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Query: UMLS:C0278080 (physical dependence)
 1,658 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Numerous problems have been associated with previous attempts to develop a suitable method for the induction and assessment of alcohol dependence and withdrawal syndrome in the rat. Using our modification of a common inhalation method for the long-term administration of ethanol, these problems can be eliminated. Adult male rats (Long Evans and Brattleboro) were exposed to ethanol vapor concentrations of 7 to 35 mg/liter of air, which cause rapid development of tolerance and physical dependence. With this inhalation method, it is possible to obtain and easily maintain high levels of ethanol in the blood (150 to 400 mg/dl). When exposure to ethanol is terminated, ethanol is eliminated from the system within 1 to 6 hr. This rapid elimination of ethanol is accompanied by a high susceptibility to withdrawal reactions. The severity of the withdrawal syndrome was assessed within 6 to 24 hr after cessation of the ethanol administration by exposing each rat individually to a 60 to 120-sec period of bell ringing. Convulsive seizures were observed in nearly 90% of the animals tested, with a mortality rate of less than 20%.
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PMID:Alcohol dependence and withdrawal in the rat. An effective means of induction and assessment. 371 3

1 Morphine and related synthetic surrogates as well as beta-endorphin and methionine enkephalin caused a contractile response of the longitudinal musculature of the terminal colon of Long Evans rats.2 The muscular contraction caused by the narcotic analgesics exhibited stereospecificity, with levorphanol being about 50 times more potent than dextrorphan and (-)-methadone 4 times more potent than (+)-methadone. In addition, the rank order in potency of a homologous series of N-alkyl substituted norketobemidones demonstrated that the activity of these compounds in eliciting contractile responses corresponded to that for analgesic efficacy in the rat and also correlated to the ability of these derivatives to inhibit the muscular twitch evoked by electrical stimulation of the guinea-pig ileum.3 Naloxone blocked the contractile response of the opiates following competitive kinetics; the naloxone pA(2) values for morphine, etorphine, levorphanol and methadone were very close, in spite of the marked differences in potency of these agents.4 The contractile effect of morphine on the rat colon was abolished by incubation of the tissues with tetrodotoxin 2.0 x 10(-7) M or by decreasing the external Ca(2+) level 100 fold. Increasing the external Ca(2+) concentration caused an apparent non-competitive antagonism of the response to morphine.5 Pretreatment of the tissues with hexamethonium 8.3 x 10(-5) M caused a modest antagonism of the morphine effect while atropine 5.8 x 10(-7) M did not significantly modify the morphine contractile effect. In contrast, methysergide 10(-5) M caused a 10 fold increase in the morphine EC(50).6 Colons from rats rendered tolerant-dependent on morphine were markedly less sensitive to the contractile effects of morphine than those from placebo-treated controls. Tolerance to morphine was also accompanied by an increased sensitivity to the contractile effects of 5-hydroxytryptamine (5-HT).7 A marked increase in the spontaneous muscular activity of segments of the terminal colon of rats chronically treated with morphine was found to occur upon removal of the residual morphine in the tissues by repetitive washings. The spontaneous activity was arrested by applications of morphine, suggesting that physical dependence can be demonstrated in vitro in this particular preparation.8 It is concluded that the opiate-induced contractile response is mediated via stereospecific, naloxone-sensitive, opiate receptors and that the muscular response involves the activation of a 5-HT neurone in the nerve terminals of the colon.
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PMID:Contractile effect of morphine and related opioid alkaloids, beta-endorphin and methionine enkephalin on the isolated colon from Long Evans rats. 617 Mar 77

The 2-[14C]deoxyglucose method was used to examine the effects of chronic, voluntary ethanol consumption on rates of local cerebral glucose utilization (LCGU). LCGU was measured in male Long-Evans rats immediately following the completion of a 60-min schedule-induced polydipsia drinking session. Three groups of animals were examined: animals with a history of ethanol consumption that received ethanol on the test day (ethanol-ethanol), animals with a similar ethanol history that were presented with water on the test day (ethanol-water), and a control group that received water throughout the experiment (water-water). Ethanol consumption on the test day resulted in a highly discrete pattern of metabolic changes, with significant decreases in glucose utilization in the hippocampal complex, habenula, anterior ventral thalamus, and mammillary bodies, whereas increases were observed in the nucleus accumbens and locus coeruleus. Rates of LCGU in the ethanol-water group were increased throughout all regions of the central nervous system examined, indicating that the long-term consumption of moderate ethanol doses that do not produce physical dependence can cause significant changes in functional brain activity.
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PMID:Metabolic mapping of the effects of chronic voluntary ethanol consumption in rats. 874 4