First generation vanadium-based PTEN inhibitors: Comparative study in vitro and in vivo and identification of a novel mechanism of action.

PTEN, a tumor suppressor phosphatase, regulates cellular functions by antagonizing the growth promoting PI3K/Akt/mTOR pathway through the dephosphorylation of the second messenger PIP. Many preclinical cellular and animal studies have used PTEN inhibitors to highlight specific disease contexts where acute activation of PI3K/Akt/mTOR pathway might offer therapeutic advantages. In the present study we have re-evaluated first-generation PTEN inhibitors, including established bisperoxo-vanadium complexes (bpVs).

Multiple Posterior Insula Projections to the Brainstem Descending Pain Modulatory System.

The insular cortex is an important hub for sensory and emotional integration. It is one of the areas consistently found activated during pain. While the insular's connections to the limbic system might play a role in the aversive and emotional component of pain, its connections to the descending pain system might be involved in pain intensity coding.

Firing Alterations of Neurons in Alzheimer's Disease: Are They Merely a Consequence of Pathogenesis or a Pivotal Component of Disease Progression?

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, yet its underlying causes remain elusive. The conventional perspective on disease pathogenesis attributes alterations in neuronal excitability to molecular changes resulting in synaptic dysfunction. Early hyperexcitability is succeeded by a progressive cessation of electrical activity in neurons, with amyloid beta (Aβ) oligomers and tau protein hyperphosphorylation identified as the initial events leading to hyperactivity.

Differential behavioral response to predator odor in neuropathic pain in mice.

Neuropathic pain, a type of chronic pain caused by injury or disease of the somatosensory system, affects ∼10% of the general population and is difficult to treat. It is strongly associated with mood disorder comorbidities and impairs quality of life. It was recently suggested that hypervigilance caused by chronic pain might be of advantage in some species, helping them avoid predators during injury when they are most vulnerable.

The Role of the Insular Cortex in Pain.

The transition from normal to chronic pain is believed to involve alterations in several brain areas that participate in the perception of pain. These plastic changes are then responsible for aberrant pain perception and comorbidities. The insular cortex is consistently found activated in pain studies of normal and chronic pain patients.

α5GABA Receptors Mediate Tonic Inhibition in the Spinal Cord Dorsal Horn and Contribute to the Resolution Of Hyperalgesia.

Neuronal inhibition mediated by GABA receptors constrains nociceptive processing in the spinal cord, and loss of GABAergic inhibition can produce allodynia and hyperalgesia. Extrasynaptic α5 subunit-containing GABA receptors (α5GABA Rs) generate a tonic conductance that inhibits neuronal activity and constrains learning and memory; however, it is unclear whether α5GABA Rs similarly generate a tonic conductance in the spinal cord dorsal horn to constrain nociception. We assessed the distribution of α5GABA Rs in the spinal cord dorsal horn by immunohistochemical analysis, and the activity and function of α5GABA Rs in neurons of the superficial dorsal horn using electrophysiological and behavioral approaches in male, null-mutant mice lacking the GABA R α5 subunit (Gabra5-/-) and wild-type mice (WT).

The heterogeneity in GABAA receptor-mediated IPSC kinetics reflects heterogeneity of subunit composition among inhibitory and excitatory interneurons in spinal lamina II.

GABAergic inhibition displays rich functional diversity throughout the CNS, which arises from variations in the nature of inputs, subunit composition, subcellular localization of receptors and synapse geometry, or reuptake mechanisms. In the spinal dorsal horn (SDH), GABAA and glycine receptors play a major role in the control of excitability and accuracy of nociceptive processing. Identifying which components shape the properties of the inhibitory synapses in different cell types is necessary to understand how nociceptive information is integrated.

Pharmacological enhancement of δ-subunit-containing GABA(A) receptors that generate a tonic inhibitory conductance in spinal neurons attenuates acute nociception in mice.

The development of new strategies for the treatment of acute pain requires the identification of novel nonopioid receptor targets. This study explored whether δ-subunit-containing GABA(A)Rs (δGABA(A)Rs) in neurons of the spinal cord dorsal horn generate a tonic inhibitory conductance in vitro and whether δGABA(A)R activity regulates acute nociception. Whole-cell recordings revealed that δGABA(A)Rs generate a tonic inhibitory conductance in cultured spinal neurons and lamina II neurons in spinal cord slices.

Inhibitory coupling between inhibitory interneurons in the spinal cord dorsal horn.

Local inhibitory interneurons in the dorsal horn play an important role in the control of excitability at the segmental level and thus determine how nociceptive information is relayed to higher structures. Regulation of inhibitory interneuron activity may therefore have critical consequences on pain perception. Indeed, disinhibition of dorsal horn neuronal networks disrupts the balance between excitation and inhibition and is believed to be a key mechanism underlying different forms of pain hypersensitivity and chronic pain states.

Functional similarities and differences of AMPA and kainate receptors expressed by cultured rat sensory neurons.

Dorsal root ganglion neurons express functional AMPA and kainate receptors near their central terminals. Activation of these receptors causes a decrease in glutamate release during action potential evoked synaptic transmission. Due to differences in kinetic properties and expression patterns of these two families of glutamate receptors in subpopulations of sensory neurons, AMPA and kainate receptors are expected to function differently.

Various divalent cations protect the isolated perfused pigeon heart against a calcium paradox.

The protective effects of various divalent cations against the irreversible damage of myocardium, a phenomenon termed "the Ca2+-paradox", were examined in the isolated perfused pigeon heart. All cations examined were added at a concentration of 200 micromol l(-1) in the "calcium-free" medium. In hearts perfused with low calcium, upon normal calcium repletion, the maximal recovery of the contractile tension (in the 2nd minute) was approximately 115% and the recovery obtained at the end of reperfusion was 81.

Neurokinin receptor 1-expressing spinal cord neurons in lamina I and III/IV of postnatal rats receive inputs from capsaicin sensitive fibers.

Dorsal horn neurons expressing receptor for substance P (SP), the neurokinin 1 (NK1) receptor, play an important role in transmission and processing of nociceptive stimuli. To identify and study these neurons in the rat spinal cord slice preparation, we used fluorescence-conjugated SP to label NK1 receptor-expressing neurons. Labeled neurons in lamina I and III/IV were patch clamped and the vanilloid receptor 1 (TRPV1) agonist, capsaicin, was applied to evoke glutamate release from central terminals of peripheral nociceptors.

Localization and function of ATP and GABAA receptors expressed by nociceptors and other postnatal sensory neurons in rat.

The role of endogenous GABA and ATP in regulating transmitter release from primary afferent terminals in the superficial dorsal horn of the spinal cord is still controversial. ATP is co-released with GABA from some inhibitory dorsal horn neurons raising the possibility that ATP could act in concert with GABA to regulate transmitter release from primary afferent terminals if receptors to both transmitters are expressed there. Using electrophysiology together with immunocytochemistry, we have investigated the expression of ATP-gated P2X and GABAA receptors by identified subpopulations of dorsal root ganglion (DRG) neurons known to project primarily to the superficial dorsal horn.

Adenosine triphosphate-evoked currents in cultured dorsal root ganglion neurons obtained from rat embryos: desensitization kinetics and modulation of glutamate release.

Sensory neurons express purinergic P2X receptors on their central and peripheral terminals as well as their cell bodies. ATP activation of these receptors drives action potential firing and glutamate release with potentially important consequences for sensory function. Here we show ATP-gated currents activated in cultured embryonic dorsal root ganglion neurons have heterogeneity of time-courses comparable to those observed in different subpopulations of acutely dissociated adult dorsal root ganglion neurons.

Functional GABA(A) receptors on human glioma cells.

Glioma cells in acute slices and in primary culture, and glioma-derived human cell lines were screened for the presence of functional GABA(A) receptors. Currents were measured in whole-cell voltage clamp in response to gamma-aminobutyric acid (GABA). While cells from the most malignant glioma, the glioblastoma multiforme, did not respond to GABA, an inward current (under our experimental conditions with high Cl- concentration in the pipette) was induced in gliomas of lower grades, namely in 71% of oligodendroglioma cells and in 62% of the astrocytoma cells.

Glutamate receptor activation can trigger electrical activity in human glioma cells.

Cells from major types of gliomas, i.e. oligodendrogliomas and glioblastomas, are able to generate action potentials upon a current injection similar to neurons (Patt et al.

Analysis of motile oligodendrocyte precursor cells in vitro and in brain slices.

Oligodendrocyte precursor cells are purported to migrate over long distances into the various brain regions where they differentiate into oligodendrocytes and fulfill their appropriate tasks, i.e., myelination of axons.

GABA(A) receptor activation triggers a Cl- conductance increase and a K+ channel blockade in cerebellar granule cells.

GABA(A) receptor activation in cerebellar granule cells induced a complex physiological response, namely the activation of a Cl- conductance in concert with a blockade of the resting K+ outward conductance (by 71% as compared to controls). Both responses were mediated by the activation of GABA(A) receptors, since they were both mimicked by the GABA(A) receptor agonist muscimol and antagonized by picrotoxin and bicuculline. A substantial decrease of the mean open time of single, outwardly rectifying K+ channels was triggered by GABA as revealed from cell-attached recordings; this finding implies that an intracellular pathway links GABA(A) receptors and K+ channels.

Neuroligand-triggered calcium signalling in cultured human glioma cells.

Cells from primary cultures of four glioblastomas (GB), three low-grade astrocytomas (A), and four low-grade oligodendrogliomas (O) were tested for the presence of neuroligand receptors linked to Ca2+ signalling by calcium imaging. Cells of days 3 to 21 in culture were incubated with 5 microM fluo-3-acetomethylester in a bath solution and stimulated with 0.1 mM ATP, 0.

Action potential-generating cells in human glioblastomas.

We studied the electrophysiological properties of cells from human glioblastomas obtained after surgery. The membrane currents were compared in cells of acute tissue slices and primary cultures using the whole cell mode of the patch-clamp technique. Very strikingly, in about a third of the tumor cells in situ and in vitro, depolarizing voltage steps elicited large, tetrodotoxin-sensitive inward currents with a threshold of about -30 mV, indicating the presence of voltage-gated sodium channels.

Neuron-like physiological properties of cells from human oligodendroglial tumors.

One of the most common symptoms of patients with oligodendrogliomas is the high frequency of epileptic seizures. We thus studied the physiological properties of cells in six human oligodendrogliomas and two oligoastrocytomas obtained from surgical material. The majority of tumor cells in living brain slices can generate action potentials as recorded with the patch-clamp technique indicating that this tissue is dominated by electrically excitable cells.

Human central neurocytoma cells show neuronal physiological properties in vitro.

Central neurocytoma is a rare brain tumor composed of small round synaptophysin-positive cells, suggesting a neuronal origin of these tumor cells. Glial properties are inferred, however, from the observation that the tumor cells exhibit a strong morphological similarity to oligodendroglioma cells and show an astrocytic differentiation in vitro. To test for neuronal or glial physiological properties, we studied cultured neurocytoma cells derived from a surgical specimen from a 44-year-old man, employing the patch-clamp technique.