Malherbe P, Masciadri R, Norcross R D, Knoflach F, Kratzeisen C, Zenner M-T, Kolb Y, Marcuz A, Huwyler J, Nakagawa T, Porter R H P, Thomas A W, Wettstein J G, Sleight A J, Spooren W, Prinssen E P
Discovery Research CNS, F Hoffmann-La Roche Ltd, Basel, Switzerland.
Br J Pharmacol. 2008 Jun;154(4):797-811. doi: 10.1038/bjp.2008.135. Epub 2008 Apr 21.
As baclofen is active in patients with anxiety disorders, GABAB receptors have been implicated in the modulation of anxiety. To avoid the side effects of baclofen, allosteric enhancers of GABAB receptors have been studied to provide an alternative therapeutic avenue for modulation of GABAB receptors. The aim of this study was to characterize derivatives of (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) as enhancers of GABAB receptors.
Enhancing properties of rac-BHFF were assessed in the Chinese hamster ovary (CHO)-Galpha16-hGABA(B1a,2a) cells by Fluorometric Imaging Plate Reader and GTPgamma[35S]-binding assays, and in rat hippocampal slices by population spike (PS) recordings. In vivo activities of rac-BHFF were assessed using the loss of righting reflex (LRR) and stress-induced hyperthermia (SIH) models.
In GTPgamma[35S]-binding assays, 0.3 microM rac-BHFF or its pure enantiomer (+)-BHFF shifted the GABA concentration-response curve to the left, an effect that resulted in a large increase in both GABA potency (by 15.3- and 87.3-fold) and efficacy (149% and 181%), respectively. In hippocampal slices, rac-BHFF enhanced baclofen-induced inhibition of PS of CA1 pyramidal cells. In an in vivo mechanism-based model in mice, rac-BHFF increased dose-dependently the LRR induced by baclofen with a minimum effective dose of 3 mg kg(-1) p.o. rac-BHFF (100 mg kg(-1) p.o.) tested alone had no effect on LRR nor on spontaneous locomotor activity, but exhibited anxiolytic-like activity in the SIH model in mice.
rac-BHFF derivatives may serve as valuable pharmacological tools to elucidate the pathophysiological roles played by GABAB receptors in the central and peripheral nervous systems.
由于巴氯芬对焦虑症患者有效，因此推测GABAB受体参与焦虑调节。为避免巴氯芬的副作用，人们对GABAB受体变构增强剂进行了研究，以提供调节GABAB受体的替代治疗途径。本研究的目的是表征(R,S)-5,7-二叔丁基-3-羟基-3-三氟甲基-3H-苯并呋喃-2-酮（rac-BHFF）的衍生物作为GABAB受体增强剂的特性。
通过荧光成像微孔板读数器和GTPγ[35S]结合试验，在中国仓鼠卵巢（CHO）-Gα16-hGABA(B1a,2a)细胞中评估rac-BHFF的增强特性，并通过群体峰电位（PS）记录在大鼠海马切片中进行评估。使用翻正反射消失（LRR）和应激诱导体温过高（SIH）模型评估rac-BHFF的体内活性。
在GTPγ[35S]结合试验中，0.3μM的rac-BHFF或其纯对映体(+)-BHFF将GABA浓度-反应曲线向左移动，这一效应分别导致GABA效力（提高15.3倍和87.3倍）和效能（提高149%和181%）大幅增加。在海马切片中，rac-BHFF增强了巴氯芬诱导的CA1锥体细胞PS抑制。在小鼠体内基于机制的模型中，rac-BHFF以剂量依赖性方式增加巴氯芬诱导的LRR，最小有效剂量为3mg kg(-1)口服。单独测试的rac-BHFF（100mg kg(-1)口服）对LRR和自发运动活性均无影响，但在小鼠SIH模型中表现出抗焦虑样活性。
rac-BHFF衍生物可能是阐明GABAB受体在中枢和外周神经系统中所起病理生理作用的有价值的药理学工具。
