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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

After thousands of painful long-lasting migraine or extremely violent cluster headache attacks no one has yet traced histological inflammatory or degenerative alterations of the interested tissues able to explain such dreadful pain. Therefore it has seemed logical to include these pains among the unjustified aimless, non finalized types of pain. Furthermore, clinical characteristics of automatism, explosiveness and the course of these pains resemble other aimless pains like those of organic deafferentation (phantom pain) which appear in a desensitized limb after denervation or even in amputated subjects. Intense and long lasting pains in opioid abstinence, mainly located in the chest and in the hip, also have all the characteristics of aimless pain. Idiopathic cephalic pain, together with deafferentation or opioid-abstinence pain, seems to be due to a dysafferentation which, through different channels, follows an analogous mechanism. This mechanism seems to be due to a deficit of autoanalgesia which in both organic deafferentation (phantom limb) and in opioid-abstinence can be related to the disuse of afferences' modulation. In idiopathic headache such a failure of autoanalgesia is likely to be due to a genetic, idiopathic mechanism. Headaches are characterized by a clear deficiency of autoanalgesia which may manifest itself not only at the level of the cephalic segment, which is so rich in afferences, but it may even involve the whole body. Even if pain is the compulsory phenomenon to diagnose headache, one must consider that migraine is a symptomatic triad in which vegetative and emotional phenomena also emerge. These phenomena are interindependent and not interdependent as each of them may appear as a first manifestation of an attack; one must therefore consider the possibility of a "unicum movens". Serotonin was taken into consideration because of its action which interests all or nearly all vegetative-emotional pain transmitting pathways. Today's identification of four types and various sub-types of 5-HT receptors has revealed the extraordinary eclecticism of this transmitter which within migraine's clinical expression underscores that migraine sufferers are characterized by a marked sensitivity to all the drugs capable of acutely or chronically interacting with serotonin metabolism and binding with many serotonin receptor types and sub-types. So even if the migraine sphinx still proposes its enigma, researchers--with their incurable curiosity--may not only find more and more accurate and effective medication for many human beings but also start penetrating a mystery, a great challenge to human imagination.
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PMID:[Noci-autonomic-affective automatism, the physiopathological essence of hemicrania. The serotonin theory as a guiding principle in the labyrinth of interpretations]. 129

The neural substrates of endogenous supraspinal opioid pain inhibition are mediated in part by connections between the midbrain periaqueductal gray (PAG) and the ventral-medial medulla, including the nucleus raphe magnus (NRM) and nucleus reticularis gigantocellularis (NRGC). To ascertain whether a serotonergic synapse participated in this pathway, the present study determined whether microinjections of methysergide into the NRM or NRGC would alter analgesia elicited by morphine microinjections into the PAG. Morphine (2.5 micrograms) in the PAG and immediately adjacent areas produced significant analgesia on the tail-flick and jump tests in rats. Pretreatment with the serotonin receptor antagonist methysergide (0.5-5 micrograms) in either the NRM or NRGC significantly reduced morphine analgesia elicited from the PAG by 69% on the tail-flick and by 50% on the jump tests without altering basal nociceptive thresholds. Medullary placements ventral or lateral to the NRM/NRGC failed to support this antagonistic effect. These data indicate that a ventro-medial medullary serotonergic synapse participates in the transmission of opioid pain-inhibitory signals from the PAG.
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PMID:Inhibition of mesencephalic morphine analgesia by methysergide in the medial ventral medulla of rats. 131 Nov 8

Supraspinal opioid analgesia is mediated in part by connections between the midbrain periaqueductal gray (PAG) and the ventral-medial medulla, including the nucleus raphe magnus (NRM) and nucleus reticularis gigantocellularis (NRGC). A serotonergic synapse appears to participate in this pathway since methysergide microinjected into the NRM-NRGC significantly reduced morphine analgesia elicited from the PAG. The present study evaluated the role of specific serotonin receptor subtypes by pretreating rats with microinjections of either the 5HT2 antagonist, ritanserin or the 5HT3 antagonist, ICS205930, into the NRM-NRGC and examining their effects upon morphine (2.5 micrograms) analgesia elicited from the PAG. Mesencephalic morphine analgesia was significantly reduced following pretreatment with both ritanserin (0.25-2.5 micrograms) on the tail-flick (81%) and jump (65%) tests and ICS205930 (0.25-5 micrograms) on the tail-flick (91%) and jump (63%) tests. Neither ritanserin nor ICS205930 altered basal nociceptive thresholds. Medullary placements ventral or lateral to the NRM/NRGC failed to support these antagonistic effects. These data indicate that ventro-medial medullary 5HT2 and 5HT3 serotonergic receptors modulate the transmission of opioid pain-inhibitory signals from the PAG.
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PMID:Serotonin receptor subtype antagonists in the medial ventral medulla inhibit mesencephalic opiate analgesia. 147 4

The antinociceptive actions of 2-deoxy-D-glucose (2-DG) are mediated in part by endogenous opioid, dopaminergic, cholinergic, histaminergic, and neurohormonal influences. Although 2-DG antinociception was not affected by tryptophan hydroxylase inhibition, a possible serotonergic role in 2-DG antinociception was investigated because of the existence of serotonin [5-hydroxytryptamine (5-HT)] receptor subtypes. The present study examined the effects of general (methysergide: 5 and 10 mg/kg), 5-HT2 (ritanserin: 2.5 mg/kg), and 5-HT3 (ICS-205,930: 0.25-5 mg/kg) receptor subtype antagonists upon 2-DG antinociception on the tail-flick and jump tests in rats. On the tail-flick test, 2-DG (450 mg/kg) antinociception was significantly reduced by all ICS-205,930 doses (48-58%) but unaffected by either methysergide (22-29% reduction) or ritanserin (6% reduction). In contrast, 2-DG antinociception on the jump test was significantly potentiated across the 120-min time course and across the 2-DG dose-response curve (100-650 mg/kg) by methysergide, ritanserin, and ICS-205,930 pretreatment. Each of the three antagonists produced significant leftward shifts in the peak and total 2-DG dose-response curve for the jump test. These data suggest different sites of action for 2-DG antinociception as a function of the pain test employed and a differential modulation by serotonin receptor subtypes at those sites.
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PMID:2-Deoxy-D-glucose antinociception and serotonin receptor subtype antagonists: test-specific effects in rats. 147 8

The past decade has seen important progress in understanding the localization, pharmacology, and function of serotonin (5-HT) receptor subtypes. At least seven subclasses have been shown to exist, and evidence is emerging to suggest further subclassification. Serotonin is involved in numerous physiological processes (e.g. feeding, sleep, pain, sexual behavior, temperature regulation) and pathophysiological ones. Serotonin reuptake blockers have been found effective in the alleviation of depression and attacks of panic, and are at varying stages of clinical evaluation in the treatment of obsessive compulsive disorder, chronic pain, and bulimia nervosa. Selective potent serotonin receptor agonists and antagonists show promise in the treatment of migraine, nausea and vomiting, schizophrenia, anxiety, hypertension, and Raynaud's disease.
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PMID:[New therapeutic possibilities with drugs affecting serotonin receptors]. 150 27

Recent evidence suggests that migraine may not be due to vasoconstriction followed by reactive vasodilation, and tension-type headache may not be due to excess muscle contraction. The prodromes of migraine may have a hypothalamic origin, and the aura and changes in cognition may have a cortical neuronal origin. The pain of migraine and tension-type headache may be generated centrally or enhanced or generated by neurogenic inflammation. Drugs used to treat headache frequently interact with serotonin receptor subtypes: abortive drugs at the 5-HT1 receptor and preventive drugs at the 5-HT2 receptor.
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PMID:Advances in understanding the pathophysiology of headache. 155 93

In a previous study, prolonged low-frequency muscle stimulation in the hind leg of the fully conscious spontaneously hypertensive rat (SHR) was shown to induce a long-lasting reduction of blood pressure. It was also shown that opioid and serotonergic (5-HT) systems were involved. More recently, we have shown that the 5-HT1 receptors are involved in the post-stimulatory decrease in blood pressure. In the present study, the influence of this type of muscle stimulation on the pain threshold was investigated. Pain perception was measured as the squeak threshold to noxious electric pulses. After cessation of the stimulation, an analgesic response was elicited within 60 min and peak analgesia developed after 120 min, being 139 +/- 10% (P less than 0.01) of the prestimulatory control value. The increased pain threshold lasted for another 2 h. One group of SHR was pretreated with PCPA, a serotonin synthesis blocker, which completely abolished the post-stimulatory analgesia. To analyse further the involvement of different serotonin systems, drugs with selective affinity for 5-HT receptors were used. In one group a prestimulatory dose of metitepine maleate (a 5-HT1&2 receptor antagonist) abolished the post-stimulatory elevation of the pain threshold. The prolonged analgesic response was still present after prestimulatory treatment with ritanserin or ICS 205-930 (5-HT2 and 5-HT3 blocking agents respectively). In another group of experiments, the serotonin receptor antagonists were administered post-stimulation to animals with fully elicited analgesia. None of the antagonists used could reverse the elevation of pain threshold towards prestimulatory levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Electrical stimulation of the gastrocnemius muscle in the spontaneously hypertensive rat increases the pain threshold: role of different serotonergic receptors. 213 3

Basic research strongly implicates the neurotransmitter serotonin as a modulator of endogenous analgesic systems. Recently, clinical strategies have been developed to activate endogenous serotonergic systems as a therapeutic approach to pain control. This paper reviews the biochemistry, anatomical distribution, and physiologic functions of serotonin. The evidence reviewed suggests that precursor loading to increase brain serotonin levels and administration of serotonin receptor inhibitors and serotonin receptor agonists may lead to novel methods of pain control and the development of useful analgesic drugs.
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PMID:Therapeutic implications of modifying endogenous serotonergic analgesic systems. 298 89

In 41 patients with Primary Raynaud's Phenomenon (PRP) the effectiveness of the serotonin receptor blocker ketanserin has been studied in a double blind cross-over study. Subjective assessments included: frequency and duration of the attacks (both per se and combined to a severity score), cold sensation, numbness, paresthesia, pain, cold water and cold weather provocation and the appearance of spontaneous attacks. The objective measurements comprised Digital Skin Temperature (DST), Digital systolic Blood Pressure (DBP) and Doppler Spectral Analysis (DOSA) of the radial and ulnar arteries. All measurements were performed both at room temperature and after instant cold provocation. The severity score, the occurrence of numbness and paresthesia and cold weather provocation improved significantly on ketanserin treatment. All objective measurements with the exception of the end-diastolic blood flow velocity of DOSA did not show significant improvements. Neither blood chemistry nor systemic blood pressure showed any significant change during ketanserin treatment. However, in the 6 (15%) patients with hypertension both systolic and diastolic blood pressure normalized. Although in objective measurements hardly any significant effects of ketanserin could be demonstrated, the results of the study suggest that orally administered ketanserin is effective for minimizing subjective complaints in patients with PRP. Ketanserin did not show any side effects.
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PMID:The effectiveness of ketanserin in patients with primary Raynaud's phenomenon. A randomized, double blind, placebo controlled study. 332 7

Previous studies have shown that brain serotonin is increased and noradrenaline decreased in acupuncture and transcutaneous nerve stimulation (TNS). Increases in available brain serotonin and decreases in noradrenaline enhance pain suppression. The present study tests the possibility that the widespread and prolonged cutaneous vasodilation which can be produced by low-frequency TNS in patients with peripheral circulatory insufficiency is similarly dependent on a central serotonergic pathway leading to sympatho-inhibition. The serotonin receptor antagonist cyproheptadine was given to 4 patients with either Raynaud's phenomenon or diabetic polyneuropathy, who all prior to drug administration responded to TNS with marked and prolonged cutaneous vasodilation in the ischaemic limbs. Cyproheptadine almost completely blocked the vascular response. Contrary to endorphin-serotonin mediated pain inhibition, vasoconstrictor inhibition is not antagonized by conventional, low doses of naloxone (Kaada, 1982a). However, the involvement of more naloxone-resistant opioid receptors in the vascular response cannot be excluded.
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PMID:In search of mediators of skin vasodilation induced by transcutaneous nerve stimulation: II. Serotonin implicated. 666 43


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