Uptake and incorporation of 'H-valine into soluble protein of cultivated astroglial cells l'rom newborn rat cerebral hemisphcres increased after incubating the cells for 4 hr in 10 -6 or 10-' M morphine. Thc effects, inhibited by high naloxonc concentrations, were not mediated by cyclic adenosine monophosphate (CAMP)activated binding sites for morphine or D-alanine2-methionine-enkephalin-amide (D-ala2-met-enk-amide). The cultures consisted of 60-70% astrogliallike cells. By changing the kinetics of labeling it was shown that morphine affects protein synthesis of the cells in a concentration-and tinie-dependent way. Even in the incubation medium increased amounts of labelcd proteins were found in a timedependent way after morphine administration in different doses.
Gel electrophoresis in sodium-dodecyl sulphate (SDS) revealed that proteins with subunits in molccular weight (m.w.) regions of 40.000-50,000 were increased in the cells and in the medium after morphine ( lop6 or M) treatment.
Labeled proteins with subunits of -40,000 and -70.000 in the cells and medium, respectively, were decreased aflcr morphine treatment. By exploring the field of glial protein metabolism after morphine treatment, information could be obtained on the interactions between astroglia and neurons in opiate action and during tolerance development.