Effect of oxytocin on neuroblastoma cell viability and growth

Abstract

Oxytocin, released in response to different physiological stimuli, could play a key role in reducing stress reaction. It was suggested that it has protective effect against inflammation and consequences of oxidative stress. Mechanisms how oxytocin effects mediated in the brain tissue are unclear. In this study, oxytocin effect on cell growth and neuronal viability was examined. Human neuroblastoma (SH-SY5Y and SK-N-SH) and glioblastoma (U87MG) cells were exposed to different concentrations of oxytocin for 12-96 h. Potential protective effect of oxytocin treatment was investigated after exposing cells to oxidative stress using hydrogen peroxide (50 mM, 2 h) or 6-hydroxydopamine (25 μM, 24 h). Cell proliferation was measured by cell counting and cell viability was examined by MTT assay. Protein expression of selected neurotrophic factors was measured as an additional parameter. Oxytocin (1 μM) significantly increased cell number in all three cell types. Viability of SH-SY5Y cells was increased in the presence of oxytocin without significant effect of dose (0.01-1 μM). Cell death induced by hydrogen peroxide was not prevented by incubation with oxytocin. Oxytocin pretreatment blunted neurotoxin 6-OHDA reduction of cell viability in SH-SY5Y cells. Oxytocin (1 μM, 12 h) elevated amount of total proteins without increasing levels of brain-derived neurotrophic factor and neurotrophic growth factor. In conclusion, oxytocin increases growth and viability of neuroblastoma and glioblastoma cells without activation of neurotrophic factors. Oxytocin does not have protective effect in oxidative stress; however, it might be important for neuroprotection to dopaminergic neurons. Its proliferative effect might be important in native cell life, euplastic processes, and tumor progression.

Fig. 1

Effect of oxytocin on cell proliferation. SH-SY5Y, SK-N-SH, and U87MG cells were incubated with or without oxytocin (10 nM, 100 nM, 1 μM). After 24, 48, 72, or 96 h cells were trypsinizated and counted. Significant effect of time and dose was demonstrated in all three cell lines. The data are expressed as the means ± SEM (n = 3)

Fig. 2

Effect of H₂O₂ and 6-OHDA treatment in SH-SY5Y cells. The MTT reduction was measured after 48 h pretreatment with or without oxytocin (10 nM, 100 nM, 1 μM) followed by treatment with H₂O₂ (50 mM, 2 h—gray bar) or 6-OHDA (25 μM, 24 h—black bar). *P < 0.05 versus control, **P < 0.01 versus control, ***P < 0.001 versus control, ^# P < 0.05. Data were normalized and expressed as a percentage of control ± SEM (n = 10)

Fig. 3

Effect of oxytocin on neuronal growth factors BDNF (a) and NGF (b). After incubation with 1 μM oxytocin for 12 h, SH-SY5Y cells were trypsinizated and lysated. BDNF and NGF levels were measured by ELISA. Oxytocin significantly (P < 0.05) decreased amount of NGF. BDNF brain-derived neurotrophic factor, NGF neurotrophic growth factor. The data are expressed as the mean ± SEM (n = 3)