Related Research Articles
Dynorphins (Dyn) are a class of opioid peptides that arise from the precursor protein prodynorphin. When prodynorphin is cleaved during processing by proprotein convertase 2 (PC2), multiple active peptides are released: dynorphin A, dynorphin B, and α/β-neo-endorphin. Depolarization of a neuron containing prodynorphin stimulates PC2 processing, which occurs within synaptic vesicles in the presynaptic terminal. Occasionally, prodynorphin is not fully processed, leading to the release of “big dynorphin.”
Buprenorphine is an opioid used to treat opioid use disorder, acute pain, and chronic pain. It can be used under the tongue (sublingual), in the cheek (buccal), by injection, as a skin patch (transdermal), or as an implant. For opioid use disorder, it is typically started when withdrawal symptoms have begun and for the first two days of treatment under direct observation of a health-care provider. In the United States, the combination formulation of buprenorphine/naloxone (Suboxone) is usually prescribed to discourage misuse by injection. Maximum pain relief is generally within an hour with effects up to 24 hours. Buprenorphine affects different types of opioid receptors in different ways. Depending on the type of receptor, it may be an agonist, partial agonist, or antagonist. In the treatment of opioid use disorder buprenorphine is an agonist/antagonist, meaning that it relieves withdrawal symptoms from other opioids and induces some euphoria, but also blocks the ability for many other opioids, including heroin, to cause an effect. Unlike full agonists like heroin or methadone, buprenorphine has a ceiling effect, such that taking more medicine will not increase the effects of the drug.
Nociceptin/orphanin FQ (N/OFQ), a 17-amino acid neuropeptide, is the endogenous ligand for the nociceptin receptor. Nociceptin acts as a potent anti-analgesic, effectively counteracting the effect of pain-relievers; it's activation is associated with brain functions such as pain sensation and fear learning.
Opioid-induced hyperalgesia (OIH) or opioid-induced abnormal pain sensitivity, also called paradoxical hyperalgesia, is generalized pain caused by the long-term use of opioids such as morphine, oxycodone, and methadone. OIH is not necessarily confined to the original affected site. This means that if the person was originally taking opioids due to lower back pain, when OIH appears, the person may experience pain in the entire body, instead of just in the lower back. Over time, individuals taking opioids can also develop an increasing sensitivity to noxious stimuli, even evolving a painful response to previously non-noxious stimuli (allodynia). This means that if the person originally felt pain from twisting or from sitting too long, the person might now additionally experience pain from a light touch or from raindrops falling on the skin.
Opiorphin is an endogenous chemical compound first isolated from human saliva. Initial research with mice shows the compound has a painkilling effect greater than that of morphine. It works by stopping the normal breakup of enkephalins, natural pain-killing opioids in the spinal cord. It is a relatively simple molecule consisting of a five-amino acid polypeptide, Gln-Arg-Phe-Ser-Arg (QRFSR).
Desmetramadol (INN), also known as O-desmethyltramadol (O-DSMT), is an opioid analgesic and the main active metabolite of tramadol. Tramadol is demethylated by the liver enzyme CYP2D6 in the same way as codeine, and so similarly to the variation in effects seen with codeine, individuals who have a less active form of CYP2D6 will tend to get reduced analgesic effects from tramadol. This also results in a ceiling effect which limits tramadol's range of therapeutic benefits to the treatment of moderate pain.
Neuromedin U is a neuropeptide found in the brain of humans and other mammals, which has a number of diverse functions including contraction of smooth muscle, regulation of blood pressure, pain perception, appetite, bone growth, and hormone release. It was first isolated from the spinal cord in 1985, and named after its ability to cause smooth muscle contraction in the uterus.
Tapentadol, brand names Nucynta among others, is a centrally acting opioid analgesic of the benzenoid class with a dual mode of action as an agonist of the μ-opioid receptor and as a norepinephrine reuptake inhibitor (NRI). Analgesia occurs within 32 minutes of oral administration, and lasts for 4–6 hours.
Pravadoline (WIN 48,098) is an antinflammatory and analgesic drug with an IC50 of 4.9 μM and a Ki of 2511 nM at CB1, related in structure to nonsteroidal anti-inflammatory drugs (NSAIDs) such as indometacin. It was developed in the 1980s as a new antiinflammatory and prostaglandin synthesis inhibitor, acting through inhibition of the enzyme cyclooxygenase (COX).
RB-101 is a drug that acts as an enkephalinase inhibitor, which is used in scientific research.
Tebanicline is a potent synthetic nicotinic (non-opioid) analgesic drug developed by Abbott. It was developed as a less toxic analog of the potent poison dart frog-derived compound epibatidine, which is about 200 times stronger than morphine as an analgesic, but produces extremely dangerous toxic side effects. Like epibatidine, tebanicline showed potent analgesic activity against neuropathic pain in both animal and human trials, but with far less toxicity than its parent compound. It acts as a partial agonist at neuronal nicotinic acetylcholine receptors, binding to both the α3β4 and the α4β2 subtypes.
Whether fish feel pain similar to humans or differently is a contentious issue. Pain is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in an animal, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
Pain negatively affects the health and welfare of animals. "Pain" is defined by the International Association for the Study of Pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Only the animal experiencing the pain can know the pain's quality and intensity, and the degree of suffering. It is harder, if even possible, for an observer to know whether an emotional experience has occurred, especially if the sufferer cannot communicate. Therefore, this concept is often excluded in definitions of pain in animals, such as that provided by Zimmerman: "an aversive sensory experience caused by actual or potential injury that elicits protective motor and vegetative reactions, results in learned avoidance and may modify species-specific behaviour, including social behaviour." Nonhuman animals cannot report their feelings to language-using humans in the same manner as human communication, but observation of their behaviour provides a reasonable indication as to the extent of their pain. Just as with doctors and medics who sometimes share no common language with their patients, the indicators of pain can still be understood.
Pain in crustaceans is a scientific debate which questions whether they experience pain or not. Pain is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in an animal, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
The tail flick test is a test of the pain response in animals, similar to the hot plate test. It is used in basic pain research and to measure the effectiveness of analgesics, by observing the reaction to heat. It was first described by D'Amour and Smith in 1941.
A nociception assay evaluates the ability of an animal, usually a rodent, to detect a noxious stimulus such as the feeling of pain, caused by stimulation of nociceptors. These assays measure the existence of pain through behaviors such as withdrawal, licking, immobility, and vocalization. The sensation of pain is not a unitary concept; therefore, a researcher must be conscious as to which nociception assay to use.
Cebranopadol is an opioid analgesic of the benzenoid class which is currently under development internationally by Grünenthal, a German pharmaceutical company, and its partner Depomed, a pharmaceutical company in the United States, for the treatment of a variety of different acute and chronic pain states. As of November 2014, it is in phase III clinical trials.
Pain is an aversive sensation and feeling associated with actual, or potential, tissue damage. It is widely accepted by a broad spectrum of scientists and philosophers that non-human animals can perceive pain, including pain in amphibians.
Pain in cephalopods is a contentious issue. Pain is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in non-human animals, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
RB-120 is an orally active analog of the drug RB-101. It acts as an enkephalinase inhibitor, which is used in scientific research. Via intravenous administration, it is approximately three times as potent as RB-101 or twice as potent as the isolated (S,S) isomer of RB101. However, via i.p. administration it is approximately twice as potent as racemic RB-101 and about as potent as the isolated (S,S) isomer of RB101. During i.v. administration RB120 is approximately twice as weak as morphine in terms of analgesia, however it is 16x weaker during i.p. and p.o. administration.
References
- ↑ Carlsson, Karl-Heinz; Jurna, Ilmar (1987). "Depression by flupirtine, a novel analgesic agent, of motor and sensory responses of the nociceptive system in the rat spinal cord". European Journal of Pharmacology. 143 (1): 89–99. doi:10.1016/0014-2999(87)90738-2. ISSN 0014-2999. PMID 3691652.
- ↑ Matera, Carlo; Flammini, Lisa; Quadri, Marta; Vivo, Valentina; Ballabeni, Vigilio; Holzgrabe, Ulrike; Mohr, Klaus; De Amici, Marco; Barocelli, Elisabetta; Bertoni, Simona; Dallanoce, Clelia (2014). "Bis(ammonio)alkane-type agonists of muscarinic acetylcholine receptors: Synthesis, in vitro functional characterization, and in vivo evaluation of their analgesic activity". European Journal of Medicinal Chemistry. 75: 222–232. doi:10.1016/j.ejmech.2014.01.032. ISSN 0223-5234. PMID 24534538.
- ↑ Eddy, NB; Leimbach, D (1953). "Synthetic analgesics. II. Dithienylbutenyl- and dithienylbutylamines". J Pharmacol Exp Ther. 107 (3): 385–393. PMID 13035677.
- ↑ ESPEJO, E; Mir, D (30 September 1993). "Structure of the rat's behaviour in the hot plate test". Behavioural Brain Research. 56 (2): 171–176. doi:10.1016/0166-4328(93)90035-O. PMID 8240711. S2CID 4022669.
- ↑ Hunskaar, Steinar; Berge, Odd-Geir; Hole, Kjell (1 August 1986). "A modified hot-plate test sensitivie to mild analgesics". Behavioural Brain Research. 21 (2): 101–108. doi:10.1016/0166-4328(86)90088-4. PMID 3755945. S2CID 3992246.
- ↑ Ripoll N, Hascoet M, Bourin M. The four-plates test: Anxiolytic or analgesic paradigm? Progress in Neuro-Psychopharmacology and Biological Psychiatry, July 2006 vol. 30 issue 5, 873-880.
- ↑ Tzschentke, T. M.; Christoph, T.; Kogel, B.; Schiene, K.; Hennies, H.-H.; Englberger, W.; Haurand, M.; Jahnel, U.; Cremers, T. I. F. H.; Friderichs, E.; De Vry, J. (23 July 2007). "( )-(1R,2R)-3-(3-Dimethylamino-1-ethyl-2-methyl-propyl)-phenol Hydrochloride (Tapentadol HCl): a Novel -Opioid Receptor Agonist/Norepinephrine Reuptake Inhibitor with Broad-Spectrum Analgesic Properties". Journal of Pharmacology and Experimental Therapeutics. 323 (1): 265–276. doi:10.1124/jpet.107.126052. PMID 17656655. S2CID 942191.
- ↑ Duman, E., Kesim, M., Kadioglu, M., Ulku, C., Kalyoncu, N., Yaris, E. 2006. Effect of gender on antinociceptive effect of paroxetine in hot plate test in mice. Progress in Neuro-Pharmacology and Biological Psychiatry. 30. 292–296.
- ↑ Hildebrand, M.; Smith, P.; Bladen, C.; Eduljee, C.; Xie, J.; Chen, L.; Fee-Maki, M.; Doering, C.; Mezeyova, J.; et al. (2011). "A novel slow-inactivation-specific ion channel modulator attenuates neuropathic pain". Pain. 152 (4): 833–843. doi:10.1016/j.pain.2010.12.035. hdl: 1880/106710 . PMID 21349638. S2CID 29622197.
- ↑ Kögel, B.; De Vry, J.; Tzschentke, T.; Christoph, T. (2011). "The antinociceptive and antihyperalgesic effect of tapentadol is partially retained in OPRM1 (μ-opioid receptor) knockout mice". Neuroscience Letters. 491 (2): 104–107. doi:10.1016/j.neulet.2011.01.014. PMID 21232580. S2CID 21141629.
- ↑ Casarrubea, M.; Sorbera, F.; Santangelo, A.; Crescimanno, G. (2012). "The effects of diazepam on the behavioral structure of the rat's response to pain in the hot-plate test: Anxiolysis vs. Pain modulation". Neuropharmacology. 63 (2): 310–321. doi:10.1016/j.neuropharm.2012.03.026. PMID 22521500. S2CID 21342382.
- ↑ Zimmermann, M. (1983). "Ethical guidelines for investigations of experimental pain in conscious animals". Pain. 16 (2): 109–10. CiteSeerX 10.1.1.651.9572 . doi:10.1016/0304-3959(83)90201-4. PMID 6877845. S2CID 38778262.
- ↑ Institutional Animal Care and Use Committee