Basil (Ocimum basilicum) Leaves Essential Oil Ameliorates GluR1 Receptor Expression, TNF-α Level, and Pain-like Behaviors in Post-operative Pain Setting

Background: Unrelieved post-operative pain is an emerging healthcare concern with ever increasing global volume of surgical procedures. GluR1 subunit coupled with tumor necrosis factor (TNF)-α expression plays a major role in the development of post-operative pain mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor. There was no existing evidence on the analgesic potential of basil essential oil (BEO) in post-operative settings, despite its well-established antinociceptive and anti-inflammatory activities. Materials and Methods: BEO was subjected to gas chromatography-mass spectrometry (GC-MS) analysis to identify the active ingredients. The antinociceptive and anti-inflammatory activities of orally administrated basil (Ocimum basilicum) essential oil were tested in a rat model of post-operative pain using hindpaw surgical incision as noxious stimuli. TNF-α and GluR1 subunit expressions were measured using enzyme-linked immunosorbent assay and immunohistochemistry methods. Spontaneous pain and mechanical hyperalgesia were measured using mouse grimace scale and Von Frey monofilament test, respectively. All outcomes were evaluated in acute post-operative pain timeframe. Results: Chemical analysis identified 14 terpenoids predominated with caryophyllene and citral. BEO administration caused a significant reduction of TNF-α (67.23 ± 2.46 vs. 70.45 ± 4.89; P = 0.019) and GluR1 (3.03 ± 0.56 vs. 3.90 ± 1.12; P = 0.005) levels at 24 h after surgical incision when compared with the control group. Significant spontaneous pain, pain threshold, and pain-like behaviors frequency reduction at 1-, 4-, and 24-h post-surgical incision were also noted. Conclusion: Effective antinociceptive activity of BEO through modulation of GluR1 and TNF-α levels was further confirmed in the behavioral outcome. Advancement into clinical translation necessitates BEO pharmacological profiling, especially given the diversity of chemotypes.