cAMP promotes differentiation of rodent neuronal progenitor cells

Abstract

Numerous studies have described neuronal differentiation of neural progenitor cells derived from fetal tissue in vitro, but the biochemical mechanisms underlying this process remain largely unknown. In the present study, the role of cAMP in promoting functional maturation of neuronal progenitor cells (NPCs) from the subventricular zone (SVZ) of rodent fetal brain was investigated. NPCs were extracted from telencephalic vesicles of E14 rat embryos and then expanded in medium containing epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). A mature neuronal fate was induced by: i) withdrawal of growth factors (basal condition); ii) addition of brain-derived neurotrophic factor (BDNF); or iii) addition of isobutylmethylxantine (IBMX). Whole cell patch clamping assessed electrophysiological properties. Immunocyto - chemistry for MAP2 confirmed neuronal differentiation. Quantification of neuronal cells, and determination of their electrophysiological properties, was performed in the cited experimental groups. IBMX significantly enhanced the yield of MAP2-positive neurons in the culture system (3.7-fold increase). Application of a one-week differentiation protocol under IBMX induced functional maturity. MAP2-positive cells presented large Na- and K- voltagedependent currents, fired bursts of action potentials, and exhibited spontaneous synaptic activity. Further, IBMX proved more effective than BDNF for promoting neuronal maturation, leading to higher evoked peak currents and current densities, as well as greater yields of cells firing action potentials and presenting active synaptic contacts. Our data indicates the importance of cAMP-dependent mechanisms for maturation of neuronal progenitor cells in vitro. This knowledge can enable future manipulation of neurogenesis in vivo in order to promote the intrinsic regenerative capacity of the central nervous system.