Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0278080 (physical dependence)
 1,658 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methionine-enkephalin and beta-endorphin, endogenous peptides with activities similar to those of opiates, were infused for 70 hours into the periaqueductal gray-fourth ventricular space of the rat brain. When challenged with a naloxone, a specific opiate antagonist, these animals manifested a typical morphine-like withdrawal syndrome. These results show that such peptides can cause physical dependence.
 ...
PMID:Physical dependence of opiate-like peptides. 98 87

Recent studies have led to a greater understanding of the behavioral, cellular, and molecular mechanisms underlying opiate tolerance and physical dependence. Behavioral studies have demonstrated that both direct pharmacological effects and the learning of interactions between drug effects and environmental cues are important in these phenomena. Behavioral studies have also revealed that N-methyl-D-aspartate receptors may play a role in their development (or acquisition). Although in early cellular studies no consistent role was found for opioid receptors or endogenous opioid peptides in opiate tolerance and dependence, recent experiments suggest that beta-endorphin, enkephalin, and dynorphin neurons may indeed have a role. Finally, studies at the molecular level suggest that a functional decoupling of opioid receptors from GTP-binding proteins (G proteins) may be important. In this review, we discuss these disparate findings and present a synthesis that shows how they might together contribute to the phenomena of opiate tolerance and physical dependence.
 ...
PMID:Opiate tolerance and dependence: recent findings and synthesis. 166 85

Previous studies have indicated increased immunoreactivity of the endogenous opioid peptide beta-endorphin in the cerebrospinal fluid (CSF) of infants under 2 years of age with apnea. To assess the role of endogenous opioids in the pathogenesis of apnea in children, the effect of oral treatment with the opioid antagonist naltrexone was studied in apneic infants, as well as in older apneic children, with demonstrated increases in CSF immunoreactive beta-endorphin (i-BE). In the 8 apneic infants with elevated i-BE in lumbar CSF (range, 55-155 pg/ml; normal, 17-52 pg/ml), no further apnea occurred during naltrexone therapy (1 mg/kg/day, by mouth). Five children (2-8 years old) with apnea of unknown cause had elevated CSF i-BE (range, 74-276 pg/ml) compared to 6 age-matched nonapneic children (range, 15-48 pg/ml). No apneic events occurred during naltrexone therapy, except in 1 child during stressful events, but apnea recurred in some patients after attempts to discontinue naltrexone treatment. Adverse effects of naltrexone included complaints of headaches in 2 children and symptoms of a narcotic withdrawal syndrome during the first 3 days of treatment in 1 child. Three children with Leigh's syndrome had elevated CSF i-BE (range, 104-291 pg/ml) and their apnea also responded to naltrexone. We conclude that elevated endogenous opioids contribute to the pathogenesis of apnea in children and may even result in physical dependence.
 ...
PMID:Naltrexone therapy of apnea in children with elevated cerebrospinal fluid beta-endorphin. 213 20

The significance of beta-endorphin for drug dependence was explored by measuring the levels of beta-endorphin-immunoreactivity (beta E-IR) in plasma and parts of pituitary and brain of rats self-administering heroin or cocaine as compared to animals offered saline. Rats that had intravenously self-administrated heroin for 5 consecutive daily sessions of 6 h, and were decapitated immediately after the last session, showed a decreased concentration of beta E-IR in the anterior lobe (AL) of the pituitary while rats that had taken cocaine showed a decreased concentration of beta E-IR in the septum. Rats that had self-administrated heroin or cocaine and were decapitated 18 h after the last session, showed an increased concentration of beta E-IR in plasma and decreased concentrations in the AL of the pituitary and in specific areas of the brain limbic system, i.e. nucleus accumbens, septum, hippocampus and rostral striatum. The finding that self-administration of both the opiate heroin, inducing psychic and physical dependence, and the non-opiate cocaine, inducing psychic but not physical dependence, is accompanied by similar changes in beta E-IR concentrations particularly in limbic brain structures, and that these effects are present 18 h but not immediately after the last session, suggests that beta E and related peptides in limbic brain regions may represent a neurochemical correlate for psychic dependence on drugs.
 ...
PMID:Beta-endorphin in brain limbic structures as neurochemical correlate of psychic dependence on drugs. 252 16

The effects of intravenous self-administration of 30 micrograms infusions of either heroin or cocaine, or saline on the concentrations of beta-endorphin-immunoreactivity (beta E-IR) in the anterior part of the rat brain limbic system were studied. Self-administration of heroin and cocaine for 5 daily sessions resulted in a marked reduction of the concentrations of beta E-IR in the nucleus accumbens, rostral striatum, septum and hippocampus at the time of the scheduled next session on day 6. In pooled extracts of these regions from rats receiving saline, combined application of high-pressure liquid chromatography (HPLC) fractionation and specific radioimmunoassays revealed the presence of a number of beta E-related peptides co-chromatographing with synthetic non-acetylated and acetylated alpha, beta- and gamma-type endorphins. Similar profiles were found after HPLC fractionation of extracts of these regions from rats self-administering heroin and cocaine. Rats self-administering heroin or cocaine, however, showed decreased amounts of all detected forms of beta-endorphin as compared to saline rats. These findings indicate that both self-administration of an opiate that induces psychic as well as physical dependence and of a non-opiate stimulant inducing psychic but not physical dependence, results in a significant decrease of beta E and related peptides in limbic brain regions of the rat. All forms of beta E detected after HPLC were equally affected, suggesting an overall effect of the drugs on peptide turnover. These results suggest that beta E and related peptides may be involved in the neurochemical mechanisms underlying psychic dependence to drugs.
 ...
PMID:Characterization of beta-endorphin-immunoreactivity in limbic brain structures of rats self-administering heroin or cocaine. 297

In previous studies, we observed that dynorphin- (1-13), but not dynorphin-(1-9), can significantly inhibit morphine- or beta-endorphin-induced analgesia despite not having any appreciable analgesic activity itself. Dynorphin-(1-13) showed no inhibitory effect on Sandoz FK33824-induced analgesia. In the present study, we examined the effect of dynorphin on morphine-, beta-endorphin-, D-ala2-D-leu5-enkephalin- or Sandoz FK33824-induced analgesia in both naive, morphine-tolerant and morphine-dependent mice. It was found that although dynorphin may inhibit morphine- or beta-endorphin-induced analgesia in naive animals, the peptide is not effective in inhibiting D-ala2-D-leu5-enkephalin- or Sandoz FK33824-induced analgesia. Dynorphin is also effective in blocking spontaneous withdrawal jumping in morphine-dependent animals. It is suggested that dynorphin-(1-13) may play a modulatory role in regulating analgesia due to morphine or beta-endorphin, but not that due to enkephalin. The action of peptides on morphine- or beta-endorphin-induced analgesia in the naive state is different from that of the tolerant state, suggesting that dynorphin may be involved in the development of morphine tolerance and physical dependence.
 ...
PMID:Possible regulatory role of dynorphin on morphine- and beta-endorphin-induced analgesia. 611 98

The interactions of thyrotropin releasing hormone, its metabolites and synthetic analogues with acute and chronic effects of endogenous and exogenous opiates have been described. The endogenous and exogenous opiates are represented by beta-endorphin and morphine, respectively. The pharmacological effects of opiates include analgesia, temperature effects, respiratory depression, catalepsy, locomotor activity, opiate receptor binding, tolerance, and physical dependence. Thyrotropin releasing hormone and related compounds appear to (a) antagonize hypothermia, respiratory depression, locomotor depression and catalepsy but not the analgesia induced by opiates, (b) inhibit the development of tolerance to the analgesic effect but not to the hypothermic effect of opiates, (c) inhibit the development of physical dependence on opiates as evidenced by the inhibition of development of certain withdrawal symptoms, and (d) suppress the abstinence syndrome in opiate dependent rodents. Thyrotropin releasing hormone does not interact with the opiate receptors in the brain. Potential therapeutic applications of thyrotropin releasing hormone and its synthetic analogues in counteracting some of the undesirable effects of opiates are discussed.
 ...
PMID:Interactions of thyrotropin releasing hormone, its metabolites and analogues with endogenous and exogenous opiates. 614 Nov 21

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.
 ...
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

Evidence exists to suggest that there are neurochemical responses common to the development of tolerance to and dependence on a variety of psychoactive drugs. Experimental data indicates that pituitary peptides such as corticotropin and vasopressin, in addition to the endorphins, influence the development of physical dependence on either morphine or ethanol. If these findings are supported by further investigations with human subjects, various manipulations of pituitary-adrenal function, such as the administration of corticotropin and vasopressin analogs or drugs such as dexamethasone, may prove to be of clinical utility.
 ...
PMID:Neuropeptide modulation of opiate and ethanol tolerance and dependence. 625 14

The effect of chronic morphine treatment on the in vitro biosynthesis of beta-endorphin by rat pars intermedia was investigated. Tolerance and physical dependence were induced in 200 g rats by the subcutaneous implantation of 75 mg morphine pellets for either 3 days or 15 days. Immediately following sacrifice of the animals the neurointermediate lobes were removed and incubated with [3H] phenylalanine. The protein extracts of the lobes were analyzed for the incorporation of the labelled amino acid into total protein, pro-opiomelanocortin, beta-lipotropin (beta-LPH) and beta-endorphin. the biosynthesized products were purified by immunoprecipitation with an antiserum to beta-endorphin. The identity and purity of beta-endorphin were verified by polyacrylamide disc gel electrophoresis with sodium dodecyl sulfate, and microsequencing. The identity of pro-opiomelanocortin (POMC) was verified by peptide mapping of its tryptic digestion products. The results showed that morphine treatment induced a decrease in the incorporation of the radioactive amino acid into total protein, pro-opiomelanocortin, beta-LPH and beta-endorphin. The decrease was more pronounced for the incorporation into beta-LPH and beta-endorphin than into pro-opiomelanocortin and total proteins, suggesting an effect of morphine treatment on the processing of the pro-opiomelanocortin to its final maturation products.
 ...
PMID:Effect of chronic morphine treatment on beta-endorphin biosynthesis by the rat neurointermediate lobe. 626 19


1 2 3 Next >>