[Methodological consideration in studying the exocytosis mechanisms using microdialysis].
Microdialysis has become an effective and frequently used technique to study the extracellular levels of monoamine, i.e. dopamine, serotonin and norepinephrine in the central nervous system. However, the detailed exocytosis mechanisms of monoamine using microdialysis has remained to be clarified. The present report introduces methods for administration of voltage-sensitive calcium channel (VSCC) inhibitors and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) inhibitors to clarify the mechanisms of monoamine exocytosis using in vivo microdialysis. The N-type and P-type VSCCs are inhibited by perfusion with omega-conotoxin GVIA and omega-agatoxin IVA, respectively; however, their diffusion rate from internal to external spaces of the microdialysis probe is lower than 1%. Unlike VSCC inhibitors, SNAP-25, synaptobrevin and syntaxin can be cleavaed with botulinum toxin type A, B and C, respectively. These toxins (with molecular weights over 500,000) bind specifically to the presynaptic membrane via the heavy chain, while the light chain enters the cytosol, where it displays zinc-endopeptidase activity directed to proteins of the neuroexocytosis apparatus. Therefore, to prevent SNARE activity, botulinum toxins are microinjected. These two methods, perfusion with VSCC inhibitors and microinjection with botulinum toxins, can contribute to the clarification of the mechanisms of monoaminergic exocytosis.
Department of Neuropsychiatry, Hirosaki University, Hirosaki, 036-8562 Japan.
Motohiro
M
Okada
Shukuko
S
Yoshida
Gang
G
Zhu
Sunao
S
Kaneko
D000818:Animals; D015306:Biogenic Monoamines / Q000502:physiology; D001905:Botulinum Toxins / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology*; D017551:Microdialysis
D015306:Biogenic Monoamines; D001905:Botulinum Toxins