RESUMO
Endocannabinoids are lipid mediators thought to modulate central and peripheral neural functions. We report here gas chromatography-electron impact mass spectrometry analysis of human brain, showing that lipid extracts contain anandamide and 2-arachidonoylglycerol (2-AG), the most active endocannabinoids known to date. Human brain also contained the endocannabinoid-like compounds N-oleoylethanolamine, N-palmitoylethanolamine and N-stearoylethanolamine. Anandamide and 2-AG (0.16 +/- 0.05 and 0.10 +/- 0.05 nmol/mg protein, respectively) represented 7.7% and 4.8% of total endocannabinoid-like compounds, respectively. N-Palmitoyethanolamine was the most abundant (50%), followed by N-oleoyl (23.6%) and N-stearoyl (13.9%) ethanolamines. A similar composition in endocannabinoid-like compounds was found in human neuroblastoma CHP100 and lymphoma U937 cells, and also in rat brain. Remarkably, human meningioma specimens showed an approximately six-fold smaller content of all N-acylethanolamines, but not of 2-AG, and a similar decrease was observed in a human glioblastoma. These ex vivo results fully support the purported roles of endocannabinoids in the nervous system.
Assuntos
Química Encefálica , Neoplasias Encefálicas/química , Canabinoides/análise , Glioblastoma/química , Linfoma/química , Meningioma/química , Amidas , Animais , Ácidos Araquidônicos/análise , Moduladores de Receptores de Canabinoides , Endocanabinoides , Etanolaminas/análise , Cromatografia Gasosa-Espectrometria de Massas , Glioblastoma/patologia , Glicerídeos/análise , Humanos , Meningioma/patologia , Neuroblastoma/química , Neuroblastoma/patologia , Ácidos Oleicos , Ácidos Palmíticos/análise , Alcamidas Poli-Insaturadas , Ratos , Ratos Wistar , Valores de Referência , Ácidos Esteáricos/análise , Células Tumorais Cultivadas , Células U937RESUMO
When chromatin matrix, "stripped" from its loosely-bound components by extraction with 3 M NaCl, is extensively digested with DNAase I, a fraction is obtained, which carries no endogenous DNA methyltransferase activity but which is a good substrate for externally added enzyme. Under the same conditions, protein-free DNA isolated from this fraction can instead hardly be methylated, this different behaviour pointing to a role of DNA-tightly-bound proteins in favoring or promoting the catalytic action of the enzyme. A similar stimulation of enzymatic methylation could also be shown when, in the presence of this same fraction, single stranded Micrococcus luteus DNA was incubated with placental methyltransferase, using S-adenosylmethionine as a methyl donor. This finding can be correlated to the existence, in chromatin loops, of small regions which resist digestion by DNAase I also after high-salt removal of their loosely-bound components (presumably because of the presence of tightly-bound proteins) and whose DNA is characterized by high methylation levels and, at the same time, by high relative content of thymine.