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 (Rattus rattus) exposed to warm vs normal environments and fed endophyte-infected (E+) or -free (E-) tall fescue seed were studied. Rats were injected IP daily with placebo or prazosin (1 mg/kg BW). Daily skin and rectal temperatures and food intake measurements were recorded. Selected brain tissues were dissected to determine treatment effects on monoamine receptor density. Rats fed E+ and injected with placebo had reduced (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 E+ and housed at 32 degrees C. Also by day 5, injection of rats consuming E+ with prazosin reduced (P < 0.01) skin and rectal temperatures 0.4 degree C compared with those consuming E+ and injected with placebo. Monoamine receptor (alpha 1, alpha 2, and D2) densities were similar (P > 0.10) among treatments. Prazosin injection reduced E+ induced body temperature increases chronically and increased food intake acutely to E- levels. Monoamine receptor densities were unchanged; therefore, E+ effects via monoamine receptors may be due to acute modulation of receptor-associated activity.
Larson
B T
BT
Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
Samford
M D
MD
Turner
J T
JT
Kerley
M S
MS
Paterson
J A
JA
D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D004435:Eating / Q000187:drug effects; D004781:Environmental Exposure / Q000009:adverse effects*; D004879:Ergotamines / Q000633:toxicity*; D007274:Injections, Intraperitoneal; D008297:Male; D006109:Poaceae; D011224:Prazosin / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000032:analysis / Q000187:drug effects; D012639:Seeds; D013696:Temperature; D014662:Vasoconstrictor Agents / Q000633:toxicity*
D000317:Adrenergic alpha-Antagonists; D004879:Ergotamines; D011942:Receptors, Adrenergic, alpha; D014662:Vasoconstrictor Agents; C076760:ergovaline; D011224:Prazosin