Immunosuppresive effect of N-arachidonoyldopamine and N-oleoyldopamine in mice splenocytes.

DE Sok, M Jin. Chungnam National University, College of Pharmacy, Republic of Korea

Endogenous N-acyl dopamines such as N-arachidonoyldopamine (NADA) and N-oleoyldopamine (OLDA) have been recently identified as endocannabinoids showing anti-inflammatory and immunomodulatory activities. In this respect, we evaluated the immunosuppressive activity of NADA and OLDA in splenocytes of BALB/C mice stimulated by concannavalin A (Con A). For this purpose, splenocytes were incubated with NADA or OLDA of various concentrations in the presence of Con A in RPMI for 48 hr at 37o C, and the viability and cytokine level were determined by MTT assay and ELISA kit assay, respectively. The values were expressed as a mean ± SED of three sets in triplicate (p<0.05). Here, both compounds (1-5 μM) were found to inhibit concannavalin A (Con A)-induced splenocyte proliferation. Moreover, it was found that both NADA (IC50, 0.39 ± 0.04 μM) and OLDA (IC50, 0.50 ± 0.14 μM) specifically inhibited the release of interferon-gamma in a concentration-dependent manner. Also, a similar concentration-dependent reduction of IL-2 and TNF-α level was also expressed by NADA and OLDA. Separately, the suppressive effect of NADA (5 μM) on viability was prevented by approximately 48% in the presence of CB1 antagonist rimonabant (SR141716) and by 28% in the presence of TRPV1 antagonist 5’-iodoresiniferatoxin. Separately, the suppressive effect of OLDA (5μM) was counteracted by 61% in the presence of 5’-Iodoresiniferatoxin, but not CB1 antagonist. Separately, NADA and OLDA markedly increased the level of 12-hydroxyeicosatetraenoic acid in a concentration-dependent manner. These findings suggest that NADA may express immunomodulatory action through CB1 and TRPV1 receptors, and OLDA, mainly through TRPV1 receptor.