Influence of postnatal hypoxia on 32P-labeling of polyphosphoinositides and phosphatidic acid in striatum synaptosomes from rat brain.

Striatum synaptosomes prepared from adult rats which had been exposed to postnatal hypoxia incorporate 32P-phosphate into phosphatidylinositol-4,5-trisphosphate (PI-4,5-P2) with decreased rate. 32P-incorporation amounted to 57% of the control for PI-4,5-P2 labeling and was slightly diminished for phosphatidic acid and PI-4-P. Exposure to hypoxia of adult rats did not affect inositol phospholipid labeling. The inhibitory effect of dopamine on 32P-phosphate incorporation was reduced only after postnatal hypoxia. 32P-incorporation rates and the dopamine inhibitory effect were not influenced by external calcium. A working hypothesis is suggested for the dopamine action on specific receptors which may be linked to the polyphosphoinositide metabolism and membrane calcium release. The long lasting effects of an early postnatal hypoxia on 32P-incorporation rates into polyphosphoinositides and phosphatidic acid could reflect the role of the proposed dopamine receptor interaction.