Developmental conditions and culture medium influence the neuromodulated response of in vitro cortical networks

Goal of this work is to show how the developmental conditions of in vitro neuronal networks influence the effect of drug delivery. The proposed experimental neuronal model consists of dissociated cortical neurons plated to Micro-Electrode Arrays (MEAs) and grown according to different conditions (i.e., by varying both the adopted culture medium and the number of days needed to let the network grow before performing the chemical modulation). We delivered rising amount of bicuculline (BIC), a competitive antagonist of GABA(A) receptors, and we computed the firing rate dose-response curve for each culture. We found that networks matured in BrainPhys for 18 days in vitro exhibited a decreasing firing trend as a function of the BIC concentration, quantified by an average IC50 (i.e., half maximal inhibitory concentration) of 4.64 +/- 4.02 mu M. On the other hand, both cultures grown in the same medium for 11 days, and ones matured in Neurobasal for 18 days displayed an increasing firing rate when rising amounts of BIC were delivered, characterized by average EC50 values (i.e., half maximal excitatory concentration) of 0.24 +/- 0.05 mu M and 0.59 +/- 0.46 mu M, respectively.