دانلود رایگان مقاله اثر سرین N-arachidonoyl-L در اندوتلیوم عروق کوچک مغزی انسان

Abstract

N-arachidonoyl-L-serine (ARA-S) is an endogenous lipid, chemically related to the endocannabinoid, N-arachidonoyl ethanolamine (i.e., anandamide) and with similar physiologic and pathophysiologic functions. Reports indicate that ARA-S possesses vasoactive and neuroprotective properties resembling those of cannabinoids. However, in contrast to cannabinoids, ARA-S binds weakly to its known classical receptors, CB1 and CB2, and is therefore considered to be a ‘cannabinoid-like’ substance. The originally described ARA-S induced-endothelial-dependent vasorelaxation was not abrogated by CB1, CB2 receptor antagonists or TRPV1 competitive inhibitor. The present report demonstrates that ARA-S enhances the fluorescence staining of both cannabinoid receptors (CB1 and CB2) in human brain endothelial cells (HBEC). This reaction is specific since it was reduced by respective selective receptor antagonist (SR141716A and SR141728A). ARA-S alone or in the presence of ET-1 was shown to alter the cytoskeleton (actin). Both ARA-S stimulated phosphorylation of various kinases (MAPK, Akt, JNK and c-JUN) and alteration of cytoskeleton are mediated via CB1, CB2 and TRPV1 receptors. The findings also showed the involvement of Rho/Rock and PI3/Akt/NO pathways in the ARA-S-induced phosphorylation of kinases and actin reorganization in HBEC. All of the above mentioned ARA-S-induced effects were reduced by the treatment with LY294002 (inhibitor of PI3/Akt kinase), except MAPK kinase. In addition, MAPK, JNK, c-JUN phosphorylation were inhibited by H1152 (inhibitor of Rho/ROCK kinase), except Akt kinase. Furthermore, PI3/Akt pathway was inhibited by pretreatment with L-NAME (inhibitor of NOS). The findings suggest that ARA-S is a modulator of Rho kinase and may play a critical role in the regulation of its activity and subsequent effects on the cytoskeleton and its role in supporting essential cell functions like vasodilation, proliferation and movement.

4. Discussion

The results of this study demonstrated the involvement of ARAS in the protein phosphorylation of a number of signal transduction pathways (e.g. MAPK, Akt, JNK, and c-JUN) that are often associated with stress, most of these factors are part of the signal transduction pathway involved in cytoskeleton actin assembly. It is noteworthy that the effects of ARA-S alone, or in combination with ET-1, were prevented by treatment with CB1, CB2 receptor antagonists, TRPV-1 competitive inhibitor or L-NAME (an inhibitor of eNOS). The reduction of ARA-S induced-increase of cannabinoid receptors (fluorescence) by specific antagonists suggests the CB1 and CB2 mediation of ARA-S-induced effects. The implicated involvement of cannabinoid receptors in these events was further explored and the precise location of these receptors, whether present on the surface or internalized inside of the membranes, was not determined in the present study. However, the internalization of the receptors does not necessarily rule out the possibility of involvement in the activation of the signal transduction pathways since this has been previously reported [10].