Nasopharyngeal lymphatic plexus is a hub for cerebrospinal fluid drainage.

Cerebrospinal fluid (CSF) in the subarachnoid space around the brain has long been known to drain through the lymphatics to cervical lymph nodes1-17, but the connections and regulation have been challenging to identify. Here, using fluorescent CSF tracers in Prox1-GFP lymphatic reporter mice18, we found that the nasopharyngeal lymphatic plexus is a major hub for CSF outflow to deep cervical lymph nodes. This plexus had unusual valves and short lymphangions but no smooth-muscle coverage, whereas downstream deep cervical lymphatics had typical semilunar valves, long lymphangions and smooth muscle coverage that transported CSF to the deep cervical lymph nodes. α-Adrenergic and nitric oxide signalling in the smooth muscle cells regulated CSF drainage through the transport properties of deep cervical lymphatics. During ageing, the nasopharyngeal lymphatic plexus atrophied, but deep cervical lymphatics were not similarly altered, and CSF outflow could still be increased by adrenergic or nitric oxide signalling. Single-cell analysis of gene expression in lymphatic endothelial cells of the nasopharyngeal plexus of aged mice revealed increased type I interferon signalling and other inflammatory cytokines. The importance of evidence for the nasopharyngeal lymphatic plexus functioning as a CSF outflow hub is highlighted by its regression during ageing. Yet, the ageing-resistant pharmacological activation of deep cervical lymphatic transport towards lymph nodes can still increase CSF outflow, offering an approach for augmenting CSF clearance in age-related neurological conditions in which greater efflux would be beneficial.

Alpha-adrenergic receptor activation after fetal hypoxia-ischaemia suppresses transient epileptiform activity and limits loss of oligodendrocytes and hippocampal neurons.

Exposure to hypoxic-ischaemia (HI) is consistently followed by a delayed fall in cerebral perfusion. In preterm fetal sheep this is associated with impaired cerebral oxygenation, consistent with mismatch between perfusion and metabolism. In the present study we tested the hypothesis that alpha-adrenergic inhibition after HI would improve cerebral perfusion, and so attenuate mismatch and reduce neural injury. Chronically instrumented preterm (0.7 gestation) fetal sheep received sham-HI (n = 10) or HI induced by complete umbilical cord occlusion for 25 minutes. From 15 minutes to 8 hours after HI, fetuses received either an intravenous infusion of a non-selective alpha-adrenergic antagonist, phentolamine (10 mg bolus, 10 mg/h infusion, n = 10), or saline (n = 10). Fetal brains were processed for histology 72 hours post-HI. Phentolamine infusion was associated with increased epileptiform transient activity and a greater fall in cerebral oxygenation in the early post-HI recovery phase. Histologically, phentolamine was associated with greater loss of oligodendrocytes and hippocampal neurons. In summary, contrary to our hypothesis, alpha-adrenergic inhibition increased epileptiform transient activity with an exaggerated fall in cerebral oxygenation, and increased neural injury, suggesting that alpha-adrenergic receptor activation after HI is an important endogenous neuroprotective mechanism.

The protective role of neuronal nitric oxide synthase in endothelial vasodilation in chronic ß-adrenoceptor overstimulation.

AIMS: Nitric oxide synthases (NOSs) are key enzymes regulating vascular function. Previously, we reported that ß-adrenergic (ß-AR) overstimulation, a common feature of cardiovascular diseases, did not impair endothelium-dependent vasodilation, although it resulted in endothelial NOS (eNOS) uncoupling and reduced NO bioavailability. In addition to NO, neuronal NOS (nNOS) produces H2O2, which contributes to vasodilation. However, there is limited information regarding vascular ß-AR signaling and nNOS. In the present study, we assessed the possible role of nNOS-derived H2O2 and caveolins on endothelial vasodilation function following ß-AR overstimulation. MAIN METHODS: Male C57BL/6 wild-type and nNOS knockout mice (nNOS-/-) were treated with the ß-AR agonist isoproterenol (ISO, 15 mg·kg-1·day-1, s.c.) or vehicle (VHE) for seven days. Relaxation responses of aortic rings were evaluated using wire myograph and H2O2 by Amplex Red. KEY FINDINGS: Acetylcholine- or calcium ionophore A23187-induced endothelium-dependent relaxation was similar in aortic rings from VHE and ISO. However, this relaxation was significantly reduced in aortas from ISO compared to VHE when (1) caveolae were disrupted, (2) nNOS was pharmacologically inhibited or genetically suppressed and (3) H2O2 was scavenged. NOS-derived H2O2 production was higher in the aortas of ISO mice than in those of VHE mice. Aortas from ISO-treated mice showed increased expression of caveolin-1, nNOS and catalase, while caveolin-3 expression did not change. SIGNIFICANCE: The results suggest a role of caveolin-1 and the nNOS/H2O2 vasodilatory pathway in endothelium-dependent relaxation following ß-AR overstimulation and reinforce the protective role of nNOS in cardiovascular diseases associated with high adrenergic tone.

Driving ß2- While Suppressing α-Adrenergic Receptor Activity Suppresses Joint Pathology in Inflammatory Arthritis.

Objective: Hypersympathetic activity is prominent in rheumatoid arthritis, and major life stressors precede onset in ~80% of patients. These findings and others support a link between stress, the sympathetic nervous system and disease onset and progression. Here, we extend previous research by evaluating how selective peripherally acting α/ß2-adrenergic drugs affect joint destruction in adjuvant-induced arthritis. Methods: Complete Freund's adjuvant induced inflammatory arthritis in male Lewis rats. Controls received no treatment. Arthritic rats then received vehicle or twice-daily treatment with the α-adrenergic antagonist, phentolamine (0.5 mg/day) and the ß2-adrenergic agonist, terbutaline (1200 µg/day, collectively named SH1293) from day (D) of disease onset (D12) through acute (D21) and severe disease (D28). Disease progression was assessed in the hind limbs using dorsoplantar widths, X-ray analysis, micro-computed tomography, and routine histology on D14, D21, and D28 post-immunization. Results: On D21, SH1293 significantly attenuated arthritis in the hind limbs, based on reduced lymphocytic infiltration, preservation of cartilage, and bone volume. Pannus formation and sympathetic nerve loss were not affected by SH1293. Bone area and osteoclast number revealed high- and low-treatment-responding groups. In high-responding rats, treatment with SH1293 significantly preserved bone area and decreased osteoclast number, data that correlated with drug-mediated joint preservation. SH1293 suppressed abnormal bone formation based on reduced production of osteophytes. On D28, the arthritic sparing effects of SH1293 on lymphocytic infiltration, cartilage and bone sparing were maintained at the expense of bone marrow adipocity. However, sympathetic nerves were retracted from the talocrural joint. Conclusion and Significance: Our findings support a significant delay in early arthritis progression by treatment with SH1293. Targeting sympathetic neurotransmission may provide a strategy to slow disease progression.

Alpha and beta adrenergic receptors modulate keratinocyte migration.

Keratinocyte migration into skin wounds is the step of the healing process that correlates with the wound closure rate. Keratinocyte migration, and wound epithelialization are decreased when beta 2-adrenergic receptors (B2AR) are activated by 1 µM epinephrine/adrenaline, resulting in delayed wound healing in human and mouse skin. In the present study, we found paradoxically, that in a subset of keratinocyte strains exposure to low concentrations of epinephrine (0.1 nM) increased, rather than decreased, their migratory rate. We find that both the alpha- and the beta-adrenergic receptors are expressed in human keratinocytes, and expression of alpha-2 AR subtypes demonstrated for the first time. Therefore, we tested if the alpha-AR could be modulating the increased migratory response observed in these cell strains. By using specific inhibitors to alpha-AR, we demonstrated that blocking A2B-AR could reverse the rapid cell migration induced by the 0.1 nM epinephrine. Phosphorylation of ERK was elevated after 1-10 minutes of the low epinephrine treatment and the A2B-AR inhibitor blocked the ERK phosphorylation. The results suggest that both the A2B-AR and B2AR mediate keratinocyte migration, in which with a low level of epinephrine treatment, A2B-AR could alter the B2AR signals and regulate the migration rate.

5-HT1A Serotonergic, α-Adrenergic and Opioidergic Receptors Mediate the Analgesic Efficacy of Vortioxetine in Mice.

Vortioxetine is a multimodal antidepressant drug that affects several brain neurochemicals and has the potential to induce various pharmacological effects on the central nervous system. Therefore, we investigated the centrally mediated analgesic efficacy of this drug and the mechanisms underlying this effect. Analgesic activity of vortioxetine (5, 10 and 20 mg/kg, p.o.) was examined by tail-clip, tail-immersion and hot-plate tests. Motor performance of animals was evaluated using Rota-rod device. Time course measurements (30-180 min) showed that vortioxetine (10 and 20 mg/kg) administrations significantly increased the response latency, percent maximum possible effect and area under the curve values in all of the nociceptive tests. These data pointed out the analgesic effect of vortioxetine on central pathways carrying acute thermal and mechanical nociceptive stimuli. Vortioxetine did not alter the motor coordination of mice indicating that the analgesic activity of this drug was specific. In mechanistic studies, pre-treatments with p-chlorophenylalanine (serotonin-synthesis inhibitor), NAN-190 (serotonin 5-HT1A receptor antagonist), α-methyl-para-tyrosine (catecholamine-synthesis inhibitor), phentolamine (non-selective α-adrenoceptor blocker), and naloxone (non-selective opioid receptor blocker) antagonised the vortioxetine-induced analgesia. Obtained findings indicated that vortioxetine-induced analgesia is mediated by 5-HT1A serotonergic, α-adrenergic and opioidergic receptors, and contributions of central serotonergic and catecholaminergic neurotransmissions are critical for this effect.

The role of α adrenergic receptors in mediating the inhibitory effect of electrical brain stimulation on epileptiform activity in rat hippocampal slices.

The Inhibitory effect of electrical low-frequency stimulation (LFS) on neuronal excitability and seizure occurrence has been indicated in experimental models, but the precise mechanism has not established. This investigation was intended to figure out the role of α1 and α2 adrenergic receptors in LFS' inhibitory effect on neuronal excitability. Epileptiform activity induced in an in vitro rat hippocampal slice preparation by high K+ ACSF and LFS (900 square wave pulses at 1 Hz) was administered at the beginning of epileptiform activity to the Schaffer collaterals. In CA1 pyramidal neurons, the electrophysiological properties were measured at the baseline, before high K+ ACSF washout, and at 15 min after high K+ ACSF washout using whole-cell, patch-clamp recording. Results indicated that after high K+ ACSF washout, prazosine (10 µM; α1 adrenergic receptor antagonist) and yohimbine (5 µM; α2 adrenergic receptor antagonist) suppressed the LFS' effect of reducing rheobase current and utilization time following depolarizing ramp current, the latency to the first spike following a depolarizing current and latency to the first rebound action potential following hyperpolarizing current pulses. Thus, it may be proposed that LFS' inhibitory action on the neuronal hyperexcitability, in some way, is mediated by α1 and α2 adrenergic receptors.

Pharmacological characterization of MT-1207, a novel multitarget antihypertensive agent.

Hypertension is a serious public health problem worldwide. MT-1207, chemically named 3-(4-(4-(1H-benzotriazole-1-yl)butyl)piperazine-1-yl) benzisothiazole hydrochloride, is a new chemical entity that has entered into clinical trial as antihypertensive agent in China. In this paper we report the pharmacological profile of MT-1207 regarding its acute, subacute, and long-term effects on hypertensive animal models, and its actions on isolated organs in vitro as well as its molecular targets. Blood pressure (BP) was measured in conscious animals; amlodipine was taken as a positive control drug. We showed that both single dose of MT-1207 (1.25-20 mg/kg, ig) in spontaneously hypertensive rats (SHR) and MT-1207 (0.25-6 mg/kg, ig) in two-kidney one-clip (2K1C) dogs dose-dependently decreased BP. MT-1207 quickly decreased BP within 5 min after administration; the hypotensive effect lasted for 8 and 12 h, respectively, in SHR and 2K1C dogs without reflex increase in heart rate. Multiple doses of MT-1207 (5 mg · kg-1 · d-1 in SHR; 2 mg · kg-1 · d-1 in 2K1C dogs, for 7 days) significantly decreased BP, slightly reduced heart rate, and both of them recovered after withdrawal. Long-term administration of MT-1207 (10 mg · kg-1 · d-1 for 4 months or more time) produced a stable BP reduction, improved baroreflex sensitivity, reduced renal and cardiovascular damage in SHR, and delayed stroke occurrence and death in stroke-prone SHR. In isolated rat aortic rings precontracted by adrenaline, KCl, noradrenaline or 5-hydroxytryptamine (5-HT), MT-1207 (10-9-10-4 M) caused concentration-dependent relaxation. In a panel of enzyme activity or radioligand binding assays of 87 molecular targets, MT-1207 potently inhibited adrenergic α1A, α1B, α1D, and 5-HT2A receptors with Ki < 1 nM. The antagonism of MT-1207 against these receptors was confirmed in isolated rabbit arteries. We conclude that MT-1207 is a novel and promising single-molecule multitarget agent for hypertension treatment to reduce hypertensive organ damage and stroke mortality.

Alpha and beta adrenoceptors activate interleukin-6 transcription through different pathways in cultured astrocytes from rat spinal cord.

In brain astrocytes, noradrenaline (NA) has been shown to up-regulate IL-6 production via ß-adrenoceptors (ARs). However, the underlying intracellular mechanisms for this regulation are not clear, and it remains unknown whether α-ARs are involved. In this study, we investigated the AR-mediated regulation of IL-6 mRNA levels in the cultured astrocytes from rat spinal cord. NA, the α1-agonist phenylephrine, and the ß-agonist isoproterenol increased IL-6 mRNA levels. The phenylephrine-induced IL-6 increase was accompanied by an increase in ERK phosphorylation, and these effects were blocked by inhibitors of PKC and ERK. The isoproterenol-induced IL-6 increase was accompanied by an increase in CREB phosphorylation, and these effects were blocked by a PKA inhibitor. Our results indicate that IL-6 increases by α1- and ß-ARs are mediated via the PKC/ERK and cAMP/PKA/CREB pathways, respectively. Moreover, conditioned medium collected from astrocytes treated with the α2-AR agonist dexmedetomidine, increased IL-6 mRNA in other astrocytes. In this study, we elucidate that α1- and α2-ARs, in addition to ß-ARs, promote IL-6 transcription through different pathways in spinal cord astrocytes.

Blockade of AIM2 inflammasome or α1-AR ameliorates IL-1ß release and macrophage-mediated immunosuppression induced by CAR-T treatment.

BACKGROUND: Interleukin (IL) 1 released from monocytes/macrophages is one of the critical determinants in mediating the adverse events of chimeric antigen receptor T cell (CAR-T) therapy, including cytokine release syndrome and neurotoxicity. However, the molecular mechanisms of IL-1 production during CAR-T therapy remain unknown. METHODS: The roles of AIM2 and α1-adrenergic receptor (α1-AR) in CAR-T treatment-induced IL-1ß release were evaluated by gene silencing, agonist or antagonist treatment. The phenotype switch of macrophages in response to CAR-T treatment was analyzed concerning cytotoxicity of CAR-T cells and proliferation of activated T cells. RESULTS: This study provided the experimental evidence that CAR-T treatment-induced activation of AIM2 inflammasome of macrophages resulted in the release of bioactive IL-1ß. CAR-T treatment-induced α1-AR-mediated adrenergic signaling augmented the priming of AIM2 inflammasome by enhancing IL-1ß mRNA and AIM2 expression. Meanwhile, tumor cell DNA release triggered by CAR-T treatment potentiated the activation of AIM2 inflammasome in macrophages. Interestingly, an apparent phenotypic switch in macrophages occurred after interacting with CAR-T/tumor cells, which greatly inhibited the cytotoxicity of CAR-T cells and proliferation of activated T cells through upregulation of programmed cell death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase (IDO) in the macrophages. Blockade of AIM2 inflammasome or α1-AR reversed the upregulation of PD-L1 and IDO and the phenotypic switch of the macrophages. CONCLUSION: Our study implicates that CAR-T therapy combined with the blockade of AIM2 inflammasome or α1-AR may relieve IL-1ß-related toxic side effects of CAR-T therapy and ensure antitumor effects of the treatment.

Multimodal 3D atlas of the macaque monkey motor and premotor cortex.

In the present study we reevaluated the parcellation scheme of the macaque frontal agranular cortex by implementing quantitative cytoarchitectonic and multireceptor analyses, with the purpose to integrate and reconcile the discrepancies between previously published maps of this region. We applied an observer-independent and statistically testable approach to determine the position of cytoarchitectonic borders. Analysis of the regional and laminar distribution patterns of 13 different transmitter receptors confirmed the position of cytoarchitectonically identified borders. Receptor densities were extracted from each area and visualized as its "receptor fingerprint". Hierarchical and principal components analyses were conducted to detect clusters of areas according to the degree of (dis)similarity of their fingerprints. Finally, functional connectivity pattern of each identified area was analyzed with areas of prefrontal, cingulate, somatosensory and lateral parietal cortex and the results were depicted as "connectivity fingerprints" and seed-to-vertex connectivity maps. We identified 16 cyto- and receptor architectonically distinct areas, including novel subdivisions of the primary motor area 4 (i.e. 4a, 4p, 4m) and of premotor areas F4 (i.e. F4s, F4d, F4v), F5 (i.e. F5s, F5d, F5v) and F7 (i.e. F7d, F7i, F7s). Multivariate analyses of receptor fingerprints revealed three clusters, which first segregated the subdivisions of area 4 with F4d and F4s from the remaining premotor areas, then separated ventrolateral from dorsolateral and medial premotor areas. The functional connectivity analysis revealed that medial and dorsolateral premotor and motor areas show stronger functional connectivity with areas involved in visual processing, whereas 4p and ventrolateral premotor areas presented a stronger functional connectivity with areas involved in somatomotor responses. For the first time, we provide a 3D atlas integrating cyto- and multi-receptor architectonic features of the macaque motor and premotor cortex. This atlas constitutes a valuable resource for the analysis of functional experiments carried out with non-human primates, for modeling approaches with realistic synaptic dynamics, as well as to provide insights into how brain functions have developed by changes in the underlying microstructure and encoding strategies during evolution.

Thromboxane A2 in the paraventricular hypothalamic nucleus mediates glucoprivation-induced adrenomedullary outflow.

Glucoprivation stimulates a rapid sympathetic response to release and/or secrete catecholamines into the bloodstream. However, the central regulatory mechanisms involving adrenoceptors and prostanoids production in the paraventricular hypothalamic nucleus (PVN) that are responsible for the glucoprivation-induced elevation of plasma catecholamines are still unresolved. In this study, we aimed to clarify whether glucoprivation-induced activation of noradrenergic neurons projecting to the PVN can induce α- and/or ß-adrenergic receptor activation and prostanoids production in the PVN to elevate plasma catecholamine levels. We examined the effects of α- and ß-adrenergic receptor antagonists, a cyclooxygenase inhibitor, a thromboxane A synthase inhibitor, and a PGE2 subtype EP3 receptor antagonist on intravenously administered 2-deoxy-D-glucose (2-DG)-induced elevation of noradrenaline in the PVN and plasma levels of catecholamine in freely moving rats. In addition, we examined whether intravenously administered 2-DG can increase prostanoids levels in the PVN microdialysates. Intracerebroventricular (i.c.v.) pretreatment with phentolamine (a non-selective α-adrenergic receptor antagonist) suppressed the 2-DG-induced increase in the plasma level of adrenaline, whereas i.c.v. pretreatment with propranolol (a non-selective ß-adrenergic receptor antagonist) suppressed the 2-DG-induced elevation of the plasma level of noradrenaline. I.c.v. pretreatment with indomethacin (a cyclooxygenase inhibitor) and furegrelate (a thromboxane synthase inhibitor) attenuated the 2-DG-induced elevations of both noradrenaline and adrenaline levels. Furthermore, 2-DG administration elevated the thromboxane B2 level, a metabolite of thromboxane A2 in PVN microdialysates. Our results suggest that glucoprivation-induced activation of α- and ß-adrenergic receptor in the brain including the PVN and then thromboxane A2 production in the PVN, which are essential for the 2-DG-induced elevations of both plasma adrenaline and noradrenaline levels.

Oxidative stress: Noradrenaline as an integrator of responses in the neuroendocrine and immune systems of the ascidian Phallusia nigra.

Neurotransmitters play key roles in regulating the homeostasis of organisms in stressful environments. Noradrenaline (NA) is the main neurotransmitter known to modulate immunological parameters, and is important in the crosstalk between the neuroendocrine and immune systems. In this study, using the ascidian Phallusia nigra, we analyzed the level of catecholamines (CA) in the plasma after mechanical stress, and the effect of NA on the oxidative stress (OS) displayed by immune cells. We measured the concentration of reactive oxygen species (ROS), and analyzed whether α- and/or ß-adrenoreceptors (ARs) are involved in ROS modulation, lipid peroxidation (LPO), antioxidant capacity against peroxyl radicals (ACAP), and activity of the enzymes catalase (CAT) and glutathione S transferase (GST) in immune cells after incubation with different concentrations of NA, with or without zymosan (ZnA) challenge. The results showed that NA reduced ROS production, even in immune cells challenged with ZnA, and that this modulation occurred through α1-and ß1-ARs. ACAP levels showed different responses, depending on whether immune cells were challenged or not with ZnA, and also depending on the NA concentration: 1.0 µM NA increased ACAP levels, but 10.0 µM reduced ACAP levels. NA enhanced the activity of CAT and GST in ZnA-challenged and non-challenged immune cells, while 1.0 and 10.0 µM NA effectively reduced LPO. Taken together, these results show that NA can protect cells from ROS damage, decreasing ROS production and LPO, and enhancing ACAP as well as the activity of CAT and GST. The approach used here with this model contributes to understanding the relationship between the neuroendocrine and immune systems, revealing new effects of NA on OS regulation in ascidians.

Pluripotent hematopoietic stem cells augment α-adrenergic receptor-mediated contraction of pulmonary artery and contribute to the pathogenesis of pulmonary hypertension.

Pulmonary hypertension (PH) is a multicellular and progressive disease with a high mortality rate. Among many cell types, hematopoietic stem cells (HSCs) are incriminated in the pathogenesis of PH. However, our understanding of the mechanisms that increase HSCs in blood and lungs of hypertensive animals or patients and the role played by HSCs in the pathogenesis of PH remains elusive. Studies suggest that glycolysis is critical for the survival and growth of HSCs. In various cell types from hypertensive lungs of animals and patients, glycolysis and the glucose-6-phosphate dehydrogenase (G6PD) activity are increased. Herein, we demonstrated in mice that chronic hypoxia increased HSCs (CD34+, CD117+, CD133+, CD34+/CD117+, and CD34+/CD133+) in bone marrow and blood and around hypertensive pulmonary arteries in a time-dependent manner. Intriguingly, we found fewer CD133+ cells in the bone marrow of C57BL/6 mice compared with Sv129J mice, and C57BL mice developed less severe chronic hypoxia-elicited PH and heart failure than Sv129J mice. Similarly, the numbers of CD34+ and CD117+ cells in blood of patients with pulmonary arterial hypertension (PAH) were higher (>3-fold) compared with healthy individuals. By allogeneic bone marrow transplantation, we found that GFP+ bone marrow cells infiltrated the lungs and accumulated around the pulmonary arteries in lungs of hypoxic mice, and these cells contributed to increased α-adrenergic receptor-mediated contraction of the pulmonary artery cultured in hypoxia. Inhibition of G6PD activity with (3ß,5α)-3,21-dihydroxypregnan-20-one, a novel and potent G6PD inhibitor, decreased HSCs in bone marrow, blood, and lungs of hypoxic mice and reduced α-agonist-induced contraction of the pulmonary artery and established hypoxia-induced PH. We did not observe CD133+ cells around the pulmonary arteries in the lungs of chronically hypoxic G6PD-deficient mice. Furthermore, knockdown of G6PD and inhibition of G6PD activity: 1) downregulated canonical and noncanonical Wnt and Fzd receptors genes; 2) upregulated Bmpr1a; 3) decreased Cxcl12, and 4) reduced HSC (CD117+ and CD133+) numbers. In all, our findings demonstrate unexpected function for bone marrow-derived HSCs in augmenting α-adrenergic receptor-mediated contraction of pulmonary arteries and remodeling of pulmonary arteries that contribute to increase pulmonary vascular resistance in PAH patients and hypoxic mice and suggest that G6PD, by regulating expression of genes in the WNT and BMPR signaling, contributed to increase and release of HSCs from the bone marrow in response to hypoxic stimuli.

Vascular effects of a polyphenolic fraction from Oxalis pes-caprae L.: role of α-adrenergic receptors Sub-types.

Oxalis pes-caprae L. is a plant of the Oxalidaceae family, from which several compounds have been previously identified. Recently, we showed that an Oxalis pes-caprae L. extract inhibits the vasopressor effect of noradrenaline. In this work we aimed to explore the mechanisms involved in this effect. The results confirmed that the flavonoid fraction present in the extract inhibits noradrenaline-induced contractions and that this effect is concentration-dependent. Also, a parallel shift to the right in the noradrenaline concentration-response curve was observed, suggesting a decrease in efficacy and also in potency. Together these results support the assumption that the extract could exert a non-competitive antagonism on the α-adrenergic receptors. However, experiments in the presence of competitive antagonists for α-adrenergic receptor sub-types (i.e. prazosin, yohimbine and phentolamine) showed that the effect may not be directly mediated by α-adrenergic receptors. Thus, the interaction of this extract with the adrenergic system remains to be confirmed.

Revisiting the Pharmacodynamic Uroselectivity of α 1-Adrenergic Receptor Antagonists.

α1-Adrenoceptor (AR) antagonists are widely used for the relief of urinary retention secondary to benign prostatic hyperplasia (BPH). While the five Food and Drug Administration-approved α 1-AR antagonists (terazosin, doxazosin, alfuzosin, tamsulosin, and silodosin) share similar efficacy, they differ in tolerability, with reports of ejaculatory dysfunction. The aim of the present work was to revisit their α 1-AR subtype selectivity as well as of LDT5 (1-(2-methoxyphenyl)-4-[2-(3,4-dimethoxyphenyl) ethyl]piperazine monohydrochloride), a compound previously described as a multitarget antagonist of α 1A-/α 1D-AR and 5-HT1A receptors, and to estimate their affinity for D2, D3, and 5-HT1A receptors, which are putatively involved in ejaculatory dysfunction. Competition binding assays were performed with native (D2, 5-HT1A) or transfected (human α 1A-, α 1B-, α 1Dt-AR, and D3) receptors for determination of the drug's affinities. Tamsulosin and silodosin have the highest affinities for α 1A-AR, but only silodosin is clearly a selective α 1A-AR antagonist, with K i ratios of 25.3 and 50.2 for the α 1D- and α 1B-AR, respectively. Tamsulosin, silodosin, and LDT5 (but not terazosin, doxazosin, and alfuzosin) have high affinity for the 5-HT1A receptor (K i around 5-10 nM), behaving as antagonists. We conclude that the uroselectivity of tamsulosin is not explained by its too-low selectivity for the α 1A- versus α 1B-AR, and that its affinity for D2 and D3 receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Present data also support the design of "better-than-LDT5" new multitarget lead compounds with pharmacokinetic selectivity based on poor brain penetration and that could prevent hyperplastic cell proliferation and BPH progression. SIGNIFICANCE STATEMENT: The present work revisits the uroselectivity of the five Food and Drug Administration-approved α1 adrenoceptor antagonists for the treatment of benign prostatic hyperplasia (BPH). Contrary to what has been claimed by some, our results indicate that the uroselectivity of tamsulosin is probably not fully explained by its too-weak selectivity for the α1A versus α1B adrenoceptors. We also show that tamsulosin affinity for D3 and 5-HT1A receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Based on our lead compound LDT5, present data support the search for a multitarget antagonist of α1A-α1D and 5-HT1A receptors with poor brain penetration as an alternative for BPH treatment.

High intensity interval training promotes total and visceral fat mass loss in obese Zucker rats without modulating gut microbiota.

AIMS: Increased visceral adipose tissue and dysbiosis in the overweight and obese promote chronic inflammation. The aim of this study was to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on the gut-adipose tissue cross-talk in obese Zucker rats. METHODS: Obese male Zucker rats (n = 36) were divided in three groups: MICT (12m.min-1 for 51min), HIIT (6 sets at 18 m.min-1 for 4min followed by 3min at 10m.min-1) and controls (CONT; no exercise). The animals ran on a treadmill 5 days/week for 10 weeks. Body composition, glycaemic control, lipid profile, inflammation, lipolysis signalling in subcutaneous and visceral adipose tissue, intestinal permeability (tight junctions and plasma lipopolysaccharide binding protein; LBP), and gut microbiota composition were assessed in the three groups. RESULTS: After 10 weeks of exercise, total and epididymal fat mass decreased only in the HIIT group. The α/ß adrenergic receptor RNA ratio in subcutaneous adipose tissue increased only in the HIIT group. The expression level of phosphorylated hormone-sensitive lipase was not modified by training. Both HIIT and MICT decreased inflammation (plasma myeloperoxidase and keratinocyte-derived chemokine secretion in adipose tissue) and improved glucose metabolism. Zonula occludens-1 and occludin were upregulated in the HIIT group. Plasma LBP was similarly reduced in both training groups. HIIT and MICT did not affect gut microbiota composition. CONCLUSION: In obese Zucker rats, HIIT and MICT improved inflammation and glucose metabolism. In contrast, only HIIT decreased total and visceral fat mass. These adaptations were not associated with modifications in gut microbiota composition.

Differential regulation of phasic dopamine release in the forebrain by the VTA noradrenergic receptor signaling.

Phasic dopamine (DA) release from the ventral tegmental area (VTA) into forebrain structures is implicated in associative learning and conditional stimulus (CS)-evoked behavioral responses. Mounting evidence points to noradrenaline signaling in the VTA as an important regulatory input. Accordingly, adrenergic receptor (AR) blockade in the VTA has been shown to modulate CS-dependent behaviors. Here, we hypothesized that α1 - and α2 -AR (but not ß-AR) activity preferentially modulates phasic, in contrast to tonic, DA release. In addition, these effects could differ between forebrain targets. We used fast-scan cyclic voltammetric measurements in rats to assess the effects of intra-VTA microinfusion of terazosin, a selective α1 -AR antagonist, on electrically evoked phasic DA release in the nucleus accumbens (NAc) core and medial prefrontal cortex (mPFC). Terazosin dose-dependently attenuated phasic, but not tonic, DA release in the NAc core, but not in the mPFC. Next, we measured the effects of intra-VTA administration of the α2 -AR selective antagonist RX-821002 on evoked DA in the NAc core. Similar to the effects of α1 -AR blockade, intra-VTA α2 -AR blockade with RX-0821002 strongly and dose-dependently attenuated phasic, but not tonic, DA release. In contrast, no regulation by RX-821002 was observed in the mPFC. This effect was sensitive to intra-VTA blockade of D2 receptors with raclopride. Finally, the ß-AR antagonist propranolol ineffectively modulated DA release in the NAc core. These findings revealed both α1 - and α2 -ARs in the VTA as selective regulators of phasic DA release. Importantly, we demonstrated that AR blockade modulated mesolimbic, in contrast to mesocortical, DA release in previously unstudied heterogeneity in AR regulation of forebrain phasic DA.

The Analgesic Effect of Venlafaxine and Its Mechanism on Oxaliplatin-Induced Neuropathic Pain in Mice.

The analgesic effect of venlafaxine (VLX), which is a selective serotonin and noradrenaline reuptake inhibitor (SNRI), has been observed on oxaliplatin-induced neuropathic pain in mice. Significant allodynia was shown after oxaliplatin treatment (6 mg/kg, i.p.); acetone and von Frey hair tests were used to assess cold and mechanical allodynia, respectively. Intraperitoneal administration of VLX at 40 and 60 mg/kg, but not 10 mg/kg, significantly alleviated these allodynia. Noradrenaline depletion by pretreatment of N-(2-Chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4, 50 mg/kg, i.p.) blocked the relieving effect of VLX (40 mg/kg, i.p.) on cold and mechanical allodynia. However, serotonin depletion by three consecutive pretreatments of para-chlorophenylalanine (PCPA, 150 mg/kg/day, i.p.) only blocked the effect of VLX on mechanical allodynia. In cold allodynia, the α2-adrenergic antagonist idazoxan (10 µg, i.t.), but not the α1-adrenergic antagonist prazosin (10 µg, i.t.), abolished VLX-induced analgesia. Furthermore, idazoxan and 5-HT3 receptor antagonist bemesetron (MDL-72222, 15 µg, i.t.), but not prazosin or mixed 5-HT1, 2 receptor antagonist methysergide (10 µg, i.t.), abolished VLX-induced analgesia in mechanical allodynia. In conclusion, 40 mg/kg of VLX treatment has a potent relieving effect against oxaliplatin-induced neuropathic pain, and α2-adrenergic receptor, and both α2-adrenergic and 5-HT3 receptors are involved in this effect of VLX on cold and mechanical allodynia, respectively.

Noradrenaline depresses spontaneous complex spikes activity of cerebellar Purkinje cells via α2-adrenergic receptor in vivo in mice.

Locus coeruleus (LC) noradrenergic neurons afferents release noradrenaline (NA) in the cerebellar cortex for modulating cerebellar neuronal circuitry function. Our previous study found that NA inhibited the spontaneous simple spikes activity of cerebellar Purkinje cells (PC) through activation of molecular layer interneurons (MLIs) in vivo in mice. We here examined the effects of NA on spontaneous complex spikes (CSs) activity of cerebellar PC in urethane-anesthetized mice by electrophysiology recording technique and pharmacological methods. Our results showed that cerebellar surface perfusion of NA significantly reduced the number of spikelets and the area under curve (AUC) of the spontaneous CSs. Application of nonselective adrenergic receptor (AR) antagonist, phentolamine, abolished the NA-induced inhibition of CSs. However applying a nonselective ß-AR blocker, propranolol, failed to prevent the NA-induced inhibition of CSs activity. The NA-induced inhibition of CSs activity was not blocked by α1-AR antagonist, prazosin, but it was abolished by α2-AR antagonist, yohimibine. Moreover, application of α2-AR agonist, UK14304 induced a depression of CSs activity and mimicked the NA-induced inhibition of CS activity. These results indicate that NA regulates spontaneous CSs activity of cerebellar PCs via activation of α2-AR in vivo in mice. Our present results suggest that noradrenergic neurons of LC may modulate the outputs of cerebellar PCs via inhibition of CSs activity.