Effect of malignant growth and chronic neurogenic pain on neurotrophin levels in rat brain

Abstract

Aim. Determination of neurotrophin levels in gray and white matter of the brain in rats with tumor growth associated with chronic neurogenic pain (CNP). Materials and methods . The study included white outbred male rats ( n = 74). In the main group, the CNP model was created (by bilateral sciatic nerve ligation), and after 45 days, M1 sarcoma was transplanted subcutaneously ( n = 11) or into the subclavian vein ( n = 11). Two comparison groups ( n = 13 each) consisted of sham operated animals with M1 sarcoma transplanted subcutaneously and intravenously, but without CNP. Control groups were animals with CNP and sham operated animals. Rats were euthanized on the 21 st day of carcinogenesis. The enzymelinked immunosorbent assay ( ELISA) was used to determine brain levels of brain-derived neurotrophic factor (BDNF) (R&D System, USA & Canada), nerve growth factor (β-NGF), neurotrophin-3 (NT-3), neurotrophin 4/5 (NT-4) (RayBiotech, USA). Results. CNP caused an increase in β-NGF levels in the cortex and white matter and BDNF levels only in white matter of the rat brain. Chronic pain stimulated M1 sarcoma growth in both subcutaneous and intravenous transplantation. The dynamics of neurotrophins levels in brain structures differed depending on the tumor site. Conclusion. Thus, the results demonstrated that in both normal peripheral tumor growth and in tumor growth against the background of CNP, changes in neurotrophin levels in the brain of experimental animals can reflect the body reaction to chronic pain and stress caused by the peripheral tumor growth.