Pain-associated opioidergic, ion channel, inflammatory and oxidative stress responses in Zebrafish epilepsy model

Pain-related responses in Zebrafish epilepsy model

Abstract

Epilepsy patients experience symptoms such as anxiety, depression, and increased pain sensitivity accompanied by pain during the preictal and ictal phases; however, the relationship between epileptic seizures and pain remains unclear. We aimed to investigate the effects of pain on the opioidergic system, ion channels, inflammation, and oxidative stress responses in a PTZ-induced zebrafish epilepsy model, as well as the effects of valproic acid on these mechanisms in this study. To examine epilepsy–pain interactions in the brain, zebrafish were divided into five groups to examine the changes in the brain caused by the interaction between epilepsy and pain: control (C), pentylenetetrazol (PTZ), acetic acid (AA), PTZ+AA, and PTZ+AA+VPA. After behavioral analysis, we determined the expressions of cox1, il6, trpa1, scn8aa, scn1a, zasic 1.3, penka, pdyn, oprk1, and oprl1 using RT-PCR. Oxidant-antioxidant parameters and acetylcholinesterase activity were determined spectrophotometrically. Neurotransmitter levels were measured by LC-MS/MS, and GABRA1 and POMC proteins expressions were determined by Western blot. Total distance, exploration rate, and average speed significantly decreased in all groups. PTZ caused increased NO and LPO levels, decreased SOD activity and increased cox1 and il6 expressions. The expression of scn8aa decreased in the PTZ and AA groups, trpa1 and zasic1.3 expression increased in the AA and PTZ+AA groups. The expressions of the pdyn, oprk1, and oprl1 genes increased in the AA group, decreased in the PTZ and PTZ+AA groups. Additionally, GABRA1 protein expression decreased in the PTZ, AA, and PTZ+AA groups, POMC protein expression showed a significant increase in all groups. In all groups, decreased dopamine, norepinephrine, serotonin and acetylcholinesterase indicate a disruption in neurotransmitter balance. This results indicate that the application of acetic acid in the PTZ-induced epilepsy model disrupts pain response mechanisms and neuromotor activities, increases pain perception during seizures, and VPA treatment reversed most of these effects.