藏药青叶胆对实验性慢性肝损伤小鼠T淋巴细胞亚群的影响

目的 观察青叶胆对小鼠慢性肝损伤的保护作用及其对小鼠脾脏T淋巴细胞亚群的调节作用。方法 采用腹腔注射四氯化碳（CCl₄）造成小鼠化学性肝损伤模型,检测小鼠血清天冬氨酸转氨酶（aspartate aminotransferase,AST）、丙氨酸转氨酶（alanine aminotransferase,ALT）、总蛋白（total protein,TP）及总胆红素（total bilirubin,TBI）;HE染色,观察肝组织形态;流式细胞术检测CD3⁺、CD4⁺及CD8⁺阳性细胞数的变化情况,计算CD4⁺/CD8⁺比例,并与模型组和对照组比较。结果 青叶胆对CCl₄造成的小鼠慢性肝脏损伤具有保护作用,与模型组相比,能明显降低小鼠血清ALT、AST含量（P<0.01）,升高TP含量（P<0.01）;与模型组相比,青叶胆低剂量组对CD3⁺细胞具有下调作用（P<0.05）,对CD8⁺细胞的上调作用和对CD4⁺/CD8⁺比值的下调作用具有显著性差异（P<0.01）;高剂量组对CD8⁺细胞的上调作用和对CD4⁺/CD8⁺比值的下调作用具有统计学意义（P<0.05）。结论 青叶胆对CCl₄诱导的小鼠慢性肝损伤具有保护作用,其机制可能是通过调节T淋巴细胞亚群,提高免疫功能。     

鸦胆子苦醇调节cGAS-STING信号通路对肝癌荷瘤小鼠肿瘤生长及免疫功能的影响

目的 探讨鸦胆子苦醇调节环磷酸鸟苷-腺苷酸合成酶（cGAS）-干扰素基因刺激因子（STING）信号通路对肝癌H22荷瘤小鼠肿瘤生长及免疫功能的影响。方法 通过左前肢腋窝sc接种H22细胞建立荷瘤小鼠模型，随机分为模型组，鸦胆子苦醇低、中、高剂量（0.916、1.832、3.664 mg·kg^-1，ig给药）组，鸦胆子苦醇（3.664 mg·kg^-1，ig给药）＋RU.521（5 mg·kg^-1，ip给药）组。干预结束后，取胸腺、脾脏、肿瘤称质量，测定小鼠胸腺和脾脏指数、抑瘤率；T淋巴细胞转化实验检测T淋巴细胞增殖指数；检测巨噬细胞吞噬鸡红细胞的能力；收集血清，试剂盒法检测白细胞介素-2（IL-2）、肿瘤坏死因子-α（TNF-α）水平；Western blotting法检测肿瘤组织中cGAS、STING蛋白表达水平。结果 与对照组相比，模型组小鼠胸腺和脾脏指数、吞噬指数、吞噬百分率、T淋巴细胞增殖指数、IL-2和TNF-α水平显著下降（P<0.05）；与模型组相比，鸦胆子苦醇低、中、高剂量组小鼠胸腺和脾脏指数、吞噬指数、吞噬百分率、T淋巴细胞增殖指数、IL-2和TNF-α水平、cGAS和STING蛋白表达显著增加（P<0.05），瘤质量显著降低（P<0.05），且作用均呈现剂量相关性；与鸦胆子苦醇高剂量组相比，鸦胆子苦醇＋RU.521组胸腺和脾脏指数、吞噬指数、吞噬百分率、T淋巴细胞增殖指数、IL-2和TNF-α水平、cGAS和STING蛋白表达显著下降（P<0.05），瘤质量显著增加（P<0.05）。结论 鸦胆子苦醇通过激活cGAS-STING信号通路抑制肝癌H22荷瘤小鼠肿瘤生长，增强其免疫功能。     

人参皂苷Rg1对移植性白血病模型小鼠的作用

目的 研究人参皂苷Rg₁对移植性白血病模型小鼠的作用。方法 采用免疫磁性分选法（MACS）从K562细胞中分离、纯化CD34⁺CD38^-人白血病干细胞（CD34⁺CD38^- LSCs）,流式细胞术检测分选细胞纯度,台盼蓝染色测定分选细胞活性。将6～8周雌性NOD/SCID小鼠27只随机分为对照组、模型组、人参皂苷Rg₁（200 mg/kg）组,每组9只,模型组和人参皂苷Rg₁组通过尾iv移植CD34⁺CD38^- LSCs构建白血病小鼠模型,ip给药30 d。观察各组小鼠一般情况及腹部包块变化;全自动血常规检测仪检测外周血白细胞、红细胞、血红蛋白、血小板水平;免疫组化法检测肝、脾脏病理学变化;流式细胞仪分析骨髓细胞周期;CCK-8法检测各组骨髓细胞的增殖能力;细胞免疫荧光染色鉴定骨髓细胞CD34阳性表达情况。结果 分选前K562细胞中CD34⁺CD38^- LSCs细胞群百分比为（9.64±1.14）%,分选后CD34⁺CD38^- LSCs纯度可达（96.45±1.63）%;台盼蓝染色显示分选后细胞活性为（95.26±2.16）%。与对照组比较,模型组小鼠腹部包块明显,生存情况较差,体质量显著下降（P<0.05）;白细胞数显著增高,红细胞数、血红蛋白水平、血小板数均显著下降（P<0.05）;肝、脾脏结构被破坏,有大量白细胞浸润;骨髓细胞周期检测显示G₀/G₁期比例显著下降（P<0.05）,S期比例显著升高（P<0.05）;骨髓细胞增殖活力显著升高（P<0.05）。与模型组比较,人参皂苷Rg₁组小鼠腹部包块明显减小,生存情况好转,体质量显著增加（P<0.05）;白细胞总数显著下降（P<0.05）,红细胞数、血红蛋白水平、血小板数均显著升高（P<0.05）;肝、脾脏结构明显恢复;骨髓细胞G₀/G₁期比例显著升高（P<0.05）,G₂/M期和S期比例显著下降（P<0.05）。细胞免疫荧光检测显示,模型组和人参皂苷Rg₁组中小鼠的骨髓细胞中存在大量的人源白血病细胞。结论 NOD/SCID小鼠尾iv移植CD34⁺CD38^- LSCs可成功构建急性髓系白血病小鼠模型,人参皂苷Rg₁能有效缓解NOD/SCID小鼠的白血病症状。     

阿胶对免疫低下模型小鼠免疫功能的影响

目的 研究阿胶对免疫低下小鼠免疫功能的影响。方法 小鼠ip环磷酰胺或氢化可的松建立免疫低下模型,高、中、低（3.00、1.50、0.75 g/kg）剂量阿胶ig给予小鼠14 d后,测定血清溶血素水平,观察阿胶对体液免疫的影响;进行二硝基氯苯诱导的小鼠耳廓肿胀实验,检测小鼠耳廓肿胀度,观察阿胶对细胞免疫的影响;流式细胞术检测阿胶对淋巴细胞亚群的影响;进行碳廓清实验,检测廓清指数K和吞噬指数α,观察阿胶对非特异性免疫的影响。结果 与模型组比较,阿胶3.0、1.5、0.75 g/kg均可显著提高免疫功能低下小鼠血清溶血素含量（P<0.001）;3.0、1.5 g/kg能明显提高小鼠耳廓肿胀度（P<0.01、0.001）;3 g/kg能显著提高小鼠CD3⁺（T淋巴细胞）、CD3⁺CD4⁺（辅助性和迟发超敏性T细胞）占淋巴细胞百分比（P<0.05）;阿胶对小鼠的碳粒廓清指数K和吞噬指数α无显著影响。结论 阿胶能显著提高免疫低下小鼠的体液免疫和细胞免疫,提高CD3⁺、CD3⁺CD4⁺阳性细胞比例,对非特异性免疫无明显影响。     

土茯苓对环孢素A诱导的免疫抑制小鼠免疫功能的影响

目的 探讨土茯苓水提液对环孢素A诱导的免疫抑制小鼠免疫功能的影响。方法 小鼠腹腔注射环孢素A 5 d致免疫抑制模型,造模成功后随机分为模型组、左旋咪唑组（3.79 g·kg^-1,阳性药）和土茯苓低、中、高剂量组（4.55,9.1,13.65 g·kg^-1）（n=16）,连续给药治疗5 d后,处死小鼠,取脾、胸腺,称重计算脾指数和胸腺指数,流式细胞术检测CD3⁺CD4⁺,CD3⁺CD8⁺;酶联免疫吸附法检测IL-2,IL-6,IFN-γ。结果 造模后小鼠脾指数显著高于正常对照组（P<0.05）,胸腺指数明显降低,脾T细胞CD3⁺CD4⁺显著降低（P<0.05）;与模型组比较,各治疗组小鼠脾指数均有不同程度降低,土茯苓水提液中剂量组差异显著（P<0.05）,但胸腺指数无显著变化;左旋咪唑组、土茯苓中、高剂量组脾T细胞CD3⁺CD4⁺数目显著增加（P<0.01）,各治疗组脾脏IFN-γ均显著下降（P<0.05）。结论 土茯苓水提液能通过降低脾指数、增加脾T细胞CD3⁺CD4⁺的数目,增强机体免疫功能,并下调脾脏内较高的IFN-γ,其调节机制可能与左旋咪唑类似。     

生脉类制剂生产过程中红参、麦冬、五味子固体废弃物组合对小鼠免疫功能的影响

目的 以注射用益气复脉（冻干）生产过程中弃去的固体废弃物为例，探讨生脉类制剂生产过程中红参、麦冬、五味子固体废弃物组合（SMGFW）对小鼠免疫功能的影响。方法 将280只SPF级ICR雄性小鼠随机分成4组：对照组和SMGFW低、中、高剂量（0.86、1.71、3.43 g·kg^-1）组，每组70只。通过刀豆蛋白A（ConA）诱导的小鼠脾淋巴细胞转化实验、绵羊红细胞（SRBC）诱导小鼠足跖增厚实验、抗体生成细胞检测实验、半数溶血值（HC₅₀）测定实验、碳廓清实验、小鼠腹腔巨噬细胞吞噬鸡红细胞实验（半体内法）和NK细胞活性测定实验（乳酸脱氢酶测定法）评价SMGFW增强小鼠免疫功能的作用。结果 与对照组比较，SMGFW低剂量组小鼠血清抗体水平显著增加（P<0.001）；SMGFW中剂量组小鼠脾脏指数显著增加（P<0.05），小鼠脾淋巴细胞增殖率显著增加（P<0.001），小鼠足跖差值显著增加（P<0.001），小鼠溶血空斑数显著增加（P<0.001），小鼠血清抗体水平显著增加（P<0.001），小鼠碳廓清吞噬指数显著增加（P<0.05），小鼠巨噬细胞对鸡红细胞吞噬百分率显著增加（P<0.001），吞噬指数显著增加（P<0.001），小鼠NK细胞活性显著增加（P<0.001）；SMGFW高剂量组小鼠体质量增加值显著降低（P<0.01），小鼠足跖差值显著增加（P<0.001），小鼠溶血空斑数显著增加（P<0.001），小鼠血清抗体水平显著增加（P<0.001），小鼠巨噬细胞对鸡红细胞吞噬百分率显著增加（P<0.05），吞噬指数显著增加（P<0.01），小鼠NK细胞活性显著增加（P<0.01）。结论 生脉类制剂生产过程中红参、麦冬、五味子固体废弃物组合具有增强小鼠免疫功能的作用。     

复方HD对环磷酰胺致免疫抑制小鼠免疫功能的影响

目的 探讨复方HD对环磷酰胺诱导的免疫抑制小鼠的免疫增强作用。方法 ICR小鼠分别以蒸馏水（对照组、模型组）、香菇多糖（200 mg/kg）、复方HD（5、10、20 g/kg）每天1次ig给药,连续10 d;除对照组外,在第4~6天ip环磷酰胺（40 mg/kg）制备免疫抑制小鼠模型（对照组除外）;每天给药前精确称量并记录小鼠体质量。于最后一次给药24 h后,测定小鼠脾指数、胸腺指数;流式细胞术进行全血中T细胞亚群分析;ELISA法检测血浆中IFN-γ和IL-4水平。结果 与模型组比较,复方HD低、中、高剂量组显著提高小鼠的胸腺指数,CD3⁺、CD3⁺CD4⁺细胞数以及CD4⁺/CD8⁺比值（P<0.05）,显著恢复血浆中IFN-γ水平和IFN-γ/IL-4比值（P<0.05）,纠正了Th1/Th2偏移,并呈现出一定的浓度相关性。结论 复方HD能够促进环磷酰胺诱导的免疫抑制小鼠免疫功能的恢复,证明其在预防及治疗免疫功能低下方面具有一定的疗效。     

人参皂苷Rg1对H2O2诱导的HaCaT细胞氧化损伤保护作用研究

目的 观察人参皂苷Rg₁对H₂O₂诱导的HaCaT细胞氧化损伤保护作用,并探讨其机制。方法 体外培养HaCaT细胞, H₂O₂诱导细胞建立氧化应激损伤模型,分为空白组、H₂O₂损伤组、人参皂苷Rg₁保护组。细胞增殖与毒性检测试剂盒(CCK-8)检测细胞存活率,Hochest染色法检测细胞凋亡情况,活性氧检测试剂盒测定细胞活性氧(ROS)水平,Western blot检测细胞中caspase-3、caspase-6、caspase-8、GAPDH蛋白表达。结果 H₂O₂诱导HaCaT细胞半数抑制浓度为100 μg?mL^-1;与H₂O₂损伤组比较,5、10和15mg?L^-1人参皂苷Rg₁预处理后,HaCaT细胞存活率明显升高(P<0.05),细胞核皱缩损伤状态明显改善,细胞凋亡数量显著减少。同时,人参皂苷Rg₁预处理可显著降低HaCaT细胞ROS水平,下调凋亡相关标志蛋白-活化型caspase-3、caspase-6、caspase-8蛋白表达水平。结论 人参皂苷Rg₁对H₂O₂诱导的HaCaT细胞氧化应激损伤具有一定的保护作用,其机制可能与增强细胞清除自由基能力及抑制凋亡相关。     

自体CIK细胞对晚期不同阶段肿瘤患者免疫状态和生活质量的影响

目的 探讨自体细胞因子诱导的杀伤细胞（CIK）治疗晚期恶性肿瘤患者,对其免疫状态和生活质量的影响。方法 选取2013年2月至2016年3月合肥市第一人民医院血液肿瘤科收治的42例晚期肿瘤患者,按照预计生存期分为A组（预计生存期<3个月）20例、B组（预计生存期≥3个月）22例,检测治疗前后A、B组患者外周血T细胞亚群的变化。观察治疗前后A、B组患者免疫功能的变化,生活质量改善情况及治疗相关不良反应。结果 CIK细胞治疗后,A组患者CD₃⁺T细胞水平较治疗前降低（P<0.05）;B组治疗后CD₃⁺、CD₄⁺和CD₄⁺/CD₈⁺水平较治疗前明显升高（P<0.05）,CD₈⁺T淋巴细胞亚群水平较治疗前降低（P<0.05）。A、B两组患者治疗后KPS评分分别较治疗前均有提高,其中A组差异无统计学意义（P>0.05）,而B组差异有统计学意义（P<0.05）。42例患者在输注CIK过程中未出现明显不良反应。结论 CIK细胞回输安全、副作用小,自体CIK细胞治疗可提高晚期恶性肿瘤患者的免疫功能,改善其生活质量,但应尽早进行。     

臭牡丹提取物对H22荷瘤小鼠体内抑瘤作用及对相关蛋白表达的影响

目的 研究臭牡丹提取物对H22实体移植瘤的抑制作用及与B淋巴细胞瘤/白血病-2（Bcl-2）和Bcl-2相关X蛋白（Bax）表达的相关性。方法 皮下接种H22瘤株建立小鼠H22实体移植瘤模型。60只荷瘤鼠随机分为模型组、5-氟尿嘧啶（5-Fu）组和臭牡丹高、中、低剂量（2.18、1.09、0.55 g/kg）组,每组12只,各组分别给予生理盐水、5-Fu（25 mg/kg,1次/d）及不同浓度的臭牡丹提取物干预。连续给药14 d后处死,检测小鼠体质量变化、抑瘤率及脾脏和胸腺指数;Western blot法检测Bcl-2和Bax蛋白的表达水平。结果 与模型组比较,臭牡丹高、中剂量组小鼠的肿瘤质量均显著降低（P<0.01）,胸腺和脾脏指数显著增加（P<0.05）;同时Bax蛋白的表达水平显著上调,Bcl-2蛋白的表达显著降低（P<0.01）。结论 臭牡丹提取物能够抑制H22实体移植瘤生长,其机制可能与上调Bax/Bcl-2比值和免疫调节有关。     

Characterization of prejunctional 5-HT1 receptors that mediate the inhibition of pressor effects elicited by sympathetic stimulation in the pithed rat

1. A study was made of the effects of 5-carboxamidotryptamine (5-CT) on pressor responses induced in vivo by electrical stimulation of the sympathetic outflow from the spinal cord of pithed rats. All animals had been pretreated with atropine. Sympathetic stimulation (0.1, 0.5, 1 and 5 Hz) resulted in frequency-dependent increases in blood pressure. Intravenous infusion of 5-CT at doses of 0.01, 0.1 and 1 μg kg⁻¹ min⁻¹ reduced the pressor effects obtained by electrical stimulation. The inhibitory effect of 5-CT was significantly more pronounced at lower frequencies of stimulation. In the present study we characterized the pharmacological profile of the receptors mediating the above inhibitory effect of 5-CT.
2. The inhibition induced by 0.01 μg kg⁻¹ min⁻¹ of 5-CT on sympathetically-induced pressor responses was partially blocked after i.v. treatment with methiothepin (10  μg kg⁻¹), WAY-100,635 (100 μg kg⁻¹) or GR127935T (250 μg kg⁻¹), but was not affected by cyanopindolol (100 μg kg⁻¹).
3. The selective 5-HT_1A receptor agonist 8-OH-DPAT and the selective 5-HT_1B/1D receptor agonists sumatriptan and L-694,247 inhibited the pressor response, whereas the 5-HT_1B receptor agonists CGS-12066B and CP-93,129 and the 5-HT_2C receptor agonist m-CPP did not modify the pressor symapthetic responses.
4. The selective 5-HT_1A receptor antagonist WAY-100,635 (100 μg kg⁻¹) blocked the inhibition induced by 8-OH-DPAT and the selective 5-HT_1B/1D receptor antagonist GR127935T (250 μg kg⁻¹) abolished the inhibition induced either by L-694,247 or sumatriptan.
5. None of the 5-HT receptor agonists used in our experiments modified the pressor responses induced by exogenous noradrenaline (NA).
6. These results suggest that the presynaptic inhibitory action of 5-CT on the electrically-induced pressor response is mediated by both r-5-HT_1D and 5-HT_1A receptors.

     

Effect of pindolol on thel-5-htp-induced increase in plasma prolactin and cortisol concentrations in man

Previous studies with direct-acting serotonin (5-HT) agonists and antagonists have demonstrated that stimulation of 5-HT_1A, 5-HT_1C and 5-HT₂ receptors may promote cortisol and prolactin (PRL) secretion in man. There is also evidence that 5-HT_1C/2 receptor stimulation contributes to the cortisol and PRL responses following administration of the 5-HT precursor,l-5-hydroxytryptophan (l-5-HTP), in man. To clarify the possible contribution of 5-HT_1A receptor stimulation to the ability ofl-5-HTP to stimulate cortisol and PRL secretion in man, the effect of pindolol, a beta adrenoceptor antagonist that is also a 5-HT_1A partial agonist, on thel-5-HTP-induced increases in cortisol and PRL secretion, was examined in 12 normal male volunteers. Pretreatment with pindolol, 30 mg orally, significantly inhibited the PRL but not the cortisol response tol-5-HTP, 200 mg PO. Pindolol alone decreased basal plasma PRL levels and increased basal plasma cortisol levels, possibly due to 5-HT_1A antagonist and agonists effects, respectively. These data, coupled with observations from other studies, suggest that thel-5-HTP-induced increase in PRL but not cortisol secretion requires 5-HT_1A receptor activation. PRL secretion due to 5-HT formed from exogenousl-5-HTP may require the availability of both intact 5-HT_1A and 5-HT₂/5-HT_1C receptors, since blockade of either receptor type inhibited the PRL response tol-5-HTP. The implication of this synergistic effect for interpretation of neuroendocrine studies involving the serotonergic system in man is discussed.     

Discriminative stimulus properties of the serotonin agonist MK 212

In an attempt to clarify the role of 5-hydroxytryptamine (5-HT) in the discriminative stimulus properties of MK 212 (6-chloro-2[1-piperazinyl]pyrazine), male Sprague-Dawley rats were trained to discriminate 0.5 mg/kg of this compound from saline. While the putative 5-HT agonists fenfluramine and m-chlorophenylpiperazine (MCPP) mimicked MK 212 in a dose-related manner, d-lysergic acid diethylamide (LSD), 8-hydroxy-2(di-n-propylamino)tetralin (8-OHDPAT), 5-methoxy-N,N-dimethyltryptamine (5-MeODMT), quipazine, Ru 24969, and 1-(m-trifluoromethylphenyl)piperazine (TFMPP) failed to substitute completely. The 5-HT₁/5-HT₂ antagonists BC 105, metergoline, and methysergide completely blocked the MK 212 cue, while the selective 5-HT₂ antagonists ketanserin and pirenperone, the dopamine antagonists haloperidol and spiperone, and the beta-noradrenergic antagonist propranolol were without effect. The substitutions of fenfluramine and MCPP for MK 212 support a role for 5-HT in the MK 212 cue; however, the lack of substitution of many other 5-HT agonists is difficult to explain. The complete antagonism by 5-HT₁/5-HT₂ but not by selective 5-HT₂, antagonists suggests the possibility that 5-HT₁ receptors mediate the stimulus properties of MK 212. Further research is needed to support this hypothesis and to investigate the relative role of 5-HT and other neurotransmitters in the stimulus effects of MK 212.Portions of this research were presented at the Meeting of the Committee on Problems of Drug Dependence Satellite Session (International Study Group Interested in Drugs as Reinforcers and the Society for the Stimulus Properties of Drugs) in Baltimore, MD (1985)     

The effects of ageing on prejunctional 5-hydroxytryptamine receptors in the rat vas deferens

Summary The prejunctional inhibitory effects of a series of 5-HT₁ receptor agonists were examined against the isometric contraction of epididymal portions of rat vas deferens evoked by single stimulus pulses in the presence of nifedipine (10 mol/l). The 5-HT_1A ligand flesinoxan produced inhibition of contractions which was not inhibited by cyanopindolol or yohimbine. However, the prejunctional inhibitory concentration response curve for the 5-HT₁ agonist 5-carboxamidotryptamine (5-CT) was biphasic in tissues from 1.5 month old animals but monophasic in tissues from 24 months animals. Cyanopindolol (1 mol/l) antagonised the inhibitory effects of 5-CT in tissues from 1.5 and 3 month animals but not in tissues from 8 or 24 months animals. Inhibitory actions of 5-CT were not prevented by pretreating animals with pertussis toxin (6 g/kg i. v.), a dose which abolished the negative inotropic response to acetylcholine in rat left atria. It is concluded that the nerve terminals of vas deferens from 1.5 month old animals contain both 5-HT_1B and other as yet unclassified 5-HT₁ receptors, but that this 5-HT_1B-mediated response is lost in maturation and ageing.Send offprint requests to J. R. Docherty at the above address     

Molecular structural basis of ligand selectivity for 5-HT2 versus 5-HT1C cortical receptors

Summary A molecular structural criterion of ligand selectivity for the 5-HT₂ versus 5-HT_1C receptor was hypothesized on the basis of radioligand binding data. Despite the large number of compounds which have been tested at both receptors, analysis of published data led to the identification of only five agents which are greater than 10-fold selective for the 5-HT₂ versus the 5-HT_1C receptor. Comparison of the two-dimensional structures revealed that, although these five compounds represent three distinct structural classes, they share a common structural feature located in the region hypothesized to be involved in receptor binding: a carbonyl or carboxyl oxygen interposed spatially between an aromatic ring and nitrogen atom. This structural feature was used to predict the relative selectivity of compounds that had not previously been analyzed at both the 5-HT₂ and 5-HT_1C receptors.All six drugs tested which contain the identified reactive carbonyl or carboxyl group were found to be selective for the 5-HT₂ versus the 5-HT_1C receptor with selectivity ratios ranging from 26 to 380. By contrast, three agents which are structurally similar but do not contain the reactive carbonyl or carboxyl group displayed equally high affinity for both receptor binding sites. Since the physiological roles of the 5-HT₂ and 5-HT_1C receptor are markedly different, it would be of potential clinical and scientific value to utilize this molecular structural feature to further identify chemical compounds which would selectively interact with only one of the two receptors. Send offprint requests to S. J. Peroutka at the current address     

mCPP-induced hyperactivity in 5-HT2C receptor mutant mice is mediated by activation of multiple 5-HT receptor subtypes

The serotonin receptor agonist mCPP induces hyperlocomotion in 5-HT2C receptor knockout (KO) mice or in the presence of a 5-HT2C receptor antagonist. In the present group of experiments, we evaluate the role of 5-HT1A, 5-HT1B and 5-HT2A receptors in mCPP-induced hyperactivity in 5-HT2C KO mice. We also assess the ability of agonists at these receptors to induce hyperactivity in wildtype (WT) mice pre-treated with a selective 5-HT2C receptor antagonist. As previously reported, mCPP (3 mg/kg) induced hyperactivity in 5-HT2C KO mice. A combination of the 5-HT1B receptor agonist CP-94,253 (20 mg/kg) and the 5-HT1A receptor agonist 8-OH-DPAT (0.5 mg/kg) induced marked hyperactivity in WT but not in 5-HT2C KO mice, nor in mice treated with the selective 5-HT2C receptor antagonist, SB 242084 (1.5 mg/kg). Neither CP-94,253 nor 8-OH-DPAT had any intrinsic effect on locomotion in WTs. mCPP-induced hyperactivity was attenuated in 5-HT2C KO mice by the 5-HT1B receptor antagonist SB 224289 (2.5 mg/kg), and the 5-HT2A receptor antagonists ketanserin (0.3 mg/kg) and M100907 (0.01 mg/kg) but not by the 5-HT1A receptor antagonist WAY 100635 (1 mg/kg). The 5-HT(2A/2B/2C) receptor agonist, Ro 60-0175 (3 mg/kg), induced a modest increase in locomotor activity in WT mice pre-treated with SB 242084. However, the combination of Ro 60-0175 with CP-94,253 induced a substantial increase in activity in 5-HT2C KO mice, an effect comparable to mCPP-induced hyperactivity. Thus, joint activation of 5-HT1A and 5-HT1B receptors stimulates locomotion in WT mice but this response is dependent on a functional 5-HT2C receptor population and hence is absent in 5-HT2C KO mice. By contrast, mCPP-induced hyperactivity depends on the inactivation of a separate 5-HT2C receptor population and is mediated by 5-HT2A and 5-HT1B receptor activation.     

Serotonergic approaches in the development of novel antipsychotics

Schizophrenia is a chronic, debilitating neuropsychological disease characterised by positive, negative, and cognitive deficits. In recent years, new pharmacological treatment strategies have been developed to treat the sequalae of schizophrenia based upon more selective receptor activity profiles in the hope that treatment efficacy can be increased without inducing the side-effect profiles seen with current available therapies. One such strategy involves the development of combined (partial) 5-HT_1A agonists and D₂ receptor (partial) antagonists such as bifeprunox, SLV313, F15063 and SSR-181507 in an attempt to increase therapeutic efficacy of all symptom domains whilst alleviating adverse side effects. Other novel drugs including SLV310 and SLV314 combine selective serotonin reuptake inhibition (SSRI) functionality with D₂ receptor antagonism in an attempt to not only improve schizophrenic symptoms, but to also relieve other affective disorders intricately linked with the disorder. The main scope of this review will evaluate the major preclinical and clinical pharmacological findings concerning the aforementioned strategies and pharmacological agents, and compare their therapeutic potential with currently available antipsychotics; however, recent developments at other emerging serotonergic targets such as 5-HT_2C, 5-HT₆ and 5-HT₇ receptors will also be considered.     

Evidence that 5-HT2C receptor antagonists are anxiolytic in the rat Geller-Seifter model of anxiety

Four non-selective 5-HT_2C/5-HT_2A receptor antagonists, mianserin (2–8 mg/kg), 1-naphthyl piperazine (1-NP) (0.5–1 mg/kg), ICI 169,369 (20 mg/kg) and LY 53857 (5 mg/kg), increased punished responding for a food reward in the rat Geller-Seifter test 30 min after subcutaneous (SC) administration. This property was shared by the benzodiazepine anxiolytic chlordiazepoxide (5 mg/kg SC). However, the selective 5-HT_2A receptor antagonists ketanserin (0.2–1 mg/kg SC) and altanserin (0.5, 1 mg/kg SC) had little effect. The 5-HT_1A, 5-HT_1B and-adrenergic receptor antagonists pindolol and cyanopindolol (6 mg/kg SC) did not affect punished responding either, nor did the 5-HT_1D receptor partial agonist and ₂ adrenergic receptor antagonist yohimbine (2.5 mg/kg SC) or the histamine H₁ receptor antagonist mepyramine (1 mg/kg SC). Unpunished responding was also modestly increased after some doses of the 5-HT_2C/5-HT_2A receptor antagonists. However, this effect was inconsistent and was also seen after chlordiazepoxide. Furthermore, it was not associated with the increase in punished responding observed in rats orally treated with mianserin (10, 20 mg/kg), 1-NP (10, 20 mg/kg) or ICI 169,369 (50 mg/kg). The action of the 5-HT_2C/5-HT_2A receptor antagonists tested is therefore consistent with anxiolysis. The results also strongly suggest that this effect is mediated by blockade of the 5-HT_2C receptor, although the possibility of 5-HT_2B receptor mediation is discussed.     

Interaction of arylpiperazines with 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptors: do discriminatory 5-HT1B receptor ligands exist?

Summary The effects of several putative 5-HT₁ receptorsubtype selective ligands were investigated in biochemical models for 5-HT_1A, 5-HT_1B, and 5-HT_1D receptors (inhibition of forskolin-stimulated adenylate cyclase activity in calf hippocampus, rat and calf substantia nigra, respectively) and 5-HT_1C receptors (stimulation of inositol phosphates production in pig choroid plexus). Following compounds were studied: 5-HT (5-hydroxytryptamine), TFMPP (1-(mtrifluoromethylphenyl)piperazine), mCPP (1-m-chlorophe-nyl)piperazine, 1 CGS 12066 (7-trifluoromethyl-4-(4-methyl1-piperazinyl)-pyrrolo[1,2-a]quinoxaline 1), isamoltane (CGP 361A, 1-(2-(1-pyrrolyl)-phenoxy)-3-isopropylamino-2-propranol), quipazine, 1-NP (1-(1-naphthyl)piperazine), and PAPP (LY165163, 1-[2-(4-aminophenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine). Among reported 5-HT_1B receptor selective drugs, TFMPP had similar potency at 5HT_1A, 5-HT_1B and 5-HT_1C receptors, mCPP did not separate between 5-HT_1B and 5-HT_1C receptors, CGS 12066 was equipotent at 5-HT_1B and 5-HT_1D receptors, and isamoltane was only slightly 5-HTIB versus 5-HT_1A selective. Quipazine showed equal potency at 5-HTIB and 5-HT_1C receptors and 1-NP did not discriminate between the four receptor subtypes. PAPP described as 5-HT_1A receptor selective, was equally potent at 5-HT_1A and 5-HT_1D receptors. The potencies determined in second messenger studies were in good agreement with the affinity values determined in radioligand binding studies. Thus 5-HT_1A, 5-HT_1B, 5-HT_1C and 5-HT_1D receptors have different pharmacological profiles as predicted from radioligand binding studies. Despite claims to the contrary, none of the tested compounds had actual selectivity for a given 5-HT₁ receptor subtype. Of interest were the properties of several of these drugs, which behaved as agonists at some receptors and as antagonists at others (e. g. quipazine, 1-NP, PAPP and isamoltane). Send offprint requests to D. Hoyer at the above address     

Pharmacological characterisation of the agonist radioligand binding site of 5-HT<Subscript>2A</Subscript>, 5-HT<Subscript>2B</Subscript> and 5-HT<Subscript>2C</Subscript> receptors

In the present study we compared the affinity of various drugs for the high affinity agonist-preferring binding site of human recombinant 5-HT_2A, 5-HT_2B and 5-HT_2C receptors stably expressed in monoclonal mammalian cell lines. To ensure that the agonist-preferring conformation of the receptor was preferentially labelled in competition binding experiments, saturation analysis was conducted using antagonist and agonist radiolabels at each receptor. Antagonist radiolabels ([³H]-ketanserin for 5-HT_2A receptor and [³H]-mesulergine for 5-HT_2B and 5-HT_2C receptor) bound to a larger population of receptors in each preparation than the corresponding agonist radiolabel ([¹²⁵I]-DOI for 5-HT_2A receptor binding and [³H]-5-HT for 5-HT_2B and 5-HT_2C receptor binding). Competition experiments were subsequently conducted against appropriate concentrations of the agonist radiolabels bound to the agonist-preferring subset of receptors in each preparation. These studies confirmed that there are a number of highly selective antagonists available to investigate 5-HT₂ receptor subtype function (for example, MDL 100907, RS-127445 and RS-102221 for 5-HT_2A, 5-HT_2B and 5-HT_2C receptors respectively). There remains, however, a lack of highly selective agonists. (–)DOI is potent and moderately selective for 5-HT_2A receptors, BW723C86 has poor selectivity for human 5-HT_2B receptors, while Org 37684 and VER-3323 display some selectivity for the 5-HT_2C receptor. We report for the first time in a single study, the selectivity of numerous serotonergic drugs for 5-HT₂ receptors from the same species, in mammalian cell lines and using, exclusively, agonist radiolabels. The results indicate the importance of defining the selectivity of pharmacological tools, which may have been over-estimated in the past, and highlights the need to find more selective agonists to investigate 5-HT₂ receptor pharmacology.