title: Down-regulation of opiate receptors in serum-free cultures of aggregating fetal brain cells.
abstract: Brain cells from rat embryos that were cultured in serum-free medium form aggregates which possess stereospecific binding of radioactive opiates. The specificity of these opiate receptors and their regulation by opiate alkaloids and enkephalin was studied. D-ala2, D-leu5-enkephalin (DADL) induced down-regulation of opiate receptors in aggregates prepared from the forebrain but had no effect on hindbrain aggregates, whereas the potent alkaloid etorphine induced down-regulation of the receptors in both tissues. Interestingly, morphine did not induce down-regulation in both tissues. The significance of these findings and their relationship to the control of different types of opiate receptors are discussed.
mesh_terms: D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D002449:Cell Aggregation; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005333:Fetus; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D003470:Culture Media; D011957:Receptors, Opioid