Short- and long-term effects of cannabinoids on the extinction of contextual fear memory in rats

A role for the ventral hippocampal endocannabinoid system in fear-conditioned analgesia and fear responding in the presence of nociceptive tone in rats

“…The role of the endocannabinoid system in fear responding per se (i.e. in the absence of nociceptive tone) has been examined extensively and the weight of evidence suggests that endocannabinoid-CB 1 receptor signalling serves to facilitate and enhance the extinction of conditioned fear responding (for review see [15,48,79]), while genetic deletion or pharmacological blockade of the CB 1 receptor attenuates short-and long-term extinction of conditioned fear responding [14,18,25,39,44,48,52,59,62,70,76]. The results of the present study, however, suggest that in the presence of formalin-evoked nociceptive tone, increased endocannabinoid signalling in the vHip (as a consequence of URB597 administration) in fact serves to inhibit rather than enhance the short-term, within-trial extinction of fear responding.…”

Cannabinoid Receptor Activation in the Basolateral Amygdala Blocks the Effects of Stress on the Conditioning and Extinction of Inhibitory Avoidance

“…The final concentration of DMSO did not affect performance in the inhibitory avoidance task. Drug concentrations are based on reports in the literature (Martin et al, 1999;Chhatwal et al, 2005;de Oliveira Alvares et al, 2005;Moreira et al, 2007;Pamplona et al, 2008) and our preliminary results. For microinjection, WIN55,212-2 was used at 2.5 g/0.5 l, 5 g/0.5 l, or 10 g/0.5 l. AM404 was used at 200 ng/0.5 l or 800 ng/0.5 l, and AM251 was used at 6 ng/0.5 l. For intraperitoneal administration, WIN 55,212-2 was used at 0.25 mg/kg.…”

Neurobiological Interactions Between Stress and the Endocannabinoid System

“…Tone presentation during extinction trials results in elevated levels of eCBs in the BLA (Gunduz-Cinar et al, 2013b; Marsicano et al, 2002). Chhatwal et al (2005) and others demonstrated that intraperitoneal or intracerebroventricular injection of AM404 enhances fear extinction via a CB1-dependent mechanism Chhatwal et al, 2005;Pamplona et al, 2008). A more recent study underlined the importance of the BLA in these AEA Endocannabinoid system in stress M Morena et al ................................................................................................................................................................ facilitating effects on memory extinction.…”