Regional variations in spermine levels in the developing rat brain following exposure to lead

Polyamines are ubiquitous compounds involved in growth and differentiation, and ornithine decarboxylase (ODC), is their rate-limiting enzyme, In an ef fort to examine whether changes in ODC enzyme activity are reflected in alt erations in the availability of polyamines, levels of the more stable end-p roduct spermine, were examined following exposure to lead (Pb). Rats were l actationally exposed to 0.2% Pb-acetate from birth to weaning, At postnatal days 3, 5, 10, 15, and 20, pups were sacrificed, and spermine was extracte d from their brain tissue and the extracts were analyzed by high-performanc e liquid chromatography coupled with a fluorescence detector. Basal spermin e levels in the cerebellum were found to be higher than those in the neocor tex, and exhibited a characteristic developmental profile. In Pb-exposed an imals, spermine levels were attenuated in both brain regions, however, ther e was a rebound in cerebellar levels during the third week after birth, Whi le basal spermine levels are in concert with reported patterns of ODC activ ity, they depart from each other following a toxic challenge to the cerebel lum. This study suggest that developmental polyamine levels are not necessa rily a direct translation of ODC activity and that modulations in their bio synthesis depend on regional stages of growth. (C) 1999 Elsevier Science In c.