Ralvenius William T, Benke Dietmar, Acuña Mario A, Rudolph Uwe, Zeilhofer Hanns Ulrich
1] Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
1] Laboratory of Genetic Neuropharmacology, McLean Hospital, 115 Mill Street, Belmont, Massachusetts 02478, USA [2] Department of Psychiatry, Harvard Medical School, 401 Park Drive, Boston, Massachusetts 02215, USA.
Nat Commun. 2015 Apr 13;6:6803. doi: 10.1038/ncomms7803.
Agonists at the benzodiazepine-binding site of GABAA receptors (BDZs) enhance synaptic inhibition through four subtypes (α1, α2, α3 and α5) of GABAA receptors (GABAAR). When applied to the spinal cord, they alleviate pathological pain; however, insufficient efficacy after systemic administration and undesired effects preclude their use in routine pain therapy. Previous work suggested that subtype-selective drugs might allow separating desired antihyperalgesia from unwanted effects, but the lack of selective agents has hitherto prevented systematic analyses. Here we use four lines of triple GABAAR point-mutated mice, which express only one benzodiazepine-sensitive GABAAR subtype at a time, to show that targeting only α2GABAARs achieves strong antihyperalgesia and reduced side effects (that is, no sedation, motor impairment and tolerance development). Additional pharmacokinetic and pharmacodynamic analyses in these mice explain why clinically relevant antihyperalgesia cannot be achieved with nonselective BDZs. These findings should foster the development of innovative subtype-selective BDZs for novel indications such as chronic pain.
γ-氨基丁酸A型受体(GABAAR)苯二氮䓬结合位点的激动剂(苯二氮䓬类药物,BDZs)通过GABAAR的四种亚型(α1、α2、α3和α5)增强突触抑制作用。将其应用于脊髓时,可减轻病理性疼痛;然而,全身给药后疗效不足以及不良反应限制了它们在常规疼痛治疗中的应用。先前的研究表明,亚型选择性药物可能有助于区分所需的抗痛觉过敏作用和不良影响,但迄今为止,由于缺乏选择性药物,无法进行系统分析。在此,我们使用四组三重GABAAR点突变小鼠,每组小鼠每次仅表达一种对苯二氮䓬敏感的GABAAR亚型,结果表明,仅靶向α2GABAARs可产生强大的抗痛觉过敏作用,并减少副作用(即无镇静、运动障碍和耐受性形成)。对这些小鼠进行的额外药代动力学和药效学分析解释了为什么非选择性BDZs无法实现临床相关的抗痛觉过敏作用。这些发现应会推动新型亚型选择性BDZs的研发,用于治疗慢性疼痛等新适应症。