Antiaversive properties of opioids in the conditioned taste aversion test in the rat.
The antiaversive effect of mu-, kappa- and delta-opioid receptor agonists against conditioned taste aversion (CTA) induced by apomorphine, lithium chloride and copper sulphate in the rat was studied, in order to evaluate whether prevention of CTA is a suitable model for the study of antiemetics. Anti-aversion was not a general characteristic of all opioid substances tested. Only one dose of the mu-agonist morphine and only one dose of the kappa-agonist ethylketocyclazocine had a consistent antiaversive effect against CTA induced by apomorphine; one dose of the delta-agonist [D-Ala2, Met5]enkephalinamide antagonized the aversion induced by lithium chloride. As the results do not correspond to our previous findings on the antiemetic effects of these opioids in the dog (all mu- and kappa-agonists tested having an antiemetic effect), we conclude that the CTA test cannot be used as a screening test for potentially antiemetic drugs.
Blancquaert
J P
JP
Heymans Institute of Pharmacology, University of Gent Medical School, Belgium.
Lefebvre
R A
RA
Willems
J L
JL
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003214:Conditioning, Classical / Q000187:drug effects; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005283:Fentanyl / Q000494:pharmacology; D008297:Male; D008691:Methadone / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects; D013649:Taste / Q000187:drug effects* / Q000502:physiology
D004723:Endorphins; D009294:Narcotics; D011957:Receptors, Opioid; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; C022118:enkephalinamide-Met, Ala(2)-; D009020:Morphine; D008691:Methadone; D005283:Fentanyl