Preemptive analgesia regimen modulates hippocampal c-fos expression in a rat postoperative uterine pain model

The study evaluated morphologically c-fos positive neuronal cells in hippocampal areas and additionally assessed rat behavior associated with the use of a preemptive analgesia regimen in rat surgical pain models.

Sixty female Sprague-Dawley rats, weighing 150-250 g and 8-10 weeks of age, were included in this laboratory-based experimental study at Khyber Medical University, Peshawar, over approximately 2 years, from January 2022 to January 2024. The rats were divided into a superficial pain group and a deep pain group. Each group was further subdivided into tramadol, buprenorphine, and saline subgroups. Isoflurane general anesthesia was administered. Pain was assessed with a subjective pain scale (Abdominal Pain Assessment, APA) at 2, 4, 6, 9, and 24 h post-surgery. Expression of c-fos in hippocampal tissue, including the dentate gyrus, CA1, and CA3 regions, was detected immunohistochemically.

Postoperative administration of a preemptive regimen comprising either buprenorphine or tramadol significantly (p < 0.01) mitigated the presence of surgically induced c-fos expressing cells in the hippocampus in both primary groups. Furthermore, across the entire time period (p ≤ 0.05) the preemptive treatment in the deep pain group resulted in a considerably lower APA than observed in the saline group. However, in the superficial pain group, the differences in APA among the three subgroups were statistically insignificant (p > 0.05).

Postoperative pain was significantly diminished in animal models with use of a preemptive regimen. This regimen not only decreased pain transmission but also ameliorated emotional distress in the animals.