Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intravenous administration of prostaglandin E2 (PGE2) to mice results in a significant distribution of PGE2 into the brain and an elevation of cyclic adenosine monophosphate (cAMP) in the midhindbrain and corpus striatum. Neither acute morphine administration nor morphine tolerance alters this response. Morphine alone also elevates cAMP levels. Although these elevations are blocked by the narcotic antagonist, naloxone, they only occur at supra-analgesic doses. Therefore morphine analgesia does not correlate with either elevation of cAMP levels of antagonism of PGE2-induced elevations of cAMP.
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PMID:Prostaglandin E2, cyclic adenosine monophosphate and morphine analgesia. 19 55

Both C-terminal fragments of lipotropin (beta-LPH) (endorphins) and N-terminal fragments (e.g., ACTH 4-10) delayed extinction of pole-jumping avoidance behavior in rats. After subcutaneous injection Met5-enkephalin appeared to be as active as ACTH 4-10 whereas beta-LPH 61-69, alpha- and beta-endorphin were more potent in delaying extinction of pole-jumping avoidance behavior (approximate ED50 of alpha-endorphin 4 x 10(-11) M rat.) However, the potency of beta-LPH 61-69 and alpha-endorphin appeared to be approximately the same whereas that of beta-endorphin was less than that of ACTH 4-10 after intraventricular administration (approximate ED50 of alpha-endorphin 0.2 x 10(-11) M rat). alpha-Endorphin and ACTH 4-10, administered subcutaneously in a dose which markedly delayed extinction of pole-jumping avoidance behavior, had only slight effects on open field behavior and on responsiveness to electric footshock. A 5 times higher dose of both peptides facilitated passive avoidance behavior. Morphine in two doses significantly delayed extinction of pole-jumping avoidance behavior but the effect was not dose dependent. The specific opiate antagonist naltrexone, however, markedly facilitated extinction of the avoidance response. ACTH 4-10, alpha- and beta-endorphin and a behaviorally potent ACTH 4-9 analog (Org 2766) restored pole-jumping avoidance behavior of rats pretreated with naltrexone. Treatment with a similar dose of naltrexone blocked beta-endorphin-induced analgesia. These results suggest that the influence of peptides related to C-terminal and N-terminal fragments of lipotropin on extinction of avoidance behavior may be dissociated from those exerted on opiate receptor sites. Subcutaneously injected beta-LPH 61-69 or intraventricularly administered beta-endorphin induced a shift from lower to higher frequencies of hippocampal theta rhythm during paradoxical sleep in the same way as that found after ACTH 4-10. This effect is interpreted as indicating an increased arousal state in certain midbrain limbic structures. This may, as has been postulated for ACTH 4-10, alter the motivational value of environmental stimuli (e.g., aversive stimulation).
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PMID:Behavioral and electrophysiological effects of peptides related to lipotropin (beta-LPH). 20 66

Central excitatory potency of morphine administered by cerebroventricular infusion in enhanced in derivatives substituted at the 3-position (phenolic group) and/or 6-position (alcoholic group). Morphine-3-glucuronide is several hundred times more potent than morphine in evoking dose-related hyperactive motor behavior which can progress to lethal convulsions. Excitatory potencies in decreasing order are: (1) 3-glucuronide; (2) 3-SO4; (3) 3-OAc, 6-OAc (heroin); (4) 6-OAc; (5) 3-OAc; (6) 3-OH, 6-OH (morphine); (7) 3-OCH3 (codeine); (8) 3-OCH3, 6-OCH3 (thebaine). Levorphanol, lacking a 6-OH group, is devoid of excitatory actions. In this series of substituted morphines, there is an inverse relationship between opiate receptor binding potency and central excitatory potency, but codeine and thebaine behave anomalously. These findings are compatible with the hypothesis that morphine acts upon a species of receptor which mediates behavioral and EEG excitation and is distinct from the recognized opiate receptor mediating sedation and analgesia.
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PMID:Morphine derivatives with diminished opiate receptor potency show enhanced central excitatory activity. 22 19

1. Morphine inhibits the electrically evoked (0.1-0.15 Hz, 1 ms) contractions of the longitudinal muscle of the mouse vas deferens but not of the rabbit, guinea-pig, rat, cat, hamster or gerbil. This effect is stereospecific and is antagonized by naloxone or naltrexone. 2. Normorphine is equiactive with morphine but its effects are more rapid in onset and decline. 3. In the mouse vas deferens, the resting outflow of tritium-labelled catecholamines is unaffected by morphine. The electrically evoked outflow is depressed by morphine or normorphine in a dose-dependent manner. The ID50 for inhibition of contraction and for depression of outflow is 0.5 muM. 4. The relative agonist potencies of compounds without antagonist component (codeine, pethidine, morphine, normorphine, heroin, levorphanol, Ba-20227, etorphine) show good correlation with the relative agonist potencies determined in the guinea-pig ileum and for analgesia in man. 5. For compounds with dual agonist and antagonist properties, the dose-response curves for agonist activity are shallow. When the lowest concentrations giving a depression of the contraction of the mouse vas deferens are used, a good correlation is obtained with the guinea-pig ileum. 6. The relative antagonist potencies of naloxone, nalorphine, levallorphan, and cyclazocine agree well with those obtained in the guinea-pig ileum; these, in turn, correlate well with the values obtained in the morphine-dependent monkey. 7. The fact that the agonist effects of drugs with dual agonist and antagonist action show little or no dependence on concentration, makes the mouse vas deferens particularly suitable for the assay of assay of antagonist activity. 8. As an assay preparation, the mouse vas deferens is less robust and consistent in its responses than the guinea-pig ileum.
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PMID:Effect of morphine on adrenergic transmission in the mouse vas deferens. Assessment of agonist and antogonist potencies of narcotic analgesics. 23 96

Morphine analgesia in mice was significantly potentiated by pretreatment with 5-hydroxytryptophan (5-HTP), especially with higher dose of morphine. Morphine analgesia was antagonised by reserpine. With l-dopa it was antogonised when the dose of morphine was minimal but with increased dosage of morphine, there was no significant effect.
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PMID:Morphine analgesia and its modification by drugs altering serotonin (5-HT) and dopamine levels in the brain. 30 4

Morphine administered intracerebrally (IC) (10 micrograms as the base on each side) into the MRF produced a significant dose dependent elevation of nociceptive threshold (i.e., analgesia) on the tail flick test and hemostat pinch test. However, morphine IC at lower doses had no analgesic effect. After morphine was injected IC (10 micrograms, bilaterally) into the MRF, naloxone, a specific narcotic antagonist, administered either IC at the same site (15 micrograms, bilaterally) or subcutaneously (10 mg/kg), antagonized the antinociceptive effects of morphine. Thirty percent of the animals given bilateral microinjection of 10 micrograms of morphine displayed hyperreactivity to mild stimuli. This hyperreactivity was not attenuated by large IC or systemic doses of naloxone. It was concluded that the MRF is a site where morphine may act to produce analgesia by a specific narcotic mechanism of action.
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PMID:Analgesia produced by direct injection of morphine into the mesencephalic reticular formation. 31 89

Sensory evoked responses were recorded simultaneously from five structures (caudate nucleus, septum, periaqueductal gray, parafascicular nucleus and reticular formation) reported to play roles in morphine's acute actions (analgesia, dyskinesia) and in the development of tolerance. Daily recordings were made from unanesthetized male Holtzman rats before and after a challenge dose of 10 mg/kg of morphine sulfate over a four day period while tolerance was induced by multiple daily injections of morphine. Three patterns of changes were observed in the individual components of the evoked responses. 1) The challenge dose caused an initial increase in the amplitudes of the P2 and N2 components of the response in the naive rats. This effect was attenuated with each day of drug administration until day four, when the challenge dose was observed to exert no effect. This pattern occurred in the parafascicular nucleus and the septum. 2) Initial increase in P2 and N2 components by morphine was augmented for 2-3 days, after which there was a sharp drop to control values by day four. This pattern was observed in the caudate nucleus and the periaqueductal gray region. 3) Morphine caused a mixture of increases and null effects in the components over the four days. This effect was observed in the reticular formation.
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PMID:Neurophysiological assessment of site specific effects of chronic morphine administration in freely behaving rats. 33 15

In rats, lesions were placed in the ventral tegmental noradrenergic tract (VT). In some animals lesions also involved the dorsal tegmental noradrenergic tract (DT). Morphine (Mf) analgesia was examined by the tail compression method 8-9 days after lesions. VT lesions produced no changes in Mf activity, while lesions involving VT + DT produced a partial attenuation of the antinoceptive action of Mf. These results suggest that the ascending NA fibres forming the VT are not essential for the antinoceptive effect of Mf.
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PMID:Studies on the effect of lesions of the ventral noradrenergic tract on the antinociceptive action of morphine. 41 53

The purpose of these experiments was to characterize the nature of tolerance to the analgesic action of nitrous oxide. Analgesia was assessed in rats using a tail-flick latency test and in mice using an abdominal constriction test. Rats and mice were exposed to nitrous oxide, 75 per cent, the balance oxygen, continuously for 16--18 hours. On re-exposure to nitrous oxide 30 min later, these animals were found tolerant to nitrous oxide in that the analgesic response was decreased by at least 50 per cent. Animals tolerant to nitrous oxide were not tolerant to morphine. Morphine (0.25--1.5 mg/kg) produced equal degrees of analgesia in control and nitrous oxide-tolerant mice and rats. In contrast, rats made tolerant to morphine by repeated daily injections of as much as 400 mg/kg subcutaneously or by subcutaneous implantation of morphine pellets (75 mg, twice) showed a decreased analgesic response to nitrous oxide. Thus the cross-tolerance between nitrous oxide and morphine appears unique in that it is unidirectional.
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PMID:Tolerance to nitrous oxide analgesia in rats and mice. 48 91

Morphine and morphine-related agents were applied by microiontophoresis in the lumbar spinal cord of spinal cats to single units classified on the basis of their responses to natural cutaneous or proprioceptive stimulation. Opiate application had a current-dependent depressant effect on the ongoing activities of about one-third of the units tested. This effect was observed in laminae I and IV--VI, but only with units responding to noxious cutaneous stimuli: the nociceptive responses were themselves depressed. Excitatory and inhibitory responses to glutamate and gamma-aminobutyric acid, respectively, were also depressed. Intravenous administration of the opiates at doses reported to produce analgesia in the cat also depressed only units responding to noxious cutaneous stimuli, including their nociceptive responses. This depression could be reversed by either the iontophoretic application (100 nA) or the intravenous administration (0.1--0.8 mg/kg) of naloxone. These results are interpreted as further evidence that the analgesic effects of opiates are at least partly due to an action at the spinal level.
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PMID:Action of narcotic analgesics and antagonists on spinal units responding to natural stimulation in the cat. 48 72


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