Jamil Jamal, Bankhele Pratik, Salvi Ankita, Mannix Jaimee E, Oger Camille, Guy Alexandre, Galano Jean-Marie, Durand Thierry, Njie-Mbye Ya Fatou, Ohia Sunny E, Opere Catherine A
Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University Medical Center, 2500 California Plaza, Omaha, NE, 68178, USA.
Neurochem Res. 2014 Dec;39(12):2360-9. doi: 10.1007/s11064-014-1436-6. Epub 2014 Sep 25.
We have evidence that F2-isoprostanes (F2-IsoPs) regulate the release of excitatory neurotransmitters in isolated bovine retina. Although 5-F3-IsoPs are generated in mammals, in vivo, their pharmacological actions on neurotransmitter release remain unknown. In this study, we investigated the effect of 5-epi-5-F3t-IsoP on K(+)-evoked [(3)H]D-aspartate release in isolated bovine retina using the superfusion method. Furthermore, we examined the role of arachidonic acid metabolites in the regulation of the neurotransmitter release by this novel IsoP. In the concentration range, 0.01 nM-0.1 µM, 5-epi-5-F3t-IsoP inhibited K(+)-evoked [(3)H]D-aspartate release in a concentration-dependent manner, achieving a maximum inhibition of 46.9 % at 0.1 µM (IC30 = 1 nM). The prostanoid receptor antagonists, AH 6809 (EP1-3/DP; 10 µM), SC 51322 (EP1; 10 µM) and SC 19220 (EP1; 1 µM) partially reversed 5-epi-5-F3t-IsoP-mediated inhibition of K(+)-induced [(3)H]D-aspartate release. Pretreatment of retinal tissues with the cyclooxygenase (COX) inhibitor, flurbiprofen (3 μM) unmasked a biphasic action of 5-epi-5-F3t-IsoP that was inhibitory at lower (0.1-10 pM) and stimulatory at higher concentrations (≥0.1 nM). The prostanoid pathway antagonists, BAY-u3405 (10 μM; TP/DP-receptors), SQ 29548 (10 μM; TP-receptor) and ozagrel (10 μM; Tx-synthase inhibitor) abolished the stimulatory action of the 5-epi-5-F3t-IsoP (0.1 μM) on neurotransmitter release. In conclusion, 5-epi-5-F3t-IsoP attenuates K(+)-induced [(3)H]D-aspartate release in a concentration-dependent manner by mechanisms that are partially dependent on activation of pre-junctional prostanoid EP1-receptors. Moreover, blockade of the COX-pathway unmasks a biphasic action for 5-epi-5-F3t-IsoP that is inhibitory at low concentrations and stimulatory at higher concentrations. Products of the thromboxane synthase pathway may partially account for the stimulatory action of this F3-IsoP on isolated bovine retina.
我们有证据表明，F2-异前列腺素（F2-IsoPs）可调节离体牛视网膜中兴奋性神经递质的释放。尽管5-F3-异前列腺素在哺乳动物体内生成，但其对神经递质释放的药理作用仍不清楚。在本研究中，我们采用灌流法研究了5-表-5-F3t-异前列腺素对离体牛视网膜中钾离子诱发的[³H]D-天冬氨酸释放的影响。此外，我们研究了花生四烯酸代谢产物在这种新型异前列腺素调节神经递质释放中的作用。在0.01 nM至0.1 μM的浓度范围内，5-表-5-F3t-异前列腺素以浓度依赖性方式抑制钾离子诱发的[³H]D-天冬氨酸释放，在0.1 μM时达到最大抑制率46.9%（IC30 = 1 nM）。前列腺素受体拮抗剂AH 6809（EP1-3/DP；10 μM）、SC 51322（EP1；10 μM）和SC 19220（EP1；1 μM）部分逆转了5-表-5-F3t-异前列腺素介导的对钾离子诱导的[³H]D-天冬氨酸释放的抑制作用。用环氧合酶（COX）抑制剂氟比洛芬（3 μM）预处理视网膜组织，揭示了5-表-5-F3t-异前列腺素的双相作用，即在较低浓度（0.1 - 10 pM）时具有抑制作用，在较高浓度（≥0.1 nM）时具有刺激作用。前列腺素途径拮抗剂BAY-u3405（10 μM；TP/DP受体）、SQ 29548（10 μM；TP受体）和奥扎格雷（10 μM；血栓素合酶抑制剂）消除了5-表-5-F3t-异前列腺素（0.1 μM）对神经递质释放的刺激作用。总之，5-表-5-F3t-异前列腺素通过部分依赖于突触前前列腺素EP1受体激活的机制，以浓度依赖性方式减弱钾离子诱导的[³H]D-天冬氨酸释放。此外，COX途径的阻断揭示了5-表-5-F3t-异前列腺素的双相作用，即在低浓度时具有抑制作用，在高浓度时具有刺激作用。血栓素合酶途径的产物可能部分解释了这种F3-异前列腺素对离体牛视网膜的刺激作用。
