Periaxonal K+ regulation in the small squid Alloteuthis. Studies on isolated and in situ axons

A novel giant axon preparation from the squid Alloteuthis is described. Properties of in situ and isolated axons are similar. Periaxonal K+ accumulation is a function of the physiological state of the animal and of the axon and its sheathing layers. Carefully dissected isolated axons, and axons in situ in a healthy mantle, show much less K+ accumulation than previously reported in squid. It is suggested that the Schwann cells are involved in the observed K+ regulation

Brain-Derived Neurotrophic Factor Stimulates AP-1 and Cyclic AMP-Responsive Element Dependent Transcriptional Activity in Central Nervous System Neurons

International audienceBrain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, regulates survival and apoptosis of several neuronal populations. These effects are initiated by high-affinity membrane receptors displaying tyrosine kinase activity (trk). However, the intracellular pathways and genetic mechanisms associated with these receptors are largely unknown. Here we show that BDNF stimulates AP1 binding activity in primary cerebellar neurons. This binding corresponds to a functional complex as it is associated with the induction of AP1-dependent transactivation. Application of AP1 partner mRNAs shows an increase in levels of c-fos and c-jun mRNAs after BDNF treatment, resulting from an induction of their promoters. The cis-acting elements by which BDNF stimulates c-fos transcription were further studied. We show that BDNF impinges on multiple regulatory elements, including the serum-responsive element, Fos AP1-like element, and cyclic AMP (cAMP)-responsive element (CRE) sequences. The latter was stimulated without any detectable increase in cAMP or Ca2+ levels. To confirm that BDNF induces c-fos transcription independently of the protein kinase A/cAMP pathway, we transfected a dominant inhibitory mutant of the regulatory subunit of protein kinase A. The overexpression of this mutant does not affect the c-fos promoter transactivation by BDNF. In summary, we show that BDNF stimulates AP1- and CRE-dependent transcription through a mechanism that is distinct from the cAMP- and Ca(2+)-dependent pathways in CNS neurons

Evidence that GABAA receptor subunit mRNA expression during development is regulated by GABA receptor stimulation: J.Neurochem.

NRC publication: Ye

Periaxonal K+ regulation in the small squid Alloteuthis. Studies on isolated and in situ axons.

A novel giant axon preparation from the squid Alloteuthis is described. Properties of in situ and isolated axons are similar. Periaxonal K+ accumulation is a function of the physiological state of the animal and of the axon and its sheathing layers. Carefully dissected isolated axons, and axons in situ in a healthy mantle, show much less K+ accumulation than previously reported in squid. It is suggested that the Schwann cells are involved in the observed K+ regulation

Etude electrophysiologique des mecanismes d'activation et d'inactivation des courants ioniques dans l'axone geant de calmar: etude cinetique et pharmacologique

CNRS AR 10904 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc