Maldevelopment of spinal cord--substance P in spina bifida.

Recent works have shown that the neuropeptide, substance P, is an important element of the central nervous system, functioning as a neurotransmitter as well as moderating neural development. In a previous communication, we provided indirect evidence that substance P played a role in the pathogenesis and pathophysiology of spina bifida by showing an elevation of CSF substance P concentrations in affected foetuses and babies. In this study, we investigated directly the occurrence of substance P in spinal cord tissues in spina bifida and compared it to that found during normal development. Using radioimmunoassay, concentrations of substance P were measured in the spinal cords of 20 normal human foetuses (aged 9-21 weeks) and 4 foetuses with spina bifida (aged 17-19 weeks). Substance P was detected in substantial amounts in the normal foetal spinal cord as early as 9 weeks' gestation, and there was progressive accumulation with age: mean concentrations +/- S.E.M. in 3 subgroups were 56.3 +/- 4.9 pmol g-1 (9-12 weeks), 59.5 +/- 7.2 pmol g-1 (13-16 weeks) and 117.3 +/- 7.2 pmol g-1 (17-21 weeks). In spina bifida, substance P was severely depleted in the dysraphic segment of the cord (mean concentration +/- S.E.M. = 22.1 +/- 2.3 pmol g-1) and moderately so in the segment above the dysraphism (mean concentration +/- S.E.M. = 47.2 +/- 4.2 pmol g-1).(ABSTRACT TRUNCATED AT 250 WORDS)