NbActiv4 medium improvement to Neurobasal/B27 increases neuron synapse densities and network spike rates on multielectrode arrays

Abstract

The most interesting property of neurons is their long-distance propagation of signals as spiking action potentials. Since 1993, Neurobasal/B27 ™ has been used as a serum-free medium optimized for hippocampal neuron survival. Neurons on microelectrode arrays (MEA) were used as an assay system to increase spontaneous spike rates in media of different compositions. We find spike rates of 0.5/second (Hz) for rat embryonic hippocampal neurons cultured in Neurobasal/B27, lower than cultures in serum-based media and offering an opportunity for improvement. NbActiv4™ was formulated by addition of creatine, cholesterol and estrogen to Neurobasal/B27 that synergistically produced an 8-fold increase in spontaneous spike activity. The increased activity with NbActiv4 correlated with a 2-fold increase in immunoreactive synaptophysin bright puncta and GluR1 total puncta. Characteristic of synaptic scaling, immunoreactive GABA Aβ puncta also increased 1.5-fold and NMDA-R1 puncta increased 1.8-fold. Neuron survival in NbActiv4 equaled that in Neurobasal/ B27, but with slightly higher astroglia. Resting respiratory demand was decreased and demand capacity was increased in NbActiv4, indicating less stress and higher efficiency. These results show that NbActiv4 is an improvement to Neurobasal/B27 for cultured networks with an increased density of synapses and transmitter receptors which produces higher spontaneous spike rates in neuron networks.

Short-latency cross- and autocorrelation identify clusters of interacting cortical neurons recorded from multi-electrode array

“…We used only 9-22 DIV MEA dishes that have a number of active electrodes not less than 25 and a total number of units not less than 60. As a general rule and on average our MEA dishes fired not less than 25 waveforms/s, which means that the average spike rate of 70 units is about 0.3 Hz, while the percentage of active electrodes is about 50% (n = 8) (Brewer et al, 2008). This may seem a low value, but it should be remembered that the burst structure of firing allows very fast intra-burst spike rate with brief peaks of spike rate in the order of 150-200 Hz (see Table 1 and Fig.…”

An anti-diabetes agent protects the mouse brain from defective insulin signaling caused by Alzheimer’s disease–associated Aβ oligomers

“…Neuronal cultures used throughout our study were maintained in Neurobasal medium supplemented with B-27, an insulin-containing supplement, considered optimal conditions to preserve synapse health and function and to grow mature hippocampal cultures (27). In order to determine whether the increase in IRSpSer described above might be related to insulin coming from B-27, we used cultures grown in insulin-free B-27.…”

An improved method for growing neurons: Comparison with standard protocols

“…Currently, the most widely used is Neurobasal medium with B27 supplement 6,7 . Moreover, several modifications to Neurobasal/B27 were proposed with the addition/modification of glycoproteins, lipid and hormone molecules (NbActiv4, NS21) [8][9][10] . Most of those protocols were designed to promote long-term neuronal survival in an almost pure neuronal culture: neurons of embryonic (E18) and postnatal (P0) origin were cultured in the presence of <1% and 6-8% of glial cells, respectively 7,11 .…”