Brain norepinephrine levels after BCG stimulation of the immune system

Brain norepinephrine, dopamine and serotonin levels were determined in right and left hemisphere from female C3H/He mice 13 days after their immune system was stimulated by an intraperitoneal injection of bacillus Calmette-Guérin (BCG) (10(7) bacilli/mouse). Increased norepinephrine levels were observed in both hemispheres but significantly only in the right one. No concomitant variations in dopamine or serotonin levels were detected. Furthermore, norepinephrine levels in the right hemisphere appeared to be correlated with the ability of lymphocytes to proliferate after concanavalin A stimulation. The modulation of the immune system by the brain neocortex has been previously shown to be lateralized. Here we show that the information from the immune system towards the central nervous system also appears to be expressed in a lateralized manner.