DESIPRAMINE MODULATION OF SIGMA-PEPTIDE AND OPIOID PEPTIDE RECEPTOR EXPRESSION IN GLIAL-CELLS

Exposure of C6 glial cell cultures to desipramine induced the appearance of opioid receptors and up-regulated sigma receptors. Opioid binding was demonstrated with H-3-etorphine and H-3-dihydromorphine (DHM), but was not observed with the mu, delta and kappa ligands H-3-DAMGE, H-3-DADLE or H-3-(-)ethylketocyclazocine in the presence of specific blockers, respectively. Competition experiments with H-3-DHM and either (-)naloxone or (+)naloxone indicated the presence of authentic opioid receptors. In similar studies with beta-endorphin, its truncated form (1-27) or their N-acetyl derivatives, beta-endorphin proved to have the highest affinity. Opioid receptors in glial cell aggregates were primarily kappa, with few mu and delta sites. Desipramine increased B(max) values for kappa but not mu and delta.