Abstract
In this work we studied the toxic effects of α-asarone, a hypolipidemic active principle
of Guatteria gaumeri Greenman, on long-term cultures of adult rat hepatocytes cultivated on a feeder layer
of 3T3 cells. The exposure for one and two weeks to α-asarone (1-50 µg/ml) produced
intracytoplasmic lipid droplets and at higher concentrations (25-50/ µg/ml) retraction
of the hepatocyte cords and cell detachment. Ultrastructurally, the treated cultures
(10 µg/ml) showed enlargement and vacuolization of the mitochondria in addition to
lipid droplets. The triacylglycerol content increased up to 2.3-fold in the cultures
treated for one week with 50 µg/ml, whereas the protein content per culture, a rough
estimate of cell number and viability, decreased by up to 53% in the cultures treated
for two weeks with 50 µg/ml. The synthesis and secretion of proteins, measured by
the incorporation of [3
H]-leucine into cellular and secreted macromolecules, decreased also in the cultures
exposed. After one and two week exposure to 50 µg/ml of α-asarone, the secretion of
labeled proteins decreased by 53 and 67%, respectively, whereas the synthesis of cellular
and total proteins decreased by 48-67%, respectively. The secretion of proteins was
the most sensitive parameter of α-asarone toxicity. The mean inhibitory dose (ID50), i.e, that producing 50% inhibition in the incorporation of the labeled precursor,
was 22.12 and 5.04 µg/ml after one and two weeks exposure, respectively. Our results
show that long-term exposure to micromolar concentrations of α-asarone produces morphologic
and ultrastructural alterations, triacylglycerol accumulation (fatty liver), and inhibition
of protein synthesis and secretion. Our results also suggest that this culture system
could be a suitable in vitro model for studying long-term effects of hepatotoxic chemicals.
Key words
α-Asarone - toxicity - cultured hepatocytes
