Abstract
Daily i.p. administration of p-chlorophenylalanine (PCPA) (320 mg/kg), which lowered brain serotonin to 34% of its normal level within three days, failed to inhibit the development of tolerance to opiate-induced running activity or analgesia. Under these same conditions, PCPA had no effect upon the development of physical dependence. Levorphanol-induced running was potentiated by PCPA and inhibited when serotonin levels were restored by administration of 5-hydroxytryptophan, even in the presence of PCPA. PCPA treatment caused neither potentiation nor inhibition of levorphanol-induced analgesia.
Footnotes
- Received July 20, 1970.
- Accepted December 28, 1970.
- © 1971, by The Williams & Wilkins Company
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