Regional distribution and effects of postmortal delay on endocannabinoid content of the human brain

Abstract

Tissue levels of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) have been determined in 16 regions and nuclei from human brains, using liquid chromatography/inline mass spectrometry. Measurements in brain samples stored at −80°C for 2 months to 13 years indicated that endocannabinoids were stable under such conditions. In contrast, the postmortal delay had a strong effect on brain endocannabinoid levels, as documented in brain samples microdissected and frozen 1 to 6h postmortem, and in neurosurgical samples 0, 5, 30, 60, 180 and 360 min after their removal from the brain. The tissue levels of AEA increased continuously and in a region-dependent manner from one hour after death, increasing about 7-fold by 6h postmortem. In contrast, concentrations of 2-AG, which were 10 to 100-times higher in human brain regions than those of AEA, rapidly declined: within the first hour, 2-AG levels dropped to 25-35% of the initial ('0 min') value, where after they remained relatively stable. As analyzed in samples removed 1-1.5h post mortem, AEA levels ranged from a high of 96.3 fmol/mg tissue in the nucleus accumbens to a low of 25.0 fmol/ mg in the cerebellum. 2-AG levels varied 8-fold, from 8.6 pmol/mg in the lateral hypothalamus to 1.1 pmol/mg in the nucleus accumbens. Relative levels of AEA and 2-AG varied from region to region, with the 2-AG:AEA ratio being high in the sensory spinal trigeminal nucleus (140:1), the spinal dorsal horn (136:1) and the lateral hypothalamus (98:1) and low in the nucleus accumbens (16:1) and the striatum (31:1). The results highlight the pitfall of analyzing endocannabinoid content in brain samples of variable postmortal delay, and document differential distribution of the two main endocannabinoids in the human brain.

Endogenous cannabinoids in amygdala and hippocampus in post-mortem brains of Cloninger type 1 and 2 alcoholics

“…Statistical significance of the differences in the EC concentrations between the three groups were evaluated by permutation type multivariate test of variance (MANCOVA). The PMI was used as a covariate because it has an effect on brain EC concentrations (Palkovits et al, 2008) and because it was observed that within the present data there was moderate correlation between EC concentrations and PMI (Pearson correlation). The 95% confidence intervals for the most important outcomes were obtained by bias-corrected bootstrapping (5,000 replications).…”

“…In the present study, we included PMI as a covariant to minimize its influence on the results, because it has an effect to the EC levels in post-mortem brain samples and that this effect is EC specific (Palkovits et al, 2008). There were moderate correlations between PMI and EC levels in the present data ( Supplementary Figures 1 and 2) further justifying the use of PMI as a covariant.Limitation of the present study, like all post-mortem studies, is that the EC levels from post-mortem samples might not fully represent the levels prior to death.…”

Determination of endocannabinoids in nematodes and human brain tissue by liquid chromatography electrospray ionization tandem mass spectrometry

“…Sugiura et al [75] also reported a rapid post-mortem increase in 2-AG and other MAGs in the rat brain, which occurs within the first 30 s after decapitation. In addition, Palkovits et al [77] found a strong postmortem effect during 6 h for ECs in micro-dissected human brains, where tissue levels of 2-AG rapidly declined while AEA increased continuously in a region-dependent manner. An influence of postmortem effect on NAEs levels in mammalian [23] and rodent brains [31,78] have also been reported.…”

The Antiepileptic Potential of Nucleosides

“…In addition, Ado receptor agonists and antagonists as well as nucleoside transport inhibitors may have different effects on seizures in the mature brain compared with the immature brain because of (i) the level and distribution of endogenous Ado, (ii) the affinity of Ado receptors for Ado, (iii) the distribution of Ado receptors and Ado transporters and (iv) the ratio of different types of Ado receptors and, consequently, the physiological and pathophysiological role of Ado in different brain areas may be changed by age [31,57,[310][311][312][313]. In addition, several other methodological circumstances, such as post mortem delay of brain tissue samples, age, gender, the species of experimental animals (subjects) and the type of solvent used, [30,57,314,315] may modify the experimental results and effects of the applied drugs on epileptic seizures.…”