EFFECTS OF ENDOPHYTE-INFECTED TALL FESCUE, ENVIRONMENTAL-TEMPERATURE AND PRAZOSIN INJECTION ON THE RAT

Effects of an alpha(1) antagonist, prazosin, injection on the rat (Rat tus rattus) exposed to warm vs normal environments and fed endophyte-i nfected (E+) or -free (E-) tall fescue seed were studied. Rats were in jected IP daily with placebo or prazosin (1 mg/kg BW). Daily skin and rectal temperatures and food intake measurements were recorded. Select ed brain tissues were dissected to determine treatment effects on mono amine receptor density. Rats fed E+ and injected with placebo had redu ced (P < 0.01) food intake compared with all other treatments. By day 5 of injection, an endophyte X temperature interaction for increased ( P < 0.03) skin and rectal temperatures was measured when rats were fed Ef and housed at 32 degrees C. Also by day 5, injection of rats consu ming E+ with prazosin reduced (P < 0.01) skin and rectal temperatures 0.4 degrees C compared with those consuming E+ and injected with place bo. Monoamine receptor (alpha(1), alpha(2), and D-2) densities were si milar (P > 0.10) among treatments. Prazosin injection reduced E+ induc ed body temperature increases chronically and increased food intake ac utely to E- levels. Monoamine receptor densities were unchanged; there fore, E+ effects via monoamine receptors may be due to acute modulatio n of receptor-associated activity.