Central effect of histamine in a rat model of acute trigeminal pain.
In conscious rats implanted with an intracerebroventricular (icv) cannula, effect of icv injections of histamine, chlorpheniramine (H(1)-receptor antagonist) and ranitidine (H(2)-receptor blocker) was investigated in a rat model of acute trigeminal pain. Acute trigeminal pain was induced by putting a drop of 5 M NaCl solution on the corneal surface of the eye and the numbers of eye wipes were counted during the first 30 s. Histamine (20, 40 microg) and chlorpheniramine (80 microg) significantly decreased the numbers of eye wipes. Ranitidine alone had no effect. Pretreatment with chlorpheniramine did not change the histamine-induced analgesia, whereas the histamine effect on pain was inhibited with ranitidine pretreatment. These results indicate that the brain histamine, through central H(2) receptors, may be involved in the modulation of the acute trigeminal pain in rats.
Tamaddonfard
Esmaeal
E
Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran. e_tamaddonfard@yahoo.com
Khalilzadeh
Emad
E
Hamzeh-Gooshchi
Nasrin
N
Seiednejhad-Yamchi
Sona
S
D018712:Analgesics, Non-Narcotic; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002744:Chlorpheniramine / Q000494:pharmacology; D003315:Cornea / Q000187:drug effects / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000008:administration & dosage / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D011899:Ranitidine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012462:Saline Solution, Hypertonic / Q000633:toxicity; D014277:Trigeminal Neuralgia / Q000139:chemically induced / Q000188:drug therapy*
D018712:Analgesics, Non-Narcotic; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D012462:Saline Solution, Hypertonic; D002744:Chlorpheniramine; D006632:Histamine; D011899:Ranitidine