Stereospecific and Nonstereospecific Effects of (+)- and (—)-Morphine: Evidence for a New Class of Receptors?
| Autor: | Ikuo Iijima, Yasuko F. Jacquet, Junichi Minamikawa, Werner A. Klee, Kenner C. Rice |
|---|---|
| Rok vydání: | 1977 |
| Předmět: |
medicine.medical_specialty
Guinea Pigs Molecular Conformation (+)-Naloxone In Vitro Techniques Binding Competitive Periaqueductal gray Cyclase Neuroblastoma Structure-Activity Relationship Internal medicine medicine Animals Receptor Microinjection Morphine Derivatives Binding Sites Multidisciplinary Behavior Animal Morphine Naloxone Chemistry Ligand binding assay Brain Muscle Smooth Stereoisomerism Glioma Rats Endocrinology Adenylyl Cyclase Inhibitors Receptors Opioid Opiate Muscle Contraction medicine.drug |
| Zdroj: | Science. 198:842-845 |
| ISSN: | 1095-9203 0036-8075 |
| DOI: | 10.1126/science.199942 |
| Popis: | The unnatural (+) enantiomer of morphine had minimal activity in three opiate assays in vitro: the rat brain homogenate binding assay, the electrically stimulated guinea pig ileum assay, and the inhibition of adenylate cyclase in neuroblastoma X glioma hybrid cell homogenates. When (+)-morphine was microinfected into the periaqueductal gray (a site known to mediate morphine analgesia) of drug-naive rats, there was only minimal analgesia, but the hyperresponsivity usually observed after microinfection of (-)-morphine occurred. Also, when (+)-morphine was microinfected into the midbrain reticular formation of drug-naive rats, rotation similar to that following microinjection of (-)-morphine occurred. These behaviors were not blocked by naloxone. Significantly, they typically occur in precipitated abstinence in morphine-dependent rats. These observations suggest that there are at least two classes of receptors, one stereospecific and blocked by naloxone and the other only weakly stereospecific and not blocked by naloxone, and that precipitated abstinence may be due, in part, to a selective blockade of receptors of the former class but not of the latter. |
| Databáze: | OpenAIRE |
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