Single-dose tolerance to morphine-induced analgesic and hypoactive effects in infant rats
β Scribed by Michael T. Bardo; Richard A. Hughes
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 580 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0012-1630
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β¦ Synopsis
Abstract
A single injection of morphine or isotonic saline was administered to rats at either 1, 5, 9, or 13 days of age. At 26β29 days of age, animals were tested for pain responsivity and activity following either morphine (5 mg/kg) or saline. Animals which received morphine at 1 day of age displayed tolerance at 26 days of age, whereas animals which received morphine at either 5, 9, or 13 days of age failed to display tolerance. This ageβdependent change in susceptibility to singleβdose morphine tolerance may involve alterations in opiate receptor ontogeny.
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