Evaluation of acute antiapoptotic effects of Li+ in neuronal cell cultures
M Yeste1, D Alvira, E Verdaguer
1Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Universitat de Barcelona, Nucli Universitari de Pedralbes, Barcelona, Spain.
Abstract:
Li(+) exerts protective effect against several neurotoxins in neuronal cell preparations. Here we examined the antiapoptotic effects of GSK3beta in cerebellar granule neurons (CGNs) in the presence of several neurotoxins. Acute treatment with Li(+) protected neurons against nocodazole and serum/potassium (S/K) deprivation, but were ineffective against kainic acid and MPP(+). Li(+) 5 mM also decreased caspase-3 activation induced by nocodazole and S/K deprivation as measured by Ac-DEVD-p-nitroaniline and the breakdown of alpha-spectrin. All the neurotoxins used in the present study activated GSK3beta, evaluated with a specific antibody phospho-GSK-3beta (Ser9) by Western-blot and immunocytochemistry and were always inhibited by Li(+) 5 mM. Our results implicate Li(+) in the regulation of apoptosis mediated by caspase activation (Type I). Furthermore inhibition of GSK3beta by acute treatment with Li(+) 5 mM is not an indicator of neuroprotection. The acute antiapoptotic function of Li(+) is discussed in terms of its inhibition of Type I pathway, the intrinsic (mitochondrial) apoptotic pathway in cerebellar granule cells.
Insights
Lithium (Li(+)) shows neuroprotective effects against certain neurotoxins by inhibiting caspase activation. However, its inhibition of GSK3beta does not guarantee neuroprotection against all toxins in cerebellar granule neurons.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- Lithium (Li(+)) is known to protect neurons from various neurotoxins.
- Glycogen synthase kinase 3 beta (GSK3beta) plays a role in neuronal apoptosis.
- Caspase activation is a key mechanism in programmed cell death.
Purpose of the Study:
- To investigate the antiapoptotic effects of Li(+) on cerebellar granule neurons (CGNs) exposed to neurotoxins.
- To determine the role of GSK3beta inhibition by Li(+) in neuroprotection.
- To elucidate the specific apoptotic pathways affected by Li(+) treatment.
Main Methods:
- Neuronal cell culture (CGNs) exposed to nocodazole, serum/potassium (S/K) deprivation, kainic acid, and MPP(+).
- Assessment of apoptosis via caspase-3 activation (Ac-DEVD-p-nitroaniline assay) and alpha-spectrin breakdown.
- Evaluation of GSK3beta activation using Western-blot and immunocytochemistry with a phospho-GSK-3beta (Ser9) antibody.
- Treatment with Li(+) (5 mM) to assess its protective and inhibitory effects.
Main Results:
- Li(+) protected CGNs against nocodazole and S/K deprivation but not kainic acid or MPP(+).
- Li(+) (5 mM) reduced caspase-3 activation and alpha-spectrin breakdown induced by nocodazole and S/K deprivation.
- Neurotoxins activated GSK3beta, which was consistently inhibited by Li(+) (5 mM).
- Acute Li(+) treatment's neuroprotection was linked to inhibition of the Type I (caspase-mediated) apoptotic pathway.
Conclusions:
- Li(+) acutely inhibits Type I apoptosis in CGNs, mediated by caspase activation.
- GSK3beta activation by neurotoxins is inhibited by Li(+), but this inhibition alone does not confer broad neuroprotection.
- The antiapoptotic effects of Li(+) are pathway-specific and do not extend to all tested neurotoxic insults.
