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RU38486 influences the core temperature response of near‐term pregnant rats to intraperitoneal administration of lipopolysaccharide
Author(s) -
Fewell James E.,
Moore Sherry L.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1450-d
Subject(s) - lipopolysaccharide , term (time) , core temperature , core (optical fiber) , administration (probate law) , medicine , chemistry , anesthesia , endocrinology , physics , quantum mechanics , political science , law , optics
Rats have an attenuated febrile response to exogenous pyrogen near the term of pregnancy at a time when blood levels of the endogenous glucocorticoid, corticosterone, are elevated. Given that glucocorticoids attenuate exogenous pyrogen‐induced fever in male rats, the present experiments were carried out to test the hypothesis that administration of RU 38486 ‐‐ a glucocorticoid type II receptor antagonist ‐‐ would restore the febrile response to E. coli LPS in pregnant rats on day 20 of gestation. Pregnant rats were randomly allocated to one of four experimental groups depending upon whether they received RU 38486 (20 mg/kg) or vehicle followed by E. coli LPS (160 μg/kg; EC 100 in nonpregnant rats) or vehicle. Basal core temperature was not altered by intragastric administration of RU 38486 or vehicle. Following intragastric administration of vehicle, intraperitoneal administration of E. coli LPS produced a significant hypothermia with latency, duration and magnitude of 1h, 1.5h and−1.3°C, respectively. Following intragastric administration of RU 38486, however, intraperitoneal administration of E. coli LPS elicited only a minimal decrease in core temperature which was not significantly different from control. Following intraperitoneal administration of E. coli LPS, core temperature increased significantly from control from 4.5h onward; the modest increase in core temperature was not influenced by the prior administration of RU 38486. Thus, our data provide evidence that endogenous glucocorticoids play a role in modulating the early core temperature response to a relatively large dose of exogenous pyrogen in rats near the term of pregnancy.