Effects of Pulsed Radiofrequency Current and Thermal Condition on the Expression of β-Endorphin in Human Monocytic Cells.

Pulsed radiofrequency (PRF) current applied to peripheral nerves is a modality used in interventional pain medicine, but its underlying mechanisms remain unclear. This study aimed to investigate whether ex vivo exposure of human monocytic THP-1 cells to PRF current or to heat induces β-endorphin production.

Methods: THP-1 cells were exposed to PRF current for 15 min or incubated at elevated temperatures (42 °C to 50 °C) for 3 or 15 min. Flow cytometry was used to assess cell viability, and β-endorphin concentrations in culture supernatants were quantified by ELISA. In a separate experiment, cells were stimulated with lipopolysaccharide (LPS) to compare its effects on β-endorphin release.

Results: A 3 min exposure to temperatures ≥ 46 °C reduced THP-1 cell viability, whereas a 15 min exposure to PRF current or to heat at 42 °C did not impair viability. Both PRF current and mild heat significantly enhanced β-endorphin release. β-Endorphin levels in the supernatant of LPS-stimulated cells were comparable to those of cells exposed to PRF current.

Conclusions: Ex vivo application of PRF current or mild heat enhanced β-endorphin production from THP-1 cells without significant cytotoxicity. These preliminary findings warrant further investigation using primary human monocytes and in vivo models to assess therapeutic potential.