Mechanical stimulation-induced purinome priming fosters osteogenic differentiation and osteointegration of mesenchymal stem cells from the bone marrow of post-menopausal women.

Background: Mechanical stimulation (MS) significantly increases the release of adenine and uracil nucleotides from bone marrow-derived mesenchymal stem cells (BM-MSCs) undergoing osteogenic differentiation. Released nucleotides acting via ionotropic P2X7 and metabotropic P2Y purinoceptors sensitive to ATP and UDP, respectively, control the osteogenic commitment of BM-MSCs and, thus, bone growth and remodelling. Yet, this mechanism is impaired in post-menopausal (Pm)-derived BM-MSCs, mostly because NTPDase3 overexpression decreases the extracellular accumulation of nucleotides below the levels required to activate plasma membrane-bound P2 purinoceptors.

Blockage of the adenosine A receptor prevents cardiac fibroblasts overgrowth in rats with pulmonary arterial hypertension.

Sustained pressure overload and fibrosis of the right ventricle (RV) are the leading causes of mortality in pulmonary arterial hypertension (PAH). Although the role of adenosine in PAH has been attributed to the control of pulmonary vascular tone, cardiac reserve, and inflammatory processes, the involvement of the nucleoside in RV remodelling remains poorly understood. Conflicting results exist on targeting the low-affinity adenosine A receptor (AAR) for the treatment of PAH mostly because it displays dual roles in acute vs.

Silencing NTPDase3 activity rehabilitates the osteogenic commitment of post-menopausal stem cell bone progenitors.

Background: Endogenously released adenine and uracil nucleotides favour the osteogenic commitment of bone marrow-derived mesenchymal stromal cells (BM-MSCs) through the activation of ATP-sensitive P2X7 and UDP-sensitive P2Y receptors. Yet, these nucleotides have their osteogenic potential compromised in post-menopausal (Pm) women due to overexpression of nucleotide metabolizing enzymes, namely NTPDase3. This prompted us to investigate whether NTPDase3 gene silencing or inhibition of its enzymatic activity could rehabilitate the osteogenic potential of Pm BM-MSCs.

A receptor-induced overexpression of pannexin-1 channels indirectly mediates adenosine fibrogenic actions by favouring ATP release from human subcutaneous fibroblasts.

Aims: Disorganization of the subcutaneous tissue due to inflammation and fibrosis is a common feature in patients with myofascial pain. Dermal accumulation of adenosine favours collagen production by human subcutaneous fibroblasts (HSCF) via A receptors (AR) activation. Adenosine mimics the fibrogenic effect of inflammatory mediators (e.

Mesial Temporal Lobe Epilepsy (MTLE) Drug-Refractoriness Is Associated With P2X7 Receptors Overexpression in the Human Hippocampus and Temporal Neocortex and May Be Predicted by Low Circulating Levels of miR-22.

: ATP-gated ionotropic P2X7 receptors (P2X7R) actively participate in epilepsy and other neurological disorders. Neocortical nerve terminals of patients with Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) express higher P2X7R amounts. Overexpression of P2X7R bolsters ATP signals during seizures resulting in glial cell activation, cytokines production, and GABAergic rundown with unrestrained glutamatergic excitation.

Non-genomic Actions of Methylprednisolone Differentially Influence GABA and Glutamate Release From Isolated Nerve Terminals of the Rat Hippocampus.

Corticosteroids exert a dual role in eukaryotic cells through their action via (1) intracellular receptors (slow genomic responses), or (2) membrane-bound receptors (fast non-genomic responses). Highly vulnerable regions of the brain, like the hippocampus, express high amounts of corticosteroid receptors, yet their actions on ionic currents and neurotransmitters release are still undefined. Here, we investigated the effect of methylprednisolone (MP) on GABA and glutamate (Glu) release from isolated nerve terminals of the rat hippocampus.

Opposing Effects of Adenosine and Inosine in Human Subcutaneous Fibroblasts May Be Regulated by Third Party ADA Cell Providers.

Human subcutaneous fibroblasts (HSCF) challenged with inflammatory mediators release huge amounts of ATP, which rapidly generates adenosine. Given the nucleoside's putative relevance in wound healing, dermal fibrosis, and myofascial pain, we investigated the role of its precursor, AMP, and of its metabolite, inosine, in HSCF cells growth and collagen production. AMP (30 µM) was rapidly (t½ 3 ± 1 min) dephosphorylated into adenosine by CD73/ecto-5'-nucleotidase.

β Adrenoceptor-induced cholinergic inhibition in human and rat urinary bladders involves the exchange protein directly activated by cyclic AMP 1 favoring adenosine release.

Background And Purpose: The mechanism by which β receptor agonists (e.g. mirabegron) control bladder overactivity may involve adenosine release from human and rat detrusor smooth muscle.

Activation of Prejunctional P2x2/3 Heterotrimers by ATP Enhances the Cholinergic Tone in Obstructed Human Urinary Bladders.

The objective of this study was to investigate the role of ATP in cholinergic neurotransmission in the urinary bladder of control men and of patients obstructed as a result of benign prostatic hyperplasia (BPH). Human detrusor samples were collected from 41 patients who submitted to transvesical prostatectomy resulting from BPH and 26 male organ donors. The release of [H]acetylcholine ([H]ACh) was evoked by electrical field stimulation (10 Hz, 200 pulses) in urothelium-denuded detrusor strips.

The Ionotropic P2X4 Receptor has Unique Properties in the Heart by Mediating the Negative Chronotropic Effect of ATP While Increasing the Ventricular Inotropy.

Mounting evidence indicate that reducing the sinoatrial node (SAN) activity may be a useful therapeutic strategy to control of heart failure. Purines, like ATP and its metabolite adenosine, consistently reduce the SAN spontaneous activity leading to negative cardiac chronotropy, with variable effects on the force of myocardial contraction (inotropy). Apart from adenosine A receptors, the human SAN expresses high levels of ATP-sensitive ionotropic P2X4 receptors (P2X4R), yet their cardiac role is unexplored.

Regulation of corneal noradrenaline release and topography of sympathetic innervation: Functional implications for adrenergic mechanisms in the human cornea.

Having established a main neuronal origin for noradrenaline (NA) in the cornea, we set out to study the physiologic determinants of its release and to correlate functional findings with sympathetic nerve density and overall topography. Whole corneas were obtained from 3 to 4 month-old rabbits and human donors. Study of prejunctional effects was carried out after incubation with radiolabelled NA (3H-NA).

Post-inflammatory Ileitis Induces Non-neuronal Purinergic Signaling Adjustments of Cholinergic Neurotransmission in the Myenteric Plexus.

Uncoupling between ATP overflow and extracellular adenosine formation changes purinergic signaling in post-inflammatory ileitis. Adenosine neuromodulation deficits were ascribed to feed-forward inhibition of ecto-5'-nucleotidase/CD73 by high extracellular adenine nucleotides in the inflamed ileum. Here, we hypothesized that inflammation-induced changes in cellular density may also account to unbalance the release of purines and their influence on [H]acetylcholine release from longitudinal muscle-myenteric plexus preparations of the ileum of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-treated rats.

Inhibition of cholinergic neurotransmission by β-adrenoceptors depends on adenosine release and A-receptor activation in human and rat urinary bladders.

The direct detrusor relaxant effect of β-adrenoceptor agonists as a primary mechanism to improve overactive bladder symptoms has been questioned. Among other targets, activation of β-adrenoceptors downmodulate nerve-evoked acetylcholine (ACh) release, but there is insufficient evidence for the presence of these receptors on bladder cholinergic nerve terminals. Our hypothesis is that adenosine formed from the catabolism of cyclic AMP in the detrusor may act as a retrograde messenger via prejunctional A receptors to explain inhibition of cholinergic activity by β-adrenoceptors.

ADP-Induced Ca Signaling and Proliferation of Rat Ventricular Myofibroblasts Depend on Phospholipase C-Linked TRP Channels Activation Within Lipid Rafts.

Nucleotides released during heart injury affect myocardium electrophysiology and remodeling through P2 purinoceptors activation in cardiac myofibroblasts. ATP and UTP endorse [Ca ] accumulation and growth of DDR-2/α-SMA-expressing myofibroblasts from adult rat ventricles via P2Y and P2Y receptors activation, respectively. Ventricular myofibroblasts also express ADP-sensitive P2Y , P2Y , and P2Y receptors as demonstrated by immunofluorescence confocal microscopy and western blot analysis, but little information exists on ADP effects in these cells.

Adenosine A receptor and ecto-5'-nucleotidase/CD73 are upregulated in hippocampal astrocytes of human patients with mesial temporal lobe epilepsy (MTLE).

Refractoriness to existing medications of up to 80 % of the patients with mesial temporal lobe epilepsy (MTLE) prompts for finding new antiepileptic drug targets. The adenosine A receptor emerges as an interesting pharmacological target since its excitatory nature partially counteracts the dominant antiepileptic role of endogenous adenosine acting via inhibitory A receptors. Gain of function of the excitatory A receptor has been implicated in a significant number of brain pathologies commonly characterized by neuronal excitotoxicity.

Ion Fluxes through KCa2 (SK) and Cav1 (L-type) Channels Contribute to Chronoselectivity of Adenosine A1 Receptor-Mediated Actions in Spontaneously Beating Rat Atria.

Impulse generation in supraventricular tissue is inhibited by adenosine and acetylcholine via the activation of A1 and M2 receptors coupled to inwardly rectifying GIRK/KIR3.1/3.4 channels, respectively.

Up-regulation of P2X7 receptor-mediated inhibition of GABA uptake by nerve terminals of the human epileptic neocortex.

Objective: Thirty percent of patients with epilepsy are refractory to medication. The majority of these patients have mesial temporal lobe epilepsy (MTLE). This prompts for new pharmacologic targets, like ATP-mediated signaling pathways, since the extracellular levels of the nucleotide dramatically increase during in vitro epileptic seizures.

Impairment of ATP hydrolysis decreases adenosine A1 receptor tonus favoring cholinergic nerve hyperactivity in the obstructed human urinary bladder.

This study was designed to investigate whether reduced adenosine formation linked to deficits in extracellular ATP hydrolysis by NTPDases contributes to detrusor neuromodulatory changes associated with bladder outlet obstruction in men with benign prostatic hyperplasia (BPH). The kinetics of ATP catabolism and adenosine formation as well as the role of P1 receptor agonists on muscle tension and nerve-evoked [(3)H]ACh release were evaluated in mucosal-denuded detrusor strips from BPH patients (n = 31) and control organ donors (n = 23). The neurogenic release of ATP and [(3)H]ACh was higher (P < 0.

Calcium signaling and the novel anti-proliferative effect of the UTP-sensitive P2Y11 receptor in rat cardiac myofibroblasts.

During myocardial ischemia and reperfusion both purines and pyrimidines are released into the extracellular milieu, thus creating a signaling wave that propagates to neighboring cells via membrane-bound P2 purinoceptors activation. Cardiac fibroblasts (CF) are important players in heart remodeling, electrophysiological changes and hemodynamic alterations following myocardial infarction. Here, we investigated the role UTP on calcium signaling and proliferation of CF cultured from ventricles of adult rats.

P2X7 receptor activation downmodulates Na(+)-dependent high-affinity GABA and glutamate transport into rat brain cortex synaptosomes.

Sodium-dependent high-affinity amino-acid transporters play crucial roles in terminating synaptic transmission in the central nervous system (CNS). However, there is lack of information about the mechanisms underlying the regulation of amino-acid transport by fast-acting neuromodulators, like ATP. Here, we investigated whether activation of the ATP-sensitive P2X7 receptor modulates Na(+)-dependent high-affinity γ-aminobutyric acid (GABA) and glutamate uptake into nerve terminals (synaptosomes) of the rat cerebral cortex.

Activation of P2Y6 Receptors Facilitates Nonneuronal Adenosine Triphosphate and Acetylcholine Release from Urothelium with the Lamina Propria of Men with Bladder Outlet Obstruction.

Purpose: Deregulation of purinergic bladder signaling may contribute to persistent detrusor overactivity in patients with bladder outlet obstruction. Activation of uridine diphosphate sensitive P2Y6 receptors increases voiding frequency in rats indirectly by releasing adenosine triphosphate from the urothelium. To our knowledge this mechanism has never been tested in the human bladder.

Deficits in endogenous adenosine formation by ecto-5'-nucleotidase/CD73 impair neuromuscular transmission and immune competence in experimental autoimmune myasthenia gravis.

AMP dephosphorylation via ecto-5'-nucleotidase/CD73 is the rate limiting step to generate extracellular adenosine (ADO) from released adenine nucleotides. ADO, via A2A receptors (A2ARs), is a potent modulator of neuromuscular and immunological responses. The pivotal role of ecto-5'-nucleotidase/CD73, in controlling extracellular ADO formation, prompted us to investigate its role in a rat model of experimental autoimmune myasthenia gravis (EAMG).

Feed-forward inhibition of CD73 and upregulation of adenosine deaminase contribute to the loss of adenosine neuromodulation in postinflammatory ileitis.

Purinergic signalling is remarkably plastic during gastrointestinal inflammation. Thus, selective drugs targeting the "purinome" may be helpful for inflammatory gastrointestinal diseases. The myenteric neuromuscular transmission of healthy individuals is fine-tuned and controlled by adenosine acting on A(2A) excitatory receptors.

P2X7-induced zeiosis promotes osteogenic differentiation and mineralization of postmenopausal bone marrow-derived mesenchymal stem cells.

Polymorphisms of the P2X7 receptor have been associated with increased risk of fractures in postmenopausal women. Although both osteoblasts and osteoclasts express P2X7 receptors, their function in osteogenesis remains controversial. Here, we investigated the role of the P2X7 receptor on osteogenic differentiation and mineralization of bone marrow mesenchymal stem cell (BMSC) cultures from postmenopausal women (age 71±3 yr, n=18).

Attenuated aortic vasodilation and sympathetic prejunctional facilitation in epinephrine-deficient mice: selective impairment of β2-adrenoceptor responses.

It has been suggested that there is a link between epinephrine synthesis and the development of β2-adrenoceptor-mediated effects, but it remains to be determined whether this development is triggered by epinephrine. The aim of this study was to characterize β-adrenoceptor-mediated relaxation and facilitation of norepinephrine release in the aorta of phenylethanolamine-N-methyltransferase-knockout (Pnmt-KO) mice. Catecholamines were quantified by reverse-phase high-performance liquid chromatography-electrochemical detection.