F11 neuroblastoma x DRG neuron hybrid cells express inhibitory mu- and delta-opioid receptors which increase voltage-dependent K+ currents upon activation.
The F11 cell line is a fusion product of cells of mouse neuroblastoma cell line N18TG-2 with embryonic rat dorsal-root ganglion (DRG) neurons. Previous biochemical results suggest that they express mu- and delta-opioid receptors that are negatively coupled to adenylate cyclase. The present study provides direct agonist-binding and electrophysiologic evidence of mu and delta, but not kappa, receptor expression in F11 cells. Radioligand binding assays show that F11 cell membranes bind the mu- and delta-opioid receptor agonists, DAGO and DPDPE with Kd = 4.5 and 4.9 nM and Bmax = 111 and 195 fmol/mg, respectively. Tight-seal patch-clamp recordings of F11 cells after several days in a differentiating culture medium (low serum, cyclic AMP and nerve growth factor) showed that: (i) the outward K+ current during pulsed depolarization in most of these cells was increased by either DAGO or DPDPE, but none were responsive to both opioids or to the kappa-opioid receptor agonist, U-50,488H. The response was blocked by relevant receptor antagonists, naloxone, beta-funaltrexamine or naltrindole; (ii) cells without processes responded neither to DAGO nor to DPDPE; (iii) treatment with pertussis toxin blocked all opioid-induced increases in outward K+ current. The opioid-induced increase in voltage-dependent membrane K+ current in F11 cells resembles the inhibitory effect elicited by mu- and delta-opioid agonists in primary cultures of mouse DRG neurons.
Fan
S F
SF
Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461.
Shen
K F
KF
Scheideler
M A
MA
Crain
S M
SM
D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000378:metabolism; D006822:Hybrid Cells / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D015221:Potassium Channels / Q000502:physiology*; D011869:Radioligand Assay; D051381:Rats; D017465:Receptors, Opioid, delta / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*
D004745:Enkephalins; D015221:Potassium Channels; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-