Abstract
Neural stem cells (NSCs) play an important role in the developing as well as adult brain. NSCs have been shown to migrate toward sites of injury in the brain and to participate in the process of brain repair. Like NSCs, cultured human neural precursor cells (NPCs) are self-renewing, multipotent cells capable of differentiating into neurons, astrocytes, and oligodendrocytes and of migrating toward chemotactic stimuli. Cellular and environmental factors are important for NPC proliferation and migration. Expression of κ-opioid receptors (KORs) and μ-opioid receptors (MORs) in murine embryonic stem cells and of MORs and δ-opioid receptors in rodent neuronal precursors, as well as hippocampal progenitors has been reported by other investigators. In this study, we demonstrated robust expression of KORs in highly enriched (>90% nestin-positive) human fetal brain-derived NPCs. We found that KOR ligands, dynorphin1–17 and trans-3,4-dichloro-N-methyl-N[2-(1-pyrolidinyl)cyclohexyl] benzeneacetamide methanesulfonate (U50,488) but not dynorphin2–17, stimulated proliferation and migration of NPCs in a concentration-dependent manner. NPC proliferation was maximally stimulated at 10–14 M dynorphin1–17 and 10–12 M U50,488. The KOR selective antagonist, nor-binaltorphimine, partially blocked the migratory and proliferative effects of KOR agonists supporting, at least in part, the involvement of a KOR-related mechanism. As has been described for rodent P19 embryonal carcinoma stem cells, retinoic acid treatment markedly suppressed KOR mRNA expression in human NPCs. Taken together, the results of this study suggest that activation of KORs alters functional properties of NPCs/NSCs that are relevant to human brain development and repair.
Footnotes
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This work was supported in part by United States Public Health Service Grant DA 009924.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.107.121988.
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ABBREVIATIONS: NSC, neural stem cell; NPCs, neural precursor cells; MOR, μ-opioid receptor; DORs, δ-opioid receptor; KOR, κ-opioid receptor; ES, embryonic stem; U50,488, trans-3,4-dichloro-N-methyl-N[2-(1-pyrolidinyl)cyclohexyl]benzeneacetamide methanesulfonate; RA, retinoic acid; SDF, stromal cell-derived factor; FITC, fluorescein isothiocyanate; phosphate-buffered saline, phosphate-buffered saline; MTT, 3,3′-3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide; PE, phycoerythrin; PI, propidium iodide; nor-BNI, nor-binaltorphimine; FITC-AA, FITC-conjugated 2-(3,4-dichlorophenyl)-N-methyl-N-[1-(3-aminophenyl)-2-(1-pyrrolidinyl)ethyl]acetamide; RT, reverse transcription; PCR, polymerase chain reaction; qPCR, quantitative polymerase chain reaction; HPRT, hypoxanthine phosphoribosyltransferase; Ct, threshold cycle; SNC80, [(+)-4-[(αR)-α-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide]; DMEM, Dulbecco's modified Eagle's medium.
- Received February 26, 2007.
- Accepted May 29, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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