TY - JOUR
T1 - Endotoxin Shock
T2 - Prevented by Naloxone in Intact but Not Hypophysectomized Rats
AU - Davis, S. D.
AU - McDonald, W. J.
AU - Kendall, J. W.
AU - Potter, D. M.
PY - 1984/3
Y1 - 1984/3
N2 - Previous studies established that naloxone reverses hypotension in endotoxin, hemorrhagic, and spinal shock. We studied endotoxin shock in hypophysectomized (Hx) rats, which have little circulating β-endorphin. Hx or intact rats received surgically implanted jugular catheters for drug injection and aortic catheters for arterial blood pressure (MAP) recording. On the second day after implantation, rats were pretreated with either naloxone or saline. Two minutes later each rat received endotoxin. Following endotoxin, all rats showed a brief biphasic hypertensive-hypotensive response followed by stabilization of MAP near baseline. Within 20 min, all Hx rats, regardless of pretreatment, and the saline-treated intact rats, showed progressive hypotension (P < 0.005). Only the naloxone-pretreated intact rats maintained a stable MAP. Plasma endorphin measured at 20 min was undetectable in Hx rats in contrast to intact rats (P < 0.001); plasma corticosterone levels were likewise suppressed in the Hx rats (P < 0.01). Thus (1) naloxone protected only the rats with an intact pituitary-adrenal-sympathetic system, and (2) pituitary endorphin is not required to generate endotoxin shock in hypophysectomized rats.
AB - Previous studies established that naloxone reverses hypotension in endotoxin, hemorrhagic, and spinal shock. We studied endotoxin shock in hypophysectomized (Hx) rats, which have little circulating β-endorphin. Hx or intact rats received surgically implanted jugular catheters for drug injection and aortic catheters for arterial blood pressure (MAP) recording. On the second day after implantation, rats were pretreated with either naloxone or saline. Two minutes later each rat received endotoxin. Following endotoxin, all rats showed a brief biphasic hypertensive-hypotensive response followed by stabilization of MAP near baseline. Within 20 min, all Hx rats, regardless of pretreatment, and the saline-treated intact rats, showed progressive hypotension (P < 0.005). Only the naloxone-pretreated intact rats maintained a stable MAP. Plasma endorphin measured at 20 min was undetectable in Hx rats in contrast to intact rats (P < 0.001); plasma corticosterone levels were likewise suppressed in the Hx rats (P < 0.01). Thus (1) naloxone protected only the rats with an intact pituitary-adrenal-sympathetic system, and (2) pituitary endorphin is not required to generate endotoxin shock in hypophysectomized rats.
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U2 - 10.3181/00379727-175-41810
DO - 10.3181/00379727-175-41810
M3 - Article
C2 - 6320213
AN - SCOPUS:0021146821
SN - 0037-9727
VL - 175
SP - 380
EP - 385
JO - Proceedings of the Society for Experimental Biology and Medicine
JF - Proceedings of the Society for Experimental Biology and Medicine
IS - 3
ER -