Activation of ERK1/2 and axogenesis induced by estradiol depend on different calcium pools in male rat hypothalamic neurons in vitro

CABRERA ZAPATA LUCAS E; BOLLO M ; CAMBIASSO MJ

Buenos Aires

Congreso; FALAN ?Federation of Latin American and Caribbean Neuroscience Societies; 2016

Activation of ERK1/2 and axogenesis induced by estradiol depend on different calcium pools in male rat hypothalamic neurons in vitroLucas E. Cabrera Zapata1, Mariana Bollo1 and María Julia Cambiasso1,21Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina.2Cátedra de Biología Celular, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina.Estradiol (E2) induces axonal growth through the extracellular signal-regulated kinase 1 and 2 (ERK1/2) cascade in hypothalamic neurons of male rat embryos in vitro. Both axogenesis and ERK1/2 activation mediated by E2 depend on Ca2+ and Ca2+-dependent PKC isoforms. In the present study, we investigated the Ca2+ pools that participate in the activation of ERK1/2 and axogenesis by E2. Hypothalamic neuron cultures were established from male rat embryos of 16 days of gestation and fed with astroglia-conditioned media for 48 hours. E2 treatment rapidly induced ERK activation, which was completely abolished by a ryanodine receptor (RyR) inhibitor (ryanodine) and partially attenuated by an L-type voltage-gated Ca2+ channel (L-VGCC) blocker (nifedipine) and an inositol-1,4,5-trisphosphate receptor (IP3R) inhibitor (2-APB). In this line of thought EGTA pre-treatment slightly decreased E2-induced ERK1/2 phosphorylation, and ryanodine treatment completely inhibited the axonal growth generated by E2. In summary, the results suggest that Ca2+ mobilization from extracellular space as well as from endoplasmic reticulum are necessary to E2-induced ERK1/2 activation and axogenesis. Besides, whereas L-VGCCs and IP3Rs might participate in the Ca2+ signaling evoked by E2, the predominant role is mediated by RyRs. Furthermore, we are currently conducting Ca2+ imaging recording using primary cultured neurons that over-express a genetically-encoded Ca2+-indicator (GCaMP6s). Preliminary results suggest that E2 induces Ca2+ oscillations, which, at least in part, depend on Ca2+.influx Financial support: CONICET, ANPCyT and SECyT-UNC, Argentina.