Investigation of melatonin, prolactin and oxytocin on neurogenesis applied to neural stem cells and protecti̇ve effect of their conditioned media against Aβ toxicity on SH-SY5Y cells

Alzheimer's disease (AD) is characterized by the accumulation of amyloid beta (Aβ), increased oxidative stress (OS) and ultimately cell death. It is known that oxytocin, melatonin and prolactin hormones are effective in neurogenesis. In this study, the protective effects of Aβ25-35 against OS in SH-SY5Y cells, which are human neuroblastoma lines, were investigated comparatively by collecting differentiation conditioned media (CM) containing oxytocin, melatonin and prolactin applied to differentiation media of neural stem cells (NSC). The effect of these hormones on the neurogenesis process in NSCs was determined by dual immunofluorescent staining of Microtubule Associated Protein-2 and Doublecortin proteins. MTT-LDH-ROS-JC1-RTCA-Annexin V FITC/ PI tests were performed in protective effect studies. Protective proteins including NRF2-Pin1-SIRT1-PPARγ, ROS-related GSK3α/β and pGSK3α/β were determined by Western Blotting method. It was observed that melatonin, prolactin and oxytocin increased neurogenesis, and it was determined that CMs containing hormones had a higher level of protective effect against OS formed by Aβ25-35 in SH-SY5Y cells than melatonin, prolactin and oxytocin alone. It has been observed that melatonin prevents hyper phosphorylation of Tau protein by decreasing GSK3 activation and increasing the amount of Pin1 protein, while prolactin and oxytocin does that by decreasing GSK3 levels. These three substances are thought to be therapeutically promising and shed light on future in vivo studies.