Effects of pantethine, cysteamine and pantothenic acid on open-field behavior and brain catecholamines in rats.

Cysteamine (1.95 mM/kg) markedly decreased the locomotor, rearing and grooming activities, as well as the number of defecation boluses in an open-field test. An equimolar dose of pantethine reduced the locomotor activity to a lesser extent, but has the same potency in decreasing the number of defecation boluses, whereas pantothenic acid did not affect the behavior of the rats. Cysteamine, and to a lesser extent pantethine, reduced the noradrenaline and increased the dopamine and DOPAC concentrations in the hypothalamus. Pantothenic acid itself did not influence the hypothalamic catecholamine concentrations. These results suggest that the lower efficacy of pantethine compared to cysteamine on both behavioral and neurochemical parameters is probably due to a rate-limiting activity of the enzyme pantetheinase in the conversion of pantetheine to cysteamine.