Vestibular stimulation as an interventional approach for cold water stress induced immunological and histopathological changes in rats

Chronic exposure to stress results in immuno-suppression. The present study was carried out to explore the therapeutic benefits of vestibular stimulation on the immune system of stress-induced Wistar rats.

Stress was intervened in the Wistar rats by cold water swimming method for a period of 14 days. Following stress, caloric vestibular stimulation was induced in the rats by irrigating external auditory meatus bilaterally with hot water (temperature 41^°C) for 2 minutes for a period of 15 days and 30 days in respective groups. At the end of the experiment, blood samples were obtained and serum corticosterone, Interleukin 2 (IL2), Immunoglobulin M (IgM) levels were analyzed using ELISA method and histopathology of brain was assessed. Brain CD4 and CD8 cells were analyzed by Immunohistochemistry.

Stress significantly increased serum corticosterone, IL2 levels and reduced IgM levels. Stress group showed increased dendritic arborization in prefrontal cortex, neuronal atrophy, nuclear pyknosis with congested blood vessels in hippocampus and mononuclear cell inflammatory infiltrate in hypothalamus. Brain extravascular CD4 and CD8 showed positive in stress group. Caloric vestibular stimulation effectively reduced serum corticosterone levels, histopathological changes, brain extravascular CD4 and CD8 cells and improved IgM in the present study.