The Effect of MS-430, a Synthetized Pyrimidine Compound, on Regeneration of Nerve Fibers of Rats after Crush Injury

―A Morphometric Study―

Abstract

One of the synthetized pyrimidine compounds, 2-piperidino-7-methyl-6-oxo-5,6-dihydro-(7H) pyrrolo [2,3-d] pyrimidine maleate (MS-430), has neurotropic effects in vitro. Therefore, we studied the effect of MS-430 on regeneration of the myelinated fibers of the peroneal and sural nerve of Sprague-Dawley rats after crush injury in two tests, intraperitoneally administered daily 1.0 mg/kg (test 1, n=7) and 7.5 mg/kg (test 2, n=8) of MS-430, respectively. We then compared the effects with the control rats (n=7) administered similarly as in the tests with physiological saline for 14 days from the day after crushing. Twenty-four hours after completion of the administration, the sural nerves at 7.5 mm and 15 mm distal to the crushed site, and the peroneal nerve at 15 mm distal to the crushed site were removed from each rat used in the two tests and from the controls, and then embedded into epoxy resin. In the sural nerve, the total number of regenerated myelinated fibers per nerve in test 2 was greater (P<0.05) than in the controls at 7.5 mm distal to the crushed site. However, it was similar among the three groups at 15 mm distal to the crushed site. In the case of the peroneal nerve, it was greater in both tests 1 and 2 than in the controls, however the difference was not statistically significant. The mean diameter of regenerated fibers was greater (P<0.001) in the controls than in tests 1 and 2, suggesting an absence of the promotion of the maturation of the regenerated myelinated fibers. Based on the data described, we concluded that the regeneration of the myelinated fibers of the sural nerve only in rats administered 7.5 mg/kg of MS-430, mainly containing sensory nerve fibers, was promoted in the nerve relatively close to the crushed site.