The hind paw edema produced by staphylococcal enterotoxin B in female mice is modulated by sex hormones.

Abstract

This paper describes the involvement of sex hormones in the edematogenic response produced by staphylococcal enterotoxin B (SEB) in the mouse hindpaw. Both the paw weight variation and the protein exudate produced by the intraplantar administration of SEB (12.5 micrograms/paw) to intact, randomly cycling female (IRCF) mice were significantly attenuated when the animals were ovariectomized (OVX). The attenuation of SEB-induced paw swelling produced by OVX was not reversed by estradiol (OE2) reposition. Thus, 4 h after the injection of SEB the increase in paw weight in OVX-mice treated with OE2 (10 micrograms/kg in corn oil) was 15.0 +/- 0.9 mg, while the exudation corresponded to 2.1 +/- 0.3 micrograms of Evans blue dye/g of tissue. Neither of these values differed significantly from those obtained 4 h after the intraplantar injection of SEB (12.5 micrograms/paw) in non-treated OVX-mice (paw swelling, 14.0 +/- 0.8 mg; dye exudation, 2.0 +/- 0.3 micrograms/g, N = 6). Pretreating IRCF mice once a day for three days with human chorionic gonadotrophin (40 IU/kg, i.m.) reduced the paw edema produced by the toxin, thus indicating an involvement of gonadotrophins in this event. A pronounced decrease in paw weight variation (about 45%) and dye exudation (61%) was detected when IRCF mice were previously treated every 72 h with three injections of OE2 (10 micrograms/kg in corn oil, i.m.). Similar situations were also seen when the animals were pretreated at 72 h intervals with three injections of testosterone (10 mg/kg in corn oil, i.m.). We conclude that the paw edema induced by SEB in female mice is hormonally regulated. Our results also indicate that the HPA-immune axis is involved in this phenomenon.