Neurotransmitter systems of female mouse brain during growth of malignant melanoma modeled on the background of chronic pain

Abstract

Biogenic amines (BA) are known to be involved in malignant growth, and their CNS levels change in pain; however, there are no studies of combined effects of chronic pain (CP) and cancer on BA dynamics in the brain. Aim: To study features of BA balance in the cerebral cortex during melanoma growth associated with CP. Material and methods. The study included 64 female mice weighing 21—22 g. In the main groups, B16/F10 melanoma was transplanted under the skin of the back two weeks following sciatic nerve ligation. Mice with melanoma without pain were used as the control. Concentrations of BA: adrenaline, noradrenaline, dopamine (DA), serotonin (5-HT), histamine and 5-HIAA were measured with ELISA. Results. Concentrations of BAs decreased in mice with CP although DA levels did not change. 5-HT metabolism involved MAO. The development of melanoma was accompanied by increases in DA and 5-HT whereas MAO was inhibited. The direction of BA changes during the development of melanoma was the same with and without CP. At the same time, CP with melanoma limited accumulation of 5-HT in the cerebral cortex, which resulted in even more aggressive course of cancer. Conclusion. CP restricted the activation of cerebral stress-limiting
mechanisms during the development of melanoma in mice, which resulted in a more aggressive course of disease.