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)

Actions of morphine include analgesia, sleep, euphoria, and depression of respiration. Transmitter or modulator substances in the brain that have actions similar to morphine may control these functions in man. This hypothesis proposes that enkephalin is a controlling neurotransmitter and its binding to opiate receptors determines mood state as well as influencing respiratory and sleep patterns. Lithium may act through modification of the opiate receptor affinity for an endogenous morphine-like substance. The theory predicts blocking action of naloxone in mania and in most drug-induced euphorias. It implies a new chemical pathophysiological basis for the phenomenology of mental illness.
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PMID:Peptide transmitters: a unifying hypothesis for euphoria, respiration, sleep, and the action of lithium. 5 53

The modifications produced by 6-hydroxydopamine (6-OHDA) on the analgesic and toxic effects of morphine have been studied in mice and cats. After intracerebral injections of 6-OHDA, mice had a lower threshold for morphine-induced convulsions. Morphine analgesia assayed by the phenylquinone test was apparently antagonized in the 6-OHDA pretreated mice, but the 6-OHDA mice showed more reactivity to the phenylquinone. Intraventricular injection of 6-OHDA in cats produced an acute syndrome with mydriasis, bradycardia, bradypnea, hypothermia and EEG slowing, which subsided after several days, 6-OHDA was successful in blocking the morphine mania, but the animals died within 24 h.
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PMID:Antinociceptive and stimulant effects of morphine after chemical sympathectomy. 95 25

Opioids have an unjustified reputation for causing mania in cats, but with refinements in dosing they are now used successfully in this species. The mu-opioid agonists are generally considered the best analgesics. Morphine (0.1-0.3 mg/kg) is effective in a clinical setting. Methadone (up to 0.5 mg/kg) has a similar profile to morphine. Pethidine (Demerol, meperidine; 2-5 mg/kg) is a useful analgesic with a faster onset but shorter duration of action than morphine. Oxymorphone and hydromorphone (0.05-0.1 mg/kg) are widely used in the USA. These opioids are more potent (up to 10 times), and longer acting than morphine in cats. Butorphanol (0.1-0.4 mg/kg) is a mu-opioid antagonist that produces its analgesic actions through kappa agonist activity. It rapidly reaches a ceiling effect, is short acting and is a weaker analgesic than pure mu opioids. Buprenorphine (0.01-0.02 mg/kg), a partial mu-agonist, is the most popular opioid used in small animal practice in the UK, other parts of Europe, Australia and South Africa. In clinical studies it has produced better analgesia than several other opioids and appears to be highly suitable for perioperative pain management in cats. NSAIDs are also used in cats for pain management, although cats metabolise these differently from other species. With appropriate dosing, carprofen (1-4 mg/kg) and meloxicam (0.3 mg/kg) have proved highly effective with few side effects. The use of ketoprofen (2 mg/kg), tolfenamic acid (4 mg/kg) and vedaprofen (0.5 mg/kg) has been reported in cats. Other less traditional analgesics such as ketamine, medetomidine and local anaesthetics are also used for clinical pain management. The transmucosal, transdermal and epidural routes offer novel methods for administration of analgesic drugs and have considerable potential for improving techniques in feline pain management.
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PMID:Pain management in cats--past, present and future. Part 2. Treatment of pain--clinical pharmacology. 1536 64

Nociceptive information may be inhibited by stimulation of opiate receptors located presynaptically on primary afferent neurons. Sensory signals entering the spinal cord inhibit nociceptive signals by a non-opioid "gate" mechanism. Descending systems also modulate pain sensitivity at the spinal level. The descending 5-hydroxytryptamine (5-HT) system has a tonic inhibitory function, with diurnal fluctuations in intensity. The strong analgesic effects of electrical stimulation and morphine microinjections in certain brainstem structures is probably mediated by other descending systems. The ascending 5-HT system may influence the results of some complex tests for pain sensitivity by altering e.g. emotionality and habituation rate. Acupuncture analgesia involves opioid systems. In high frequency electroacupuncture and transcutaneous nerve stimulation, a non-opioid "gate" mechanism may predominate. Acute stress may produce analgesia by opioid as well as non-opioid mechanisms. The control of pain sensitivity is influenced by learning (e.g. biofeedback techniques and social factors), and may be affected in depression, mania and schizophrenia.
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PMID:Regulation of pain sensitivity in the central nervous system. 1564 34