ANTINOCICEPTIVE EFFECTS OF ANTIHISTAMINES INFUSED INTRACEREBROVENTRICULARLY IN RATS

• Published in: Comptes rendus de l'Academie bulgare des Sciences Vol. 69; no. 6; p. 793
• Main Authors: Georgieva, Verginia, Tashev, Roman, Belcheva, Stiliana
• Format: Journal Article
• Language: English
• Published: Bulgarian Academy of Sciences 01.01.2016
• ISSN: 1310-1331

H1-receptor blockers, also called antihistamines, inhibit the histamine receptors and terminate the effect of the released histamine. They are divided into three generations, according to the time of their synthesis, properties and their side effects. The objective of this research was to investigate the effects of antihistamines (1st, 2nd, and 3rd generation), infused i.c.v., on nociception of male Wistar rats. Nociception was examined by applying mechanical pressure on the left hind paw of the rat (analgesy-meter test, Randall and Selitto). Injected i.c.v., histamine (0.5 [micro]g) decreased the pain threshold (hyperalgesia). Antihistamines from 1st (Chlorpheniramine 10 and 20 [micro]g), 2nd (Loratadine 10 and 20 [micro]g) and 3rd generation (Levocetirizine 10 and 20 [micro]g), infused i.c.v., increased dose-dependently the pain threshold, i.e. exerted antinociceptive effect as compared to the saline-treated controls on 1st day and on the 7th day after every day treatment. These results demonstrated the nociceptive histamine effect and the antinociceptive effect of antihistamines, suggesting involvement of HT1 receptors in nociception and that the inhibition of brain H1 receptors is responsible for the antinociceptive response to antihistamines.Key words: antihistamines, histamine, H1-antagonists, nociception, rat