Biphasic effects of anandamide on behavioural responses: emphasis on copulatory behaviour.

Endocannabinoids have emerged as important modulators of different neurotransmitter systems in the brain by acting as retrograde messengers. They are released from postsynaptic cell bodies, travel backwards across the synapsis and bind to their receptors located at the presynaptic terminal to inhibit neurotransmitter release. The fatty acid amide, arachidonoylethanolamide (anandamide), is an important endogenous ligand of the G-protein-coupled cannabinoid receptors CB1 and CB2. The aim of this mini-review is to outline the recent literature on the biphasic nature of the behavioural actions of anandamide, with particular focus on male rat sexual behaviour, and to examine whether dose-related activation of distinct receptors plays a role in the biphasic effects of this prototypical endocannabinoid.