Central effects of certain drugs and allergic encephalomyelitis in the circumstances of increased or decreased histamine in CNS.

The significance of the effect of histamine (Hi) in CNS has been demonstrated. By way of the inhibition of imidazol-N-methyltranspherase the amount of Hi in the brain can be increased, whereas by means of decaborane or thiazolil-metoxamine it can be lowered. It has been shown that Hi sensitizes the effect of acetylcholine (ACh) in CNS and, consequently, intensifies or weakens certain pharmacological reactions associated with ACh. It has been noted, as the most important result of the decreased Hi in CNS, that certain symptoms of motion sickness (such as vomiting, nistagmus etc.) disappear. Similarly, the increase of Hi in CNS prevents the development of the allergic encephalomyelitis in rats.