Interaction between endocannabinoids and the adrenergic system before and after stress-exposure

Cold stress-induced analgesia (c-SIA) has been evaluated in male Wistar rats injected with cannabinoid receptors type 1 and a 2 -adrenergic receptor agonists and antagonists in different combinations before or after stress exposure. The aim of the study was to evaluate whether the endogenous cannabinoid and the adrenergic systems influenced c-SIA, and the patterns of their potential interaction. Exogenous administration of anandamide and Clonidine together, before or after stress exposure, increased c-SIA even with differences in the time of manifestation of the effect, its duration and the degree. The two systems differently contribute to c-SIA pathogenesis and mediation. Administered before stress exposure cannabinoids and the adrenergic system seem to oppose each other: the latter rather potentiates, while cannabinoids suppress c-SIA. Administered after stress exposure, instead, the two systems appear to exert a synergistic effect, and antagonization of each one of them abolishes the analgesic effect.