Received February 17, 2006
Revised March 22, 2006
Accepted after revision April 26, 2006
Placental-Perinatal [275]
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RU 38486 Influences the Core Temperature Response of
Term Pregnant Rats to Intraperitoneal Lipopolysaccharide
Sherry L. Moore 1
James E Fewell 1*
1 University of Calgary
* To whom correspondence should be addressed. E-mail: fewell{at}ucalgary.ca.
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Abstract |
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Pregnancy alters the cytokine, prostanoid and core temperature responses of rats to infectious stimuli at a time when blood levels of the endogenous glucocorticoid, corticosterone, are elevated. Given that glucocorticoids attenuate bacterial pyrogen-induced fever in rats, the present experiments were carried out to test the hypothesis that administration of RU38486 -- a glucocorticoid type II receptor antagonist -- would restore the febrile response to E. coli LPS in pregnant rats on day 21 of gestation. Pregnant rats were randomly allocated to one of four experimental groups depending upon whether they received RU38486 (20 mg/kg) or vehicle followed by E. coli LPS (160 g/kg; EC100 in nonpregnant rats) or vehicle. Basal core temperature was not altered by intragastric administration of RU38486 or vehicle. Following intragastric administration of vehicle, intraperitoneal administration of E. coli LPS produced a significant hypothermia with latency, duration and magnitude of 0.5 h, 2 h and -1.3oC, respectively. Following intragastric administration of RU38486, however, intraperitoneal administration of E. coli LPS elicited only a minimal decrease in core temperature which was not significantly different from control. Thus, our data provide evidence that endogenous glucocorticoids play a role in modulating the early core temperature response to a relatively large dose of bacterial pyrogen in rats at term of pregnancy.
Key Words:
Fever, Pregnancy, Rat
