Antihistaminic activity of stobadine in the peripheral and central nervous system.

Stobadine in low doses induced hyperpolarization, and in high doses depolarization and inhibition of transmission in the cat superior cervical ganglion. The ganglionic depolarizing action of histamine was inhibited by stobadine in low doses. Stobadine partially depressed ganglionic responses to isoprenaline, serotonin, M1 muscarinic agonist McN-A-343 and clonidine only in high doses. Stobadine administered into the third cerebral ventricle of anaesthetized cats evoked dose-dependent hypotension without changes in heart rate. Intracerebroventricular (i.c.v.) administration of histamine evoked hypertension followed by hypotension. Both effects were inhibited by i.c.v. pretreatment with stobadine. These results indicate that in nervous tissue stobadine antagonises histamine responses presumably due to H1-receptor stimulation.