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EFFECT OF AROCLOR 1254 ON THE TRANSCRIPTION FACTOR CREB AND CELL VIABILITY IN A PRIMARY CULTURE OF IMMATURE CORTICAL CELLS.
Citation:
Inglefield, J R., W R. Mundy, AND T J. Shafer. EFFECT OF AROCLOR 1254 ON THE TRANSCRIPTION FACTOR CREB AND CELL VIABILITY IN A PRIMARY CULTURE OF IMMATURE CORTICAL CELLS. Presented at Society of Toxicology, San Franscisco, CA, March 25-29, 2001.
Description:
Considerable work indicates that elevations in Ca2+ levels and kinase activity are sensitive responses to polychlorinated biphenyls (PCBs), which are developmental neurotoxicants. In cortical cells in vitro the PCB mixture Aroclor 1254 (A1254) induces temporally and mechanistically complex Ca2+i signals. Ortho-substituted PCBs in A1254 are important for initiating Ca2+ disturbances, though no individual congener elicits the same actions as the A1254. The consequences of such heightened signaling are the focus of the present studies. Cortical cultures were treated with A1254 (2-20 M, 1-24 hr) in the absence of serum and the impact on a Ca2+- activated nuclear transcription factor (CREB), cell viability, and apoptosis studied. CREB activation was measured using western blots with selective antibodies to phospho-CREB (on ser-133) and total CREB following gel electrophoresis. Cell viability was determined by trypan blue exclusion after a 24 hr exposure. Apoptosis was determined by caspase 3 activity at 6-8 hr as well as by morphological examination of in situ TUNEL or fluorescent dye-stained nuclei at 24 hr exposure. A1254 (2-20 M) induced phospho-CREB 2-fold, which persisted at least 1 hr. Cortical cells exposed to A1254 for 24 hr exhibited cell death at 20 M (21-50%) which was restricted to mature-type cells (at 7 days in vitro, DIV) while the number and morphology of younger (DIV 4-6) cells was not impaired. Neither 24 hr serum deprivation alone nor serum deprivation with A1254 (10 or 20 M) increased the number of TUNEL- stained nuclei in DIV 7 cells. Moreover, caspase 3 activity, an upstream protease in the apoptotic pathway, was not increased by A1254. In view of limited cytotoxicity, especially at 10 M, and lack of apoptosis (even at 20 M), the finding of CREB activation by PCBs may be important in terms of consequences on neuronal development or long-term synaptic plasticity. (This abstract does not necessarily reflect EPA policy.)