ABSTRACT
Introduction: antibiotic supplements are regularly used in neuronal culture media to control contamination; however, they can interfere with the neuronal excitability and affect electrophysiological properties. Therefore, in this study, the effect of penicillin/streptomycin supplements on the spontaneous electrophysiological activity of hippocampal pyramidal neurons was examined
Methods: electrophysiological whole-cell patch-clamp recordings from rat hippocampal pyramidal cells in primary culture were performed to investigate the effects of antibiotic supplements on the intrinsic excitability of cultured cells
Results: the present findings indicated that presence of antibiotic supplements [penicillin/streptomycin] in the culture medium altered the intrinsic electrical activity of hippocampal pyramidal neurons in primary culture. These alterations included: 1] depolarized resting membrane potential; 2] a significant enhancement in the after-hyperpolarization amplitude; 3] a significant increase in the area under the action potential and in the decay and rise time of the action potential; 4] a significant broadening of action potential and 5] a significant reduction in the firing frequency
Conclusion: these findings suggest that addition of antibiotic supplements to culture media influences the neuronal excitability and alters the electrophysiologicalproperties of cultured neurons, possibly through changing the ionic conductance underlying neuronal excitability. Iran. Biomed. J. 17 [2]: 101-106, 2013
ABSTRACT
Considering that cannabinoids protect neurons against neurodegeneration, in this study, the neuroprotective effect of WIN55,212-2 in paraoxon induced neurotoxicity in PC12 cells and the role of the N-methyl-D-aspartate [NMDA] receptor were evaluated. In this study PC12 cells were maintained in Dulbecco's modified eagle's medium [DMEM+F12] culture medium supplemented with 10% fetal bovine serum. The cells were treated with paraoxon [200 micro M] in the presence or absence of WIN55,212-2 [0.1 micro M], NMDA receptor agonist NMDA [100 micro M], cannabinoid receptor antagonist AM251 and NMDA receptor antagonist MK801 [1 micro M] at 15 minutes intervals. After 48 hours of exposure, cellular viability and protein expression of the CB1 receptor were evaluated in PC12 cells. Following the exposure of PC12 cells to paraoxon [200 micro M], a reduction in cell survival and protein level of the CB1 receptor was observed [p<0.01]. Treatment of the cells with WIN55,212-2 [0.1 micro M] and NMDA [100 micro M] prior to paraoxon exposure significantly elevated cell survival and protein level of the CB1 receptor [p<0.01]. Also, AM251 [1 micro M] did not inhibit the cell survival and protein level of the CB1 receptor increase induced by WIN55,212-2 [p<0.001]. However, MK801 [1 micro M] did inhibit cell survival and protein expression of the CB1 receptor increase induced by NMDA [p<0.001]. The results indicate that WIN55,212-2 and NMDA protect PC12 cells against paraoxon induced toxicity. In addition, the neuroprotective effect of WIN55,212-2 and NMDA was cannabinoid receptor-independent and NMDA receptor dependent, respectively