Abstract
In cats treated with subcutaneous or intraperitoneal injections of the monoamine oxidase inhibitor phenylisopropylhydrazine, the effects of 5-hydroxytryptamine injected into the lateral cerebral ventricle were greatly intensified and prolonged; the effects of adrenaline were potentiated to a lesser extent. Those of noradrenaline, dopamine and tryptamine were not intensified and were prolonged to only a slight degree.