Psychopharmacology
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Subchronic administration of stimulants reduces basal dopamine (DA) concentrations and blocks stress-induced DA release in the nucleus accumbens (NA) of rats during withdrawal. However, no studies have attempted to relate early withdrawal from chronic drug exposure to stress reactivity and changes in DA transmission. ⋯ These results suggest that subchronic METH exposure selectively increases NA DAT and consequently reduces basal and stress-induced DA release in the NA SHELL during early withdrawal.
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Comparative Study
Ultra-low-dose naltrexone suppresses rewarding effects of opiates and aversive effects of opiate withdrawal in rats.
Ultra-low-dose opioid antagonists enhance opiate analgesia and attenuate tolerance and withdrawal. ⋯ Ultra-low-dose NTX coadministration blocks the acute rewarding effects of analgesic doses of oxycodone or morphine as well as the anhedonia of withdrawal from chronic administration.
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Randomized Controlled Trial Comparative Study
Dronabinol and marijuana in HIV(+) marijuana smokers: acute effects on caloric intake and mood.
No studies to date have directly compared the tolerability and efficacy of smoked marijuana and oral dronabinol in HIV(+) marijuana smokers. ⋯ These data suggest that for experienced marijuana smokers with clinically significant muscle mass loss, both dronabinol (at acute doses at least four to eight times the current recommendation) and marijuana produce substantial and comparable increases in food intake without producing adverse effects.
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Comparative Study
Social and environmental influences on opioid sensitivity in rats: importance of an opioid's relative efficacy at the mu-receptor.
Evidence indicates that social and environmental enrichment can influence the functional maturation of the central nervous system and may affect an organism's sensitivity to centrally acting drugs. ⋯ These findings may be taken as evidence that enriched rats are more sensitive than isolated rats to the effects of lower-efficacy mu-opioids and that social and environmental enrichment leads to functional alterations in opioid receptor populations.
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Comparative Study
Functional magnetic resonance imaging studies of opioid receptor-mediated modulation of noxious-evoked BOLD contrast in rats.
Functional magnetic resonance imaging (fMRI) in rats can non-invasively identify brain regions activated by physiological stimuli and the effects of pharmacological intervention on these responses. ⋯ Our data demonstrate that morphine modulates noxious-evoked changes in signal intensity in discrete brain regions. fMRI studies in rats are able to identify specific brain regions involved in the pharmacological modification of physiologically evoked changes in regional brain activation.