تاثير مركزي هيستامين و آنتي هيستامين ها بر درجه حرارت بدن در خرگوش

The central effects of histamine and antihistamines on body temperature in the rabbit.

Objective: To study the effects of intracerebroventricular injection of histamine, its HI and 112 antagonists on body temperature in rabbits. Design: Experimental study. Animals: Thirty male New Zealand White rabbits weighing 2.5 --3 kg. Procedure: Implantation of a stainless steel guide cannula into the lateral cerebral ventricule, intracerebroventricular injections of histamine (25, 50 and 100 g/rahbit), prometazine (150 g/rabbit), ranitidine (150 g/rabbit) and normal saline (as control) with a 25 µl hamilton syringe, measurement of rectal temperature at 15, 30, 45, 60, 75 and 90 minutes post - injection by a digital thermometer. Statistical analysis: Repeated measures one way ANOVA. Duncanʹs Measures Relnge test. pen-eel °t" test. Results: ICV injection of histamine at close rates of 50 and 75p g/rabbit decreased the rectal temperature for 30 and 60 minutes post - injection, respectively. Promethazine (t50ug/rabbit) had no effect, whereas ranitidine (150µg/ rabbit)incrcased rectal temperature for 30 minutes post - injection. In addition, pretreatment with promethazine didnʹt inhibit the hypothermic effect of histamine but pretreatment with ranitidine prevented this effect. Clinical implication: From the results it is concluded that the activation of brain histaminergic system produces a hypothermic effect which is mediated through its central I12 but not H, receptors in rabbits. J. Fac. Vet. Med. Univ. Tehran.57, 3: 7-12, 2002.