Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE, 68178, USA.
Department of Pharmaceutical & Environmental Health Sciences, College of Pharmacy & Health Sciences, Texas Southern University, 3100 Cleburne Street, Houston, TX, 77004, USA.
Neurochem Res. 2018 Mar;43(3):692-701. doi: 10.1007/s11064-018-2471-5. Epub 2018 Jan 20.
We investigated the pharmacological actions of a slow-releasing HS donor, GYY 4137; a substrate for the biosynthesis of HS, L-cysteine and its precursor, N-acetylcysteine on potassium (K; 50 mM)-evoked [H]D-aspartate release from bovine isolated retinae using the Superfusion Method. GYY 4137 (10 nM-10 µM), L-cysteine (100 nM-10 µM) and N-acetylcysteine (10 µM-1 mM) elicited a concentration-dependent decrease in K-evoked [H]D-aspartate release from isolated bovine retinae without affecting basal tritium efflux. At equimolar concentration of 10 µM, the rank order of activity was as follows: L-cysteine > GYY 4137 > N-acetylcysteine. A dual inhibitor of the biosynthetic enzymes for HS, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), amino-oxyacetic acid (AOA; 3 mM) reversed the inhibitory responses caused by GYY 4137, L-cysteine and N-acetylcysteine on K-evoked [H]D-aspartate release. Glibenclamide (300 µM), an inhibitor of K channels blocked the inhibitory action of GYY 4137 and L-cysteine but not that elicited by N-acetylcysteine on K-induced [H]D-aspartate release. The inhibitory effect of GYY 4137 and L-cysteine on K-evoked [H]D-aspartate release was reversed by the non-specific inhibitor of nitric oxide synthase (NOS), L-NAME (300 µM). Furthermore, a specific inhibitor of inducible NOS (iNOS), aminoguanidine (10 µM) blocked the inhibitory action of L-cysteine on K-evoked [H]D-aspartate release. We conclude that both donors and substrates for HS production can inhibit amino acid neurotransmission in bovine isolated retinae, an effect that is dependent, at least in part, upon the intramural biosynthesis of this gas, and on the activity of K channels and NO synthase.
我们用灌流方法研究了一种缓慢释放的 HS 供体 GYY 4137（HS 生物合成的底物，L-半胱氨酸及其前体 N-乙酰-L-半胱氨酸）对牛离体视网膜中钾（K；50mM）诱发的[H]D-天冬氨酸释放的药理学作用。GYY 4137（10nM-10μM）、L-半胱氨酸（100nM-10μM）和 N-乙酰-L-半胱氨酸（10μM-1mM）在不影响基础氚流出的情况下，浓度依赖性地抑制 K 诱发的[H]D-天冬氨酸从离体牛视网膜中的释放。在等摩尔浓度 10μM 时，活性顺序如下：L-半胱氨酸>GYY 4137>N-乙酰-L-半胱氨酸。HS 生物合成酶胱硫醚β合酶（CBS）和胱硫醚γ裂解酶（CSE）的双重抑制剂氨基氧乙酸（AOA；3mM）逆转了 GYY 4137、L-半胱氨酸和 N-乙酰-L-半胱氨酸对 K 诱发的[H]D-天冬氨酸释放的抑制反应。K 通道抑制剂格列本脲（300μM）阻断了 GYY 4137 和 L-半胱氨酸的抑制作用，但不阻断 N-乙酰-L-半胱氨酸对 K 诱导的[H]D-天冬氨酸释放的抑制作用。GYY 4137 和 L-半胱氨酸对 K 诱发的[H]D-天冬氨酸释放的抑制作用被非特异性一氧化氮合酶（NOS）抑制剂 L-NAME（300μM）逆转。此外，诱导型 NOS（iNOS）的特异性抑制剂氨基胍（10μM）阻断了 L-半胱氨酸对 K 诱发的[H]D-天冬氨酸释放的抑制作用。我们的结论是，HS 的供体和底物都可以抑制牛离体视网膜中的氨基酸神经递质传递，这种作用至少部分依赖于这种气体的内源性生物合成，以及 K 通道和 NO 合酶的活性。
