Effects of histamine and H1 and H2-receptor antagonists on wet-dog-shake episodes in rats induced with tranylcypromine and 5-methoxytryptamine.

Intraperitoneally administered tranylcypromine and 5-methoxytryptamine induced in rats the so called wet-dogs-shake behaviour. Histamine injected intraventricularly had no effect on the number or episodes of this behaviour during the first 40 minutes of observation. On the other hand, dimaprit in doses of 5 micrograms/rat injected also intraventricularly increased the number of these episodes. Thenalidine and antazoline--antagonists of the H1-receptor, and cimetidine and ranitidine--antagonists of the H2-receptor, decreased the number of these episodes proportionally to the injected dose. Similar effects were obtained after cimetidine injection into the lateral ventricle. In the light of these observations it may be supposed that these antihistaminic agents exert an inhibitory effect not only on the histaminergic system but decrease indirectly also the activity of the serotoninergic system.