The synthetic kappa-opioid agonist (-)U50,488 does not affect calcium transport into R1.1 mouse thymoma cell line

Reduction of cell proliferation and potentiation of Fas-induced apoptosis by the selective kappa-opioid receptor agonist U50 488 in the multiple myeloma LP-1 cells

As opioid receptors modulate proliferation and apoptosis of immune cells, we hypothesized that they could reduce malignant haematopoietic cells. After screening, we selected the human multiple myeloma LP-1 cells which express mu- (MOP-) and kappa-opioid receptors (KOP-R). U50 488 produces a modest but significant decrease in viability associated with an arrest in the G0/G1 phase, but not antagonized by NorBNI and not associated with modulation of p21(Cip1), p27(Kip1) or p53 expression. In contrast, no effect was observed with dynorphin, U69 593 and morphine. In conclusion, the anti-proliferative effects of U50 488 are not mediated by KOP-R in the LP-1 cells.

Signal transduction induced by opioids in immune cells: a review

New data regarding signal transduction triggered by opioid ligands in immune cells are reviewed, and the signal transduction in neuronal cells is documented. Similar signaling pathways are induced by opioids in immune as well as neuronal cells. Opioids altered second messenger cAMP, intracellular calcium, and second messenger-induced kinases in immune cells. Met-enkephalin, preferentially delta-opioid, was bimodally regulated, while kappa-opioids inhibited these second messengers. delta-, kappa- and micro-opioids altered nitric oxide secretion, inducing cGMP as the second messenger in immune cells. Coupling of opioid agonists to opioid receptors activated mitogen-activated protein/extracellular signal-regulated protein kinases and various transcription factors in immune cells. Activator protein 1 (AP-1), c-fos, and nuclear factor-kappaB (NF-kappaB) are transcription factors shared by neuronal and immune cells. Delta-opioids activated AP-1, c-fos, activating transcription factor 2, Ikaros-1 and Ikaros-2 transcription factors in immune cells. Induction of kappa-opioid receptor gene by retinoic acid resulted in increased binding of Sp1 transcription factor to the promoter of the kappa-opioid receptor. Micro-opioids inhibited synthesis of common transcription factors AP-1, c-fos, NF-kappaB, and nuclear factor of activated T cells in activated or stimulated immune cells, whereas micro-opioids activated NF-kappaB, GATA-3, and Kruppel-like factor 7 transcription factors in non-stimulated immune cells.

The kappa-opioid agonist U-69593 affects intracellular calcium level in R1.1 mouse thymoma cell line

In this study, the effect of the kappa-opioid agonist U-69593 on the intracellular calcium level in R1.1. cells was investigated using FURA 2-AM dye. In the previous study, calcium transport into R1.1 cells was not affected by the kappa-opioid agonist (-)U50,488 [Int. J. Immunopharmacol. 21 (1999) 133]. In this study, the kappa-opioid agonist U-69593 (10(-10)-10(-6) M), decreased intracellular calcium level in unstimulated cells. This decrease could not be reversed by the kappa-opioid antagonist NBI (10(-5) or 10(-6) M). Ionophore A23187 was used to increase intracellular calcium level. Stimulation of intracellular calcium level by Ionophore A23187 was potentiated by the kappa-opioid agonist U-69593. Thus, we have shown that basal intracellular calcium level was decreased in R1.1 by the kappa-opioid agonist U-69593 and increased in R1.1 cells stimulated by Ionophore A23187.

Endogenous opiates: 1999

This paper is the twenty-second installment of the annual review of research concerning the opiate system. It summarizes papers published during 1999 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunologic responses.