RESUMEN
Oxidative stress and excess of iron in the brain has been implicated in a variety of acute and chronic neurological conditions. The neonatal period is critical for the establishment of normal iron content in the adult brain. In the present study, the long-term oxidative effects of iron exposure during this period were assessed by treating Wistar rats orally with 0, 7.5 or 15 mg Fe(+2)/kg of body weight on postnatal days 10-12. Thiobarbituric acid reactive species, protein carbonyl, superoxide dismutase activity were measured at the age of 3 months. It was found that there was an increase in thiobarbituric acid reactive species and protein carbonyl in the substantia nigra of iron treated rats. In contrast, oxidative stress in the striatum was decreased. Superoxide dismutase activity was decreased in the substantia nigra iron treated rats. There were no differences in cerebellum measures among the groups. Our results demonstrated that iron supplementation in a critical neonatal period induced oxidative stress and modulated SOD activity in the adult life in selective brain regions.
Asunto(s)
Hierro/farmacología , Estrés Oxidativo/efectos de los fármacos , Sustancia Negra/efectos de los fármacos , Sustancia Negra/metabolismo , Factores de Edad , Animales , Animales Recién Nacidos , Cerebelo/efectos de los fármacos , Cerebelo/metabolismo , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Femenino , Masculino , Enfermedad de Parkinson/metabolismo , Embarazo , Ratas , Ratas Wistar , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
Two experiments investigated the effects of Fe(2+), administered postnatally to rat pups on days 10-12, upon tests of memory performance and motor behaviour. In experiment I, Wistar rat pups were administered Fe(2+) at doses of either 2.5, 7.5, 15.0 or 30.0 mg/kg, or vehicle, postnatally, and tested in the open-field at 3 months of age, followed 6 weeks later by testing in the radial arm maze. In the open-field test, only the 30.0 mg/kg Fe(2+) group showed a significantly decreased number of ambulations, but not rearings. In the radial arm maze, all four dose groups, demonstrated deficits in acquisition performance from test days 3 to 5. Retention quotients confirmed the cognitive deficits over all four Fe(2+) groups. In experiment II, rats were administered either 2.5, 7.5 or 22.5 mg Fe(2+) per kg, or vehicle, postnatally, and tested in the inhibitory avoidance (IA) conditioning and retention test at 3 months of age. In the IA conditioning test, groups were either given five 10-min preexposures to the test chamber (preexposed) or simply moved to another cage (non-preexposed). IA retention was blocked in non-preexposed rats administered 7.5 and 22.5 mg Fe(2+) per kg whereas in preexposed rats the 7.5 mg/kg group did not differ from the control (vehicle) group, although the preexposed control group showed significantly better retention than the non-preexposed control group. Postnatal iron administration appears to induce long-lasting detrimental effects upon performance of both appetitively and negatively reinforced tests of memory. Analysis of iron content indicated significant increases in the substantia nigra of the 7.5, 15.0 and 30.0 mg/kg dose groups, but not in the 2.5 mg/kg dose group. Postnatal iron administration appears to induce far-reaching effects upon the performance of certain learned behaviours.