Intake of and preference for sweet solutions are attenuated in morphine-withdrawn rats.
The hypothesis that intake of sweet solutions is partially controlled by endogenous opioid peptides was tested in 2 experiments that examined the effects of repetitive morphine administration and withdrawal on subsequent intake of and preference for saccharin solutions in rats. Experiment 1 established that 17 hr after morphine withdrawal, rats consumed less saccharin, but not less water, than did controls. The groups did not differ 8 days later. In Experiment 2, using a 2-bottle saccharin-preference test, rats exhibited a reduced preference to saccharin solutions (1, 3, 9, 30, or 60 mM) for 6 days after morphine withdrawal. The difference between the groups was most pronounced at the most preferred concentrations (9 and 30 mM). The results suggest that cross-tolerance occurs between morphine and the opioid-mediated hedonic effects of sweet solutions.
Lieblich
I
I
Hebrew University of Jerusalem, Mount Scopus, Israel.
Yirmiya
R
R
Liebeskind
J C
JC
D000818:Animals; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D004361:Drug Tolerance; D004723:Endorphins / Q000502:physiology*; D005260:Female; D005518:Food Preferences / Q000187:drug effects* / Q000502:physiology*; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects* / Q000502:physiology*; D012439:Saccharin; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013649:Taste / Q000187:drug effects* / Q000502:physiology*
D004723:Endorphins; D011957:Receptors, Opioid; D009020:Morphine; D012439:Saccharin