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Objective: To examine the central role of histamine and its H1 and
H2’ receptors on behavior in the rabbit.
Design: Experimental study Animals: Thirty-five male New Zealand White rabbits weighing 2 2.5kg.
Procedure: Implantation of a 23 - gauge. 15 mm long stainless steel guide cannula into the lateral ventricle ol brain,intracerebroventricular injection of normal saline (control), histamine
(50g), promethazine (H1 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 lh post - injection.
Statistical analysis: One - way ANOVA, Duncan’s. 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 Hi receptor produces inhibitory and excitatory effects on feeding and locomotion respectively. The central 11 receptor may involve in
histamine - induced anorexia too. It also induces a suppressive
effect on grooming which is not mediated through its central I-It and H, receptors. In treatment of some behavioral disorders, the
use of blood - brain barrier penetrating H1 and H2 antihistamines
could be recommended.