigated invivo effects of selective ۵-HT۴ receptor agonist (RS۶۷۳۳۳) / antagonist (RS۲۳۵۹۷-۱۹۰) on memory consolidation deficit induced by a CB۱ cannabinoid receptor agonist (ACPA), in the Pre-Limbic (PL) cortex. Conclusion: The results revealed that RS۶۷۳۳۳ (۰.۵ μg/rat) increased IA memory consolidation, while RS۲۳۵۹۷-۱۹۰ alone at the applied doses did not affect it. In addition, concurrent administration of the inactive doses of ACPA (۰.۰۰۱ µg/rat) and RS۶۷۳۳۳ (۰.۰۰۵ µg/rat) intensified memory impairment. Although co-administration of RS۶۷۳۳۳ (۰.۰۰۵ ug/rat) with the active dose of ACPA (۰.۱ μg/rat) prevented memory impairment induced by ACPA. Moreover, co-administration of the inactive dose of RS۲۳۵۹۷-۱۹۰ (۰.۵ µg/rat) plus the active dose of ACPA (۰.۱ μg/rat) potentiated the ACPA response. None of the above interventions altered locomotor activity. These observations provide evidence that ۵-HT۴ receptors are probably implicated in modulating of the memory consolidation deficit caused by ACPA, in the pre-limbic cortex.

کلیدواژه ها:

RS۶۷۳۳۳ ، RS۲۳۵۹۷-۱۹۰ ، ACPA ، pre-limbic cortex ، memory