Brain interleukin asymmetries and paw preference in mice

The two sides of the brain are differently involved in the modulation of immune responses as demonstrated by lesion and behavioral approaches. To study the interactions between cerebral cortex cytokines and brain lateralization, three groups of BALB/c mice were selected on the basis of their performance in the paw preference test (left-pawed, ambidextrous and right-pawed) and the levels of interleukin-1β and interleukin-6 were measured in the two cerebral cortices after an intraperitoneal saline or lipopolysaccharide. Generally, right cortices had higher interleukin-1β and interleukin-6 levels than left cortices for both saline and lipopolysaccharide-treated mice. A strong correlation between the levels of interleukin-1β and interleukin-6 in right and left cortices and behavioral lateralization was observed. For the saline-treated mice: in their left cortices, interleukin-1β levels were higher for ambidextrous mice than for right-pawed mice ( P