Some pharmacological properties of brain ganglioside.

The effects of a preparation of purified brain ganglioside and of neuraminic acid have been studied on various pharmacological test preparations. In concentrations of 10 mug/ml. or more, ganglioside stimulates the isolated guinea-pig ileum; graded responses are usually obtained. Various substances, known to antagonize the actions of other stimulant substances, fail to affect the response to ganglioside. Ganglioside and neuraminic acid neither stimulate the superior cervical ganglion of the cat nor do they affect ganglionic transmission. Ganglioside and neuraminic acid did not change the response of the frog rectus abdominis muscle to acetylcholine, nor did they affect the blood pressure of the cat. Ganglioside (2 mug/ml. or more) stimulates the isolated heart of Venus mercenaria, but the response, which develops slowly, decreases with repeated administration of ganglioside. The response is not blocked by 2-bromo-lysergic acid diethylamide and there is no indication that it is due to the liberation of endogenous 5-hydroxytryptamine or related indole compounds. For both the heart of Venus mercenaria and guinea-pig ileum, the activity demonstrated by brain ganglioside is specifically a property of the whole molecule, since neither neuraminic acid itself nor a preparation of brain ganglioside from which only two-thirds of its neuraminic acid had been removed are active.