Dynamic characteristics of dopamine, norepinephrine and serotonin metabolism in axonal endings of the rat hypothalamus and striatum during hypoxia: a study using HPLC with electrochemical detection.

The metabolism of dopamine, norepinephrine and serotonin was studied in normoxic or hypobaric hypoxic rats, using HPLC with electrochemical detection. The changes in serotonin and its metabolite 5 hydroxy indolacetic acid (5 HIAA) levels in the hypoxic striatum and hypothalamus suggest an inhibition of 5 HIAA formation and a complex interaction between synthesis, release and uptake. Hypoxia caused a decrease of the striatal levels of homovanillic acid (HVA), dihydroxy 3-4 phenylacetic acid (DOPAC) [inhibition of tyrosine hydroxylase (TH) and monoamine oxidase (MAO)] and 3-methoxytyramine (3 MT) (inhibition of release). Striatal dopamine levels were increased, suggesting an increase in granular dopamine storage, with an impaired release. Hypothalamic levels of norepinephrine were decreased during hypoxia [(inhibition of TH, MAO, and dopamine beta-hydroxylase (DBH)].