Intracellular Zn(2+) signaling in cognition.
Brain zinc homeostasis is strictly controlled under healthy conditions, indicating the importance of zinc for physiological function in the brain. A part of zinc in the brain exists in the synaptic vesicles, is released from a subclass of glutamatergic neurons (i.e., zincergic neurons), and serves as a signal factor (Zn(2+) signal) in the intracellular (cytosol) compartment as well as in the extracellular compartment. Zn(2+) signaling is dynamically linked to glutamate signaling and may be involved in synaptic plasticity, such as long-term potentiaion and cognitive activity. In zincergic synapses, intracellular Zn(2+) signaling in the postsynaptic neurons, which is linked to Zn(2+) release from zincergic neuron terminals, plays a role in cognitive activity. When nonzincergic synapses participate in cognition, on the other hand, it is possible that intracellular Zn(2+) signaling, which is due mainly to Zn(2+) release from the internal stores and/or metallothioneins, also is involved in cognitive activity, because zinc-dependent system such as zinc-binding proteins is usually required for cognitive process. Intracellular Zn(2+) dynamics may be modified via an endocrine system activity, glucocorticoid secretion in both zincergic and nonzincergic neurons, which is linked to a long-lasting change in synaptic efficacy. On the basis of the evidence of cognitive decline caused by the lack and/or the blockade of synaptic Zn(2+) signaling, this article summarizes the involvement of intracellular Zn(2+) signaling in zincergic synapses in cognition and a hypothetical involvement of that in nonzincergic synapses.
Department of Bioorganic Chemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan; Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
Atsushi
A
Takeda
Hiroaki
H
Fujii
Tatsuya
T
Minamino
Haruna
H
Tamano
D000818:Animals; D003071:Cognition / Q000502:physiology*; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D015032:Zinc / Q000378:metabolism*
D015032:Zinc
Zn2+ signal; cognition; glucocorticoid; glutamate; hippocampus