Central effects of histamine H2-receptor agonists and antagonists on nociception in the rat

• DOI: 10.1007/bf02142554
• Publication Date: 2005-09-15T19:38:23Z
• Authors: C. Netti; F. Guidobono; V. Sibilia; I. Villa; E. Cazzamalli; A. Pecile
• Keywords: Male; 0301 basic medicine; 0303 health sciences; Methylhistamines; Thiourea; Nociceptors; Rats, Inbred Strains; Rats, Inbred Strains; Rats; Dimaprit; Animals; Methylhistamines; Thiourea; Nociceptors; Receptors, Histamine H2; Male; Histamine H2 Antagonists; Rats; 03 medical and health sciences; Histamine H2 Antagonists; Dimaprit; Animals; Receptors, Histamine H2

The effects of intracerebroventricular injection of histamine H2-receptor agonists (4-methylhistamine, 4-MeH; dimaprit, DIM), H2-antagonists (cimetidine, CIM; ranitidine, RAN; famotidine, FAM) and of the DIM chemical analogue SK&F 91487 on hot-plate latency in rats were examined. Both DIM (0.4-0.8 mumol/rat) and 4-MeH (0.4-0.8 mumol/rat) significantly enhanced the pain threshold, whereas SF&F 91487 (0.8 mumol/rat) had no effect, indicating that DIM antinociception is specifically due to its activity on histamine (HA) receptors. The H2-antagonists CIM (0.8 mumol/rat) and RAN (0.6 mumol/rat) also enhanced the pain threshold, while FAM (0.03 mumol/rat) did not modify pain latency. When injected before 4-MeH, FAM reduced the antinociceptive effect of 4-MeH. These findings suggest that the antinociceptive activity of CIM and RAN is not related to specific blockade of H2-receptors and that the activation of HA-H2-receptors is inhibitory to nociception.