Lipina Tatiana V, Giang Huy, Thacker Jonathan S, Wetsel William C, Caron Marc G, Beaulieu Jean Martin, Salahpour Ali, Ramsey Amy J
Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada.
Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, Toronto, Ontario, Canada.
Int J Neuropsychopharmacol. 2024 Dec 1;27(12). doi: 10.1093/ijnp/pyae060.
Glutamatergic system dysfunction contributes to a full spectrum of schizophrenia-like symptoms, including the cognitive and negative symptoms that are resistant to treatment with antipsychotic drugs (APDs). Aripiprazole, an atypical APD, acts as a dopamine partial agonist, and its combination with haloperidol (a typical APD) has been suggested as a potential strategy to improve schizophrenia. Recently, an analog of aripiprazole, UNC9994, was developed. UNC9994 does not affect dopamine 2 receptor (D2R)-mediated Gi/o protein signaling but acts as a partial agonist for D2R/β-arrestin interactions. Hence, one of our objectives was to probe the behavioral effects of co-administrating haloperidol with UNC9994 in the N-methyl-D-aspartate receptor (NMDAR) mouse models of schizophrenia. The biochemical mechanisms underlying the neurobiological effects of dual haloperidol × UNC9994 action are currently missing. Hence, we aimed to explore D2R- and NMDAR-dependent signaling mechanisms that could underlie the effects of dual drug treatments.
NMDAR hypofunction was induced pharmacologically by acute injection of MK-801 (NMDAR pore blocker; 0.15 mg/kg) and genetically by knockdown of Grin1 gene expression in mice, which have a 90% reduction in NMDAR levels (Grin1 knockdown [Grin1-KD]). After intraperitoneal injections of vehicle, haloperidol (0.15 mg/kg), UNC9994 (0.25 mg/kg), or their combination, mice were tested in open field, prepulse inhibition (PPI), Y-maze, and Puzzle box. Biochemical effects on the phosphorylation of Akt, glycogen synthase kinase-3 (GSK-3), and CaMKII in the prefrontal cortex (PFC) and striatum of MK-801-treated mice were assessed by western blotting.
Our findings indicate that low dose co-administration of UNC9994 and haloperidol reduces hyperactivity in MK-801-treated animals and in Grin1-KD mice. Furthermore, this dual administration effectively reverses PPI deficits, repetitive/rigid behavior in the Y-maze, and deficient executive function in the Puzzle box in both animal models. Pharmacological inhibition of NMDAR by MK-801 induced the opposite effects in the PFC and striatum on pAkt-S473 and pGSK3β-Ser9. Dual injection of haloperidol with UNC9994 reversed MK-801-induced effects on pAkt-S473 but not on pGSK3β-Ser9 in both brain structures.
The dual administration of haloperidol with UNC9994 at low doses represents a promising approach to ameliorate symptoms of schizophrenia. The combined drug regimen elicits synergistic effects specifically on pAkt-S473, suggesting it as a potential biomarker for antipsychotic actions.
谷氨酸能系统功能障碍会导致一系列精神分裂症样症状，包括对抗精神病药物（APD）治疗有抗性的认知和阴性症状。阿立哌唑是一种非典型抗精神病药物，作为多巴胺部分激动剂，其与氟哌啶醇（一种典型抗精神病药物）联合使用被认为是改善精神分裂症的一种潜在策略。最近，开发了阿立哌唑的类似物UNC9994。UNC9994不影响多巴胺2受体（D2R）介导的Gi/o蛋白信号传导，但作为D2R/β-抑制蛋白相互作用的部分激动剂。因此，我们的目标之一是探究在精神分裂症的N-甲基-D-天冬氨酸受体（NMDAR）小鼠模型中，氟哌啶醇与UNC9994联合给药的行为效应。目前尚不清楚氟哌啶醇×UNC9994双重作用的神经生物学效应背后的生化机制。因此，我们旨在探索可能是双重药物治疗效果基础的D2R和NMDAR依赖性信号传导机制。
通过急性注射MK-801（NMDAR孔道阻滞剂；0.15mg/kg）药理学诱导NMDAR功能低下，并通过敲低小鼠中Grin1基因表达在基因水平上诱导，这些小鼠的NMDAR水平降低了90%（Grin1基因敲低[Grin1-KD]）。在腹腔注射溶剂、氟哌啶醇（0.15mg/kg）、UNC9994（0.25mg/kg）或它们的组合后，对小鼠进行旷场试验、前脉冲抑制（PPI）试验、Y迷宫试验和拼图盒试验。通过蛋白质免疫印迹法评估对MK-801处理小鼠前额叶皮质（PFC）和纹状体中Akt、糖原合酶激酶-3（GSK-3）和CaMKII磷酸化的生化影响。
我们的研究结果表明，低剂量联合使用UNC9994和氟哌啶醇可降低MK-801处理动物和Grin1-KD小鼠的多动。此外，这种联合给药在两种动物模型中均有效逆转PPI缺陷、Y迷宫中的重复/刻板行为以及拼图盒试验中的执行功能缺陷。MK-801对NMDAR的药理学抑制在PFC和纹状体中对pAkt-S473和pGSK3β-Ser9产生相反的影响。氟哌啶醇与UNC9994联合注射在两个脑区均逆转了MK-801对pAkt-S473的影响，但未逆转对pGSK3β-Ser9的影响。
低剂量联合使用氟哌啶醇和UNC9994是改善精神分裂症症状的一种有前景的方法。联合用药方案对pAkt-S473产生特异性协同作用，表明其作为抗精神病作用潜在生物标志物的可能性。
