Nuclear matrix preparations obtained from purified nuclei of NG108-15 cells, display high affinity opioid antagonist binding (1). Under conditions of opioid agonist-induced desensitization of cell surface receptors, nuclear matrix associated opioid binding was abolished, but expectedly binding densities in P20 (membranes sedimenting at 20,000 g) were unaffected. Here, binding changes were monitored in P20 and nuclear matrix fractions during agonist-induced down-regulation. D-Ala2-D-Leu5-enkephalin (DADLE, 0.1 μM, 1 h) treatment of NG108-15 cells caused an increase in nuclear matrix-associated binding, while diminishing that in P20. Taken together with other findings, these results suggest that a subpopulation of opioid binding sites, originally in the plasma membrane, are internalized and migrate to the nuclear matrix.
ASJC Scopus subject areas
- Clinical Biochemistry
- Cellular and Molecular Neuroscience