Evidence for an inhibitory role of central histamine on carrageenin-induced hyperalgesia.
The effects of intracerebroventricular (i.c.v.) injection of histamine, the H1 agonist 2-methyl-histamine and the H2 agonist dimaprit were tested on carrageenin induced hyperalgesia by the Randall-Selitto paw pressure test in the rat. Treatment with histamine (0.1, 0.2, 0.4 mumol/rat, i.c.v.) 150 min after intraplantar carrageenin (0.1 ml of 1% solution) caused a significant increase of paw pressure thresholds in inflamed (but not in non-inflamed) paws. The magnitude and the duration of the antinociceptive effects of histamine were dose-dependent. Administration of 2-methyl-histamine (0.2, 0.4, 0.8, 1.0 mumol/rat, i.c.v.) and dimaprit (0.1, 0.2, 0.4, 0.8 mumol/rat, i.c.v.) also displayed dose-dependent blockade of carrageenin-induced hyperalgesia. Antinociceptive ED50 values calculated 30 min after drug treatments were: histamine 0.18 mumol/rat; 2-methyl-histamine 0.65 mumol/rat; dimaprit 0.33 mumol/rat. These data indicate that histamine through central H1 and H2 receptors exerts an inhibitory role in the control of nociception in pain resulting from inflammation.
Netti
C
C
Department of Pharmacology, Chemotherapy and Medical Toxicology, University of Milan, Italy.
Sibilia
V
V
Guidobono
F
F
Villani
P
P
Pecile
A
A
Braga
P C
PC
D000818:Animals; D002351:Carrageenan; D002490:Central Nervous System / Q000503:physiopathology*; D017259:Dimaprit / Q000494:pharmacology; D006632:Histamine / Q000502:physiology*; D017442:Histamine Agonists / Q000494:pharmacology; D006930:Hyperalgesia / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D017442:Histamine Agonists; D008761:Methylhistamines; D006632:Histamine; D002351:Carrageenan; C026259:2-methylhistamine; D017259:Dimaprit