Anti-nociceptive effect of bovine milk-derived lactoferrin in a rat lumbar disc herniation model.

Abstract

An experimental animal study. We evaluated the efficacy of lactoferrin (LF) compared with diclofenac to reduce the pain, using a rat lumbar disc herniation model. LF is a multifunctional protein that is found in milk. Recent studies have reported that LF reduces nociception in various experimental models. Rats were operated on the left L5 vertebral arch. The left L5 nerve root and dorsal root ganglion (DRG) were exposed by a L5 partial laminectomy. An L-shaped stainless steel rod was inserted from the laminectomy toward the intervertebral foramen to compress the nerve root. In addition, nucleus pulposus from coccygeal discs was applied on the nerve root. At 1 day before operation, all rats were tested regarding the withdrawal threshold of the left plantar surface using von Frey filaments to determine baseline values. Additional von Frey tests were performed on postoperative days 3, 7, 14, and 21. Thirty minutes before each test except for baseline, the rats received LF (100 mg/kg), diclofenac (10 mg/kg), or saline by intraperitoneal injection (n = 6). As compared with the control group, thresholds of rats in the diclofenac group were significantly higher on postoperative days 3 and 7. However, on postoperative days 14 and 21, there were no significant differences. Thresholds of rats in the LF group were significantly higher on all postoperative days compared with the control group. Analgesic effect of diclofenac reduced with time. However, the effect of LF continued during the whole experimental period. LF might become useful as pain-killer.