Strain differences in binding properties of estrogen receptors in immatureand adult BALB/c and MRL/MP-lpr/lpr mice, a model of systemic lupus erythematosus

The aim was to compare binding properties of estrogen receptors in brain, r eproductive and immune tissues of immature and adult female BALB/c mice, an d in the same tissues of MRL/MP-lpr/lpr mice. The latter strain spontaneous ly develops an autoimmune disease resembling human systemic lupus erythemat osus (lupus; SLE). It is hypothesized that estradiol, through its receptors , mediates the progression of murine SLE. High-speed cytosols were prepared from hypothalamus, spleen, thymus and uterus of both strains, and incubate d with the synthetic estrogen H-3-moxestrol (NEN). Scatchard plots were der ived from binding isotherms obtained after in vitro incubation. In addition , cervical lymph nodes from MRL mice could be used, but were too small in B ALB/c mice. There was a significant increase in the affinity of the binding reaction i.e. a decrease in the apparent molar dissociation constant (Kd), in immune tissues and uterus with maturation in MRL but not BALB/c mice, w hose tissues had, overall, a lower affinity for H-3-moxestrol. Receptor con centrations were significantly higher in spleen and cervical lymph nodes of adult compared with immature MRL mice, but the opposite pattern was observ ed in BALB/c mouse spleen on maturation. These properties of estrogen recep tors in MRL mice may underlie estrogen-mediated exacerbation of murine SLE. (C) 2000 International Society for Immunopharmacology. Published by Elsevi er Science Ltd. All rights reserved.