اثرات مركزي هيستامين و آنتاگونيت هاي H1 و H2 آن بر رفتار در خرگوش

The central effects of histamine and its H1and H2

Objective: To examine the central role of histamine and its Hl and H2 receptors on behavior in the rabbit. Design: Experimental study Animals: Thirty-five male New Zealand White rabbits weighing 2- 2.5 kg. Procedure: Implantation of a 23 - gauge, 15 mm long stainless steel guide cannula into the lateral ventricle of brain, intracerebroventricular injection of normal saline (control), histamine (50g), promethazine (Ht antagonist, 100 g) and ranitidine (H, antagonist, 100 g) through the guide cannula with a 25 - I hamilton syringe, recording of animal behavior including feeding, grooming and locomotion for 1 h post - injection. Statistical analysis: One - way ANOVA, Duncanʹs, Multiple Range test and paired t - test. Results: Histamine decreased feeding, grooming and increased locomotion. Promethazine alone, with no effect on grooming, increased feeding and decreased locomotion and pretreatment by it will prevent the histamine effects on feeding and locomotion, but it will not inhibit the suppressive effect of histamine on grooming. Ranitidine alone, without any effects on grooming and locomotion, increase feeding and pretreatment by inhibitation the effects of histamine on feeding. No significant changes observed among control groups. Clinical implication: From the results of this study it is concluded that in the rabbit the brain histaminergic system via its central H, receptor produces inhibitory and excitatory effects on feeding and locomotion, respectively. The central Il, receptor may involve in histamine - induced anorexia too. It also induces a suppressive effect on grooming which is not mediated through its central II, and H, receptors. In treatment of some behavioral disorders, the use of blood - brain barrier penetrating H, and H2 antihistamines could be recommended.