Splenic norepinephrine is decreased in MRL-lpr/lpr mice

The MRL-lpr/lpr mouse, a genetic model of the human autoimmune disease systemic lupus erythematosus, has been studied extensively to determine the etiology and the pathological course of the disease in lymphoid organs. At approximately 8 weeks of age, splenomegaly develops due to a massive increase in an abnormal population of T cells, resulting in a disruption of the normal splenic architecture. Part of the normal splenic architecture includes postganglionic noradrenergic sympathetic nerve fibers, which can exert influence on a variety of immunological functions. Noradrenergic innervation and norepinephrine content of spleens from both male and female MRL-lpr/lpr mice and MRL(-)+/+ congenic controls were examined at 6, 12, 18, and 24 weeks of age. Norepinephrine content is reduced in MRL-lpr/lpr male and female mice prior to the onset of observed splenomegaly and remains reduced at all ages examined. Remaining noradrenergic fibers are found in their usual compartments, but are greatly diminished compared with controls.