Improved Outcome after Peripheral Nerve Injury in Mice with Increased Levels of Endogenous Omega-3 Polyunsaturated Fatty Acids

Functional recovery after a peripheral nerve injury (PNI) is often poor. There is a need for therapies that protect neurons against injury and enhance regeneration. Omega-3 polyunsaturated fatty acids (PUFAs) have been shown to have therapeutic potential in a variety of neurological disorders, including acute traumatic injury. The objective of this study was to assess the neuroprotective and proregenerative potential of omega-3 PUFAs in PNI. We investigated this in mice that express the fat-1 gene encoding for omega-3 fatty acid desaturase, which leads to an increase in endogenous omega-3 PUFAs and a concomitant decrease in omega-6 PUFAs. Dorsal root ganglion (DRG) neurons from wild-type or fat-1 mice were subjected to a mechanical strain or hypoxic injury, and cell death was assessed using ethidium homodimer-1 labeling. The fat-1 background appears to confer robust neuroprotection against both injuries. We then examined the early functional and morphological changes in wild-type and fat-1 mice after a sciatic nerve crush. An accelerated functional recovery 7 d after injury was seen in fat-1 mice when assessed using von Frey filaments and the sciatic nerve functional index. These observations were also mapped to changes in injury-related markers. The injury-induced expression of ATF-3 was decreased in the DRG of fat-1 mice, whereas the axons detected 6 mm distal to the crush were increased. Fat-1 animals also had some protection against muscle atrophy after injury. In conclusion, both in vitro and in vivo experiments support the idea that a higher endogenous omega-3 PUFA could lead to beneficial effects after a PNI.