Live-cell imaging microscopy and quantitative analysis of Ca2+-dependent effects of neurotransmitters on DNA in snail neurons

The effects of serotonin and glutamate on DNA spatial fluorescent pattern after preliminary application of nifedipine and verapamil (inhibitors of L-type of potential-regulated Ca2+ channels) or caffeine (ryanodine receptors agonist) or BAPTA AM (membrane-permeable Ca2+ buffer) were in vivo studied in L-RPl1 neurons in isolated snail CNS preparation stained with SYTO16 AM. It was found out that preliminary applied BAPTA AM, caffeine, nifedipine or verapamil suppressed the neurotransmitter-induced changes in the number and size of spots in the neuronal nucleus of edible snail. At the same time by 30–120 min after an application of neurotransmitters in the presence of nifedipine, verapamil or BAPTA AM but not caffeine a pronounced increase in the number of large spots is produced, that probably reflects an activation of DNA compactization and chromatin condensation for this period. Obtained data suggest the presence of two consequent phases of DNA transformation evoked by neurotransmitters: (1) — extracellular Ca2+ dependent phase of chromatin decondensation and DNA decompactization (duration: about 1–2 h) and (2) subsequent (in 30 min after application of transmitters) extracellular Ca2+ independent caffeine-susceptible phase within which DNA compactization, chromatin condensation and the restoration of the initial DNA state occur.