PT  - JOURNAL ARTICLE
AU  - Shuster, Louis
AU  - Hannam, Ruth V.
AU  - Boyle, William E.
TI  - A SIMPLE METHOD FOR PRODUCING TOLERANCE TO DIHYDROMORPHINONE IN MICE
DP  - 1963 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 149--154
VI  - 140
IP  - 2
4099  - http://jpet.aspetjournals.org/content/140/2/149.short
4100  - http://jpet.aspetjournals.org/content/140/2/149.full
SO  - J Pharmacol Exp Ther1963 May 01; 140
AB  - Mice became tolerant within a few days to the analgesic and exciting effects of narcotics as a result of drinking dilute evaporated milk containing dihydromorphinone HCl (Dilaudid). Tolerant mice could be maintained in good physical condition for 1 month or more while drinking between 50 and 70 mg per kg of dihydro-morphinone HCl daily. When tolerant mice were withdrawn they lost as much as 15% of their body weight over-night, indicating that physical dependence was established. The extent of tolerance increased with increasing daily intake of dihydromorphinone and with the length of time, up to about 7 days, that animals were maintained on one given dose. Mice made tolerant by drinking dihydromorphinone showed decreased excitability. This was manifested by decreased spontaneous activity and a decreased response to the exciting effects of morphine, meperidine, codeine, cocaine, and, to a lesser extent, d-amphetamine. There was tolerance to the analgesic effects of morphine, meperidine and cocaine. The assay, by means of a photoelectric counter, of motor activity following a test dose of narcotic is a sensitive and convenient method for measuring narcotic tolerance in mice.