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[Sensory neuropeptide SP modulating expression of EGF, FGF-2 and their receptors in fibroblasts of granulation in vivo and in vitro].

OBJECTIVE
To study the modulating effect of sensory neuropeptide substance P (SP) on gene expression of epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2) and EGF receptor (EGFR), FGF receptor-1 (FGFR-1) in granulation fibroblast.


METHODS
The study consisted of two parts, in vivo and in vitro. In vivo, fifty wistar rats were randomly arranged into capsaicin group and control group. The rats in capsaicin group were subcutaneously injected with neurotoxin dose of capsaicin (50 mg/kg) on the back of the rats to chemically destroy sensory nerves to prevent the release of SP. After one week, full-thickness skin wounds were created on the rats' back. SP content and EGF, EGFR, FGF-2, FGFR-1 gene expression in the granulation tissue were observed using immunohistochemistry and in situ hybridization combined with image analysis on 3rd, 6th, 9th 12th after skin injury, respectively. The experimental procedure in control group were similar with that in capsaicin group except injection with capsaicin. In vitro, SP (10(-9)-10(-5) mol/L) was added into culture medium for cultured fibroblasts from granulation and mRNA expressions of EGF, FGF-2 and their receptors were assayed with RT-PCR.


RESULTS
In the present study, immunoreactive stain for SP in granulation tissue were correlated with gene expression of EGF, FGF-2 and their receptors using in situ hybridization in vivo. Once sensory nerves were destroyed and SP release was inhibited in capsaicin group, the gene expression of above growth factors and their receptors were attenuated. SP concentrations in culture medium for upregulation of mRNA expressions of EGF and EGFR in cultured fibroblasts were from 10(-8) mol/L to 10(-6) mol/L and from 10(-6) mol/L to 10(-5) mol/L, respectively. SP concentration was from 10(-9) mol/L to 10(-5) mol/L for upregulation of FGF-2 mRNA expression in cultured fibroblasts and from 10(-6) mol/L to 10(-5) mol/L for upregulation of FGFR-1.


CONCLUSION
Sensory neuropeptide SP released from sensory nerve participates in upregulation of gene expressions of EGF, EGF-2 and their receptors in granulation fibroblasts during wound healing.