Influence of stress in the effects of morphine on pituitary-adrenocortical activity in the guinea-pig.
1. Modifications by stress of the effects of morphine on pituitary-adrenocortical activity were examined in the guinea-pig at different lengths of time. 2. An increase in plasma cortisol but not in beta-endorphin levels was obtained in guinea-pigs stressed for 60 min. 3. Morphine (50 mg kg i.p.) enhanced beta-endorphin and cortisol levels 5 min after injection and decreased beta-endorphin concentration 30 and 90 min after its administration. 4. In stressed guinea-pigs plasma beta-endorphin levels were reduced 5 min after morphine injection. 5. These results indicate that stress can alter the effects of morphine on pituitary-adrenal activity in the guinea-pig and that the type of modification may be dependent on the time of the sampling.
Vargas
M L
ML
Department of Physiology and Pharmacology, University School of Medicine, Murcia, Spain.
Martínez
J A
JA
Fuente
T
T
del Rio-Garcia
J
J
Milanés
M V
MV
D000818:Animals; D005260:Female; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects*; D011863:Radioimmunoassay; D013315:Stress, Psychological / Q000503:physiopathology*; D001615:beta-Endorphin / Q000097:blood
D001615:beta-Endorphin; D009020:Morphine; D006854:Hydrocortisone