Mize A L, Alper R H
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas School of Medicine, 3901 Rainbow Boulevard, Kansas City, KS 66160-7417, USA.
Brain Res. 1999 Jul 31;836(1-2):229-36. doi: 10.1016/s0006-8993(99)01660-1.
Serotonin (5-hydroxytryptamine; 5-HT) receptor ligands were used to assess agonist-stimulated [(35)S]GTPgammaS binding in rat and guinea pig striatal membranes. The assay contained 45-60 microgram protein, 300 microM GDP and 0.1 nM [(35)S]GTPgammaS, incubated at 37 degrees C for 20 min. The non-selective agonists 5-HT, 5-CT (5-carboxyamidotryptamine), and L-694,247, and the selective 5-HT(1B) receptor agonist CP 93,129 produced concentration-dependent increases in [(35)S]GTPgammaS binding in rat striatum, whereas the selective 5-HT(1A) receptor agonist R(+)-8-OH-DPAT [R(+)-8-hydroxy-2-(di-n-propylamino)tetralin] was inactive. Cyanopindolol, a 5-HT(1A/1B) receptor antagonist, completely blocked the effect of 5-HT. Methiothepin, yohimbine and cyanopindolol also blocked 5-CT-stimulated [(35)S]GTPgammaS binding with the following rank order of potency: cyanopindolol >/= methiothepin >>> yohimbine, consistent with rat 5-HT(1B) receptor pharmacology. Neither cyanopindolol nor methiothepin altered basal [(35)S]GTPgammaS binding by themselves while yohimbine had weak partial agonist activity. Furthermore, cyanopindolol shifted the 5-CT concentration-response curve rightward, increasing the EC(50) and decreasing the maximal response, but did not affect L-694, 247-stimulated [(35)S]GTPgammaS binding. The ability of cyanopindolol or spiperone (a 5-HT(1A/1D) receptor antagonist) to alter CP 93,129-stimulated [(35)S]GTPgammaS binding was determined. Cyanopindolol produced a rightward shift in the CP 93,129 concentration-response curve, while spiperone had no affect. Finally, in guinea pig striatum and hippocampus, L-694,247 produced a concentration dependent increase in [(35)S]GTPgammaS binding. In conclusion, these studies indicate that 5-HT(1B) receptor function can be assessed using agonist-stimulated [(35)S]GTPgammaS binding in rat striatal membranes using CP 93,129, 5-HT or 5-CT, but not L-694, 247.
血清素（5-羟色胺；5-HT）受体配体被用于评估激动剂刺激的大鼠和豚鼠纹状体膜中[（35）S]GTPγS结合情况。该检测包含45 - 60微克蛋白质、300微摩尔GDP和0.1纳摩尔[（35）S]GTPγS，于37℃孵育20分钟。非选择性激动剂5-HT、5-CT（5-羧酰胺基色胺）和L-694,247，以及选择性5-HT(1B)受体激动剂CP 93,129在大鼠纹状体中引起[（35）S]GTPγS结合呈浓度依赖性增加，而选择性5-HT(1A)受体激动剂R(+)-8-OH-DPAT [R(+)-8-羟基-2-(二正丙基氨基)四氢萘]无活性。5-HT(1A/1B)受体拮抗剂氰吲哚洛尔完全阻断了5-HT的作用。甲硫哒嗪、育亨宾和氰吲哚洛尔也阻断了5-CT刺激的[（35）S]GTPγS结合，其效力顺序如下：氰吲哚洛尔≥甲硫哒嗪>>育亨宾，这与大鼠5-HT(1B)受体药理学一致。氰吲哚洛尔和甲硫哒嗪自身均未改变基础[（35）S]GTPγS结合，而育亨宾具有较弱的部分激动剂活性。此外，氰吲哚洛尔使5-CT浓度-反应曲线右移，增加了半数有效浓度（EC50）并降低了最大反应，但不影响L-694,247刺激的[（35）S]GTPγS结合。测定了氰吲哚洛尔或螺哌隆（一种5-HT(1A/1D)受体拮抗剂）改变CP 93,129刺激的[（35）S]GTPγS结合的能力。氰吲哚洛尔使CP 93,129浓度-反应曲线右移，而螺哌隆无影响。最后，在豚鼠纹状体和海马体中，L-694,247使[（35）S]GTPγS结合呈浓度依赖性增加。总之，这些研究表明，使用CP 93,129、5-HT或5-CT通过激动剂刺激的大鼠纹状体膜中[（35）S]GTPγS结合可评估5-HT(1B)受体功能，但L-694,247不行。
