Thymoquinone eases postoperative pain in rats by calming spinal oxidative, inflammatory and apoptotic pathways

Thymoquinone, the primary bioactive compound of the seed oil of Nigella sativa, has drawn attention as a possible plant-derived alternative for managing acute postoperative pain, a condition that matters clinically because it can progress to chronic pain. A new rat study published in BMC Neuroscience examined whether this natural compound could blunt the mechanical hypersensitivity that follows a surgical incision, and whether its effects run through spinal cord oxidative, inflammatory and apoptotic pathways. The work compared thymoquinone with celecoxib, a widely used nonsteroidal anti-inflammatory drug whose utility is frequently limited by side effects.

The researchers induced acute postoperative pain through a plantar hind paw incision, a standard model of postsurgical pain. Rats then received thymoquinone or celecoxib orally at 4 hours after surgery and again on postoperative days 1 and 2, or a single dose injected intrathecally, delivering the drug directly into the spinal canal. Mechanical allodynia, pain hypersensitivity to normally innocuous touch, was measured with von Frey filaments, which quantify the paw withdrawal threshold. Locomotor activity was assessed in an open-field test to check that any apparent pain relief was not simply sedation or impaired movement. After treatment, spinal cord tissue was assayed for biomarkers of oxidative stress, inflammation and apoptosis.

The incision itself produced the expected effect: a marked decrease in paw withdrawal thresholds on postoperative days 1 through 3 in vehicle-treated animals, confirming significant mechanical allodynia. Oral thymoquinone at 5 and 10 mg/kg and oral celecoxib at 10 mg/kg attenuated this hypersensitivity, as did intrathecal injection of 25 and 200 µg of either compound. In both cases the drugs normalized paw withdrawal thresholds without impairing locomotor function, indicating genuine antinociceptive activity rather than general motor suppression.

Biochemical analysis of the spinal cord revealed the mechanisms the title of the study points to. Surgery elevated levels of malondialdehyde, a marker of lipid peroxidation and oxidative stress; TNF-α, a pro-inflammatory cytokine central to neuroinflammation; and caspase-3, the executioner enzyme of the apoptotic cell-death pathway. Both thymoquinone and celecoxib effectively mitigated these surgery-induced elevations while restoring the activity of superoxide dismutase, a key antioxidant enzyme that defends neural tissue against reactive oxygen species. In other words, the treatment acted simultaneously on oxidative damage, inflammatory signaling and programmed cell death within the spinal cord.

A notable finding was the absence of statistically significant differences between thymoquinone and celecoxib at the corresponding tested doses. The natural compound matched the reference analgesic in behavioral relief and in each of the three biochemical domains measured. The authors conclude that thymoquinone exhibits strong antinociceptive activity in postsurgical pain, an effect likely attributable to its concurrent modulation of spinal oxidative stress, neuroinflammation and apoptotic pathways, with efficacy comparable to that of celecoxib.

Equally significant was the route of administration. Equivalent anti-allodynic activity via both oral and intrathecal routes suggests favorable bioavailability and central target engagement: the compound reaches the spinal cord in effective amounts when given systemically, and acts directly on spinal targets when delivered intrathecally. The researchers interpret this as supporting thymoquinone’s potential as a naturally derived alternative in acute postoperative pain management, particularly given the side-effect limitations of conventional systemic and local analgesics.

The study’s framing is cautious where it needs to be. The title states that the antinociceptive action may be associated with modulation of these spinal pathways, and the conclusions describe the mechanistic link as likely rather than proven. The experiments were conducted in a single animal model of incisional pain, with behavioral and biochemical endpoints measured over a few postoperative days. As with any preclinical rodent study, translation to human postoperative care would require further research, and the abstract notes that this early-release version is subject to further edits before the final Version of Record.

Nevertheless, the convergence of behavioral and molecular evidence gives the findings weight. Pain behavior, oxidative stress markers, inflammatory cytokines and apoptotic enzymes all moved in the same direction after treatment, and the open-field results rule out the most obvious behavioral confound. For a field searching for alternatives to drugs with limiting side effects, a seed-derived compound that normalizes paw withdrawal thresholds, restores antioxidant enzyme activity and suppresses spinal TNF-α and caspase-3, performing on par with celecoxib, is a result worth watching as the research moves from rats toward potential clinical evaluation.

Subject of Research: Antinociceptive effects of thymoquinone in a rat model of acute postoperative incision pain, mediated through spinal oxidative, inflammatory and apoptotic pathways

Article Title: The antinociceptive action of thymoquinone on hind paw incision-evoked pain may be associated with modulation of the spinal cord oxidative, inflammatory, and apoptotic pathways

Article References: Ghoreishi, S. S., Azizi, S., Tamaddonfard, E., & Aghazadeh, S. (2026). The antinociceptive action of thymoquinone on hind paw incision-evoked pain may be associated with modulation of the spinal cord oxidative, inflammatory, and apoptotic pathways. BMC Neuroscience. https://doi.org/10.1186/s12868-026-01066-7

Image Credits: AI Generated

DOI: 10.1186/s12868-026-01066-7

Keywords: thymoquinone, Nigella sativa, postoperative pain, mechanical allodynia, spinal cord, oxidative stress, neuroinflammation, apoptosis, celecoxib, rat model, hind paw incision, antinociception