Presynaptic cGMP sets synaptic strength in the striatum and is important for motor learning.

The striatum is a subcortical brain region responsible for the initiation and termination of voluntary movements. Striatal spiny projection neurons receive major excitatory synaptic input from neocortex and thalamus, and cyclic nucleotides have long been known to play important roles in striatal function. Yet, the precise mechanism of action is unclear.

Freeze-Frame Imaging of Dendritic Calcium Signals With TubuTag.

The extensive dendritic arbor of neurons is thought to be actively involved in the processing of information. Dendrites contain a rich diversity of ligand- and voltage-activated ion channels as well as metabotropic receptors. In addition, they are capable of releasing calcium from intracellular stores.

Endoplasmic reticulum visits highly active spines and prevents runaway potentiation of synapses.

In hippocampal pyramidal cells, a small subset of dendritic spines contain endoplasmic reticulum (ER). In large spines, ER frequently forms a spine apparatus, while smaller spines contain just a single tubule of smooth ER. Here we show that the ER visits dendritic spines in a non-random manner, targeting spines during periods of high synaptic activity.

Freeze-frame imaging of synaptic activity using SynTagMA.

Information within the brain travels from neuron to neuron across billions of synapses. At any given moment, only a small subset of neurons and synapses are active, but finding the active synapses in brain tissue has been a technical challenge. Here we introduce SynTagMA to tag active synapses in a user-defined time window.

Myosin V regulates synaptopodin clustering and localization in the dendrites of hippocampal neurons.

The spine apparatus (SA) is an endoplasmic reticulum-related organelle that is present in a subset of dendritic spines in cortical and pyramidal neurons, and plays an important role in Ca homeostasis and dendritic spine plasticity. The protein synaptopodin is essential for the formation of the SA and is widely used as a maker for this organelle. However, it is still unclear which factors contribute to its localization at selected synapses, and how it triggers local SA formation.

Improved methods for marking active neuron populations.

Marking functionally distinct neuronal ensembles with high spatiotemporal resolution is a key challenge in systems neuroscience. We recently introduced CaMPARI, an engineered fluorescent protein whose green-to-red photoconversion depends on simultaneous light exposure and elevated calcium, which enabled marking active neuronal populations with single-cell and subsecond resolution. However, CaMPARI (CaMPARI1) has several drawbacks, including background photoconversion in low calcium, slow kinetics and reduced fluorescence after chemical fixation.

Insulin Regulates Astrocytic Glucose Handling Through Cooperation With IGF-I.

Brain activity requires a flux of glucose to active regions to sustain increased metabolic demands. Insulin, the main regulator of glucose handling in the body, has been traditionally considered not to intervene in this process. However, we now report that insulin modulates brain glucose metabolism by acting on astrocytes in concert with IGF-I.

Human native Ca1 channels in chromaffin cells: contribution to exocytosis and firing of spontaneous action potentials.

The present study was performed to evaluate the Ca1 channel subtypes expressed in human chromaffin cells and the role that these channels play in exocytosis and cell excitability. Here we show that human chromaffin cells obtained from organ donors express Ca1.2 and Ca1.

The insulin-like growth factor I receptor regulates glucose transport by astrocytes.

Previous findings indicate that reducing brain insulin-like growth factor I receptor (IGF-IR) activity promotes ample neuroprotection. We now examined a possible action of IGF-IR on brain glucose transport to explain its wide protective activity, as energy availability is crucial for healthy tissue function. Using (18) FGlucose PET we found that shRNA interference of IGF-IR in mouse somatosensory cortex significantly increased glucose uptake upon sensory stimulation.

Automated analysis of spine dynamics on live CA1 pyramidal cells.

Dendritic spines may be tiny in volume, but are of major importance for neuroscience. They are the main receivers for excitatory synaptic connections, and their constant changes in number and in shape reflect the dynamic connectivity of the brain. Two-photon microscopy allows following the fate of individual spines in brain slice preparations and in live animals.

Structural and functional plasticity of astrocyte processes and dendritic spine interactions.

Experience-dependent plasticity of synaptic transmission, which represents the cellular basis of learning, is accompanied by morphological changes in dendritic spines. Astrocytic processes are intimately associated with synapses, structurally enwrapping and functionally interacting with dendritic spines and synaptic terminals by responding to neurotransmitters and by releasing gliotransmitters that regulate synaptic function. While studies on structural synaptic plasticity have focused on neuronal elements, the structural-functional plasticity of astrocyte-neuron relationships remains poorly known.

Confocal microscopy for astrocyte in vivo imaging: Recycle and reuse in microscopy.

In vivo imaging is one of the ultimate and fundamental approaches for the study of the brain. Two-photon laser scanning microscopy (2PLSM) constitutes the state-of-the-art technique in current neuroscience to address questions regarding brain cell structure, development and function, blood flow regulation and metabolism. This technique evolved from laser scanning confocal microscopy (LSCM), which impacted the field with a major improvement in image resolution of live tissues in the 1980s compared to widefield microscopy.

Astrocyte-neuron interaction at tripartite synapses.

Astrocytes, classically considered as supportive cells for neurons without a direct role in brain information processing, are emerging as relevant elements in brain physiology through their ability to regulate neuronal activity and synaptic transmission and plasticity. In relation to the key role of astrocyte-neuron interactions in synaptic physiology, accumulating evidence suggests that dysfunctions of neuron-astrocyte signaling may be linked to the pathology of various neurological and neurodegenerative diseases. In this article, we summarize the evidence supporting the importance of astrocyte-neuron communication in synaptic physiology, which have led to reveal astrocytes as integral elements of synaptic function.

Exocytotic dynamics in human chromaffin cells: experiments and modeling.

Chromaffin cells have been widely used to study neurosecretion since they exhibit similar calcium dependence of several exocytotic steps as synaptic terminals do, but having the enormous advantage of being neither as small or fast as neurons, nor as slow as endocrine cells. In the present study, secretion associated to experimental measurements of the exocytotic dynamics in human chromaffin cells of the adrenal gland was simulated by using a model that combines stochastic and deterministic approaches for short and longer depolarizing pulses, respectively. Experimental data were recorded from human chromaffin cells, obtained from healthy organ donors, using the perforated patch configuration of the patch-clamp technique.

Selectivity of action of pregabalin on Ca(2+) channels but not on fusion pore, exocytotic machinery, or mitochondria in chromaffin cells of the adrenal gland.

The present study was planned to investigate the action of pregabalin on voltage-dependent Ca(2+) channels (VDCCs) and novel targets (fusion pore formed between the secretory vesicle and the plasma membrane, exocytotic machinery, and mitochondria) that would further explain its inhibitory action on neurotransmitter release. Electrophysiological recordings in the perforated-patch configuration of the patch-clamp technique revealed that pregabalin inhibits by 33.4 ± 2.

Native α6β4* nicotinic receptors control exocytosis in human chromaffin cells of the adrenal gland.

In the present study, we have electrophysiologically characterized native nicotinic acetylcholine receptors (nAChRs) in human chromaffin cells of the adrenal gland as well as their contribution to the exocytotic process. α-Conotoxin AuIB blocked by 14 ± 1% the acetylcholine (ACh)-induced nicotinic current. α-Conotoxin MII (α-Ctx MII) exhibited an almost full blockade of the nicotinic current at nanomolar concentrations (IC(50)=21.

Pharmacological characterization of native α7 nicotinic ACh receptors and their contribution to depolarization-elicited exocytosis in human chromaffin cells.

Background And Purpose: Expression of α7 nicotinic acetylcholine receptors (nAChRs) and their role in exocytosis have not yet been examined in human chromaffin cells.

Experimental Approach: To characterize these receptors and investigate their function, patch-clamp experiments were performed in human chromaffin cells from organ donors.

Key Results: The nicotinic current provoked by 300µM ACh in voltage-clamped cells was blocked by the nicotinic receptor antagonists α-bungarotoxin (α-Bgtx; 1µM; 6 ± 1.

Past, present and future of human chromaffin cells: role in physiology and therapeutics.

Chromaffin cells are neuroendocrine cells mainly found in the medulla of the adrenal gland. Most existing knowledge of these cells has been the outcome of extensive research performed in animals, mainly in the cow, cat, mouse and rat. However, some insight into the physiology of this neuroendocrine cell in humans has been gained.

Different roles attributed to Cav1 channel subtypes in spontaneous action potential firing and fine tuning of exocytosis in mouse chromaffin cells.

This study examines the Cav1 isoforms expressed in mouse chromaffin cells and compares their biophysical properties and roles played in cell excitability and exocytosis. Using immunocytochemical and electrophysiological techniques in mice lacking the Cav1.3α1 subunit (Cav1.

Pharmacological and biophysical properties of Ca2+ channels and subtype distributions in human adrenal chromaffin cells.

In this study, we explored the pharmacological and biophysical properties of voltage-activated Ca2+ channels in human chromaffin cells using the perforated-patch configuration of the patch-clamp technique. According to their pharmacological sensitivity to Ca2+ channel blockers, cells could be sorted into two groups of similar size showing the predominance of either N- or P/Q-type Ca2+ channels. R-type Ca2+ channels, blocked by 77% with 20 muM Cd2+ and not affected by 50 muM Ni2+, were detected for the first time in human chromaffin cells.

Key role of the nicotinic receptor in neurotransmitter exocytosis in human chromaffin cells.

The whole-cell secretory response evoked by acetylcholine (ACh) in human chromaffin cells was examined using a new protocol based on quickly switching from the voltage-clamp to the current-clamp (CC) configuration of the patch-clamp technique. Our experiments revealed that Ca(2+) entry through the nicotinic receptor at hyperpolarized membrane potentials contributed as much to the exocytosis (100.4 +/- 27.