ABSTRACT
The effects of hypoxia in adult and newborn rats on the release rate of DA from slices and synaptosomes of striatum were studied. In adult animals hypoxia (10 kPa oxygen tension in the inspiratory air) induces a decrease of the FER of DA from slices up to 70% dependent on the duration of the hypoxia. An early postnatal hypoxia (10 kPa, 2nd -11th day of life) brings about a long-term increase of the FER of DA from slices by about 30% when the release is measured at the age of 2-3 month. Slices show a relatively low release rate compared to synaptosomes. The hypoxia effects found with slices, i.e. a decrease of the FER in adult animals and increase in those that had experienced an early postnatal hypoxia, could not be confirmed in synaptosomes. The much lower release rate from slices suggests the action of inhibitory factors controlling the release of DA. In that case hypoxia would exert an indirect influence.
Subject(s)
Corpus Striatum/metabolism , Dopamine/metabolism , Hypoxia, Brain/physiopathology , Aging , Animals , Animals, Newborn , Corpus Striatum/growth & development , In Vitro Techniques , Male , Rats , Rats, Inbred Strains , Reference Values , Synaptosomes/metabolismABSTRACT
The effects of hypoxanthine (HX) and xanthine oxidase (XO) on the (3H)-dopamine (DA) uptake into synaptosomes of rat striatum were examined. Preincubation with 20 mU XO and 0.25 mM HX for 10 min diminished the uptake to 55% of controls. Under these conditions no increase of TBARS as an indicator of lipid peroxidation was observed. Kinetic studies revealed that the decrease in DA uptake was related to the high-affinity transport whereas the low-affinity transport carrier remained unaffected. SOD did not influence uptake inhibition, Catalase completely restituted DA uptake at an activity of 50 U. Thus, hydrogen peroxide and the hydroxyl radical appears to be involved in the deleterious action of HX/XO. The effects of this radical generating system seems to be directed to specific sites of biological membranes.
