Effects of Intrathecal Carbenoxolone Treatment on Nociception and Analgesia in Rat

Abstract

Background: Gap junctions (GJ) are important in pain signalling at the spinal cord level. Aims: The aim of this investigation was to study the effects of GJ on nociception and the analgesic/hyperalgesic effects of mor­phine following administration of carbenoxolone as a GJ blocker. Male Wistar rats (200-250 g) were divided into three groups: saline i.p., 10 mg/kg and 1 μg/kg i.p. morphine, each with two subgroups. One was treated intrathecally with saline and the other with carben­oxolone. Study Design: Animal experiment. Methods: The thermal nociception threshold was measured prior to and after injections using the tail flick test. Chemical nociception assessment was conducted using a 0.05-mL subplantar injection of 2.5% formalin. Results: Both formalin-induced neurogenic and inflammatory nociception were reduced in the [saline i.p./carbenoxolone i.t.] and [morphine 1 µg/kg, i.p./carbenoxolone i.t.] subgroups (p<0.001). The 10 mg/kg i.p. morphine, i.t./carbenoxolone treatment reduced morphine-induced analgesia in the inflammatory phase (p<0.05), while it was ineffective in the neurogenic phase. Carbenoxolone decreased 1 µg/kg i.p. morphine-induced hyperalgesia in the tail flick test (p<0.001). Conclusion: Based on the results, GJ probably play a role in nociception at the spinal cord level. This may be due to the facilitation of inflammatory mediators released from glial cells or the connection between stimulatory interneurons and projection neurons. GJ blocking attenuated morphine-induced analgesia. This may be due to the attenuation of pre/post-synaptic inhibitory effects of morphine at the spinal cord level. As demonstrated by the investigations, GJ are present between inhibitory interneurons. Therefore, we can assume that blockage of GJ between inhibitory interneurons will reduce morphine-induced analgesia at the spinal cord level. However, this requires further investigation.

Keywords

• Carbenoxolone, gap junction, morphine, nociception, spinal cord

Effects of Intrathecal Carbenoxolone Treatment on Nociception and Analgesia in Rat

Öz

Kaynakça

1. 1. Bradesi S. Role of spinal cord glia in the central processing of peripheral pain perception. Neurogastroenterol Motil 2010;22:499-511. [CrossRef]
2. 2. Basbaum AI, Bautista DM, Scherrer G, Julius D. Cellular and molecular mechanisms of pain. Cell 2009;139:267-83. [CrossRef]
3. 3. Daehyun Jo, Chapman CR, Alan RL. Glial mechanisms of neuropathic pain and emerging interventions. Korean J Pain 2009;22:1-15. [CrossRef]
4. 4. Bennett MVL. Gap junctions as electrical synapses. J Neurocytol 1997;26:349-66. [CrossRef]
5. 5. Meşe G, Richard G, White TW. Gap junctions: basic structure and function. J Invest Dermatol 2007;127:2516-24. [CrossRef]
6. 6. Juszczak GR, Swiergiel AH. Properties of gap junction blockers and their behavioral, cognitive and electrophysiological effects: animal and human studies. Prog Neuropsychopharmacol Biol Psychiatry 2009;33:181-98. [CrossRef]
7. 7. Söhl G, Maxeiner S, Willecke K. Expression and functions of neuronal gap junctions. Nat Rev Neurosci 2005;6:191-200. [CrossRef]
8. 8. Spataro LE, Sloane EM, Milligan ED, Wieseler-Frank J, Schoeniger D, Jekich BM, et al. Spinal gap junctions: potential involvement in pain facilitation. J Pain 2004;5:392-405. [CrossRef]

9. 9. Schomberg D, Olson JK. Immune responses of microglia in the spinal cord: contribution to pain states. ExpNeurol 2012;234:262-70. [CrossRef]
10. 10. Watkins LR, Milligan ED, Maier SF. Glial activation: a driving force for pathological pain. Trends Neurosci 2001;24:450-4. [CrossRef]
11. 11. Ren K. Emerging role of astroglia in pain hypersensitivity. Jpn Dent Sci Rev 2010;46:86-92. [CrossRef]
12. 12. Gao YJ, Ji RR. Targeting astrocyte signaling for chronic pain. Neurotherapeutics 2010;7:482-93. [CrossRef]
13. 13. Roh DH, Yoon SY, Seo HS, Kang SY, Han HJ, Beitz AJ, et al. Intrathecal injection of carbenoxolone, a gap junction decoupler, attenuates the induction of below-level neuropathic pain after spinal cord injury in rats. Exp Neurol 2010;224:123-32. [CrossRef]
14. 14. Chiang CY, Li Z, Dostrovsky JO, Sessle BJ. Central sensitization in medullary dorsal horn involves gap junctions and hemichannels. Neuroreport 2010;21:233-7. [CrossRef]
15. 15. Suzuki M, Narita M, Nakamura A, Suzuki T. Role of gap junction in the expression of morphine-induced antinociception. Eur J Pharmacol 2006;535:169-71. [CrossRef]
16. 16. Zimmermann M. Ethical considerations in relation to pain in animal experimentation. Acta Physiol Scand Suppl 1986;554: 221-33.
17. 17. Abbasi Z, Fereidoni M, Behnam-Rassouli M. Effects of intrathecal administration of genipin on pain and morphine induced analgesia in rats. Physiol Pharmacol 2013;17:164-75.
18. 18. Yaksh TL, Rudy TA. Narcotic analgestics: CNS sites and mechanisms of action as revealed by intracerebral injection techniques. Pain 1978;4:299-359. [CrossRef]
19. 19. D’Amour FE, Smith DL. A method for determining loss of pain sensation. J Pharmacol Exp Ther 1941;72:74-8.
20. 20. Dubuisson D, Dennis SG. The formalin test: a quantitative study of the analgesic effects of morphine, meperidine, and brain stem stimulation in rats and cats. Pain 1977;4:161-74. [CrossRef]
21. 21. Nevin RL. Investigating channel blockers for the treatment of multiple sclerosis: considerations with mefloquine and carbenoxolone. J Neuroimmunol 2012;243:106-7. [CrossRef]
22. 22. Hald A, Nedergaard S, Hansen RR, Ding M, Heegaard AM. Differential activation of spinal cord glial cells in murine models of neuropathic and cancer pain. Eur J Pain 2009;13:138-45. [CrossRef]
23. 23. Svensson CI, Brodin E. Spinal astrocytes in pain processing: non-neuronal cells as therapeutic targets. MolInterv 2010;10:25-38. [CrossRef]
24. 24. Alvarez-Maubecin V, Garcia-Hernandez F, Williams JT, Van Bockstaele EJ. Functional coupling between neurons and glia. J Neurosci 2000;20:4091-8.
25. 25. Ji RR, Kawasaki Y, Zhuang ZY, Wen YR, Decosterd I. Possible role of spinal astrocytes in maintaining chronic pain sensitization: review of current evidence with focus on bFGF/JNK pathway. Neuron Glia Biol 2006;2:259-69. [CrossRef]
26. 26. Thalakoti S, Patil VV, Damodaram S, Vause CV, Langford LE, Freeman SE, et al. Neuron-glia signaling in trigeminal ganglion: implications for migraine pathology. Headache 2007;47:1008-25. [CrossRef]
27. 27. Mogil JS. Animal models of pain: progress and challenges. Nat Rev Neurosci 2009;10:283-94. [CrossRef]
28. 28. Basbaum AI, Jessell TM. The perception of pain. In: Kandel ER, Schwartz JH, Jessell TM, editors. Principles of neural science. 4th Ed. New York: McGraw-Hill Companies; 2000:404-20.
29. 29. Kuner R. Central mechanisms of pathological pain. Nat Med 2010;16:1258-66. [CrossRef]
30. 30. Sinatra R, Jahr JS, Watkins-Pitchford JM. The essence of analgesia and analgesics. Cambridge: Cambridge University Press; 2010. [CrossRef]
31. 31. Hameed H, Hameed M, Christo PJ. The effect of morphine on glial cells as a potential therapeutic target for pharmacological development of analgesic drugs. Curr Pain Headache Rep 2010;14:96-104. [CrossRef]
32. 32. Ruscheweyh R, Sandkühler J. Opioids and central sensitisation: II. Induction and reversal of hyperalgesia. Eur J Pain 2005;9:149-52. [CrossRef]
33. 33. Angst MS, Clark DJ. Opioid-induced hyperalgesia: a qualitative systematic review. Anesthesiology 2006;104:570-87. [CrossRef]
34. 34. Jones T. The management of opioid-induced hyperalgesia. Brit J ClinPharmaco 2010;2:153-6.
35. 35. Kielian T. Glial connexins and gap junctions in CNS inflammation and disease. J Neurochem 2008;106:1000-16. [CrossRef]
36. 36. Crain SM, Shen KF. Neuraminidase inhibitor, oseltamivir blocks GM1 ‎ganglioside-regulated excitatory opioid receptor-mediated hyperalgesia, ‎enhances opioids analgesia and attenuates tolerance in mice. Brain Res 2004;995:260-6. [CrossRef]