Specialist in Pharmacology, Assistant Professor of Human Physiology, Lecturer in Human Physiology, Lecturer of Neurophysiology, Member of the Nanomedicine Center, of the POLARIS Center and of the Neuroscience Center of the University of Milano-Bicocca. Dr. Sancini has a long experience in the evaluation of the targeting properties and the biocompatibility of new developed nanotechnology-based systems for diagnosis and therapy and in neurophysiological studies. Furthermore, Dr. Sancini research activities is aiming at establishing the relationship between air pollutants (particulate matter) and neurological and brain neurodevelopmental dysfunctions.
The actions of the antiepileptic drug topiramate (TPM) on Na+ currents were assessed using whole-... more The actions of the antiepileptic drug topiramate (TPM) on Na+ currents were assessed using whole-cell patch-clamp recordings in dissociated neocortical neurons and intracellular recordings in neocortical slices. Relatively low TPM concentrations (25-30 microM) slightly inhibited the persistent fraction of Na+ current in dissociated neurons and reduced the Na+-dependent long-lasting action potential shoulders, which can be evoked in layer V pyramidal neurons after Ca++ and K+ current blockade. Conversely, the same drug concentrations were ineffective in reducing the amplitude of the fast Na+-dependent action potentials evoked in slices or the peak of transient Na+ (INaf) current evoked in isolated neurons from a physiological holding potential. Consistent INaf inhibition became, however, evident only when the neuronal membrane was kept depolarized to enhance resting Na+ channel inactivation. TPM (100 microM) was ineffective on the voltage dependence of activation but induced a leftward shift of the steady-state INaf inactivation curve. The drug-induced inhibitory effect increased with the duration of membrane depolarization, and the recovery of INaf after long membrane depolarizations was slightly delayed in comparison with that observed under control conditions. The obtained evidence suggests that the anticonvulsant action of TPM may operate by stabilizing channel inactivation, which can be induced by depolarizing events similar to those occurring in chronic epileptic conditions. Concurrently, the slight but significant inhibition of the persistent fraction of the Na+ current, obtained with the application of relatively low TPM concentrations, may contribute toward its anticonvulsant effectiveness by modulating the near-threshold depolarizing events that are sustained by this small current fraction.
This review analyses the mechanisms by which lung fluid balance is strictly controlled in the air... more This review analyses the mechanisms by which lung fluid balance is strictly controlled in the air-blood barrier (ABB). Relatively large trans-endothelial and trans-epithelial Starling pressure gradients result in a minimal flow across the ABB thanks to low microvascular permeability aided by the macromolecular structure of the interstitial matrix. These edema safety factors are lost when the integrity of the interstitial matrix is damaged. The result is that small Starling pressure gradients, acting on a progressively expanding alveolar barrier with high permeability, generate a high transvascular flow that causes alveolar flooding in minutes. We modeled the trans-endothelial and trans-epithelial Starling pressure gradients under control conditions, as well as under increasing alveolar pressure (Palv) conditions of up to 25 cmH2O. We referred to the wet-to-dry weight (W/D) ratio, a specific index of lung water balance, to be correlated with the functional state of the interstitial s...
The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons a... more The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons and presynaptic glial cells within the neurovascular unit. Glutamate does so by causing an increase in intracellular Ca2+ concentration ([Ca2+]i) in the target cells, which activates the Ca2+/Calmodulin‐dependent nitric oxide (NO) synthase to release NO. It is unclear whether brain endothelial cells also sense glutamate through an elevation in [Ca2+]i and NO production. The current study assessed whether and how glutamate drives Ca2+‐dependent NO release in bEND5 cells, an established model of brain endothelial cells. We found that glutamate induced a dose‐dependent oscillatory increase in [Ca2+]i, which was maximally activated at 200 μM and inhibited by α‐methyl‐4‐carboxyphenylglycine, a selective blocker of Group 1 metabotropic glutamate receptors. Glutamate‐induced intracellular Ca2+ oscillations were triggered by rhythmic endogenous Ca2+ mobilization and maintained over time by extracellular Ca2+ entry. Pharmacological manipulation revealed that glutamate‐induced endogenous Ca2+ release was mediated by InsP3‐sensitive receptors and nicotinic acid adenine dinucleotide phosphate (NAADP) gated two‐pore channel 1. Constitutive store‐operated Ca2+ entry mediated Ca2+ entry during ongoing Ca2+ oscillations. Finally, glutamate evoked a robust, although delayed increase in NO levels, which was blocked by pharmacologically inhibition of the accompanying intracellular Ca2+ signals. Of note, glutamate induced Ca2+‐dependent NO release also in hCMEC/D3 cells, an established model of human brain microvascular endothelial cells. This investigation demonstrates for the first time that metabotropic glutamate‐induced intracellular Ca2+ oscillations and NO release have the potential to impact on neurovascular coupling in the brain.
The actions of the antiepileptic drug topiramate (TPM) on Na+ currents were assessed using whole-... more The actions of the antiepileptic drug topiramate (TPM) on Na+ currents were assessed using whole-cell patch-clamp recordings in dissociated neocortical neurons and intracellular recordings in neocortical slices. Relatively low TPM concentrations (25-30 microM) slightly inhibited the persistent fraction of Na+ current in dissociated neurons and reduced the Na+-dependent long-lasting action potential shoulders, which can be evoked in layer V pyramidal neurons after Ca++ and K+ current blockade. Conversely, the same drug concentrations were ineffective in reducing the amplitude of the fast Na+-dependent action potentials evoked in slices or the peak of transient Na+ (INaf) current evoked in isolated neurons from a physiological holding potential. Consistent INaf inhibition became, however, evident only when the neuronal membrane was kept depolarized to enhance resting Na+ channel inactivation. TPM (100 microM) was ineffective on the voltage dependence of activation but induced a leftward shift of the steady-state INaf inactivation curve. The drug-induced inhibitory effect increased with the duration of membrane depolarization, and the recovery of INaf after long membrane depolarizations was slightly delayed in comparison with that observed under control conditions. The obtained evidence suggests that the anticonvulsant action of TPM may operate by stabilizing channel inactivation, which can be induced by depolarizing events similar to those occurring in chronic epileptic conditions. Concurrently, the slight but significant inhibition of the persistent fraction of the Na+ current, obtained with the application of relatively low TPM concentrations, may contribute toward its anticonvulsant effectiveness by modulating the near-threshold depolarizing events that are sustained by this small current fraction.
This review analyses the mechanisms by which lung fluid balance is strictly controlled in the air... more This review analyses the mechanisms by which lung fluid balance is strictly controlled in the air-blood barrier (ABB). Relatively large trans-endothelial and trans-epithelial Starling pressure gradients result in a minimal flow across the ABB thanks to low microvascular permeability aided by the macromolecular structure of the interstitial matrix. These edema safety factors are lost when the integrity of the interstitial matrix is damaged. The result is that small Starling pressure gradients, acting on a progressively expanding alveolar barrier with high permeability, generate a high transvascular flow that causes alveolar flooding in minutes. We modeled the trans-endothelial and trans-epithelial Starling pressure gradients under control conditions, as well as under increasing alveolar pressure (Palv) conditions of up to 25 cmH2O. We referred to the wet-to-dry weight (W/D) ratio, a specific index of lung water balance, to be correlated with the functional state of the interstitial s...
The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons a... more The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons and presynaptic glial cells within the neurovascular unit. Glutamate does so by causing an increase in intracellular Ca2+ concentration ([Ca2+]i) in the target cells, which activates the Ca2+/Calmodulin‐dependent nitric oxide (NO) synthase to release NO. It is unclear whether brain endothelial cells also sense glutamate through an elevation in [Ca2+]i and NO production. The current study assessed whether and how glutamate drives Ca2+‐dependent NO release in bEND5 cells, an established model of brain endothelial cells. We found that glutamate induced a dose‐dependent oscillatory increase in [Ca2+]i, which was maximally activated at 200 μM and inhibited by α‐methyl‐4‐carboxyphenylglycine, a selective blocker of Group 1 metabotropic glutamate receptors. Glutamate‐induced intracellular Ca2+ oscillations were triggered by rhythmic endogenous Ca2+ mobilization and maintained over time by extracellular Ca2+ entry. Pharmacological manipulation revealed that glutamate‐induced endogenous Ca2+ release was mediated by InsP3‐sensitive receptors and nicotinic acid adenine dinucleotide phosphate (NAADP) gated two‐pore channel 1. Constitutive store‐operated Ca2+ entry mediated Ca2+ entry during ongoing Ca2+ oscillations. Finally, glutamate evoked a robust, although delayed increase in NO levels, which was blocked by pharmacologically inhibition of the accompanying intracellular Ca2+ signals. Of note, glutamate induced Ca2+‐dependent NO release also in hCMEC/D3 cells, an established model of human brain microvascular endothelial cells. This investigation demonstrates for the first time that metabotropic glutamate‐induced intracellular Ca2+ oscillations and NO release have the potential to impact on neurovascular coupling in the brain.
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Papers by Giulio Sancini