Research paperDual effect of Zn2+ on multiple types of voltage-dependent Ca2+ currents in rat palaeocortical neurons
Section snippets
Cell preparation
Young (P12–P22) Wistar rats of either sex were decapitated, according to a procedure approved by the University of Pavia Ethical Committee and compliant with the national laws on animal research. The brain was quickly extracted under hypothermic conditions, the two hemispheres were separated, and each was cut with a McIlwain tissue chopper into 350-μm thick slices, the plane of which was normal to the main axis of the lateral olfactory tract. Layer II of anterior piriform cortex was carefully
Results
Voltage-dependent IBas and ICas were recorded in 145 pyramidal neurons from rat PC layer II. Currents were routinely elicited by delivering 50-ms depolarizing steps starting from 2-s prepulses at –60 mV, which allowed for recording of HVA currents in isolation (see Magistretti and de Curtis, 1998). Unless otherwise explicitly stated, 5 mM Ba2+ was routinely used as the charge carrier.
Discussion
The present study shows that zinc ions can exert a relatively potent blocking action on multiple subtypes of HVA Ca2+ currents in mammalian paleocortical neurons. Although most group VIIA-IIB metal divalent cations (including Mn2+, Co2+, Ni2+, and Cd2+) are known to interact with voltage-gated Ca2+ channels in a number of cell systems, thus exerting, on the corresponding currents, more or less potent inhibitory effects that have been characterized in detail Lansman et al 1986, Swandulla and
Conclusions
In conclusion, we have demonstrated that Zn2+ modulates multiple types of neuronal voltage-gated Ca2+ channels at concentrations that are likely to be of physiological relevance in the CNS. This modulation could modify presynaptic processes, but also postsynaptic excitability (directly, via the action on VDCC, or indirectly, by affecting Ca2+-dependent conductances) and/or Ca2+-dependent cell functions. The verification of these possibilities deserves further investigations.
References (55)
- et al.
Selective release of endogenous zinc from the hippocampal mossy fibers in situ
Brain Res
(1987) - et al.
Neuronal calcium channelskinetics, blockade and modulation
Prog Biophys Mol Biol
(1989) Structure and function of neuronal Ca2+ channels and their role in neurotransmitter release
Cell Calcium
(1998)- et al.
Zinc metabolism in the brainrelevance to human nuerodegenerative disorders
Neurobiol Dis
(1997) - et al.
Zinc modulation of ionic currents in the horizontal limb of the diagonal band of Broca
Neuroscience
(1999) Neurobiology of zinc and zinc-containing neurons
Int Rev Neurobiol
(1989)- et al.
Cytoarchitectonic distribution of zinc in the hippocampus of man and the rat
Brain Res
(1983) - et al.
Molecular determinants of presynaptic active zones
Curr Opin Neurobiol
(2000) - et al.
Multiple calcium channel types control glutamatergic synaptic transmission in the hippocampus
Neuron
(1993) - et al.
Association of neuronal calcium channels with modular adaptor proteins
J Biol Chem
(1999)