title: Qualitative and quantitative estimation of comprehensive synaptic connectivity in short- and long-term cultured rat hippocampal neurons with new analytical methods inspired by Scatchard and Hill plots.
abstract: To investigate comprehensive synaptic connectivity, we examined Ca(2+) responses with quantitative electric current stimulation by indium-tin-oxide (ITO) glass electrode with transparent and high electro-conductivity. The number of neurons with Ca(2+) responses was low during the application of stepwise increase of electric current in short-term cultured neurons (less than 17 days in-vitro (DIV)). The neurons cultured over 17 DIV showed two-type responses: S-shaped (sigmoid) and monotonous saturated responses, and Scatchard plots well illustrated the difference of these two responses. Furthermore, sigmoid like neural network responses over 17 DIV were altered to the monotonous saturated ones by the application of the mixture of AP5 and CNQX, specific blockers of NMDA and AMPA receptors, respectively. This alternation was also characterized by the change of Hill coefficients. These findings indicate that the neural network with sigmoid-like responses has strong synergetic or cooperative synaptic connectivity via excitatory glutamate synapses.
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Tanamoto
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shindo
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Niwano
authors.affiliation: Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522, Japan.
authors.forename: Norihisa
authors.initials: N
authors.lastname: Miki
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Hotta
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Japan. Electronic address: oka@bio.keio.ac.jp.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Oka
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002623:Chemistry Techniques, Analytical; D004558:Electric Stimulation / Q000379:methods; D004566:Electrodes; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000196:embryology / Q000378:metabolism / Q000502:physiology*; D009415:Nerve Net; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D017971:Tin Compounds
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D017971:Tin Compounds; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C109984:indium tin oxide; D002118:Calcium
keywords: Ca(2+) imaging; Indium-tin-oxide (ITO) glass; Neural network maturation; Synaptic connectivity