Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acupuncture and non-acupuncture points were differentiated by their connection to different pathways in the central nervous system. We have found that the pathway connected to the acupuncture point is different from the pathway connected to the non-acupuncture point. In addition, pathway connected to the non-acupuncture point is inhibited within the lateral periaqueductal gray when the analgesia inhibitory system (AIS) is activated. We have explored these pathways by means of selective lesioning of discrete brain regions, selective stimulation of brain regions, as well as by recording evoked potentials arising from stimulation of acupuncture and non-acupuncture points. It was found that the lateral centromedian nucleus of the thalamus and the posterior hypothalamus are parts of the AIS. The acupuncture (tibialis muscle) and non-acupuncture (abdominal muscle) points are both connected to the AIS. Analgesia caused by stimulation of the acupuncture point is naloxone reversible, while that caused by stimulation of the non-acupuncture point after lesion of AIS is dexamethasone reversible. Stress-induced analgesia caused by low frequency electrical shock is naloxone as well as dexamethasone reversible. All three kinds of analgesia were abolished by hypophysectomy. The features and the degree of analgesia caused by intraperitoneal 0.5 mg/kg morphine were similar to analgesia caused by acupuncture point stimulation. D-phenylalanine acts like a lesion of AIS in analgesia caused by stimulation of acupuncture and non-acupuncture points, and enhances naloxone reversible analgesia. The descending pain inhibitory system plays a role as the common pathway to produce these three kinds of analgesia. This pathway is found in the arcuate nucleus (dopaminergic), ventromedian nucleus of the hypothalamus, raphe nucleus (serotonergic), reticular gigantocellular nucleus (noradrenergic) and reticular paragigantocellular nucleus.
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PMID:Differentiation between acupuncture and non-acupuncture points by association with analgesia inhibitory system. 286 73

The effect D-phenylalanine (DPA), a putative inhibitor of enkephalin degradation, on the two separate pain components produced by the submaximal effort tourniquet test was evaluated in healthy human volunteers (N = 8). DPA attenuated the increase of the intensity of the ischemic and pressure pain components with increasing ischemia duration, but only the effect on the pressure pain component was significant. The results support some earlier reports suggesting that DPA has analgetic properties.
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PMID:Attenuation of tourniquet-induced pain in man by D-phenylalanine, a putative inhibitor of enkephalin degradation. 289 66

It has been claimed that the mechanism of acupuncture analgesia can be explained in part by endogenous opioids. If so, it might be possible to enhance the analgesic effect of acupuncture by the administration of endorphins. If D-phenylalanine (DPA), an inhibitor of the endorphin degrading enzyme, is administered, the analgesic effect of acupuncture should be prolonged due to the increased level of endorphins. From the changes of the pain threshold (PT), we investigated whether or not the pre-administration of DPA can enhance the analgesic effect of acupuncture in humans. In addition, we examined the inhibitory effect of naloxone. 1) In all five subjects whose PT was raised after acupuncture anesthesia (respondents), the rise in PT was significantly prolonged by DPA. 2) Out of 10 subjects whose PT remained almost unchanged after acupuncture anesthesia (non-respondents), the PT was increased by DPA in 5 cases. 3) The rise in PT was most prominent when DPA was administered 30 minutes before the start of acupuncture anesthesia. 4) In all 4 respondents in whom the rise in PT persisted after DPA and acupuncture anesthesia, their raised PT dropped after the intravenous injection of naloxone (10 mg). 5) These findings show that DPA enhances the analgesic effect of acupuncture by the "endorphin mechanism."
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PMID:Studies on the enhanced effect of acupuncture analgesia and acupuncture anesthesia by D-phenylalanine (first report)--effect on pain threshold and inhibition by naloxone. 290 13

It has been accepted that the periaqueductal gray matter of the mid brain (PAG) and the reticular formation of the medulla oblongata in the brain stem have antinociceptive roles in the pain control pathways of mammals, and met5-enkephalin may act as one of the pain control substances in those regions. In the present study, the effects of 2S,3R 3-amino-2-hydroxy-4-phenylbutanoic acid (AHPA) derivatives on met5-enkephalin-induced antinociception were examined by a hot plate method in mice. The elevation of pain threshold induced by an intracisternal administration of met5-enkephalin was enhanced by AHPA derivatives. The rank order of potency for these agents was as follows: bestatin greater than D-Phe-AHPA greater than AHPA-D-Ala greater than p-OH-AHPA-D-Phe greater than AHPA. This order was roughly correlated to that of the enkephalinase inhibitory activity of the AHPA derivatives. These results indicate that the inhibition of enkephalinase may produce the augmentation of the exogenous met5-enkephalin-induced antinociception. It is also suggested that AHPA derivatives may cause the enhancement of the endogenous met5-enkephalin-mediated antinociception.
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PMID:2S,3R 3-amino-2-hydroxy-4-phenylbutanoic acid derivatives, enkephalinase inhibitors, augment met5-enkephalin-induced antinociception. 316 81

Intermittent claudication is associated with adaptation in muscle metabolism. This study has evaluated the metabolism of amino acids at rest and during non-steady state exercise in patients with arterial insufficiency of at least six months duration in comparison with matched control individuals. The exchange of amino acids were measured during two periods of acute exercise; one initial exercise period with a standardized work load and exercise time and a second exercise period which continued until further exercise was impossible due to pain in the patients and exhaustion in the controls. The maximum blood flow was reduced by 40% in the patients but the maximum oxygen uptake per unit power developed was almost the same in patients and controls. The patients had significantly lower concentrations of glutamine, lysine and taurine at rest compared with the controls. The exchange of amino acids across the resting leg did not differ between the two groups. Exercise increased the efflux of amino acids in both patients and controls. The efflux of glutamine (896 +/- 205 vs. 48 +/- 359 nmol/100 ml/min/watt) was higher in the patients compared to the controls at the first exercise period with inverse changes in the opposite direction of asparagine (149 +/- 105 vs. 799 +/- 121 and 27 +/- 70 vs. 633 +/- 334 nmol/100 ml/min/watt at the first and second exercise, respectively. Alanine release did not differ between the groups. The complementary patterns of glutamine and asparagine during hypoxic exercise in the patients may reflect the fact that these amino acids share a common carrier system. The similarity in the efflux of non-metabolized amino acids, such as methionine, phenylalanine, tyrosine and 3-methylhistidine, indicated that muscle hypoxia in claudication patients did not promote net degradation of either globular or myofibrillar proteins, although exercise increased the efflux of 3-methylhistidine three- to fourfold in both patients and control individuals (from 1 +/- 0.4 to 4 +/- 1.8 and from 0 +/- 0.7 to 6 +/- 2.5 nmol/100 ml/min/watt, respectively). The exercise-induced alterations in leg exchange of amino acids were restored within 10-20 min following exercise regardless of hypoxia. The results demonstrate that patients with arterial insufficiency have altered intermediary metabolism of amino acids during exercise. However, muscle hypoxia in such patients does not seem to promote a negative protein balance or induce serious alterations in cell membrane integrity.
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PMID:Leg exchange of amino acids during exercise in patients with arterial insufficiency. 340 84

1. The effect of bradykinin (BK) and some analogues of BK on the human blister base was studied. 2. BK produced reproducible dose-related increases in pain responses. A characteristic delay, which was not dose-related occurred between application of BK and the resultant response. 3. The rank order of potency of several kinin analogues on the pain response was BK much much greater than sigma-cyclo-(Lys1-Gly6)-BK = sigma-cyclo-kallidin greater than des-Arg9-BK. 4. No increase in pain response was seen with repeated application of the selective B1 receptor agonist des-Arg9-BK to the same blister base at 4 h intervals. The B1 receptor antagonist des-Arg9-Leu8-BK was without effect against BK-induced responses. 5. The B2 receptor antagonists, D-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-D-Phe-Thi-Arg-TEA and D-Pro-Phe-Arg-heptylamide produced significant antagonism of the bradykinin-induced pain responses at doses which had no effect against 5-hydroxytryptamine or potassium chloride. 6. It is concluded that the kinin receptor mediating pain on the human blister base is of the B2 type.
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PMID:The effect of kinin agonists and antagonists on the pain response of the human blister base. 344 81

D-Phenylalanine, along with morphine, acetylsalicylic acid and zomepirac sodium were evaluated for their antinociceptive actions in monkeys (M. fascicularis) trained to autoregulate nociceptive stimulation using a discrete-trials, aversive-threshold paradigm. Morphine sulfate produced dose-related increases in aversive threshold which were reversible after administration of naloxone (12.5 or 25 micrograms/kg i.m.). D-Phenylalanine (500 mg/kg p.o.) produced a small increase in aversive threshold which was not statistically significant and not naloxone reversible. Acetylsalicylic acid (200 mg/kg p.o.) but not zomepirac sodium (200 mg/kg p.o.) in combination with D-phenylalanine (500 mg/kg) produced a small statistically significant increase in aversive threshold. Our results argue against the hypothesis that D-phenylalanine is responsible for increasing aversive thresholds via opiate receptor mechanisms involving increased activity of enkephalins at synaptic loci. Previous studies by others in rats and mice showed that D-phenylalanine and acetylsalicylic acid produced increases in nociceptive thresholds which were naloxone reversible. Our failure to find opiate receptor mediated analgesia in a primate model with demonstrated opiate receptor selectivity and sensitivity is discussed in terms of previous basic and clinical research indicating an analgesic role for D-phenylalanine. Possible species difference in drug action is discussed in terms of inhibition by D-phenylalanine of carboxy-peptidase-like enkephalin processing enzymes as well as inhibition of carboxypeptidase-like enkephalin degrading enzymes.
Pain 1986 Feb
PMID:D-phenylalanine: a putative enkephalinase inhibitor studied in a primate acute pain model. 351 91

Enkephalins are a biochemical pathway for endogenous analgesia. A number of compounds inhibit degradation of enkephalins within the body. One of these compounds, D-phenylalanine (DPA), has been shown to increase the pain threshold in animals. It is hypothesized that this naloxone reversible analgesia is induced by DPA blockage of enkephalin degradation by the enzyme carboxypeptidase A. Preliminary studies of chronic pain patients have shown a response rate to DPA from 32% to 75%. This study was a double-blind crossover evaluation of a randomized parallel design to determine the efficacy of DPA in 30 subjects with chronic pain from varied etiology which was unrelieved by multiple therapeutic interventions. Each patient received a stabilized therapeutic regimen during this study consisting of four weeks of either DPA 250 mg or lactose (placebo) orally four times a day. After four weeks the DPA and placebo groups were crossed over for an additional four weeks of treatment. Pain was quantified using a visual analog pain scale and a cold pressor test. Data from the pain questionnaires revealed more pain relief on DPA reported by 25% of the patients, more pain relief on placebo reported by 22% of the patients, and no difference in pain relief reported by 53% of the patients. Lowest pain level of the visual analog scale was reported by 47% of the patients on DPA and 53% on placebo. There appears to be no significant analgesic effect from D-phenylalanine in chronic pain patients when compared to placebo.
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PMID:Analgesic effectiveness of D-phenylalanine in chronic pain patients. 352 9

In experiments on rats it was shown that morphine and D-phenylalanine in doses of 5 and 100 mg/kg, respectively, produce a similar by the degree increase of pain reaction thresholds at stimulation of paws through the electrified floor of the chamber. Experiments on rabbits demonstrated that the main factor in morphine action is a decrease of excitability and blood filling of the reticular formation of the midbrain and the central gray matter and an increase of excitability of the dorsal hippocamp without significant changes in the frontal cortex excitability. D-phenylalanine also caused a decrease of excitability of the reticular formation but in contrast to morphine failed to change excitability of the dorsal hippocamp and enhanced excitability of the central gray matter.
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PMID:[Comparative characteristics of the functioning of brain structures exposed to morphine and D-phenylalanine]. 358 28

Highly sensitive radioimmunoassays were developed and used in studies of the distribution and chromatographic properties of two mammalian FMRF-NH2-like peptides recently isolated from bovine brain; an octapeptide with the structure Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (F-8-F-NH2) and on octadecapeptide, Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe-NH2 (A-18-F-NH2). F-8-F-NH2 and A-18-F-NH2 immunoreactivities are unevenly distributed in bovine brain. The highest concentrations (pmol g-1) of F-8-F-NH2 and A-18-F-NH2 are found in dorsal spinal cord (9.8 and 16.4 respectively), periaqueductal grey (8.6 and 6.8) and pons medulla (7.0 and 8.9); lowest quantities are in cortex, cerebellum and striatum. HPLC analysis coupled with radioimmunoassay reveals that the major immunoreactivities are identical to synthetic F-8-F-NH2 and A-18-F-NH2 while there are additional immunoreactive materials, distinct from NPY, whose structures still remain to be determined. The enrichment of these peptides in dorsal cord and periaqueductal grey, areas important in opioid-mediated pain perception, suggest that they may play a role in mediating antinociception.
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PMID:Distribution and characterization of two putative endogenous opioid antagonist peptides in bovine brain. 362 81


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