Dopamine release from striatum slices of rats at different age: influence of hypoxia

During the maturation and aging of rats the dopamine release from striatum slices shows different dynamics in dependence on the stimuli used. Electrically evoked release is very constant. Amphetamine induced release is fully developed at the age of day 14 and declines after 9 months. The K+ stimulated release develops to a maximum at 10 weeks and decreases thereafter. The stimulus and age dependent inhibition of dopamine release after an 18 h hypoxic exposure may be the result of peroxidative reactions of membranous phospholipid components induced by free radicals. Adult rats exposed to a 200 h hypoxia reveal no change in dopamine release after the last exposure probably in consequence of adaptive processes of physiological protection, among other things, by scavenging of free radicals. Adult rats exposed to long term hypoxia postnatally during the growth spurt period of neuronal structures show an increased dopamine release and no posthypoxic release inhibition. Our data indicate that different mechanisms are operative during hypoxia in animals of different age.