Abstract
Purpose: :
Neuropeptide Y (NPY) is a 36 amino acid peptide that acts through the activation of six G–protein–coupled receptors named NPY Y1, Y2, Y3, Y4, Y5, and y6. NPY is present in the retina, but its physiological role is unknown. Some studies demonstrated that NPY promotes cell proliferation in rat post–natal hippocampal precursor cells and in post–natal olfactory epithelium cells. In this study, we investigated the role of NPY on cell proliferation in rat retinal neural cell cultures.
Methods: :
Rat retinal neural cells were prepared from newborn Wistar rats and cultured for 9 days. Cell proliferation was evaluated by incorporation of 5–bromo–2’–deoxyuridine (BrdU), followed by immunocytochemistry. Co–localization studies with Ki–67 (proliferative marker) and nestin (undifferentiated stem cell marker) were also performed. The effect of NPY incubation (48 h), with or without NPY receptors antagonists, on the number of BrdU positive cells was evaluated.
Results: :
In control conditions 20.9 ± 0.7 cells/field were in division (BrdU positive cells). BrdU positive cells co–localized with Ki–67. Treatment with NPY (100 nM) increased the number of BrdU positive cells (40.5 ± 1.8 cells/field). Thirty percent of BrdU labelled cells were nestin–positive cells (neural stem cells). The proliferative effect of NPY was inhibited by the antagonists of NPY Y1 (BIBP 3226, 1 µM), NPY Y2 receptor (BIIE 0246, 1 µM), and NPY Y5 (L–152,804, 1 µM) receptors. The agonist of NPY Y4 receptor (r–PP, 100 nM) had no effect on retinal cell proliferation.
Conclusions: :
In this study, we showed that NPY stimulates cell proliferation in rat retinal neural cell cultures through NPY Y1, Y2 and Y5 receptor subtypes. Stimulation of endogenous cell proliferation by NPY may be a putative strategy to attenuate retinal damage in certain eye pathologies.
Keywords: proliferation • neuropeptides • differentiation