Abstract
The cysteinyl leukotrienes are inflammatory mediators closely associated with neuronal injury after brain ischemia through the activation of their receptors, CysLT1R and CysLT2R. Here we investigated the involvement of both receptors in oxygen-glucose deprivation/recovery (OGD/R)-induced ischemic neuronal injury and the effect of the novel CysLT2R antagonist HAMI 3379 in comparison with the CysLT1R antagonist montelukast. In primary neurons, neither the non-selective agonist leukotriene D4 (LTD4) nor the CysLT2R agonist N-methyl-leukotriene C4 (NMLTC4) induced neuronal injury, and HAMI3379 did not affect OGD/R-induced neuronal injury. However, in addition to OGD/R, LTD4 and NMLTC4 induced cell injury and neuronal loss in mixed cultures of cortical cells, and neuronal loss and necrosis in neuron-microglial co-cultures. Moreover, they induced phagocytosis and cytokine release (IL-1β and TNF-α) from primary microglia, and conditioned medium from the treated microglia induced neuronal necrosis. HAMI 3379 inhibited all these responses, and its effects were the same as those of CysLT2R interference by CysLT2R shRNA, indicating CysLT2R dependence. In comparison, montelukast moderately inhibited OGD/R-induced primary neuronal injury, and most OGD/R- and LTD4-induced (but not NMLTC4-induced) responses in mixed cultures, co-cultures, and microglia. The effects of montelukast were both dependent and independent of CysLT1Rs because inference by CysLT1R siRNA had limited effects on neuronal injury in neuron-microglial co-cultures and on cytokine release from microglia. Our findings indicated that HAMI 3379 effectively blocked CysLT2R-mediated microglial activation, thereby indirectly attenuating ischemic neuronal injury. Therefore, CysLT2R antagonists may represent a new type of therapeutic agent in the treatment of ischemic stroke.
- The American Society for Pharmacology and Experimental Therapeutics