In the adult rat forebrain, brain-derived neurotrophic factor (BDNF) expression is very rapidly induced by neuronal activity, suggesting that this might occur without intervening protein synthesis. The rat BDNF gene has four differentially regulated promoter regions; each gives rise to an mRNA containing a unique 5' exon (I-IV) and a common 3' exon (V) that codes for mature BDNF protein. The present study used exon-specific in situ hybridization and both in vivo and in vitro preparations to determine whether activity induces BDNF as an "immediate-early gene" (IEG) from specific promoter regions and to compare the regulation of BDNF and nerve growth factor (NGF). In cultured hippocampal slices, kainic acid markedly increased pan-BDNF (exon V) and NGF mRNA content; cycloheximide attenuated the effect of kainic acid on both. In vivo stimulation of a paroxysmal afterdischarge increased both pan-BDNF and NGF mRNA levels in the dentate gyrus granule cells; pretreatment with anisomycin modestly attenuated the paroxysmal afterdischarge-induced increase of both transcripts. To determine whether partial drug effects on BDNF expression reflect the differential regulation of transcript species, levels of mRNAs containing exons I-IV were evaluated. A single afterdischarge increased exon I-IV-containing mRNA levels; anisomycin significantly attenuated the increase in exon I- and II-containing mRNAs but had no effect on the increase in exon III- and IV-containing mRNAs. These data show that for mature forebrain neurons, activity induces the expression of BDNF exon III- and IV-containing transcripts as IEG responses.

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Abstract. We present the first evidence that adhesion mediated by a member of the cadherin gene family can be regulated by a G protein-coupled receptor. We show that activating the M3 muscarinic acetylcholine receptor (mAChR) rapidly induces E-cadherin-mediated adhesion in a small cell lung carcinoma (SCLC) cell line. This response is inhibited by E-cadherin antibodies, and does not occur in another SCLC cell line which expresses functional mAChR but reduced levels of E-cadherin. Protein kinase C may be involved, since phorbol 12-myristate 13-acetate also induces E-cadherin-mediated aggregation. Immunofluorescence analyses indicate that mAChR activation does not grossly alter E-cadherin surface expression or localization at areas of cell-cell contact, suggesting mAChR activation may increase E-cadherin binding activity. Our findings suggest that G protein-coupled receptors may regulate processes involving cadherin-mediated adhesion, such as embryonic development, neurogenesis, and cancer metastasis.

To determine whether recombinant human GH (rhGH) and glutamine (GLN), alone or in combination, have a protein anabolic effect and whether rhGH alters GLN kinetics in cystic fibrosis (CF), nine 9.6 +/- 0.5-yr-old children with CF who were either undernourished (weight/height, <50th percentile) or short (height, <5th percentile) received 2-h infusions of [(13)C]bicarbonate (to assess CO(2) production), followed by 4-h infusions of [(13)C]leucine and [(15)N]GLN, on 4 separate days in the postabsorptive state: 1) at baseline, and after a 4-wk treatment with 2) oral GLN (0.7 g/kg.d), 3) rhGH (0.3 mg/kg.wk), and 4) GLN and rhGH combined (GLN and rhGH regimens were in randomized order). No significant effect of GLN on leucine kinetics was detectable. In contrast, rhGH induced a 32% reduction in leucine oxidation and a 13% stimulation of nonoxidative leucine disposal, an index of protein synthesis (P < 0.05), with no change in proteolysis or GLN kinetics. The combined GLN plus rhGH regimen had similar effects as rhGH alone. We conclude that in children with CF, 1) oral GLN may not promote protein gain in the fasting state; and 2) a short course of rhGH has a potent anabolic effect that is mediated by stimulation of protein synthesis and does not affect GLN kinetics.