Elsevier

Neuropharmacology

Volume 36, Issue 1, January 1997, Pages 125-133
Neuropharmacology

δ-opioid Receptor Mobilization of Intracellular Calcium in SH-SY5Y Cells: Lack of Evidence for δ-receptor Subtypes

https://doi.org/10.1016/S0028-3908(96)00144-XGet rights and content

Abstract

δ-opioid receptor agonists mobilize intracellular Ca2+([Ca2+]i) in SH-SY5Y cells when applied in the presence of muscarinic agonists. The putative δ1 receptor agonist [D-Pen2,D-Pen5]-enkephalin (DPDE) elevated [Ca2+]i with an EC50 of 11 nM and the putative δ2 agonist deltorphin II elevated [Ca2+]i, with an EC50 of 14 nM. The maximal elevations of [Ca2+]i caused by both agonists were not different, nor were maximally effective concentrations of DPDPE (1 μM) and deltorphin II (1 μM) applied together more effective than either agonist applied alone. The elevations of [Ca2+]i caused by DPDPE (1 μM) and deltorphin II (1 μM), in the presence of carbachol, desensitized rapidly with continued opioid exposure and the cross-desensitization between DPDPE and deltorphin II was complete. The putative δ1 selective antagonist 7-benzylidenenaltrexone (BNTX) and the putative δ2 selective antagonist naltriben both reduced the elevations of [Ca2+]i caused by DPDPE (30 nM) and deltorphin II (10 nM), by greater than 50% at concentrations of less than 10 nM. In SH-SY5Y cells δ-receptor mediated elevation of [Ca2+]i is mediated by a population of receptors, which does not discriminate between agonists and antagonists purportedly selective for δ1 or δ2 receptors. © 1997 Elsevier Science Ltd. All rights reserved.

Section snippets

Cell culture

These studies were performed on SH-SY5Y cells obtained from the European Collection of Animal Cell Cultures. The cells were cultured in Dulbecco's Modified Eagles Medium (DMEM) supplemented with glutamine (4 mM), penicillin (100 i.u./ml), streptomycin (100 μg/ml) and fetal bovine serum (12.5%) in a humidified incubator with 5% CO2. Cells used for Ca2+ measurements were seeded onto plastic slides and cultured in Leighton tubes (Costar, High Wycombe, U.K.) until confluent. Cells were passaged

DPDPE and deltorphin II mobilize intracellular calcium in the presence of carbachol

When either the putative δ1 agonist DPDPE or the putative δ2 agonist deltorphin II was applied to SH-SY5Y cells alone there was no alteration of [Ca2+]i (Fig. 1). However, when either DPDPE or deltorphin II was applied in the continued presence of carbachol (1 μM) there was a rapid and robust elevation of [Ca2+]i (Fig. 1). The elevations of [Ca2+]i were reproducible on a given population of cells and occurred in all cell populations tested. Concentration-response curves for deltorphin II in the

DISCUSSION

SH-SY5Y cells are a human neuroblastoma cell line, that expresses both δ- and μ-opioid receptors (Kazmi and Mishra, 1987). Activation of both δ- and μ-receptors results in inhibition of N-type Ca channels (Seward et al. (1990), Seward et al. (1991)) and adenylyl cyclase (Kazmi and Mishra, 1987) in SH-SY5Y cells. Recently, it has been observed that in SH-SY5Y cells both δ- and μ-opioid receptor agonists elevate intracellular Ca2+, when applied in the presence of carbachol (Connor and Henderson,

References (33)

  • M.A Connor et al.

    δ- and μ-opioid receptor mobilization of intracellular calcium in SH-SY5Y human neuroblastoma cells

    Br. J. Pharmacol.

    (1996)
  • M.A Connor et al.

    δ-Opioid receptor mobilization of intracellular calcium in SH-SY5Y cells: lack of evidence for receptor subtypes

    Analgesia

    (1995)
  • M.A Connor et al.

    Desensitization of δ opioid mobilization of intracellular calcium in SH-SY5Y cells

    Br. J. Pharmacol.

    (1995)
  • R Cotton et al.

    The use of [3H]-[d-Pen2,d-Pen5]enkephalin as a highly selective ligand for the δ-binding site

    Br. J. Pharmacol.

    (1985)
  • V Erspamer et al.

    Deltorphins: a family of naturally occurring peptides with high affinity and selectivity for δ opioid binding sites

    Proc. natn. Acad. Sci. U.S.A.

    (1989)
  • C.J Evans et al.

    Cloning of a delta opioid receptor by functional expression

    Science

    (1992)
  • Cited by (0)

    View full text