Muakkassah-Kelly S F, Andresen J W, Shih J C, Hochstein P
J Neurochem. 1983 Nov;41(5):1429-39. doi: 10.1111/j.1471-4159.1983.tb00842.x.
Ascorbate-induced lipid peroxidation, as measured by malonyldialdehyde (MDA) production, caused irreversible decreases in Bmax of both [3H]5-HT and [3H]spiperone binding. CaCl2 (4 mM) inhibited ascorbate-induced MDA formation at ascorbate concentrations greater than 0.57 mM, but not at less than or equal to 0.57 mM. Under the standard assay conditions (5.7 mM ascorbate and 4 mM CaCl2), CaCl2 inhibited the MDA production caused by ascorbate by 88%, and the loss in [3H]5-HT binding by 57%. Ascorbate still decreased [3H]5-HT binding when lipid peroxidation was completely inhibited by EDTA. This additional effect of ascorbate was reversible after washing the membranes. Other reducing agents (dithiothreitol, glutathione, and metabisulfite) also decreased the binding of [3H]serotonin. In contrast, [3H]spiperone binding was not affected by ascorbate in the absence of lipid peroxidation or by other reducing agents. These experiments demonstrate that ascorbate has a dual and differential effect on serotonin binding sites. First, ascorbate-induced lipid peroxidation irreversibly inactivates both [3H]5-HT and [3H]spiperone binding. Second, independent of lipid peroxidation, there is a direct, reversible effect of ascorbate on [3H]serotonin but not on [3H]spiperone binding, which is probably due to the difference in the biochemical nature of the two serotonin binding sites.
通过丙二醛（MDA）生成量测定的抗坏血酸诱导的脂质过氧化作用，导致[3H]5-羟色胺（5-HT）和[3H]螺哌隆结合的最大结合量（Bmax）出现不可逆下降。当抗坏血酸浓度大于0.57 mM时，氯化钙（4 mM）可抑制抗坏血酸诱导的MDA形成，但在小于或等于0.57 mM时则不能。在标准测定条件下（5.7 mM抗坏血酸和4 mM氯化钙），氯化钙可使抗坏血酸引起的MDA生成减少88%，[3H]5-HT结合的损失减少57%。当脂质过氧化作用被乙二胺四乙酸（EDTA）完全抑制时，抗坏血酸仍会降低[3H]5-HT结合。在洗涤膜后，抗坏血酸的这种额外作用是可逆的。其他还原剂（二硫苏糖醇、谷胱甘肽和焦亚硫酸氢钠）也会降低[3H]血清素的结合。相反，在没有脂质过氧化作用的情况下，抗坏血酸或其他还原剂对[3H]螺哌隆结合没有影响。这些实验表明，抗坏血酸对血清素结合位点具有双重和不同的作用。首先，抗坏血酸诱导的脂质过氧化作用会不可逆地使[3H]5-HT和[3H]螺哌隆结合失活。其次，与脂质过氧化作用无关，抗坏血酸对[3H]血清素具有直接、可逆的作用，但对[3H]螺哌隆结合没有影响，这可能是由于两种血清素结合位点的生化性质不同所致。
