Feyzi Hanieh, Khakpai Fatemeh, Khakpay Roghaieh, Hesari Farzam Sheikhzadeh, Semnanian Saeed
Department of Animal Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran.
Department of Physiology, Faculty of Medicine, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
Acta Neurobiol Exp (Wars). 2022;82(4):521-533. doi: 10.55782/ane-2022-050.
This study was designed to investigate a possible interaction between 17β‑estradiol and glutamate receptors of the paragigantocellularis lateralis (LPGi) nucleus on pain coping behavior using the formalin test in ovariectomized (OVX) rats. The results showed that intra‑LPGi injection of 17β‑estradiol declined flexing behavior in both phases of the formalin test. Still, it only diminished the late phase of licking behavior in the OVX rats. NMDA receptor antagonist, AP5, reversed the analgesic effect of 17β‑estradiol on flexing behavior in both phases of the formalin test in the OVX rats. The 17β‑estradiol‑induced anti‑nociceptive effect on the flexing duration was prevented by CNQX (AMPA receptor antagonist) only in the early phase of the formalin test in the OVX rats. AP5 and CNQX reduced the anti‑nociceptive effect of 17β‑estradiol in the late phase, but not the early phase of licking response in the OVX rats. These results suggested: (i) The intra‑LPGi injection of 17β‑estradiol is satisfactory in producing modest analgesia on the formalin‑induced inflammatory pain in the OVX rats; (ii) Co‑treatment of glutamate receptors (NMDA and AMPA) antagonists and 17β‑estradiol in the LPGi nucleus decrease the analgesic effect of 17β‑estradiol in the OVX rats; (iii) There is a possible association between 17β‑estradiol and glutamate receptors of the LPGi nucleus on pain coping behavior in the OVX rats.
本研究旨在通过福尔马林试验，研究17β-雌二醇与去卵巢（OVX）大鼠外侧巨细胞旁核（LPGi）的谷氨酸受体之间在疼痛应对行为上可能存在的相互作用。结果显示，向LPGi内注射17β-雌二醇可降低福尔马林试验两个阶段的屈曲行为。不过，它仅减少了OVX大鼠舔舐行为的后期阶段。NMDA受体拮抗剂AP5可逆转17β-雌二醇对OVX大鼠福尔马林试验两个阶段屈曲行为的镇痛作用。仅在OVX大鼠福尔马林试验的早期阶段，CNQX（AMPA受体拮抗剂）可阻止17β-雌二醇对屈曲持续时间的抗伤害感受作用。AP5和CNQX在后期阶段降低了17β-雌二醇的抗伤害感受作用，但在OVX大鼠舔舐反应的早期阶段则没有。这些结果表明：（i）向LPGi内注射17β-雌二醇可有效减轻OVX大鼠福尔马林诱导的炎性疼痛；（ii）在LPGi核内联合使用谷氨酸受体（NMDA和AMPA）拮抗剂与17β-雌二醇可降低17β-雌二醇对OVX大鼠的镇痛作用；（iii）在OVX大鼠的疼痛应对行为方面，17β-雌二醇与LPGi核的谷氨酸受体之间可能存在关联。
