Brain research. Molecular brain research
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Brain Res. Mol. Brain Res. · Apr 2005
Comparative StudyExercise activates the phosphatidylinositol 3-kinase pathway.
Physical exercise is known to enhance psychological well-being and coping capacity. Voluntary physical exercise in rats also robustly and rapidly up-regulates hippocampal brain-derived neurotrophic factor (BDNF) mRNA levels, which are potentiated following a regimen of chronic antidepressant treatment. Increased BDNF levels are associated with enhanced activity of cyclic AMP response element binding protein (CREB). ⋯ Immunoblotting analyses revealed that in exercising rats, there was a significant increase in PI-3 kinase expression (4.61 times that of controls, P = 0.0161) and phosphorylation of PDK-1 (2.73 times that of controls, P = 0.0454), thr308-Akt (2.857 times that of controls, P = 0.0082), CREB (60.27 times that of controls, P = 0.05), and Trk (35.3 times that of controls, P < 0.0001) in the hippocampi of exercising animals; BDNF was also increased (3.2 times that of controls), but this was not statistically significant. In rats receiving both exercise and tranylcypromine, BDNF (4.51 times that of controls, P = 0.0068) and PI-3 kinase (4.88 times that of controls, P = 0.0103), and the phospho- forms of Trk (13.67 times that of controls, P = 0.0278), thr308-Akt (3.644 times that of controls, P = 0.0004), GSK-3beta (2.93 times that of controls, P = 0.026), and CREB (88.97 times that of controls, P = 0.0053) were significantly increased. These results suggest that the exercise-induced expression of BDNF is associated with the increased expression of several key intermediates of the PI-3 kinase/Akt pathway, which is known for its role in enhancing neuronal survival.
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Brain Res. Mol. Brain Res. · Apr 2005
Comparative StudyDistribution of OL-protocadherin in axon fibers in the developing chick nervous system.
OL-protocadherin (OL-pc) is a homophilic cell adhesion molecule that belongs to the cadherin gene superfamily. We cloned and characterized the chicken homologue of OL-pc and examined its expression pattern in chick embryos mainly from embryonic day (E) 3.5 to E6.5. The structure of chick OL-pc was found to be essentially the same as that of mammalian OL-pc's except for some small deletions and insertions in the amino acid sequence. ⋯ Interestingly, OL-pc-positive motor nerves such as those to the sternocoracoideus became segregated from OL-pc-faint/weak motor nerves at the plexus region. Moreover, OL-pc was distributed along the path of the branchial nerves. These results suggest that OL-pc might play some roles in axon navigation such as in axon elongation, selective fasciculation, and pathfinding in the early stage of neural development.
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Brain Res. Mol. Brain Res. · Apr 2005
Comparative StudyLow voltage-activated calcium and fast tetrodotoxin-resistant sodium currents define subtypes of cholinergic and noncholinergic neurons in rat basal forebrain.
Neurons of the basal forebrain (BF) possess unique combinations of voltage-gated membrane currents. Here, we describe subtypes of rat basal forebrain neurons based on patch-clamp analysis of low-voltage activated (LVA) calcium and tetrodotoxin-resistant (TTX-R) sodium currents combined with single-cell RT-PCR analysis. Neurons were identified by mRNA expression of choline acetyltransferase (ChAT+, cholinergic) and glutamate decarboxylase (GAD67, GABAergic). ⋯ The TTX-R currents were faster and larger in GAD+ neurons compared to ChAT-/GAD- neurons. The properties of ChAT+/GAD+ neurons resemble those of ChAT+ neurons, rather than of GAD+ neurons. These results suggest novel features of subtypes of cholinergic and noncholinergic neurons within the BF that may provide new insights for understanding normal BF function.