Amino acid incorporation during morphine intoxication. II: Electrophoretic separation of extracellular proteins from cerebral hemisphere slices and astroglia-enriched primary cultures.
Radioactively labeled proteins were identified in a broad molecular weight range in the incubation medium of rat cerebral hemisphere slice preparations or primary cultures after incubation with radioactive valine. Morphine chloride caused an increase in labeled media proteins with MW approximately 40,000 and 65,000 in both preparations, whereas a fraction with MW, approximately 80,000 decreased in amount. In the culture preparation a MW approximately 15,000 fraction also decreased after morphine treatment. The effects on the MW 40,000 and 65,000 fractions by morphine could not be blocked by naloxone hydrochloride, an opiate antagonist. Labeled media proteins from primary cultures obtained from various brain regions showed many similarities. After 10(-5) or 10(-6) M morphine, protein fractions with MW approximately 15,000, 25,000, 40,000, 65,000-70,000, 80,000, and 100,000 changed with increases or decreases in the various morphine concentrations. The 3H-labeling of the MW approximately 40,000 fraction increased in all cultures, where it decreased. In conclusion, proteins synthesized within cells in brain slices or in astroglia-enriched cultures are released or secreted into the incubation media. Some protein fractions are affected in different directions by morphine. The effects were not correlated with the presence of classical opiate receptors on the cells. This was so even though more changes in media proteins occurred in astroglial cultures from opiate receptor-rich brain regions than in similar cultures from opiate receptor-poor regions. The possible significance of proteins synthesized in astroglial cells and released extracellularly in opiate action is discussed.
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects*; D002478:Cells, Cultured; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005110:Extracellular Space / Q000032:analysis*; D008297:Male; D008970:Molecular Weight; D009020:Morphine / Q000633:toxicity*; D009419:Nerve Tissue Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D003470:Culture Media; D009419:Nerve Tissue Proteins; D009020:Morphine