The cannabinoid CB1 receptor antagonist rimonabant dose-dependently inhibits memory recall in the passive avoidance task in domestic chicks (Gallus domesticus)

The effect of endocannabinoids on synaptic plasticity has been demonstrated in a variety of species and brain regions. Relatively little is known about the localization and significance of cannabinoid (CB) receptors in the avian brain. The objective of the present study was to investigate the effect of a specific CB₁ receptor antagonist upon the acquisition and consolidation of memory in young domestic chicks. One-day-old domestic chicks (Gallus domesticus) were trained and tested by the passive avoidance paradigm. Systemic (i.p.) administration of the CB₁ receptor antagonist rimonabant in a dose of 1 mg/kg 30 min before the training failed to affect learning, but a similar treatment 30 min before the recall (5.5 h after training) attenuated the retention in 60% of animals. In another set of animals, a dose of 0.01 mg/kg produced no significant impairment, whereas doses 0.1 mg/kg and 1.0 mg/kg resulted in significant attenuation in passive avoidance performance when tested 30 min prior to recall. The results are discussed in terms of a putative mediating role of CB receptors in the consolidation of memory.