Furthermore, we report sustained multi-mode oscillations and potentially chaotic see more behavior caused by a sequestration-based feedback mechanism. Finally, we investigate the interplay between sequestration and external feedback loops. Our analysis thereby confirms, extends and generalizes previous results obtained by conventional modeling and points out the diversity of dynamics that sequestration can bring about. (C) 2010 Elsevier Ltd. All
“Brain vasopressin plays a role in behavioral and cognitive functions and in pathological conditions. Relevant examples are pair bonding, social recognition, fear responses, stress disorders, anxiety and depression. At the neuronal level, vasopressin exerts its effects by binding to Via receptors. In the brainstem, vasopressin can excite facial motoneurons by generating a sustained
inward current which is sodium-dependent, tetrodotoxin-insensitive and voltage-gated. This effect is independent of intracellular calcium mobilization and is unaffected by phospholipase C beta (PLC beta) or protein kinase C (PKC) inhibitors. There are two major unsolved problems. (i) What is the intracellular signaling pathway activated by vasopressin? (ii) What is the exact nature of the vasopressin-sensitive cation channels? We performed recordings in brainstem slices. Facial motoneurons were voltage-clamped in the whole-cell selleck inhibitor configuration. We show that a major fraction, if not the totality, of the peptide effect was mediated by cAMP signaling and that the vasopressin-sensitive cation channels were directly gated by cAMP. These channels appear to exclude lithium, are suppressed by 2-aminoethoxydiphenylborane
(2-APB) and flufenamic acid (FFA) but not by ruthenium red or amiloride. They are distinct from transient receptor channels and from cyclic nucleotide-regulated channels involved in visual and olfactory transduction. They present striking similarities with cation channels present in a variety of molluscan Sinomenine neurons. To our knowledge, the presence in mammalian neurons of channels having these properties has not been previously reported. Our data should contribute to a better knowledge of the neural mechanism of the central actions of vasopressin, and may be potentially significant in view of clinical applications. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.”
“Dynasore was recently developed as a small molecule, selective non-competitive inhibitor of the protein dynamin. This inhibitor has been shown to block dynamin-dependent endocytosis and is now used commonly to study vesicular recycling at synapses. We have measured the effects of dynasore on spontaneous and evoked transmitter release at the frog neuromuscular junction and shown that, in addition to inhibiting endocytosis, dynasore increases the probability of transmitter release.