Psychopharmacology
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Opioid receptors are divided into three types: kappa, mu, and delta receptors. Receptor-selective antagonists are useful experimental tools for evaluation of opioid receptor-mediated processes. 5'-Guanidinonaltrindole (GNTI) was recently developed as a novel kappa-selective antagonist. ⋯ These results suggest that GNTI is a potent and selective kappa antagonist with a slow onset and long duration of action in rhesus monkeys. Relative to the prototype kappa antagonist nor-binaltorphimine, GNTI may have some advantages as a tool for the study of kappa receptor-mediated processes.
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Historical Article
Determinants of the behavioral effects of opioids and their antagonists: contributions of the Laboratory of Psychobiology.
The behavioral pharmacology of opioids has been influenced significantly by the research and writings of Drs. Peter B. Dews, Roger T. Kelleher, and William H. Morse, their colleagues, and their students. ⋯ The conceptual and methodological approach taken by the group, as well as their discoveries in the behavioral pharmacology of opioids, will continue to exert a positive influence on the field.
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Comparative Study
Age-related differences in sensitivity to the antinociceptive effects of kappa opioids in adult male rats.
Significant differences in the potency and effectiveness of opioid analgesics have been reported in subject populations differing in age. Although the relationship between aging and sensitivity to the antinociceptive effects of mu opioids has been examined extensively, relatively few studies have examined this relationship in kappa opioids. ⋯ These data may be taken as evidence that: (1) aged male rats are more sensitive than young male rats to the antinociceptive effects of kappa opioids, (2) U69,593 and U50,488 display agonist activity in the warm-water, tail-withdrawal procedure under some conditions in which they fail to produce antinociceptive effects, and (3) butorphanol and nalbuphine possess only limited agonist activity at the kappa receptor.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the subjective effects of Delta(9)-tetrahydrocannabinol and marijuana in humans.
There has been controversy about whether the subjective, behavioral or therapeutic effects of whole plant marijuana differ from the effects of its primary active ingredient, Delta(9)-tetrahydrocannabinol (THC). However, few studies have directly compared the effects of marijuana and THC using matched doses administered either by the smoked or the oral form. ⋯ These results support the idea that the psychoactive effects of marijuana in healthy volunteers are due primarily to THC.
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Comparative Study Clinical Trial Controlled Clinical Trial
Benzodiazepines have no effect on fear-potentiated startle in humans.
Pre-clinical and clinical investigations have provided a great deal of evidence that the fear-potentiated startle paradigm represents a valid model for the objective assessment of emotional states of anxiety and fear. ⋯ At least one type of fear-potentiated startle, i.e. potentiation by a cue-specific fear manipulation, is not susceptible to benzodiazepine treatment. In contrast, effects of manipulations more akin to anxiety (darkness, context) appear sensitive to benzodiazepines. Human experimental models differentiating between these cue specific and contextual responses are needed to shed more light on differences in the anatomy and pharmacology of anxiety disorders.