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