TY - JOUR
T1 - Repeated treatment with high doses of morphine produces comparable tolerance to low- and high-dose discriminative stimulus effects of morphine
AU - Vanecek, Susan A.
AU - Young, Alice M.
PY - 1996
Y1 - 1996
N2 - Morphine tolerance was studied in pigeons (Columba livia, N = 9) trained to discriminate among a low dose of morphine (1.8 mg/kg), a high dose of morphine (10 mg/kg), and saline. Doses of morphine required for low-dose or high-dose stimulus effects were determined before, during, and after a 4-week treatment period, during which training was suspended. Treatment with 56 mg/kg, but not 10 mg/kg, morphine, b.i.d., increased the doses required for either low-dose or high-dose stimulus effects by approximately 10-fold. Both treatments increased doses required for rate suppression. Sensitivity recovered after a week of saline treatment. Acute treatment with 56 mg/kg morphine did not change sensitivity. These results suggest that chronic morphine treatment can produce surmountable, reversible tolerance to morphine acting as a discriminative stimulus, without disrupting a discrimination between low-dose and high-dose stimulus effects.
AB - Morphine tolerance was studied in pigeons (Columba livia, N = 9) trained to discriminate among a low dose of morphine (1.8 mg/kg), a high dose of morphine (10 mg/kg), and saline. Doses of morphine required for low-dose or high-dose stimulus effects were determined before, during, and after a 4-week treatment period, during which training was suspended. Treatment with 56 mg/kg, but not 10 mg/kg, morphine, b.i.d., increased the doses required for either low-dose or high-dose stimulus effects by approximately 10-fold. Both treatments increased doses required for rate suppression. Sensitivity recovered after a week of saline treatment. Acute treatment with 56 mg/kg morphine did not change sensitivity. These results suggest that chronic morphine treatment can produce surmountable, reversible tolerance to morphine acting as a discriminative stimulus, without disrupting a discrimination between low-dose and high-dose stimulus effects.
UR - http://www.scopus.com/inward/record.url?scp=0029795899&partnerID=8YFLogxK
U2 - 10.1037/1064-1297.4.3.251
DO - 10.1037/1064-1297.4.3.251
M3 - Article
AN - SCOPUS:0029795899
SN - 1064-1297
VL - 4
SP - 251
EP - 257
JO - Experimental and Clinical Psychopharmacology
JF - Experimental and Clinical Psychopharmacology
IS - 3
ER -