Wirt Jonah L, Assis Ferreira Luana, Jesus Carlos Henrique Alves, Woodward Taylor J, Oliva Idaira, Xu Zhili, Crystal Jonathon D, Pepin Robert H, Silverman Richard B, Hohmann Andrea G
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405.
Program in Neuroscience, Indiana University, Bloomington, IN 47405.
Proc Natl Acad Sci U S A. 2025 Jan 7;122(1):e2318833121. doi: 10.1073/pnas.2318833121. Epub 2024 Dec 30.
Dysregulation of GABAergic inhibition is associated with pathological pain. Consequently, enhancement of GABAergic transmission represents a potential analgesic strategy. However, therapeutic potential of current GABA agonists and modulators is limited by unwanted side effects. We postulated that inhibition of GABA's degradation enzyme, GABA aminotransferase (GABA-AT), would increase endogenous GABA levels and produce analgesia. We evaluated antinociceptive efficacy of the potent GABA-AT inhibitor OV329 in rodent models of neuropathic and inflammatory pain and assessed possible side effects (i.e., reward and motor impairment). OV329 attenuated the development and maintenance of mechanical and cold hypersensitivities induced by the chemotherapeutic agent paclitaxel. Prophylactic OV329, administered systemically, normalized paclitaxel-induced increases in glutamate levels and suppressed neuropathic nociception. Intrathecal OV329 suppressed paclitaxel-induced mechanical hypersensitivity, elevating GABA, and reducing glutamate levels in the lumbar spinal cord, consistent with a spinal site of action. Furthermore, OV329 largely synergized with paclitaxel to enhance 4T1 tumor cell line cytotoxicity without altering viability of nontumor cells. OV329 also attenuated inflammation-induced mechanical hypersensitivity induced by intraplanar injection of complete Freund's adjuvant (CFA) with efficacy comparable to morphine. Unlike morphine, OV329 did not produce reward in a conditioned place preference assay in mice and was not self-administered intravenously by rats. Antinociceptive efficacy of OV329 was observed at doses that did not impair motor function or produce tolerance following chronic dosing. Thus, inhibition of GABA-AT with OV329 represents a unique therapeutic strategy to alleviate neuropathic and inflammatory pain with no apparent abuse liability, potentially producing a beneficial spectrum of pharmacological effects through enzymatic regulation.
γ-氨基丁酸(GABA)能抑制作用的失调与病理性疼痛相关。因此,增强GABA能传递是一种潜在的镇痛策略。然而,目前的GABA激动剂和调节剂的治疗潜力受到不良副作用的限制。我们推测,抑制GABA的降解酶——GABA转氨酶(GABA-AT),会增加内源性GABA水平并产生镇痛作用。我们评估了强效GABA-AT抑制剂OV329在神经性疼痛和炎性疼痛啮齿动物模型中的抗伤害感受效能,并评估了可能的副作用(即奖赏和运动障碍)。OV329减轻了化疗药物紫杉醇诱导的机械性和冷超敏反应的发生和维持。全身给予预防性OV329可使紫杉醇诱导的谷氨酸水平升高恢复正常,并抑制神经性伤害感受。鞘内注射OV329可抑制紫杉醇诱导的机械性超敏反应,提高腰脊髓中的GABA水平并降低谷氨酸水平,这与脊髓作用部位一致。此外,OV329在很大程度上与紫杉醇协同作用,增强4T1肿瘤细胞系的细胞毒性,而不改变非肿瘤细胞的活力。OV329还减轻了平面内注射完全弗氏佐剂(CFA)诱导的炎症性机械性超敏反应,其效能与吗啡相当。与吗啡不同,OV329在小鼠的条件性位置偏爱试验中未产生奖赏效应,大鼠也不会静脉内自我给药。在不损害运动功能或长期给药后不产生耐受性的剂量下观察到了OV329的抗伤害感受效能。因此,用OV329抑制GABA-AT代表了一种独特的治疗策略,可缓解神经性和炎性疼痛,且无明显的滥用可能性,可能通过酶调节产生有益的药理学效应谱。