High Omega-3 Polyunsaturated Fatty Acids in fat-1 Mice Reduce Inflammatory Pain.

Omega-3 and omega-6 polyunsaturated fatty acids (PUFAs), such as α-linolenic and linoleic acids, are essential fatty acids in mammals, because they cannot be synthesized de novo. However, fat-1 transgenic mice can synthesize omega-3 PUFAs from omega-6 PUFAs without dietary supplementation of omega-3, leading to abundant omega-3 PUFA accumulation in various tissues. In this study, we used fat-1 transgenic mice to investigate the role of omega-3 PUFAs in response to inflammatory pain. A high omega-3 PUFA tissue content attenuated formalin-induced pain sensitivity, microglial activation, inducible nitric oxide synthase expression, and the phosphorylation of NR2B, a subunit of the N-methyl-d-aspartate (NMDA) receptor. Our findings suggest that elevated omega-3 PUFA levels inhibit NMDA receptor activity in the spinal dorsal horn and modulate inflammatory pain transmission by regulating signal transmission at the spinal dorsal horn, leading to the attenuation of chemically induced inflammatory pain.

Heated carrier fluids in decreasing propofol injection pain: a randomized, controlled trial.

BACKGROUND: Propofol is a commonly used intravenous drug during anesthetic induction because of its rapid onset and short duration. However, the injection pain that patients experience is so severe that they recall the induction of anesthesia as the most painful part of the perioperative period. Therefore, the objective of this study was to determine the effect of heated carrier fluids (40℃) in decreasing propofol injection pain. METHODS: A randomized, controlled clinical trial was conducted in 90 patients aged 18 to 65 who were scheduled for either elective or urgent surgery under general anesthesia classified as American Society of Anesthesiologists physical status I or II. Patients were allocated into the following 3 groups: 1) Group W (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to propofol injection; 2) Group L (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to 0.5 mg/kg 1%lidocaine 1 minute before propofol injection; 3) Group C (control group, n = 30) who received 200 ml of room temperature fluids prior to propofol injection. Pain was evaluated using verbal pain score (VPS). RESULTS: Group W and Group L showed significant reduction (P = 0.001) in the incidence and severity of injection pain compared to Group C. VPS scores were significantly lower in Group W and Group L compared to those of Group C. Incidence of propofol injection pain was statistically different between Group W (P = 0.005) and Group L (P = 0.037) compared to Group C, but not statistically different between Group W and Group L (P = 0.432). CONCLUSIONS: Both sole injection of heated carrier fluids and the combination of 0.5 mg/kg 1%lidocaine pretreatment effectively reduced propofol injection pain.