caa a22 4500 465737595 CHVBK 20180323111759.0 cr unu---uuuuu 170327e19901001xx s 000 0 eng 10.1007/BF02245930 doi (NATIONALLICENCE)springer-10.1007/BF02245930 Rönnbäck Lars Institute of Neurobiology and Department of Neurology, University of Göteborg, P.O.Box 33 031, S-400 33, Göteborg, Sweden aut Morphine preference in individual rats after morphine ingestion [Elektronische Daten] [Lars Rönnbäck] Individual differences in drug intake were investigated. Inbred Sprague-Dawley male rats were choice-tested after various periods of morphine ingestion. Nearly 10% of the rats showed more than 50% preference already after 4 days ingestion on 340 mg morphine/kg/day, while a further 10% had a mean preference less than 30% over 6 days of choice, even after as long as 38 days' treatment on this same dose. High morphine preference was stable for long choice periods. It was also found that a high morphine preference level in an individual rat persisted over several choice tests, even if the animals had been without morphine for several months. The α2-agonist clonidine diminished high preference to the same extent as it diminished over-all morphine preference. There were no differences in food intake, body weight gain, severity of abstinence reactions, morphine serum levels, taste sensitivity tested with quinine, or learning the choice test behaviour comparing extremely high and low morphine preference rats. Thus, two subgroups of high and low morphine-ingesting rats were identified in the Sprague-Dawley strain. Springer-Verlag, 1990 Abstinence nationallicence Choice-test nationallicence Clonidine nationallicence Morphine nationallicence Preference nationallicence Psychopharmacology Springer-Verlag 102/2(1990-10-01), 257-262 0033-3158 102:2<257 1990 102 213 https://doi.org/10.1007/BF02245930 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02245930 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Rönnbäck Lars Institute of Neurobiology and Department of Neurology, University of Göteborg, P.O.Box 33 031, S-400 33, Göteborg, Sweden aut NATIONALLICENCE 773 0- Psychopharmacology Springer-Verlag 102/2(1990-10-01), 257-262 0033-3158 102:2<257 1990 102 213 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer