Vagotomy does not affect thermal responsiveness to intrabrain prostaglandin E2 and cholecystokinin octapeptide

Subdiaphragmatic vagotomy has been repeatedly shown to attenuate the febrile response to peripherally injected pyrogens. In the present study, we investigated whether vagotomy-induced attenuation of febrile responsiveness reflects a decreased sensitivity of the brain to central fever mediators, prostaglandin E-2 (PGE(2)) and cholecystokinin octapeptide (CCK-8). Male rats were subjected to subdiaphragmatic vagotomy (or sham surgery) on day 0 and had a cannula implanted into the lateral cerebral ventricle on day 24. On day 30-36, the thermal responsiveness of the rats to PGE(2) or CCK-8 was tested. Each animal was injected in the ventricle with either PGE(2) (0, 10, 100, or 500 ng) in pyrogen-free saline with 0.5% ethanol (5 mu l) or CCK-8 (0 or 1.6 mu g) in artificial cerebro-spinal fluid (5 mu l). While the 0-dose of either PGE(2) or CCK-8 (vehicle alone) induced no thermal response, all the higher doses of either agent caused a body temperature rise preceded by tail skin vasoconstriction. The vagotomized rats did not respond differently than their sham-operated counterparts to any dose of either drug. It is concluded that subdiaphragmatic vagotomy does not change the rat's thermal responsiveness to intrabrain PGE(2) and CCK-8. (C) 1999 Published by Elsevier Science B.V. All rights reserved.