Dental pulp fibroblasts express neuropeptide Y Y1 receptor but not neuropeptide Y

To investigate whether dental pulp fibroblasts express neuropeptide Y (NPY) and NPY-Y1 in vitro and to determine the effects of the cytokines including interleukin-1β (IL-1β), TGF- β(1) , substance P and NPY on the expression of NPY Y1.

Three primary fibroblast cell strains were obtained from freshly extracted human third molar teeth. RT-PCR was utilized to detect expression of NPY and mRNA expression. Membrane protein samples were isolated, and protein expression was determined by Western blotting. Radioimmunoassay was used to quantify NPY expression in healthy (n = 35) and carious (n = 39) whole pulp samples, and the student's t-test was used to test for statistical significance. In addition, the 3-(4,5-Dimethylthiazol,2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to assay fibroblast cell growth.

mRNA transcripts were found in all three fibroblast cell populations with the cytokines having a stimulatory effect on its expression (P < 0.05). NPY mRNA was not detected in the cell strains. NPY-Y1 receptor protein expression was visualized by Western blotting, and there was no effect of IL-1β or TGF- β(1) on its expression. The mean concentration of NPY-Ir determined by radioimmunoassay in non-carious teeth was 19.40 ng x g(-1) (±17.03 SD) compared to 29.95 ng x g(-1) (±20.99 SD) in carious teeth (P < 0.05).

Human dental pulp fibroblasts express, but do not synthesize, NPY, demonstrating that the fibroblast is a target cell for NPY. The effect of proinflammatory cytokines suggests that fibroblasts play a neuroimmunomodulatory role in the pulpal response to dental caries and injury.