Background: Xylazine is an α adrenoceptor agonist that is extensively used in veterinary medicine and animal experimentation procedures to produce analgesia, sedation and muscle relaxation without causing general anesthesia. Considering the lack of knowledge of the mechanisms involved in peripheral antinociception induced by xylazine and the potential interactions between the adrenergic and endocannabinoid systems, the present study investigated the contribution of the latter system in the mechanism of xylazine.
Methods: The rat paw pressure test, in which hyperalgesia was induced by the intraplantar injection of prostaglandin E, was performed.
Results: Xylazine administered via an intraplantar injection (25, 50 and 100 μg) induced a peripheral antinociceptive effect against prostaglandin E (2 μg)-induced hyperalgesia. This effect was blocked by treatment with the selective CB cannabinoid antagonist AM251 (20, 40 and 80 μg) but not by the selective CB cannabinoid antagonist AM630 (100 μg). The anandamide reuptake inhibitor VDM11 (2.5 μg) intensified the peripheral antinociceptive effect of a submaximal dose of xylazine (25 μg), and the inhibitor of endocannabinoid enzymatic hydrolysis, MAFP (0.5 μg), showed a tendency towards this same effect. In addition, liquid-chromatography mass spectrometric analysis indicated that xylazine (100 μg) treatment was associated with an increase in anandamide levels in the rat paws treated with PGE.
Conclusions: The present results provides evidence that the peripheral antinociceptive effect of the α adrenoceptor agonist xylazine probably results from anandamide release and subsequent CB cannabinoid receptor activation.
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http://dx.doi.org/10.1007/s43440-019-00053-6 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405.
Dysregulation of GABAergic inhibition is associated with pathological pain. Consequently, enhancement of GABAergic transmission represents a potential analgesic strategy. However, therapeutic potential of current GABA agonists and modulators is limited by unwanted side effects.
View Article and Find Full Text PDFPharmacol Res
January 2025
University Hospital of Jena, Institute of Physiology 1, D-07740 Jena, Germany. Electronic address:
Musculoskeletal pain has a high prevalence of transition to chronic pain and/or persistence as chronic pain for years or even a lifetime. Possible mechanisms for the development of such pain states are often reflected in inflammatory or neuropathic processes involving, among others, cytokines and other molecules. Since biologics such as blockers of TNF or IL-6 can attenuate inflammation and pain in a subset of patients with rheumatoid arthritis, the question arises to what extent cytokines are involved in the generation of pain in human musculoskeletal diseases.
View Article and Find Full Text PDFPharmaceuticals (Basel)
November 2024
Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de Mexico 04510, Mexico.
Trigeminal neuralgia (TN) is chronic pain caused by damage to the somatosensorial system on the trigeminal nerve or its branches, which involves peripheral and central dysfunction pain pathways. Trigeminal pain triggers disruptive pain in regions of the face, including within and around the mouth. Besides clinical experiences, translating the language of suffering into scientific terminology presents substantial challenges.
View Article and Find Full Text PDFBiomolecules
December 2024
Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan.
Nociceptive information is transmitted by action potentials (APs) through primary afferent neurons from the periphery to the central nervous system. Voltage-gated Na channels are involved in this AP production, while transient receptor potential (TRP) channels, which are non-selective cation channels, are involved in receiving and transmitting nociceptive stimuli in the peripheral and central terminals of the primary afferent neurons. Peripheral terminal TRP vanilloid-1 (TRPV1), ankylin-1 (TRPA1) and melastatin-8 (TRPM8) activation produces APs, while central terminal TRP activation enhances the spontaneous release of L-glutamate from the terminal to spinal cord and brain stem lamina II neurons that play a pivotal role in modulating nociceptive transmission.
View Article and Find Full Text PDFThe mu-opioid receptor (MOR) is a major target for the treatment of pain. However, opioids are prone to side effects which limit their effectiveness as analgesics and can lead to opioid use disorders or, even, lethal overdose. The systemic administration of opioid agonists makes it both very difficult to decipher their underlying circuit mechanisms of action and to limit drug action to specific receptor subpopulations to isolate therapeutic effects from adverse side effects.
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