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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analgesia and locomotor activity are genetically differentiated in C 57 and DBA mice. In fact, DBA strain, unlike C 57, is very sensitive to the analgesic effects of morphine. On the contrary, morphine elicits an increase of locomotor activity only in C 57 mice. We have used this genetic approach to study the in vitro response of vas deferens contractions to morphine and methionine-enkephalin. The results obtained are the following: 1. The percentage of morphine inhibition of the electrically evoked contractions of the longitudinal muscle of the vas deferens is greater in DBA strain, which is sensitive to the analgesic effects of morphine, than in C 57 mice in which morphine exerts a stimulating effect of the locomotor activity; 2. Met-enkephalin has been found to be more active than morphine on the same preparation; 3. The inhibitory effects of Met-enkephalin appear to be greater in C 57 than in DBA mice; 4. Different doses of Naltrexone are required to reverse the effects of morphine and Met-enkephalin; 5. Cumulative doses of Met-enkephalin and morphine induce different responses in the vas deferens of C 57 and DBA mice. The results emphasize the usefulness to study analgesic activity in these strains of mice.
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PMID:Genotype dependent response of morphine and methionine-enkephalin on the electrically induced contractions of the mouse vas deferens. 72 70

Systemic and intracerebroventricular administration of analgesic doses of morphine resulted in large increments of spontaneous multiple unit activity in the periaqueductal gray matter of the awake rat. Intracerebroventricular injection of methionine enkephalin gave analgesia in only 8 of 19 rats, but in all 8, and in no others, increased periaqueductal multiple unit firing was also seen. These findings support the view that the periaqueductal gray matter is actively involved in endogenous mechanisms of analgesia. A striking observation was that enkephalin caused electrographic and behavioral epileptic phenomena in most animals. This observation together with other recent findings suggests that endogenous enkephalin may play some role in epileptogenesis.
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PMID:Morphine and enkephalin: analgesic and epileptic properties. 86 56

[D-Ala2]-Met-enkephalinamide (DALA), a synthetic enkephalin analog designed by in vitro analysis, binds to opiate receptors almost as tightly as methionine-enkephalin. Since it is not susceptible to degradation by brain enzymes, low doses (5 to 10 micrograms) cause profound, long-lasting, morphine-like analgesia when microinjected into rat brain.
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PMID:(D-Ala2)-Met-enkephalinamide: a potent, long-lasting synthetic pentapeptide analgesic. 96 85

Male Wistar rats were treated with morphine or pentazocine subcutaneously (sc) and then intrathecally (it) by methionine- or leucine-enkephalin, neurotensin, substance P or cholecystokinin octapeptide 26-33. Then antinociceptive effect was measured during 1 h using tail-immersion test. Leucine-enkephalin potentiated and methionine-enkephalin antagonized morphine or pentazocine analgesia. Neurotensin, substance P and cholecystokinin acted biphasically on morphine induced antinociception. After short elevation, the diminution of antinociceptive effect was seen. Neurotensin diminished but substance P and cholecystokinin elevated analgesic effect elicited by pentazocine. Experimental model employed by us may be useful for preliminary screening of pharmacological interactions between neuropeptides and opioid analgesics on the spinal level. Our data confirm the results of other authors that individual enkephalins have different pharmacological features.
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PMID:Pharmacological interaction between neuropeptides and morphine or pentazocine in rat spinal cord. 172 98

Our previous pharmacological studies using animals indicated that a systemic administration of L-arginine induces an antinociceptive effect and an increase in the brain level of kyotorphin (L-tyrosinyl-L-arginine) which is an endogenous analgesic peptide and a methionine-enkephalin releaser in the brain. The aims of this study were to investigate the analgesic effect of L-arginine, a precursor of kyotorphin, in persistent pain. We selected 12 patients with various kinds of pain of at least 6 months duration. L-Arginine (10% solution, 300 ml (30 g)/patient) was administered by intravenous drip at a rate of 5 ml (0.5 g)/min during a period of 60-70 min. Pain was assessed by the patient using a 10-cm visual analogue scale (VAS), before and after the L-arginine infusion. L-Arginine treatment resulted in slight analgesia at 10-15 min after the onset of infusion and in marked analgesia at 30-40 min after that. This effect lasted for 6-24 h. L-Arginine-induced analgesia was dose-dependent and blocked by intravenous injection of naloxone. In each case, the L-arginine-induced analgesia was statistically significant as compared with the saline-induced effect. Side effects of L-arginine were a slight decrease in mean blood pressure (10-15 mm Hg), and dryness of the month. A suppressive role of a functional link between the L-arginine-kyotorphin system and the enkephalin system of the brain in persistent pain is suggested.
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PMID:Analgesic effect of L-arginine in patients with persistent pain. 182 18

Antiserum of methionine-enkephalin (Met-Enk) applied intrathecally abolished acupuncture analgesia (AA) caused by low frequency stimulation of an acupuncture point (tibial muscle, APS) of rats, but antisera of leucine-enkephalin (Leu-Enk) and dynorphin (Dyn) did not. Antiserum of Dyn applied intrathecally abolished analgesia (NAA) produced by stimulation of a nonacupuncture point (NAPS) which was revealed by lesion in the analgesia inhibitory system (AIS), whereas antisera of Met-Enk and Leu-Enk did not. NAA was antagonized by the kappa-receptor antagonist, Mr2266, and analgesia was produced by the kappa-agonist, U50-488H, in the AIS lesioned rats. Potentials in the dorsal periaqueductal central gray (D-PAG) evoked by APS were antagonized by naloxone and antiserum of Met-Enk, and those in the lateral PAG (L-PAG) evoked by NAPS were antagonized by Mr2266 and antiserum of Dyn. After adrenalectomy, AA, potentials in the D-PAG, and analgesia caused by stimulation (SPA) of the D-PAG were abolished 12 hour; and NAA, potentials in the L-PAG, and SPA of the L-PAG were abolished in 24 hour. All were then restored one hour after intravenous application of 1 ml of 5% NaCl solution. AA and NAA which were augmented for several hours before their abolition after adrenalectomy were not antagonized by naloxone nor M 2266, respectively. However naloxone and Mr2266 did antagonize AA and NAA, respectively, one hour after treatment with 1 ml of 5% NaCl solution.
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PMID:Differentiation of acupuncture and nonacupuncture points by difference of associated opioids in the spinal cord in production of analgesia by acupuncture and nonacupuncture point stimulation, and relations between sodium and those opioids. 198 42

1. Prominent strain differences of mice were found in analgesic effects of D-amino acids. 2. In C57BL/6CrSlc and C3H/HeSlc mice, pain threshold, which was determined by using a hot-plate method, increased to 140-175% of the control after the systemic treatment of all three D-amino acids employed, such as D-phenylalanine, -leucine and -methionine, whereas in DBA/2CrSlc or BALB/cCrSlc mice, out of three only one D-amino acid, D-phenylalanine or -leucine, produced significant increase of pain threshold. 3. This lack of ability to perceive analgesic effects of specific amino acids observed in the latter two strains suggests that there probably exist different analgesia-inducing mechanisms for each of three D-amino acids in mice and the latter two strains lack two of them.
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PMID:Analgesic effects of D-amino acids in four inbred strains of mice. 198 75

It has been suggested that the endogenous opioid peptides, methionine and leucine enkephalin, participate only in naloxone-facilitated antinociceptive responses. To reassess this proposal, analgesic effects resulting from complete inhibition of enkephalin metabolism by intracerebroventricular (i.c.v.) administration of the mixed inhibitor RB 38A (R,S)HONHCOCH2CH(CH2 phi)CONHCH(CH2 phi)COOH) were compared to the effects of morphine (i.c.v.) in various assays commonly used to select analgesics: mouse hot plate-test, tail flick test with mice and rats, electrical stimulation of the tail (TES), paw pressure test with rats, and phenylbenzoquinone-induced writhing test with mice. The ED50s of morphine vs. ED50s of RB 38A in the writhing, hot plate (jumping) and tail flick tests with mice were 0.24 nmol vs. 38 nmol, 1 nmol vs. 36 nmol and 3.2 nmol vs. 285 nmol, respectively. RB 38A (ED30 153 nmol) was only 15 times less active in the tail flick test with rats than morphine and only halve as active in the paw pressure test. Noxious TES in rat was very sensitive to the inhibitory action of endogenous opioids protected by RB 38A, particularly the post-vocalization response which was also shown to be alleviated by antidepressants. All the analgesic effects observed were reversed by naloxone. This first direct evidence of analgesia resulting from peptidase inhibition, in the tail flick test with mice and rats, hot plate (paw lick) and TES shows that the pain suppressive effects of endogenous opioid peptides are not restricted to naloxone-facilitated noxious stimuli but occur more generally, in all morphine-sensitive tests. The differential effects of RB 38A in the various assays is likely to be related to the amount of enkephalins released and to the efficiency of peptidase inactivation in particular brain regions implicated in the control of a given nociceptive input. This mechanism could account for the reduction in side-effects compared to those of morphine following chronic administration of RB 38A.
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PMID:Analgesic responses elicited by endogenous enkephalins (protected by mixed peptidase inhibitors) in a variety of morphine-sensitive noxious tests. 203 57

The effects of two endogenous mammalian FMRFamide (Phe-Met-Arg-Phe-NH2)-related peptides, an octapeptide F8Fa (Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) and an octadecapeptide A18Fa (Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Pro-Gln-Arg-Phe-NH2 ), and IgG from serum against them on the responses to aggression and defeat-induced analgesia were examined in subordinate mice in "resident-intruder" pairings. Intracerebroventricular (ICV) administrations of F8Fa and A18Fa (0.10-10 micrograms) reduced, in a dose-dependent manner, the number of bites to obtain defeat in the subordinate mice during the agonistic encounters, as well as attenuating defeat-induced analgesia, with F8Fa having a greater inhibitory effect than A18Fa. Peripheral administration of naloxone (1.0 mg/kg) had a similar inhibitory effect on the number of bites to defeat and the level of defeat-induced analgesia. In contrast, ICV administrations of F8Fa-IgG and A18Fa-IgG antisera increased the number of bites to defeat and augmented the levels of defeat-induced analgesia, with F8Fa-IgG having a greater effect than A18Fa-IgG. These results provide further evidence that the peptides, F8Fa and A18Fa, are involved in the modulation of opioid-mediated analgesia accompanying biological stressors and suggest that these endogenous FMRF-NH2-related peptides may also be associated with the expression of opioid-sensitive components of aggressive behavior.
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PMID:Effects of mammalian FMRF-NH2-related peptides and IgG from antiserum against them on aggression and defeat-induced analgesia in mice. 206 75

The effects of two endogenous mammalian FMRFamide (Phe-Met-Arg-Phe-NH2)-related peptides, an octapeptide F8Fa (Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) and an octadecapeptide A18Fa (Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe -NH2) on morphine- and restraint stress-induced analgesia and basal nociceptive sensitivity, as measured by the latency of a foot-lifting response to a warmed surface, were examined in male mice. Intracerebroventricular (i.c.v.) administrations of F8Fa and A18Fa (0.10-10 micrograms) during the day-time significantly reduced morphine (10 mg/kg) and restraint-induced analgesia at 30 min after administration, with F8Fa having a greater inhibitory effect than A18Fa. At night during the dark period i.c.v. F8Fa also significantly reduced the elevated nocturnal thermal response latency, while not affecting the shorter day-time nociceptive responses. Peripheral administrations of the prototypic opiate antagonist, naloxone (1.0 mg/kg), had similar inhibitory effects on morphine- and stress-induced analgesia, and the day-night rhythm of nociceptive sensitivity. These results indicate that F8Fa and A18Fa are involved in the modulation of opioid analgesia and suggest that these endogenous FMRFamide-related peptides may be associated with the expression of the day-night rhythm of opioid-mediated nociceptive sensitivity.
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PMID:Inhibitory influences of mammalian FMRFamide (Phe-Met-Arg-Phe-amide)-related peptides on nociception and morphine- and stress-induced analgesia in mice. 223 8


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