Development, maturation, and perturbation of neuronal networks and applications of a synaptic signal on neuronal and neuromuscular development

Ex vivo cultures established on micro-electrode arrays provide insight into the development and regulation of neuronal networks. Networks can be monitored to elucidate critical aspects of development and maturation difficult to monitor in situ. We examined several facets of activity through network stimulation and perturbation, and utilized a synaptic signal to induce differentiation in skeletal muscle cells.;We compared the developmental profile of networks with and without stimulation by a prerecorded synaptic signal as a model for sensory input. Unstimulated networks displayed an increase in individual signals that declined at maturation, yielding a high percentage of mature bursts. Stimulation hastened this developmental signaling without changing the overall profile. Networks exposed to the GABAergic inhibitor bicuculline displayed a delayed developmental profile, suggesting that the initial excitatory phase of GABAergic neurons is integral to their shift to inhibition. Stimulation of a mature network increased overall signaling, including the percent of signals that are bursts. This increase was prevented by bicuculline, suggesting that GABAergic neurons play an essential role in plasticity.;The impact of exogenously applied amyloid-beta (Abeta), a peptide known to accumulate in Alzheimer's disease, on signaling was examined. Perturbation of synaptic transmission was observed within hours, suggesting the possible presence of cognitive problems not yet detectable by traditional clinical approaches. This effect was prevented by the calcium chelator BAPTA, indicating that calcium is required for signal inhibition by Abeta. Abeta-induced signal inhibition was not prevented by L-voltage gated or NMDA receptor antagonists, suggesting that Abeta may induce calcium influx by either channel or through additional channels.;Developing myofibers require chemical and electrical signals to form functional muscle tissue. Tissue engineering utilizes either/both of these to initiate differentiation ex vivo. High-voltage electrical signals currently used may harm developing muscle. In attempts to mimic in situ development, we stimulated continuous cell line and primary cultures with the synaptic signal. Larger, more adherent myofibers were observed in those stimulated with the synaptic signal through size determination, trypsinization, and biochemical assay of differentiation markers. Use of the synaptic signal in neuron and muscle may provide insight into the essential nature of neuronal signaling in situ.