Estrogen receptor levels in a murine model of systemic lupus erythematosus

Offspring of a cross between the NZB and NZW mice (F1) develop a disease similar to SLE in humans. Female mice of the F1 strain develop the disease at a younger age and die earlier than the males. In order to test the hypothesis that estrogen receptor concentrations in the lymphoid organs of these mice may correlate with increased female susceptibility, estrogen receptor assays were performed on cytosol from the uterus, thymus, spleen, and liver of affected animals and the parental stock using the dextran-charcoal method. Specific binding of the receptor was analysed by Scatchard analysis. There were no differences among receptor concentrations in the uterus, thymus, and spleen of NZB, NZW, and F1 mice. However, the estrogen receptor concentrations in the liver from NZW and F1 mice were twice that of NZB mice. This observation may be of importance since the liver is involved in steroid metabolism and abnormalities of estrogen metabolism have been reported in human SLE.