Do serum endocannabinoid and N-acylethanolamine concentrations reflect their brain levels in two different rat stress models?

Abstract

Background: Although the brain is not the only source of circulating endocannabinoids and their levels can be affected by many factors, it is underlined that serum endocannabinoid levels can be used as a biomarker in psychiatric disorders. In this study, we aimed to examine whether serum endocannabinoid and N-acylethanolamine concentrations reflect their brain levels.

Methods: In the present study acute immobilisation (AIS) and post-traumatic stress (PTSD) models were applied to Wistar albino male rats. Rota rod performance, forced swim, open field and elevated plus maze tests were performed. Endocannabinoid and N-acylethanolamine levels in serum and hippocampus, amygdala and cortex were assessed using LC-MS/MS.

Results: We observed significant increases in anandamide (AEA), palmitoylethanolamide (PEA) and oleoethylethanolamide (OEA) levels in the amygdala and hippocampus in both models except PEA in amygdala in the AIS group, while 2-AG levels decreased. There was no change in serum AEA and 2-AG levels in all groups; in the PTSD group serum PEA levels were higher whereas OEA levels were lower in both the AIS and the PTSD groups.

Conclusion: Our results show that there is no correlation in endocannabinoid and N-acylethanolamine levels between serum and specific brain regions in two stress models of rat.