Pseudospondias microcarpa is used in ethnomedicine to manage central nervous system diseases. The hydroethanolic extract (PME) from the leaves of the plant has shown anxiolytic-like properties in mice anxiety models. However, its effects in chronic anxiety models and possible mechanism(s) of action were not studied. Therefore, the current study evaluated the anxiolytic-like mechanisms of PME in zebrafish models of anxiety. The zebrafish light dark test (LDT) and novel tank test (NTT) were employed to assess the anxiolytic-like effects of PME (0.1, 0.3, 1.0 mg mL⁻¹), fluoxetine (3 × 10⁻⁵ mg mL⁻¹) and diazepam (1.5 × 10⁻⁷ mg mL⁻¹). The chronic unpredictable stress (CUS) test was used to further evaluate the extract’s anxiolytic-like properties. The potential mechanisms of anxiolytic action of the extract was evaluated after pre-treated with flumazenil, granisetron, methysergide, or pizotifen, all at 1 × 10⁻³ mg mL⁻¹. The extract significantly decreased anxiety behaviours in the NT and LD tests. These observed effects of the extract were however counteracted by flumazenil, granisetron, methysergide and pizotifen pre-treatment. In addition, PME treatment significantly reversed CUS-induced anxiety behaviours in zebrafish. Results show that PME possesses anxiolytic-like effects possibly through interaction with serotonergic and gamma-aminobutyric acid mediated pathways.

Graphical abstract

中文翻译：

---

Pseudospondias microcarpa 氢乙醇叶提取物对斑马鱼的抗焦虑样作用：可能涉及 GABA 能和血清素能途径

Pseudospondias microcarpa在民族医学中用于治疗中枢神经系统疾病。该植物叶子的氢乙醇提取物（PME）在小鼠焦虑模型中显示出类似抗焦虑的特性。然而，尚未研究其对慢性焦虑模型的影响和可能的作用机制。因此，本研究评估了 PME 在斑马鱼焦虑模型中的抗焦虑样机制。采用斑马鱼亮暗试验（LDT）和新型坦克试验（NTT）评估PME（0.1、0.3、1.0 mg mL ^-1）、氟西汀（3 × 10 ^-5  mg mL ^-1）的抗焦虑样作用和地西泮（1.5 × 10 ^-7  mg mL ^-1）。慢性不可预测压力（CUS）测试用于进一步评估提取物的抗焦虑样特性。^{用氟马西尼、格拉司琼、美西麦角或吡唑替芬（均为 1 × 10 -3}  mg mL ^{-1 ）}预处理后，评估提取物抗焦虑作用的潜在机制。该提取物显着降低了 NT 和 LD 测试中的焦虑行为。然而，观察到的提取物的这些作用被氟马西尼、格拉司琼、美西麦角和匹佐替芬预处理所抵消。此外，PME 治疗显着逆转了 CUS 引起的斑马鱼焦虑行为。结果表明，PME 可能通过与血清素能和 γ-氨基丁酸介导的途径相互作用而具有抗焦虑样作用。

图形概要