[Changes of Substance P in the substantia gelatinosa of the dorsal horn field after liquid nitrogen freezing of severed nerve for prevention of terminal neuroma].

OBJECTIVE

To determine the changes of Substance P in the substantia gelatinosa of the dorsal horn field after transient liquid nitrogen freezing of severed rat sciatic nerve for prevention of terminal neuroma.

METHODS

The bilateral sciatic nerves of 20 SD rats were severed, and the left sciatic nerves was subjected to transient liquid nitrogen freezing with the right sciatic nerve as control. After 20 and 28 weeks, the nerve ends were resected and prepared for microscopic examination, and Substance P in the substantia gelatinosa of the dorsal horn field was determined by immunohistochemistry.

RESULTS

Typical neuromas occurred in the severed ends of the right sciatic nerves but not in the left sciatic nerves. The distribution and optical density of Substance P in the substantia gelatinosa of the dorsal horn field was significantly smaller in the left than in the right nerves (P<0.05).

CONCLUSION

Liquid nitrogen freezing of the severed sciatic nerve results in decreased release of Substance P in the substantia gelatinosa of the dorsal horn field, suggesting that noxious stimulation may increase Substance P release in the substantia gelatinosa of the dorsal horn field.