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.
Department of Pharmacology, Chemotherapy and Medical Toxicology, University of Milan, Italy.
C
C
Netti
V
V
Sibilia
F
F
Guidobono
P
P
Villani
A
A
Pecile
P C
PC
Braga
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