Exogenous Nkx2-5 gene expression induces the expression of cardiac markers during P19 cell differentiation in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of homeobox gene Nkx2-5 in cardiac myogenesis.</p><p><b>METHODS</b>Two P19 cell lines, namely cells transfected with exogenous expression of Nkx2-5 gene and non-transfected cells, were cultured in suspension for 4 days to induce cell aggregation, and the cell aggregates were transferred to the Petri dish for further adherent culture. On days 4, 8, 12 and 16 of adherent culture, the expressions of α-sarcomeric actin (α-SA) and cardiac troponin T (cTnT) protein were detected by immunocytochemistry, and the mRNA expressions of GATA-4, α-myosin heavy chain (α-MHC) and atrial natriuretic factor (ANF) genes by RT-PCR.</p><p><b>RESULTS</b>In the transfected cells, α-SA and cTnT protein expressions were detected on days 8, 12 and 16 of adhere culture, and their expressions increased gradually with time. α-SA and cTnT expression was significantly higher on day 16 than on day 8 of culture (P<0.01). RT-PCR analysis of the transfected cell showed the presence of GATA-4 expression on day 4 of adherent culture, and the expression increased on days 8 and 12 but decreased on day 16. ANF and α-MHC expressions were found on days 8, 12, and 16, increasing gradually over time and showing significant differences from those on day 4 (P<0.05 or P<0.01). The expression of α-MHC was significantly higher on days 12 and 16 than on day 8 (P<0.05 or P<0.01), and ANF expression was significantly higher on day 16 than on days 8 and 12 (P<0.01). The non-transfected cells were negative for the expressions of all these genes.</p><p><b>CONCLUSION</b>Exogenous expression of Nkx2-5 gene can induce P19 cells to express cardiac markers in vitro.</p>

Neuroprotective effects of learning on glutamate-induced neuronal damage in rat hippocampus / 中国应用生理学杂志

<p><b>AIM</b>To investigate the neuroprotective effect of learning on glutamate-induced neuronal damage.</p><p><b>METHODS</b>SD rats were intraperitoneally injected with monosodium glutamate (MSG) during the period of 3-9 days after born, and were trained to find their food by light-dark discrimination at 1 month old or 2 months old. At 3 months old, all rats were killed and their brains were taken out and cut into sections and ultrathin sections. The survival neurons in hippocampus were counted under light microscope, and under electric microscope, the ultrastructure, the numbers of synapses and the length of synaptic active zone in fields CA1 of hippocampus were observed.</p><p><b>RESULTS</b>The survival neurons in field CA3 and CA4, the number of synapses and the length of synaptic active zone in field CA1 of hippocampus increased in learning group than non-learning group.</p><p><b>CONCLUSION</b>These finding indicate that discriminative learning can alleviate neuronal injury of hippocampus induced by MSG.</p>