PT  - JOURNAL ARTICLE
AU  - D E Selley
AU  - J M Bidlack
TI  - Effects of beta-endorphin on mu and delta opioid receptor-coupled G-protein activity: low-Km GTPase studies.
DP  - 1992 Oct 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 99--104
VI  - 263
IP  - 1
4099  - http://jpet.aspetjournals.org/content/263/1/99.short
4100  - http://jpet.aspetjournals.org/content/263/1/99.full
SO  - J Pharmacol Exp Ther1992 Oct 01; 263
AB  - Human beta-endorphin 1-31 (beta-END) stimulated low-Km GTPase activity in a concentration-dependent and saturable manner in membranes prepared from the delta opioid receptor-containing hybrid cell line NG108-15 and from the mu opioid receptor-enriched human neuroblastoma cell line SK-N-SH. Naloxone and the delta-selective antagonist, ICI 174,864, blocked the stimulation of the GTPase activity produced by beta-END in NG108-15 cell membranes, whereas only naloxone inhibited the beta-END-induced stimulation in SK-N-SH cell membranes, suggesting that beta-END was acting through both mu and delta opioid receptors. Treatment of the cells with Bordetella pertussis toxin before the preparation of membranes blocked the stimulation of low-Km GTPase by beta-END in both cell lines. Activation of NG108-15 and SK-N-SH low-Km GTPase by beta-END was sodium-dependent, and lithium and potassium were poor promoters of this activation. These results demonstrate that beta-END stimulates the interaction of both mu and delta opioid receptors with B. pertussis toxin-sensitive G-proteins in SK-N-SH and NG108-15 cell membranes, respectively.