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N. G. N. Milton
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E. W. Hillhouse
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A. S. Milton
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ABSTRACT

The pyrogenic interferon inducer polyinosinic: polycytidylic acid (Poly I: C) was shown to stimulate rises in both prostaglandin E2 (PGE2) and prostaglandin F (PGF) in conscious rabbits in vivo. Poly I:C (2·5 μg/kg) stimulated a fivefold rise in circulating immunoreactive (ir) PGE2, with a lag phase of 60 min, which was sustained during the subsequent 4-h period of observation. Poly I:C also stimulated a 2·5-fold rise in circulating irPGF with a lag phase of 90 min, which was followed by a return to basal levels after 5 h. The rises in circulating irPGE2 and irPGF stimulated by Poly I:C were prevented by pretreatment with the non-steroidal anti-inflammatory drug ketoprofen. Both the irPGE2 and irPGF responses to Poly I:C (2·5 μg/kg, i.v.) were antagonized by the corticotrophin-releasing factor-41 (CRF-41) receptor antagonist (α-helical CRF (9–41), 25 μg/kg, i.v.) administered 5 min prior to the pyrogen. Peripheral immunoneutralization using an anti-CRF-41 monoclonal antibody (KCHMB001, 2·5 mg/kg, i.v.) administered 5 min prior to the pyrogen, also inhibited both the PGE2 and PGF responses to Poly I:C (2·5 μg/kg, i.v.). However, control mouse IgG also inhibited the PGE2 response. In conclusion, these results suggest a modulatory role for endogenous peripheral CRF-41 in the circulating prostaglandin responses to the pyrogen Poly I: C and this effect may be responsible for the antipyretic actions of peripherally administered CRF-41 antagonists and antibodies.

Journal of Endocrinology (1993) 138, 7–11

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N. G. N. Milton
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E. W. Hillhouse
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A. S. Milton
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ABSTRACT

The pyrogenic interferon inducer polyinosinic: polycytidylic acid (Poly I: C) was shown to activate the rabbit hypothalamo-pituitary-adrenocortical (HPA) axis in vivo. The immunoreactive cortisol response to Poly I:C (2·5 μg/kg) was shown to have a corticotrophin-releasing factor-41 (CRF-41)-dependent component which was abolished by peripheral immunoneutralization using an anti-CRF41 monoclonal antibody (KCHMB001; 2·5 mg/kg i.v.). Peripheral administration of the arginine vasopressin (AVP) V1 receptor antagonist ([deaminoPen1, O-Me-Tyr2, Arg8]-vasopressin; 225 nmol/kg i.v.) had no effect on the response of immunoreactive cortisol to Poly I:C, suggesting that AVP was not involved in activation of the HPA axis. Poly I: C increased both body temperature and circulating immunoreactive prostaglandin E2; these responses were abolished by the cyclo-oxygenase inhibitor ketoprofen (3 mg/kg s.c.). The immunoreactive cortisol response to Poly I: C, however, remained after the administration of ketoprofen, indicating a prostaglandin (PG)-independent component. The immunoreactive cortisol levels in control, saline vehicle-treated, animals were reduced by both the CRF-41 receptor antagonist (α-helical CRF (9–41); 6·25 mmol/kg i.v.) and ketoprofen (3 mg/kg s.c.) indicating that this basal state is dependent on both CRF-41 and PGs.

Journal of Endocrinology (1992) 135, 69–75

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