Research ReportNicotine regulates SH-SY5Y neuroblastoma cell proliferation through the release of brain-derived neurotrophic factor
Introduction
There is growing evidence suggesting a role for nicotine in neuroprotection (Singh et al., 2004). While post-mortem studies have shown substantial reductions in the density of central nicotinic receptors in patients with Parkinson's disease (PD) (Perry et al., 2000, Quik and Kulak et al., 2002) and Alzheimer's disease (AD) (Perry et al., 1995), epidemiologic studies have shown that cigarette smoking and nicotine injection can have beneficial effects on cognition in PD and AD (Singh et al., 2004). Such effects, however, cannot always be replicated (Alves et al., 2004, Lemay et al., 2003, Lemay et al., 2004). Similarly, PET studies performed on AD patients at early stages of the disease have demonstrated a significant reduction in [11C]-nicotine binding in frontal cortex and hippocampus (Nordberg et al., 1995).
In animals, a large number of studies have demonstrated that nicotine increases the expression of nicotinic receptors as well as improving cognitive function in animal models of neurodegenerative disease (Ryan et al., 2001).
However, the mechanisms underlying neuroprotection by nicotine and nicotinic agonists (Singh et al., 2004) remain poorly understood. Recently, a growing body of evidence has implicated neurotrophic factors in the mediation of the long-term effects of nicotine. In particular, Maggio et al. (Maggio et al., 1998, Maggio et al., 1997) have reported that the neuroprotective effect of nicotine in 2 animal models of PD is accompanied by a corresponding increase in BDNF levels in the striatum. Similarly, intrahippocampal administration of nicotine transiently increased nerve growth factor (NGF) expression and TrkB message levels in the CA1 and in dentate gyrus (French et al., 1999). Exposure of PC12 cells to nicotine also resulted in an increase in NGF receptor expression (Terry and Clarke, 1994). On the other hand, decreased expression of BDNF and of its full-length receptor, TrkB, was observed in the frontal cortex and hippocampus of patients with AD (Ferrer et al., 1999).
Hence, these data support a role for the BDNF signalling pathway in the mediation of the neuroprotective effects of nicotine. However, the cellular mechanisms for protection triggered by nicotine and its agonists remain unexplored and their elucidation may provide insights into the development of more effective neuroprotective agents.
The neuroblastoma cell line SH-SY5Y natively expresses nicotinic receptor alpha-3, alpha-5, alpha-7, beta-2 and beta-4 subunits (Gould et al., 1992, Wang et al., 1996). Furthermore, when treated with retinoic acid, they differentiate into neuronal cells and express functional TrkB receptors (Kaplan et al., 1993, Lucarelli et al., 1994, Ruiz-Leon and Pascual et al., 2003). It has been shown that, at that stage, proliferation of the differentiated cells can be driven through the BDNF–TrkB pathway (Ruiz-Leon and Pascual et al., 2003). In the present study, the proliferation of the differentiated neuroblastoma was used as a quantifiable index of the functionality of the BDNF–TrkB pathway to investigate the effects of nicotinic agents on BDNF signalling.
Section snippets
Effect of nicotine on [14C]-thymidine incorporation in SH-SY5Y cells
Nicotine produced a time-dependent increase in [14C]-thymidine incorporation into the SH-SY5Y cells compared with controls. The effect of nicotine on cell growth was significant after an exposure of 42 h then plateaued after 48 h of exposure. For all subsequent experiments, [14C]-thymidine incorporation was estimated after an exposure to nicotine of 48 h (Fig. 1) when cells in both control and treated conditions were still growing.
Nicotine produced a bell-shaped dose–response curve on cell
Discussion
The goal of the present study was to define to what extent nicotine interacts with the BDNF–TrkB pathway. The neuroblastoma cell line SH-SY5Y endogenously expresses native nicotinic subunits such as alpha-3, alpha-5, alpha-7, beta-2 and beta-4 subunits (Gould et al., 1992), which form a number of different receptors subtypes and therefore provide a suitable model for studying neuronal mechanisms and identifying the receptor subtype involved in nicotine effects. Moreover, upon differentiation
Conclusion
In conclusion, the present data showed that nicotine interacts with the neurotrophin pathway by increasing BDNF secretion and by recruiting TrkB receptors onto the cell surface. Given the difficulty in producing agonists capable of crossing the blood–brain barrier and activating TrkB receptors, drugs such as nicotinic agonists capable of enhancing the release and signalling of neurotrophins may represent an alternative strategy for modulation of the BDNF pathway.
Cell culture
SH-SY5Y neuroblastoma cells were grown in a 1:1 mixture of Eagle's minimal essential medium–F12 medium, containing foetal calf serum (10%), glutamine (2 mM), penicillin (50 U/ml) and streptomycin (50 μg/ml) in a humidified incubator (95% air/5% CO2) at 37 °C. Cells were subcultured at a 1:10 ratio, left to attach for 2 days and treated with retinoic acid (10 μM) for an additional 5 days. Only cells between passages P6 to P20 were used in the studies.
Drugs
Drugs used were: nicotine, mecamylamine,
References (39)
- et al.
Expression of trkB in human neuroblastoma in relation to MYCN expression and retinoic acid treatment
Lab. Invest.
(2003) - et al.
Hippocampal neurotrophin and trk receptor mRNA levels are altered by local administration of nicotine, carbachol and pilocarpine
Brain Res. Mol. Brain Res.
(1999) - et al.
Nicotinic acetylcholine receptors in human neuroblastoma (SH-SY5Y) cells
Neurosci. Lett.
(1992) - et al.
Dual effects of nicotine on oxidative stress and neuroprotection in PC12 cells
Neurochem. Int.
(2003) - et al.
Regulation of nicotinic acetylcholine receptors on human neuroblastoma cells during differentiation
Biochem. Pharmacol.
(1995) - et al.
Induction of TrkB by retinoic acid mediates biologic responsiveness to BDNF and differentiation of human neuroblastoma cells, Eukaryotic Signal Transduction Group
Neuron
(1993) - et al.
Lack of efficacy of a nicotine transdermal treatment on motor and cognitive deficits in Parkinson's disease
Prog. Neuropsychopharmacol. Biol. Psychiatry
(2004) - et al.
Brain-derived neurotrophic factor promotes survival and chemoprotection of human neuroblastoma cells
J. Biol. Chem.
(1999) - et al.
Up-regulation of human alpha7 nicotinic receptors by chronic treatment with activator and antagonist ligands
Eur. J. Pharmacol.
(1998) - et al.
Nicotinic receptor subtypes in human brain ageing, Alzheimer and Lewy body diseases
Eur. J. Pharmacol.
(2000)
Alteration in nicotine binding sites in Parkinson's disease, Lewy body dementia and Alzheimer's disease: possible index of early neuropathology
Neuroscience
Nicotine and nicotinic receptors; relevance to Parkinson's disease
Neurotoxicology
Induction of tyrosine kinase receptor b by retinoic acid allows brain-derived neurotrophic factor-induced amyloid precursor protein gene expression in human SH-SY5Y neuroblastoma cells
Neuroscience
Ca2+ influx regulates BDNF transcription by a CREB family transcription factor-dependent mechanism
Neuron
Nicotine stimulation of nerve growth factor receptor expression
Life Sci.
Assembly of human neuronal nicotinic receptor alpha5 subunits with alpha3, beta2, and beta4 subunits
J. Biol. Chem.
Chronic nicotine treatment up-regulates human alpha3 beta2 but not alpha3 beta4 acetylcholine receptors stably transfected in human embryonic kidney cells
J. Biol. Chem.
Cigarette smoking in Parkinson's disease: influence on disease progression
Mov. Disord.
Cellular mechanisms regulating activity-dependent release of native brain-derived neurotrophic factor from hippocampal neurons
J. Neurosci.
Cited by (0)
- 1
Present address: Drug Discovery Today, 84 Theobald's Road, Holborn, London WC1X8RR.