5-Hydroxytryptamine(1B/1D) and 5-hydroxytryptamine1F receptors inhibit capsaicin-induced c-fos immunoreactivity within mouse trigeminal nucleus caudalis.
In order to investigate the c-fos response within the trigeminal nucleus caudalis (Sp5C) after noxious meningeal stimulation, capsaicin (0.25, 0.5, 1 and 5 nmol) was administered intracisternally in urethane (1 g/kg) and alpha-chloralose (20 mg/kg) anaesthetized male mice. Capsaicin induced a robust and dose-dependent c-fos-like immunoreactivity (c-fos LI) within Sp5C. C-fos LI was observed within laminae I and II of the entire brain stem from the area postrema to C2 level, being maximum at the decussatio pyramidum level. The area postrema, solitary tract, medullary and lateral reticular nuclei were also labelled. The 5-hydroxytryptamine(1B/1D/1F) receptor agonist sumatriptan (0.01, 0.1, 1 and 10 mg/kg), administered intraperitoneally 15 min before capsaicin stimulation (1 nmol), decreased the c-fos response within Sp5C, but not within solitary tract. The novel specific 5-hydroxytryptamine1F agonist LY 344864 (0.1 and 1 mg/kg, i.p.) significantly decreased the c-fos LI within the Sp5C as well. These findings suggest that intracisternally administered capsaicin activates the trigeminovascular system and that the pain neurotransmission can be modulated by 5-hydroxytryptamine(1B/1D/1F) receptors in mice. Thus, the availability of this model in mice, taken together with the possibility of altering the expression of specific genes in this species, may help to investigate further the importance of distinct proteins in the neurotransmission of cephalic pain.
Stroke and Neurovascular Regulation Laboratory, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA. dmitsikostas@ath.forthnet.gr
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D018681:Anesthetics, General; D000818:Animals; D031608:Area Postrema / Q000378:metabolism; D001933:Brain Stem / Q000378:metabolism; D002211:Capsaicin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002227:Carbazoles / Q000494:pharmacology; D002698:Chloralose; D002946:Cisterna Magna; D004305:Dose-Response Relationship, Drug; D005464:Fluorobenzenes / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D016762:Genes, fos; D006439:Hemodynamics / Q000187:drug effects; D007267:Injections; D008297:Male; D051379:Mice; D023421:Models, Animal; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D010146:Pain / Q000503:physiopathology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000502:physiology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D018170:Sumatriptan / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects; D014275:Trigeminal Caudal Nucleus / Q000187:drug effects* / Q000378:metabolism; D014520:Urethane; D014666:Vasomotor System / Q000503:physiopathology; D000096642:Receptor, Serotonin, 5-HT1F
D018681:Anesthetics, General; D002211:Capsaicin; D002227:Carbazoles; D002698:Chloralose; D005464:Fluorobenzenes; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D018170:Sumatriptan; D014520:Urethane; D000096642:Receptor, Serotonin, 5-HT1F; C109453:LY 344864