Heuring R E, Peroutka S J
J Neurosci. 1987 Mar;7(3):894-903. doi: 10.1523/JNEUROSCI.07-03-00894.1987.
3H-5-Hydroxytryptamine (5-HT) binding sites were analyzed in bovine brain membranes. The addition of either the 5-HT1A-selective drug 8-OH-DPAT (100 nM) or the 5-HT1C-selective drug mesulergine (100 nM) to the assay resulted in a 5-10% decrease in specific 3H-5-HT binding. Scatchard analysis revealed that the simultaneous addition of both drugs decreased the Bmax of 3H-5-HT binding by 10-15% without affecting the KD value (1.8 +/- 0.3 nM). Competition studies using a series of pharmacologic agents revealed that the sites labeled by 3H-5-HT in bovine caudate in the presence of 100 nM 8-OH-DPAT and 100 nM mesulergine appear to be homogeneous. 5-HT1A selective agents such as 8-OH-DPAT, ipsapirone, and buspirone display micromolar affinities for these sites. RU 24969 and (-)pindolol are approximately 2 orders of magnitude less potent at these sites than at 5-HT1B sites which have been identified in rat brain. Agents displaying nanomolar potencies for 5-HT1C sites such as mianserin and mesulergine are 2-3 orders of magnitude less potent at the 3H-5-HT binding sites in bovine caudate. In addition, both 5-HT2- and 5-HT3-selective agents are essentially inactive at these binding sites. These 3H-5-HT sites display nanomolar affinity for 5-carboxyamidotryptamine, 5-methoxytryptamine, metergoline, and 5-HT. Apparent Ki values of 10-100 nM are obtained for d-LSD, RU 24969, methiothepin, tryptamine, methysergide, and yohimbine, whereas I-LSD and corynanthine are significantly less potent. In addition, these 3H-5-HT labeled sites are regulated by guanine nucleotides and calcium. Regional studies indicate that this class of sites is most dense in the basal ganglia but exists in all regions of bovine brain. These data therefore demonstrate the presence of a homogeneous class of 5-HT1 binding sites in bovine caudate that is pharmacologically distinct from previously defined 5-HT1A, 5-HT1B, 5-HT1C, 5-HT2, and 5-HT3 receptor subtypes. We therefore suggest that this class of sites be designated the 5-HT1D subtype of binding sites labeled by 3H-5-HT.
对牛脑膜中的3H - 5 - 羟色胺（5 - HT）结合位点进行了分析。在检测中加入5 - HT1A选择性药物8 - 羟基二苯丙胺（8 - OH - DPAT，100 nM）或5 - HT1C选择性药物美舒麦角林（100 nM），会导致特异性3H - 5 - HT结合减少5 - 10%。Scatchard分析表明，同时加入这两种药物会使3H - 5 - HT结合的Bmax降低10 - 15%，而不影响KD值（1.8±0.3 nM）。使用一系列药理剂进行的竞争研究表明，在100 nM 8 - OH - DPAT和100 nM美舒麦角林存在的情况下，牛尾状核中被3H - 5 - HT标记的位点似乎是同质的。5 - HT1A选择性药物如8 - OH - DPAT、伊沙匹隆和丁螺环酮对这些位点显示出微摩尔亲和力。RU 24969和（ - ）吲哚洛尔在这些位点的效力比在大鼠脑中已鉴定出的5 - HT1B位点低约2个数量级。对5 - HT1C位点显示出纳摩尔效力的药物如米安色林和美舒麦角林，在牛尾状核的3H - 5 - HT结合位点的效力低2 - 3个数量级。此外，5 - HT2和5 - HT3选择性药物在这些结合位点基本无活性。这些3H - 5 - HT位点对5 - 羧酰胺色胺、5 - 甲氧基色胺、麦角新碱和5 - HT显示出纳摩尔亲和力。对d - LSD、RU 24969、甲硫噻平、色胺、甲基麦角新碱和育亨宾获得的表观Ki值为10 - 100 nM，而l - LSD和柯楠因的效力明显较低。此外，这些3H - 5 - HT标记的位点受鸟嘌呤核苷酸和钙的调节。区域研究表明，这类位点在基底神经节中最为密集，但存在于牛脑的所有区域。因此，这些数据证明在牛尾状核中存在一类同质的5 - HT1结合位点，其药理学特性与先前定义的5 - HT1A、5 - HT1B、5 - HT1C、5 - HT2和5 - HT3受体亚型不同。因此，我们建议将这类位点指定为被3H - 5 - HT标记的5 - HT1D亚型结合位点。
