calyculin-a and fluorexon

Cultures of embryonic rat septum were exposed for 24-48 h to 2-5 nm okadaic acid (OA), an inhibitor of pp1A and pp2A phosphatases. This stress killed approximately 75% of neurons. A neurotrophin (NT) combination (nerve growth factor and brain-derived neurotrophic factor, each 100 ng/mL) plus a bone morphogenetic protein (BMP6 or BMP7, 5 nm) reduced the death of both cholinergic and non-cholinergic neurons, and preserved choline acetyltransferase (ChAT) activity assayed 2-6 days post-stress. This NT + BMP combination preserved ChAT activity better than either NTs or BMPs alone, and was effective even if trophic factor addition was delayed until 12 h after stress onset. A general caspase inhibitor (qVD-OPH, 10 micro g/mL) also increased survival of stressed cholinergic neurons, but its protection of ChAT activity was shorter lived than that produced by the NT + BMP combination. Neither the NT + BMP combination nor the caspase inhibitor reduced the OA-induced increase in tau phosphorylation. These findings indicate that NTs and BMPs have synergistic protective effects against an OA stress, and suggest that at least some of these protective effects occur upstream of caspase activation.

Topics: Acetylcholinesterase; Animals; bcl-X Protein; Bone Morphogenetic Proteins; Caspase 3; Caspases; Cell Death; Cell Survival; Cells, Cultured; Dose-Response Relationship, Drug; Drug Combinations; Embryo, Mammalian; Enzyme Inhibitors; Fluoresceins; Glial Fibrillary Acidic Protein; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Immunohistochemistry; Marine Toxins; Nerve Growth Factors; Nuclear Proteins; Okadaic Acid; Oxazoles; Phosphoric Monoester Hydrolases; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Rats; Septal Nuclei; Stress, Physiological; tau Proteins; Time Factors; Transfection