The present study aimed to examine the potential inhibitory activity of oleoylethanolamide (OEA) on α-melanocyte stimulating hormone (α-MSH)-stimulated melanogenesis and the molecular mechanism(s) involved in the process in B16 mouse melanoma cells. Our data demonstrated that OEA markedly inhibited melanin synthesis and tyrosinase activity in α-MSH-stimulated B16 cells. In addition, the expression of melanogenesis-related proteins, such as melanocortin-1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TRP-1) and tyrosinase, was suppressed in a concentration-dependent manner by OEA. In addition, OEA may suppress melanogenesis through a peroxisome proliferator-activated receptor α (PPARα)-independent pathway. Moreover, OEA activated ERK, Akt, p38 pathways and inhibits CREB pathway in α-MSH-stimulated B16 cells. The specific ERK inhibitor PD98059 partly blocked OEA-inhibited melanin synthesis and tyrosinase activity and partly abrogated the OEA-suppressed expression of melanogenic proteins. Furthermore, OEA presented remarkable inhibition on the body pigmentation in the zebrafish model system. Our findings demonstrated that OEA is an effective inhibitor of hyperpigmentation through activation of ERK, Akt and p38 pathways, inhibition of the CREB pathway, and subsequent down-regulation of MITF, TRP-1 and tyrosinase production.

BackgroundLeading to more and more deaths and disabilities, stroke has become a serious threat to human health. What’s more, few effective drugs are available in clinic till now.ResultsIn this research, we prepared a novel neuroprotective nanoformation (OEA–SPC NPs) via the combination of the nanoparticle drug delivery system with the endogenous N-oleoylethanolamine (OEA). By forming hydrogen bond between OEA and the carrier—soybean phosphatidylcholine (SPC), the form of OEA was turned into amorphus state when loading to the nanoparticles, which greatly improved its bioavailability. Then the following systematic experiments revealed the efficient neuroprotective effect of OEA–SPC NPs in vivo. Compared with the MCAO group, the cerebral infarct volume was reduced by 81.1%, and the edema degree by 78.4% via the oral administration of OEA–SPC NPs. And the neurological deficit scores illustrated that the MCAO rats treated with OEA–SPC NPs exhibited significantly less neurological dysfunction. The Morris water maze test indicated that the spatial learning and memory of cerebral ischemia model rats were almost recovered to the normal level. Besides, the OEA–SPC NPs could inhibit the inflammation of reperfusion to a very slight level.ConclusionsThese results suggest that the OEA–SPC NPs have a great chance to be a potential anti-stroke formation for clinic application and actually bring hope to thousands of stroke patients.Electronic supplementary materialThe online version of this article (10.1186/s12951-019-0442-x) contains supplementary material, which is available to authorized users.

The extract of Moringa oleifera seeds has been shown to possess various pharmacological properties. In the present study, we assessed the neuropharmacological effects of 70% ethanolic M. oleifera seed extract (MSE) on cognitive impairment caused by scopolamine injection in mice using the passive avoidance and Morris water maze (MWM) tests. MSE (250 or 500 mg/kg) was administered to mice by oral gavage for 7 or 14 days, and cognitive impairment was induced by intraperitoneal injection of scopolamine (4 mg/kg) for 1 or 6 days. Mice that received scopolamine alone showed impaired learning and memory retention and considerably decreased cholinergic system reactivity and neurogenesis in the hippocampus. MSE pretreatment significantly ameliorated scopolamine-induced cognitive impairment and enhanced cholinergic system reactivity and neurogenesis in the hippocampus. Additionally, the protein expressions of phosphorylated Akt, ERK1/2, and CREB in the hippocampus were significantly decreased by scopolamine, but these decreases were reversed by MSE treatment. These results suggest that MSE-induced ameliorative cognitive effects are mediated by enhancement of the cholinergic neurotransmission system and neurogenesis via activation of the Akt, ERK1/2, and CREB signaling pathways. These findings suggest that MSE could be a potent neuropharmacological drug against amnesia, and its mechanism might be modulation of cholinergic activity via the Akt, ERK1/2, and CREB signaling pathways.

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