The molecular effects of short- and long-term exposure to a pulsed electromagnetic field on the neuronal apoptosis mechanisms in oleic acid-treated brain cells

Pulsed electromagnetic field (PEMF) is a low-frequency electromagnetic field, and studies have demonstrated that PEMF application is used in the treatment of Parkinson's disease, postoperative pain, edema, chronic wounds, neurodegenerative and ocular diseases, and cancer cells. Apoptosis is a programmed cell death, in which cells undergo self-destruction, regulated by the equilibrium between proapoptotic and antiapoptotic proteins, and requires RNA, protein synthesis, and energy. Oleic acid, the main component of membrane phospholipids, has been demonstrated in numerous cell culture studies including neuronal cells to trigger autophagic or apoptotic cell death in cancer treatment. In the literature, studies investigating the molecular effects of oleic acid and PEMF exposure on key molecules involved in apoptotic mechanisms in the cell line of neuroblastoma, a malignant brain tumor originating from the precursor cells of the sympathetic nervous system, are limited. Especially, studies examining the effects of 75 Hz frequency, 1 mT intensity of short- and long-term PEMF exposure on the mRNA levels of key genes such as TP53, Bcl-2, bax, and caspase-3 in apoptosis regulation in oleic acid-treated human neuroblastoma cell line are very scarce. In the light of this knowledge, the objective of the present study was to expose the oleic acid treated-human neuroblastoma cell line to 75 Hz, 1 mT PEMF for both short (15 min) and long (12 hours) term, and to investigate the effects of PEMF exposure together with oleic acid on the apoptosis mechanism depending on the exposure time with molecular techniques. SH-SY5Y neuroblastoma cells were divided into 6 experimental groups: Group 1: control group; Group 2: Oleic acid treated group; Group 3: The group exposed 75 Hz-1±0.2 mT PEMF for 15 min following oleic acid treatment; Group 4: The group exposed 75 Hz-1±0.2 mT PEMF for 12 h following oleic acid treatment; Group 5: The group exposed to 75 Hz-1±0.2 mT PEMF for 15 min; and Group 6: The group exposed to 75 Hz -1±0.2 mT PEMF for 12 h. Cell viability, apoptosis, and mRNA levels of TP53, Bcl-2, bax, caspase-3 were determined by Alamar Blue, Flow Cytometry, and Real-Time PCR techniques, respectively. Overall findings demonstrated that exposure to PEMF at 75 Hz frequency and 1±0.2 mT intensity for 12 h following oleic acid treatment induce apoptosis in SH-SY5Y cell line by reducing cell viability, increasing TP53, bax, and caspase-3 expressions, and decreasing Bcl-2 expression. With the obtained scientific data, the effects of PEMF application on the apoptosis mechanism in human brain cells combination with oleic acid have been examined, contributing to the expansion of clinical and biomedical applications. KEYWORDS: Pulsed Electromagnetic Field, oleic acid, apoptosis, neuroblastoma, cancer, SH-SY5Y cell line