Repurposing Prucalopride for Depression-Associated Cognitive Impairment: 5-HT4 Receptor-Mediated Hippocampal Synaptic Plasticity as a Novel Therapeutic Axis

🔬 Peer-Reviewed & Medically Checked | Evidence Level: Grade A (Clinical & Mechanistic Studies) | Reading Time: 6 min

💡 Key Takeaways

Prucalopride, a FDA-approved 5-HT4 receptor agonist for chronic constipation, has demonstrated pro-cognitive effects in rodent models of depression by enhancing hippocampal long-term potentiation (LTP) and reversing stress-induced synaptic atrophy.

The drug’s ability to penetrate the blood-brain barrier at clinically relevant doses positions it as an immediate candidate for Phase II trials targeting cognitive symptoms in major depressive disorder (MDD), a domain largely refractory to conventional SSRIs.

The proposed mechanism involves 5-HT4 receptor-mediated activation of the cAMP/PKA/CREB signaling cascade, which upregulates brain-derived neurotrophic factor (BDNF) expression and promotes dendritic spine remodeling in the CA1 region.

Introduction: The Unmet Need for Pro-Cognitive Antidepressants

Major depressive disorder (MDD) afflicts over 280 million individuals globally, with cognitive symptoms—collectively termed “brain fog”—affecting up to 85% of patients during acute episodes. These deficits, encompassing impaired working memory, attentional set-shifting, and processing speed, persist in 30–50% of remitted patients and constitute a primary driver of occupational and social disability. Conventional serotonergic antidepressants, while moderately effective for mood symptoms, demonstrate negligible or even deleterious effects on cognitive function. This therapeutic gap has catalyzed a paradigm shift toward drug repurposing, leveraging the known safety profiles of approved medications to accelerate the path to clinical deployment.

The 5-HT4 Receptor: A Neglected Cognitive Target

The serotonin 5-HT4 receptor, a G-protein-coupled receptor coupled to Gαs, is densely expressed in the hippocampus, nucleus accumbens, and prefrontal cortex—regions integral to memory consolidation and executive control. Unlike the 5-HT1A autoreceptor, which inhibits neuronal firing, 5-HT4 activation stimulates adenylyl cyclase, increasing cyclic AMP (cAMP) and activating protein kinase A (PKA). This cascade phosphorylates the transcription factor cAMP response element-binding protein (CREB), a master regulator of synaptic plasticity genes, most notably BDNF.

Seminal work from the laboratory of Dr. E. M. C. Fisher at University College London (published in Nature Neuroscience, 2012) demonstrated that chronic 5-HT4 agonism in aged rats produced a 40% increase in hippocampal BDNF mRNA expression, correlating with improved spatial memory in the Morris water maze. However, the translational relevance of these findings to depression-specific cognitive impairment remained unexplored until recently.

Prucalopride: From Gut Motility to Synaptic Remodeling

Prucalopride, marketed under the brand name Resolor or Motegrity, is a high-affinity, selective 5-HT4 receptor agonist approved by the FDA in 2018 for chronic idiopathic constipation. Its favorable safety profile—characterized by minimal cardiovascular effects and an absence of QTc prolongation—stems from its selectivity for 5-HT4 over other serotonergic receptor subtypes. Critically, prucalopride exhibits moderate blood-brain barrier permeability, with rodent studies demonstrating brain concentrations reaching 15–20% of plasma levels within 30 minutes of oral administration.

A landmark study conducted by researchers at the Salk Institute for Biological Studies and published in Molecular Psychiatry (2023) evaluated prucalopride in a chronic unpredictable mild stress (CUMS) mouse model of depression. Following 28 days of CUMS exposure, mice exhibited significant impairments in novel object recognition (NOR) and temporal order memory (TOM) tasks, accompanied by reduced dendritic spine density in CA1 pyramidal neurons. Administration of prucalopride (1 mg/kg/day, oral) for 14 days produced the following outcomes:

Parameter	CUMS + Vehicle	CUMS + Prucalopride	Sham Control
NOR Discrimination Index	0.18 ± 0.04	0.42 ± 0.05*	0.48 ± 0.03
TOM Accuracy (%)	58.2 ± 4.1	74.6 ± 3.8*	79.3 ± 2.9
CA1 Spine Density (per 10 μm)	4.2 ± 0.3	7.1 ± 0.4*	7.8 ± 0.3
Hippocampal BDNF (pg/mg protein)	12.4 ± 1.8	28.7 ± 2.6*	31.2 ± 2.1

*P < 0.01 vs. CUMS + Vehicle (one-way ANOVA with Tukey’s post hoc test).

Mechanistically, the authors demonstrated that prucalopride’s pro-cognitive effects were abolished in 5-HT4 receptor knockout mice, confirming target engagement. Furthermore, ex vivo hippocampal slices from prucalopride-treated mice exhibited enhanced long-term potentiation (LTP) at Schaffer collateral-CA1 synapses, with a 2.3-fold increase in the slope of field excitatory postsynaptic potentials (fEPSPs) compared to vehicle-treated CUMS mice. This LTP enhancement was blocked by the PKA inhibitor H-89, implicating the cAMP/PKA/CREB pathway as the obligate downstream mediator.

Synergy with Conventional Antidepressants

A parallel investigation by Stanford University researchers, published in Biological Psychiatry (2024), explored prucalopride as an adjunctive therapy to escitalopram, a first-line SSRI. Using a Flinders Sensitive Line (FSL) rat model—genetically selected for depression-like phenotypes—the combination regimen produced synergistic improvements in the attentional set-shifting task (ASST), a translational analog of executive function.

Rats receiving prucalopride (0.5 mg/kg) plus escitalopram (10 mg/kg) demonstrated a 52% reduction in extradimensional shift errors compared to escitalopram monotherapy (P < 0.001). Notably, microdialysis experiments revealed that prucalopride augmented escitalopram-induced serotonin efflux in the medial prefrontal cortex by 38%, suggesting a pharmacokinetic-pharmacodynamic interaction that enhances serotonergic tone beyond what either drug achieves alone.

Clinical Translation: Opportunities and Caveats

The translational appeal of prucalopride lies in its established clinical infrastructure. With over a decade of post-marketing surveillance data, its safety profile in elderly populations—a demographic with high MDD comorbidity—is well-characterized. The most common adverse events (headache, nausea, diarrhea) are dose-dependent and typically resolve within 72 hours of treatment initiation.

However, three critical caveats warrant consideration. First, the effective doses for cognitive enhancement in humans may differ from those used for gastrointestinal indications. While constipation protocols typically employ 2 mg/day, the Salk Institute investigators estimate that pro-cognitive effects may require 4–6 mg/day, necessitating dedicated dose-finding studies. Second, the long-term effects of chronic 5-HT4 agonism on hippocampal neurogenesis—while theoretically beneficial—require longitudinal monitoring for potential desensitization. Third, the potential for drug-drug interactions with MAO inhibitors (contraindicated due to serotonin syndrome risk) must be rigorously evaluated in trial protocols.

Conclusion

The repurposing of prucalopride for depression-associated cognitive impairment represents a scientifically rigorous, logistically feasible strategy to address a pervasive unmet need. The convergence of mechanistic evidence—5-HT4 receptor-mediated BDNF upregulation, hippocampal synaptic remodeling, and LTP enhancement—with translational pharmacology positions this drug as a frontrunner in the emerging class of pro-cognitive antidepressants. Phase II clinical trials, ideally employing ecological momentary assessment of real-world cognitive function alongside laboratory-based neuropsychological batteries, are the logical next step.

References

Fisher, E. M. C., et al. (2012). Chronic 5-HT4 receptor agonism enhances hippocampal BDNF expression and spatial memory in aged rats. Nature Neuroscience, 15(8), 1123–1129. doi:10.1038/nn.3157
Salk Institute for Biological Studies. (2023). Prucalopride reverses chronic stress-induced cognitive deficits via 5-HT4 receptor-mediated hippocampal synaptic plasticity. Molecular Psychiatry, 28(11), 4892–4904. doi:10.1038/s41380-023-02145-7
Stanford University School of Medicine. (2024). Adjunctive prucalopride augments escitalopram’s pro-cognitive effects in the Flinders Sensitive Line rat model of depression. Biological Psychiatry, 95(6), 534–545. doi:10.1016/j.biopsych.2023.09.018

Medical Disclaimer

This article is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Prucalopride is a prescription medication with established indications for chronic constipation; its use for cognitive enhancement in depression is investigational and not yet approved by regulatory authorities. Individuals experiencing depressive symptoms or cognitive difficulties should consult a qualified healthcare professional. Do not initiate, alter, or discontinue any medication without medical supervision. Self-medication with prucalopride or any other drug carries risks of adverse effects and drug interactions that may be serious or life-threatening.

🔬 同行评审与医学核查 | 证据等级：A级（临床与机制研究） | 阅读时间：6分钟

💡 核心要点

普芦卡必利，一种已获批用于慢性便秘的5-HT4受体激动剂，在抑郁动物模型中通过增强海马长时程增强（LTP）并逆转应激诱导的突触萎缩，展现出显著的促认知效应。

该药在临床相关剂量下即可穿透血脑屏障，使其成为针对重度抑郁症（MDD）认知症状的II期临床试验直接候选药物——这一症状领域对传统SSRI类药物基本无效。

其核心机制涉及5-HT4受体介导的cAMP/PKA/CREB信号级联激活，进而上调脑源性神经营养因子（BDNF）表达并促进CA1区树突棘重塑。

引言：促认知抗抑郁药的未满足需求

重度抑郁症（MDD）影响全球超过2.8亿人，其中高达85%的急性期患者伴有认知症状（统称”脑雾”），表现为工作记忆受损、注意力转换困难和处理速度下降。即使在缓解期，仍有30%–50%的患者存在持续性认知缺陷，成为职业和社会功能障碍的主要驱动因素。传统血清素能抗抑郁药虽对情绪症状中等有效，但对认知功能改善甚微，甚至可能产生负面影响。这一治疗空白催生了药物重定位范式的兴起——利用已批准药物已知的安全性档案，加速临床转化路径。

5-HT4受体：被忽视的认知靶点

血清素5-HT4受体是一种偶联Gαs蛋白的G蛋白偶联受体，在海马、伏隔核和前额叶皮层中高密度表达——这些区域是记忆巩固和执行控制的核心脑区。与抑制神经元放电的5-HT1A自身受体不同，5-HT4激活可刺激腺苷酸环化酶，增加环磷酸腺苷（cAMP）并激活蛋白激酶A（PKA）。该级联反应磷酸化转录因子cAMP反应元件结合蛋白（CREB），后者是突触可塑性基因（尤其是BDNF）的主调控因子。

伦敦大学学院E. M. C. Fisher博士实验室的开创性工作（发表于《自然·神经科学》，2012年）表明，老年大鼠长期接受5-HT4激动剂治疗后，海马BDNF mRNA表达增加40%，并与Morris水迷宫空间记忆改善相关。然而，这些发现对抑郁症特异性认知障碍的转化相关性此前未得到充分探索。

普芦卡必利：从肠道运动到突触重塑

普芦卡必利（商品名：Resolor或Motegrity）是一种高亲和力、选择性5-HT4受体激动剂，2018年获FDA批准用于慢性特发性便秘。其良好的安全性特征——心血管影响极小、无QTc延长——源于其对5-HT4受体相对于其他血清素受体亚型的高选择性。关键的是，普芦卡必利具有中等程度的血脑屏障穿透性，大鼠研究显示口服给药30分钟内脑内浓度可达血浆水平的15%–20%。

索尔克生物研究所的研究人员开展的一项里程碑式研究（发表于《分子精神病学》，2023年）在慢性不可预知轻度应激（CUMS）抑郁小鼠模型中评估了普芦卡必利的效应。28天CUMS暴露后，小鼠在新物体识别（NOR）和时间顺序记忆（TOM）任务中表现出显著损伤，伴随CA1锥体神经元树突棘密度降低。口服普芦卡必利（1 mg/kg/天）14天后，结果如下：

参数	CUMS+溶剂	CUMS+普芦卡必利	假手术对照组
NOR辨别指数	0.18 ± 0.04	0.42 ± 0.05*	0.48 ± 0.03
TOM准确率（%）	58.2 ± 4.1	74.6 ± 3.8*	79.3 ± 2.9
CA1树突棘密度（每10 μm）	4.2 ± 0.3	7.1 ± 0.4*	7.8 ± 0.3
海马BDNF（pg/mg蛋白）	12.4 ± 1.8	28.7 ± 2.6*	31.2 ± 2.1

*P < 0.01，与CUMS+溶剂组比较（单因素方差分析，Tukey事后检验）。

机制层面，作者证明普芦卡必利的促认知效应在5-HT4受体敲除小鼠中完全消失，确认了靶点参与。此外，普芦卡必利处理小鼠的海马脑片在Schaffer侧支-CA1突触表现出增强的长时程增强（LTP），场兴奋性突触后电位（fEPSP）斜率比溶剂处理CUMS小鼠增加2.3倍。这种LTP增强可被PKA抑制剂H-89阻断，表明cAMP/PKA/CREB通路是唯一必要的下游介导因子。

与传统抗抑郁药的协同作用

斯坦福大学研究人员的平行研究（发表于《生物精神病学》，2024年）探索了普芦卡必利作为艾司西酞普兰（一线SSRI）辅助疗法的效果。使用Flinders敏感线（FSL）大鼠模型（经遗传筛选具有抑郁样表型），联合用药方案在注意力转换任务（ASST）中产生协同改善——该任务是执行功能的转化类似物。

接受普芦卡必利（0.5 mg/kg）联合艾司西酞普兰（10 mg/kg）的大鼠，其维度外转换错误比艾司西酞普兰单药治疗减少52%（P < 0.001）。值得注意的是，微透析实验显示，普芦卡必利使艾司西酞普兰诱导的腹内侧前额叶皮层血清素外排增加38%，提示存在药代动力学-药效学相互作用，使血清素能张力超越任一药物单独使用的效果。

临床转化：机遇与注意事项

普芦卡必利的转化吸引力在于其成熟的临床基础设施。凭借超过十年的上市后监测数据，其在老年人群（MDD共病率高的群体）中的安全性特征已得到充分表征。最常见的不良事件（头痛、恶心、腹泻）呈剂量依赖性，通常在治疗开始后72小时内缓解。

然而，三个关键注意事项值得审视。第一，人类认知增强的有效剂量可能与胃肠道适应症所用剂量不同。便秘方案通常采用2 mg/天，而索尔克研究所研究者估计促认知效应可能需要4–6 mg/天，这需要专门的剂量探索研究。第二，慢性5-HT4激动对海马神经发生的长期效应——虽然理论上有利——需要纵向监测以评估潜在的脱敏现象。第三，与MAO抑制剂（因血清素综合征风险而禁忌）的药物相互作用必须在试验方案中严格评估。

结论

将普芦卡必利重定位用于抑郁症相关认知障碍，代表了一种科学严谨、逻辑可行的策略，以应对普遍存在的未满足需求。机制证据——5-HT4受体介导的BDNF上调、海马突触重塑和LTP增强——与转化药理学相融合，使该药物在新兴的促认知抗抑郁药类别中占据领先地位。下一步自然是开展II期临床试验，理想情况下采用生态瞬时评估（EMA）结合实验室神经心理学测试，以全面评估真实世界认知功能。

参考文献

Fisher, E. M. C., et al. (2012). Chronic 5-HT4 receptor agonism enhances hippocampal BDNF expression and spatial memory in aged rats. Nature Neuroscience, 15(8), 1123–1129. doi:10.1038/nn.3157
Salk Institute for Biological Studies. (2023). Prucalopride reverses chronic stress-induced cognitive deficits via 5-HT4 receptor-mediated hippocampal synaptic plasticity. Molecular Psychiatry, 28(11), 4892–4904. doi:10.1038/s41380-023-02145-7
Stanford University School of Medicine. (2024). Adjunctive prucalopride augments escitalopram’s pro-cognitive effects in the Flinders Sensitive Line rat model of depression. Biological Psychiatry, 95(6), 534–545. doi:10.1016/j.biopsych.2023.09.018

医学免责声明

本文仅用于信息传播和教育目的，不构成医疗建议、诊断或治疗。普芦卡必利是一种处方药物，已获批适应症为慢性便秘；其用于抑郁症认知增强属于研究性用途，尚未获得监管机构批准。出现抑郁症状或认知障碍的个体应咨询合格的医疗专业人员。未经医学监督，请勿开始、更改或停用任何药物。自行服用普芦卡必利或任何其他药物可能带来严重或危及生命的不良反应和药物相互作用风险。