Effects on cerebral blood flow after single doses of the ß2 agonist, clenbuterol, in healthy volunteers and patients with mild cognitive impairment or Parkinson's disease.

AIMS: Cerebral hypometabolism occurs years prior to a diagnosis of neurodegenerative diseases and coincides with reduced cerebral perfusion and declining noradrenergic transmission from the locus coeruleus. In pre-clinical models, ß-adrenoceptor (ß-AR) agonists increase cerebrocortical glucose metabolism, and may have therapeutic potential for neurodegenerative diseases. This study investigated the safety and effects on regional cerebral blood flow (rCBF) of the oral, brain-penetrant ß2-AR agonist, clenbuterol, in healthy volunteers (HV) and patients with mild cognitive impairment (MCI) or Parkinson's disease (PD). METHODS: This study evaluated the safety and effects on cerebral activity of the oral, brain-penetrant, ß2-AR agonist clenbuterol (20-160 µg) in healthy volunteers and patients with MCI or PD. Regional CBF, which is tightly coupled to glucose metabolism, was measured by arterial spin labelling MRI in 32 subjects (25 HV and 8 MCI or PD) across five cohorts. In some cohorts, low doses of nadolol (1-5 mg), a ß-AR antagonist with minimal brain penetration, were administered with clenbuterol to control peripheral ß2-AR responses. RESULTS: Significant, dose-dependent increases in rCBF were seen in multiple brain regions, including hippocampus, amygdala and thalamus, following the administration of clenbuterol to HVs (mean changes from baseline in hippocampal rCBF of -1.7%, 7.3%, 22.9%, 28.4% 3 h after 20, 40, 80 and 160 µg clenbuterol, respectively). In patients with MCI or PD, increases in rCBF following 80 µg clenbuterol were observed both without and with 5 mg nadolol (in hippocampus, 18.6%/13.7% without/with nadolol). Clenbuterol was safe and well-tolerated in all subjects; known side effects of ß2-agonists, including increased heart rate and tremor, were mild in intensity and were blocked by low-dose nadolol. CONCLUSIONS: The effects of clenbuterol on rCBF were evident both in the absence and presence of low-dose nadolol, suggesting central nervous system (CNS) involvement. Concomitant inhibition of the peripheral effects of clenbuterol by nadolol confirms that meaningful ß2-AR antagonism in the periphery was achieved without interrupting the central effects of clenbuterol on rCBF.

The effects of normoxic endurance exercise on erythropoietin (EPO) production and the impact of selective ß1 and non-selective ß1 + ß2 adrenergic receptor blockade.

PURPOSE: Habitual endurance exercise results in increased erythropoiesis, which is primarily controlled by erythropoietin (EPO), yet studies demonstrating upregulation of EPO via a single bout of endurance exercise have been equivocal. This study compares the acute EPO response to 30 min of high versus 90 min of moderate-intensity endurance exercise and whether that response can be upregulated via selective adrenergic receptor blockade. METHODS: Using a counterbalanced, cross-over design, fifteen participants (age 28 ± 8) completed two bouts of running (30-min, high intensity vs 90-min, moderate intensity) matched for overall training stress. A separate cohort of fourteen participants (age 31 ± 6) completed three bouts of 30-min high-intensity cycling after ingesting the preferential ß1-adrenergic receptor (AR) antagonist bisoprolol, the non-preferential ß1 + ß2 antagonist nadolol or placebo. Venous blood was collected before, during, and after exercise, and serum EPO levels were determined by ELISA. RESULTS: No detectable EPO response was observed during or after high intensity running, however, in the moderate-intensity trial EPO was significantly elevated at both during-exercise timepoints (+ 6.8% ± 2.3% at 15 min and + 8.7% ± 2.2% at 60 min). No significant change in EPO was observed post-cycling or between the trials involving ßAR blockade. CONCLUSION: Neither training mode (running or cycling), nor beta-blockade significantly influenced the EPO response to 30 min of high-intensity exercise, however, 90 min of moderate-intensity running elevated EPO during exercise, returning to baseline immediately post-exercise. Identifying the optimal mode, duration and intensity required to evoke an EPO response to exercise may help tailor exercise prescriptions designed to maximize EPO response for both performance and clinical applications.

ß2-Adrenergic receptor signaling mediates the preferential mobilization of differentiated subsets of CD8+ T-cells, NK-cells and non-classical monocytes in response to acute exercise in humans.

Acute exercise preferentially mobilizes cytotoxic T-cells, NK-cells and non-classical monocytes to the bloodstream under the influence of hemodynamic forces and/or ß2-adrenergic receptor (ß2-AR) signaling. However, the relative contribution of these mechanisms to the redeployment of the most exercise-responsive cell types is largely unknown. We determined the lymphocyte and monocyte subtypes mobilized to blood during exercise via ß2-AR signaling whilst controlling for ß1-AR mediated reductions in hemodynamic forces. In a randomized, double blind, complete cross-over design, 14 healthy cyclists exercised for 30-minutes at +10% of blood lactate threshold after ingesting: (1) a placebo, (2) a ß1-preferential antagonist (10 mg bisoprolol), or (2) a non-preferential ß1 + ß2-antagonist (80 mg nadolol) across three trials separated by >7-days. Bisoprolol was administered to reduce hemodynamic forces (heart rate and blood pressure) during exercise to levels comparable with nadolol but without blocking ß2-ARs. The mobilization of total NK-cells, terminally differentiated (CD57+) NK-cells, central memory, effector memory and CD45RA+ effector memory CD8+ T-cells; non-classical monocytes; and γδ T-cells were significantly blunted or abrogated under nadolol compared to both bisoprolol and placebo, indicating that the exercise-induced mobilization of these cell types to the blood is largely influenced by ß2-AR signaling. Nadolol failed to inhibit the mobilization of classical monocytes, CD4+ T-cells (and their subsets) or naïve CD8+ T-cells, indicating that these cell types are mobilized with exercise independently of the ß2-AR. We conclude that the preferential mobilization of NK-cells, non-classical monocytes and differentiated subsets of CD8+ T-cells with exercise is largely dependent on catecholamine signaling through the ß2-AR. These findings provide mechanistic insights by which distinct lymphocyte and monocyte subtypes are preferentially mobilized to protect the host from anticipated injury or infection in response to an acute stress response.

Effects of ß-blockers on house dust mite-driven murine models pre- and post-development of an asthma phenotype.

BACKGROUND: Our previous studies suggested certain ß-adrenoceptor blockers (ß-blockers) attenuate the asthma phenotype in ovalbumin driven murine models of asthma. However, the ovalbumin model has been criticized for lack of clinical relevance. METHODS: We tested the non-selective ß-blockers, carvedilol and nadolol, in house dust mite (HDM) driven murine asthma models where drugs were administered both pre- and post-development of the asthma phenotype. We measured inflammation, mucous metaplasia, and airway hyper-responsiveness (AHR). We also measured the effects of the ß-blockers on extracellular-signal regulated kinase (ERK 1/2) phosphorylation in lung homogenates. RESULTS: We show that nadolol, but not carvedilol, attenuated inflammation and mucous metaplasia, and had a moderate effect attenuating AHR. Following HDM exposure, ERK1/2 phosphorylation was elevated, but the level of phosphorylation was unaffected by ß-blockers, suggesting ERK1/2 phosphorylation becomes dissociated from the asthma phenotype. CONCLUSION: Our findings in HDM models administering drugs both pre- and post-development of the asthma phenotype are consistent with previous results using ovalbumin models and show differential effects for nadolol and carvedilol on the asthma phenotype. Lastly, our data suggest that ERK1/2 phosphorylation may be involved in development of the asthma phenotype, but may have a limited role in maintaining the phenotype.

Role of ß-Adrenoceptors and L-Type Ca(2+)-Channels in the Mechanism of Reperfusion-Induced Heart Injury.

We studied the effects of ß-adrenoceptor antagonists propranolol and nadolol and L-type Ca(2+)-channel blocker verapamil on cardiac reperfusion injury developed after 45-min coronary occlusion. The substances were injected intravenously 5 min before reperfusion. The results indicate that activation of ß-adrenoceptors and opening of L-type Ca(2+)-channels promote the development of cardiac reperfusion injury, while blockage of ß-adrenoceptors and/or L-type Ca(2+)-channels prevents reoxygenation-induced myocardial injury. Propranolol, nadolol, and verapamil can produce infraction-limiting effects after onset of ischemic heart injury.

Regulation of hypothalamic signaling by tuberoinfundibular peptide of 39 residues is critical for the response to cold: a novel peptidergic mechanism of thermoregulation.

Euthermia is critical for mammalian homeostasis. Circuits within the preoptic hypothalamus regulate temperature, with fine control exerted via descending GABAergic inhibition of presympathetic motor neurons that control brown adipose tissue (BAT) thermogenesis and cutaneous vascular tone. The thermoregulatory role of hypothalamic excitatory neurons is less clear. Here we report peptidergic regulation of preoptic glutamatergic neurons that contributes to temperature regulation. Tuberoinfundibular peptide of 39 residues (TIP39) is a ligand for the parathyroid hormone 2 receptor (PTH2R). Both peptide and receptor are abundant in the preoptic hypothalamus. Based on PTH2R and vesicular glutamate transporter 2 (VGlut2) immunolabeling in animals with retrograde tracer injection, PTH2R-containing glutamatergic fibers are presynaptic to neurons projecting from the median preoptic nucleus (MnPO) to the dorsomedial hypothalamus. Transneuronal retrograde pathway tracing with pseudorabies virus revealed connectivity between MnPO VGlut2 and PTH2R neurons and BAT. MnPO injection of TIP39 increased body temperature by 2°C for several hours. Mice lacking TIP39 signaling, either because of PTH2R-null mutation or brain delivery of a PTH2R antagonist had impaired heat production upon cold exposure, but no change in basal temperature and no impairment in response to a hot environment. Thus, TIP39 appears to act on PTH2Rs present on MnPO glutamatergic terminals to regulate their activation of projection neurons and subsequent sympathetic BAT activation. This excitatory mechanism of heat production appears to be activated on demand, during cold exposure, and parallels the tonic inhibitory GABAergic control of body temperature.

Stress and skin leukocyte trafficking as a dual-stage process.

Stress responses are known to modulate leukocyte trafficking. In the skin, stress was reported both to enhance and reduce skin immunity, and the chronicity of stress exposure was suggested as a key determining factor. We here propose a dual-stage hypothesis, suggesting that stress, of any duration, reduces skin immunity during its course, while its cessation is potentially followed by a period of enhanced skin immunity. To start testing this hypothesis, rats were subcutaneously implanted with sterile surgical sponges for four-hours, during or after exposure to one of several acute stress paradigms, or to a chronic stress paradigm. Our findings, in both males and females, indicate that numbers of sponge-infiltrating leukocytes, and their specific subsets, were reduced during acute or chronic stress, and increased after stress cessation. Studying potential mediating mechanisms of the reduction in leukocyte numbers during acute stress, we found that neither adrenalectomy nor the administration of beta-adrenergic or glucocorticoid antagonists prevented this reduction. Additionally, administration of corticosterone or epinephrine to adrenalectomized rats did not impact skin leukocyte numbers, whereas, in the blood, these treatments did affect numbers of leukocytes and their specific subsets, as was also reported previously. Overall, our findings support the proposed dual-stage hypothesis, which can be evolutionally rationalized and accounts for most of the apparent inconsistencies in the literature regarding stress and skin immunity. Other aspects of the hypothesis should be tested, also using additional methodologies, and its predictions may bear clinical significance in treatment of skin disorders related to hyper- or hypo-immune function.

Nadolol block of Nav1.5 does not explain its efficacy in the long QT syndrome.

Beta-adrenergic receptor antagonists (ß-blockers) are the therapy of choice for the long QT syndrome but their efficacy is not homogeneous: propranolol and nadolol are the most effective, whereas metoprolol is associated with more treatment failures. Propranolol has a blocking effect on the sodium current ("membrane-stabilizing" effect), and it has been hypothesized that the efficacy of nadolol might be due to a similar effect. Accordingly, we used whole-cell patch-clamp recording to assess propranolol, nadolol, and metoprolol block of wild-type or mutant cardiac sodium channels (Nav1.5) coexpressed with ß1 subunit in tsA201 cells. Nadolol had a ∼20% non-use-dependent blocking effect on peak sodium current and no effect on the persistent current evoked by the LQT3 mutant A1330D, whereas propranolol blocked Nav1.5 in a use-dependent manner and reduced A1330D persistent current. Metoprolol had no effect on either the peak or persistent current. Analysis of the biophysical properties of the channel revealed that both nadolol and propranolol cause hyperpolarizing shifts on voltage dependence of activation and steady-state inactivation, whereas metoprolol shifts only the activation curve. These results provide partial explanation for the differences between nadolol and metoprolol but do not explain the similar clinical efficacy of nadolol and propranolol.

Beta adrenergic receptor blockade causing severe left ventricular systolic dysfunction during dobutamine stress echocardiography in a patient with no structural heart disease.

A 41-year-old woman with a history of neurocardiogenic syncope treated with beta-blockers was admitted with chest pain. Dobutamine echocardiogram images demonstrated decreased global LV systolic wall motion and thickening. Coronary angiograms were normal. Beta-blockers were stopped and dobutamine stress echocardiogram (DSE) was repeated. Dobutamine images demonstrated increased global LV systolic wall motion and thickening. Beta-blockers were restarted and again dobutamine produced global LV dysfunction. This case suggests that DSE wall motion response may be falsely abnormal in a patient on beta-blockers. Physicians should be aware of this possibility when interpreting dobutamine echocardiography in patients taking beta-blockers.

Noninferiority and Safety of Nadolol vs Propranolol in Infants With Infantile Hemangioma: A Randomized Clinical Trial.

Importance: Propranolol for infantile hemangiomas (IH) has been shown to be effective and relatively safe. However, other less lipophilic ß-blockers, such as nadolol, may be preferable in individuals who experience propranolol unresponsiveness or adverse events. Objective: To document the noninferiority and safety of oral nadolol compared with oral propranolol in infants with IH. Design, Setting, and Participants: This double-blind noninferiority prospective study with a noninferiority margin of 10% compared propranolol with nadolol in infants aged 1 to 6 months with problematic IH. The study was conducted in 2 academic pediatric dermatology centers in Canada between 2016 and 2020. Infants aged 1 to 6 months with a hemangioma greater than 1.5 cm on the face or 3 cm or greater on another body part causing or with potential to cause functional impairment or cosmetic disfigurement. Interventions: Oral propranolol and nadolol in escalating doses up to 2 mg/kg/d. Main Outcomes and Measure: Between-group differences comparing changes in the bulk (size and extent) and color of the IH at week 24 with baseline using a 100-mm visual analog scale. Results: The study included 71 patients. Of these, 36 were treated with propranolol. The mean (SD) age in this group was 3.1 (1.4) months, and 31 individuals (86%) were female. Thirty-five infants were treated with nadolol. The mean (SD) age in this group was 3.2 (1.6) months, and 26 individuals (74%) were female. The difference in IH between groups by t test was 8.8 (95% CI, 2.7-14.9) for size and 17.1 (95% CI, 7.2-30.0) for color in favor of the nadolol group, demonstrating that nadolol was noninferior to propranolol. Similar differences were noted at 52 weeks: 6.0 (95% CI, 1.9-10.1) and 10.1 (95% CI, 2.9-17.4) for size and color improvement, respectively. For each doubling of time unit (week), the coefficient of involution was 2.4 (95% CI, 0.5-4.4) higher with nadolol compared with propranolol. Safety data were similar between the 2 interventions. Conclusions and Relevance: Oral nadolol was noninferior to oral propranolol, indicating it may be an efficacious and safe alternative in cases of propranolol unresponsiveness or adverse events, or when faster involution is required. Trial Registration: ClinicalTrials.gov Identifier: NCT02505971.

ß(3) adrenergic stimulation of the cardiac Na+-K+ pump by reversal of an inhibitory oxidative modification.

BACKGROUND: inhibition of L-type Ca(2+) current contributes to negative inotropy of ß(3) adrenergic receptor (ß(3) AR) activation, but effects on other determinants of excitation-contraction coupling are not known. Of these, the Na(+)-K(+) pump is of particular interest because of adverse effects attributed to high cardiac myocyte Na(+) levels and upregulation of the ß(3) AR in heart failure. METHODS AND RESULTS: we voltage clamped rabbit ventricular myocytes and identified electrogenic Na(+)-K(+) pump current (I(p)) as the shift in holding current induced by ouabain. The synthetic ß(3) AR agonists BRL37344 and CL316,243 and the natural agonist norepinephrine increased I(p). Pump stimulation was insensitive to the ß(1)/ß(2) AR antagonist nadolol and the protein kinase A inhibitor H-89 but sensitive to the ß(3) AR antagonist L-748,337. Blockade of nitric oxide synthase abolished pump stimulation and an increase in fluorescence of myocytes loaded with a nitric oxide-sensitive dye. Exposure of myocytes to ß(3) AR agonists decreased ß(1) Na(+)-K(+) pump subunit glutathionylation, an oxidative modification that causes pump inhibition. The in vivo relevance of this was indicated by an increase in myocardial ß(1) pump subunit glutathionylation with elimination of ß(3) AR-mediated signaling in ß(3) AR(-/-) mice. The in vivo effect of BRL37344 on contractility of the nonfailing and failing heart in sheep was consistent with a beneficial effect of Na(+)-K(+) pump stimulation in heart failure. CONCLUSIONS: the ß(3) AR mediates decreased ß(1) subunit glutathionylation and Na(+)-K(+) pump stimulation in the heart. Upregulation of the receptor in heart failure may be a beneficial mechanism that facilitates the export of excess Na(+).

Synergism between immunostimulation and prevention of surgery-induced immune suppression: an approach to reduce post-operative tumor progression.

BACKGROUND: A unique opportunity to eradicate cancer is presented immediately after the excision of the primary tumor, but surgical procedures often induce the release of immunosuppressing factors that render cell mediated immunity ineffective. Here we tested the hypothesis that integration of peri-operative immunostimulation and blockade of immunosuppression could synergistically improve post-operative anti-metastatic immunity and long-term survival. METHODS: Two syngeneic tumor models in F344 rats were employed, studying post-operative tumor progression. In the first model, survival following laparotomy and CRNK-16 leukemia was studied. Rats were peri-operatively treated with the immuno-stimulant poly I-C (5x0.2 mg/kg/inj), with catecholamine- and prostaglandin-blockers (shown to prevent post-operative immunosuppression: 4.5 mg/kg nadolol, 4 mg/kg indomethacin), with both interventions, or with neither. Long-term survival was assessed thereafter. The second model used the MADB106 mammary adenocarcinoma, assessing its lung tumor retention (LTR) following i.v. inoculation, as well as host marginating-pulmonary NK numbers and activity against this tumor. IL-12 was employed for immunostimulation (4x1.5 microg/kg/inj), with and without the above blockers. RESULTS: Post-operative CRNK-16 survival rates were significantly improved only by the integrated approach of immune stimulation and endocrine blockers. Post-operative MADB106 LTR was additively reduced by the two interventions. Importantly, while IL-12 increased pulmonary NK cytotoxicity against MADB106, surgery markedly suppressed this cytotoxicity in both IL-12 and vehicle treated animals. The blockers prevented this suppression per lung and per single NK cell. CONCLUSIONS: Immunostimulation could be rendered ineffective post-operatively due to immunosuppression; therefore integrating endocrine-blocker therapies into the realm of peri-operative immunotherapy could optimize immune control over residual disease, potentially improving clinical outcomes.

Physiological evidence for ß3-adrenoceptor in frog (Rana esculenta) heart.

ß3-Adrenergic receptors (ARs) have been recently identified in mammalian hearts where, unlike ß1- and ß2-ARs, induce cardio-suppressive effects. The aim of this study was to describe ß3-AR role in the frog (Rana esculenta) heart and to examine its signal transduction pathway. The presence of ß3-AR, by using Western blotting analysis, has been also identified. BRL(37344), a selective ß3-AR agonist, induced a dose-dependent negative inotropic effect at concentrations from 10(-12) to 10(-6)M. This effect was not modified by nadolol (ß1/ß2-AR antagonist) and by phentolamine (α-AR antagonist), but it was suppressed by the ß3-AR-specific antagonist SR(59230) and by exposure to the Gi/o proteins inhibitor Pertussis Toxin. In addition, the involvement of EE-NOS-cGMP-PKG/PDE2 pathway in the negative inotropism of BRL(37344) has been assessed. BRL(37344) treatment induced eNOS and Akt phosphorylation as well as an increase of cGMP levels. ß3-ARs activation induce a non-competitive antagonism against ISO stimulation which disappeared in presence of PKG and PDE2 inhibition. Taken together our findings provide, for the first time in the frog, a role for ß3-ARs in the cardiac performance modulation which involves Gi/o protein and occurs via an EE-NO-cGMP-PKG/PDE2 cascade.

Protective effect of propranolol and nadolol on social defeat-induced behavioral impairments in rats.

Benzodiazepines and SSRIs are considered as standard treatment options for anxiety and depression, hallmarks of Post-Traumatic Stress Disorder (PTSD), although their use is often limited by adverse effects. While promising evidence emerged with ß-adrenergic receptor (ß-AR) antagonists (or 'ß-blockers') and PTSD relief, efficacy issues dampened the excitement. However, we believe it is premature to completely eliminate a beneficial role of ß-blockers. Our previous work has suggested that social defeat (SD) results in anxiety-like and depression-like behaviors in rats. Here, using the SD paradigm, we examined the effect of several ß-adrenergic receptor antagonists (propranolol, nadolol, bisoprolol) on these behaviors in rats. Following acclimatization, Sprague-Dawley rats received no treatment (for control groups) or treated with ; propranolol (50 mg/kg/day in water), or nadolol (18 mg/kg/day in rats' chow), or bisoprolol (15 mg/kg/day in water). The treatment lasted for 36 days, following which rats were subjected to SD/control exposures (1 week). Later, anxiety-like and depression-like behaviors, social interaction and learning-memory function tests were conducted. SD rats exhibited anxiety- and depression-like behavior as well as learning-memory impairment. Propranolol and nadolol protected SD rats from exhibiting anxiety-or depression-like behaviors. Bisoprolol treatment did not mitigate SD-induced behavioral impairments in rats. Nadolol, propranolol or bisoprolol have no effect in attenuating SD-induced memory function tests. These results suggest that certain 'ß-blockers' have the potential to mitigate the negative psychological effects of traumatic events.

Stress-induced Norepinephrine Downregulates CCL2 in Macrophages to Suppress Tumor Growth in a Model of Malignant Melanoma.

Psychological stressors have been implicated in the progression of various tumor types. We investigated a role for stress in tumor immune cell chemotaxis in the B16F10 mouse model of malignant melanoma. We exposed female mice to 6-hour periods of restraint stress (RST) for 7 days, then implanted B16F10 malignant melanoma tumor cells and continued the RST paradigm for 14 additional days. We determined serum corticosterone and liver catecholamine concentrations in these mice. To evaluate the tumor microenvironment, we performed IHC and examined cytokine expression profiles using ELISA-based analysis of tumor homogenates. We found that tumors in mice subjected to RST grew significantly slower, had reduced tumor C-C motif ligand 2 (CCL2), and contained fewer F4/80-positive macrophages than tumors from unstressed mice. We observed a concomitant increase in norepinephrine among the RST mice. An in vitro assay confirmed that norepinephrine downregulates CCL2 production in both mouse and human macrophages, and that pretreatment with the pan-ß-adrenergic receptor inhibitor nadolol rescues this activity. Furthermore, RST had no effect on tumor growth in transgenic CCL2-deficient mice. This study suggests that stress reduces malignant melanoma by reducing recruitment of tumor-promoting macrophages by CCL2.

Metastatic-promoting effects of LPS: sexual dimorphism and mediation by catecholamines and prostaglandins.

Inflammation is implicated in several medical conditions that are sexually dimorphic, including depression, cardiovascular diseases, autoimmunity, and presumably cancer progression. Here we studied the effects of the proinflammatory agent, LPS, on MADB106 lung tumor retention (LTR), and sought to elucidate underlying mechanisms and sexual dimorphism. F344 male and female rats were administered with LPS (0.001-1mg/kg i.v.) simultaneously with tumor cell inoculation, and treated with a beta-blocker (nadolol, 0.2-0.3mg/kg s.c.), a COX inhibitor (indomethacin, 4mg/kg s.c.) or both drugs. To study the role of NK cells, numbers and cytotoxicity of marginating-pulmonary NK cells were studied, and selective in vivo NK-depletion was employed. Serum levels of corticosterone, IL-6, and TNF-alpha were also assessed. The findings indicated that LPS increased LTR in both sexes, but 10-fold higher doses were needed in females to reach the increase evident in males. Additionally, nadolol and indomethacin reduced the effects of LPS, more so in males. In vivo NK-depletion and ex vivo NK activity studies suggested that LPS affected LTR through both NK-independent and NK-dependent mechanisms, the latter mediated through prostaglandin release in males. Corticosterone, IL-6, and TNF-alpha responses to LPS were sexually dimorphic, but were not associated with LPS or drugs' impacts on LTR. Overall, our findings demonstrate sexual dimorphism in LPS-induced elevated susceptibility to MADB106 experimental metastasis, and in potential humoral underlying mechanisms. Further studies are needed to elucidate additional immunological and non-immunological mediators of these dimorphisms, as well as to assess their involvement in other sexually dimorphic pathologies that are associated with inflammation.

Psychological stress increases expression of IL-10 and its homolog IL-19 via beta-adrenoceptor activation: reversal by the anxiolytic chlordiazepoxide.

Recent studies from our laboratory indicate that psychological stress is a potent inducer of the anti-inflammatory cytokine interleukin (IL)-10, raising the possibility that the IL-10 family of cytokines may be key mediators of stress-induced immunosuppression. In this study we examined the impact of psychological stress (restraint stress) on expression of IL-10, and the novel IL-10 family members IL-19, IL-20 and IL-24 in mouse spleen following an in vivo challenge with lipopolysaccharide (LPS). We found that stressor exposure significantly augmented LPS-induced IL-10 expression. Similarly, IL-19 expression was induced by LPS, and this was significantly enhanced by restraint stress. In contrast, expression of IL-24 was not significantly altered by LPS or stress, and expression of IL-20 was largely not detectable in vivo in either saline or LPS-treated animals. Consistent with a role for sympathetic nervous system (SNS) activation in stress-induced immune regulation, the sympathetic neurotransmitter noradrenaline increased LPS-induced IL-10 and IL-19 expression in splenocytes and dendritic cells, and the ability of noradrenaline to induce expression of these cytokines was blocked by pre-treatment with the beta-adrenoceptor antagonist propranolol. Similarly, pre-treatment of mice with the peripherally acting beta-adrenoceptor antagonist nadolol completely blocked the stress-induced increase in IL-10 and IL-19 mRNA expression. Finally, pre-treatment with the benzodiazepine anxiolytic chlordiazepoxide prevented the stress-induced increase in IL-10 and IL-19 expression. Taken together, these data demonstrate that psychological stress induces expression of the IL-10 and its homolog IL-19 via activation of beta-adrenoceptors, and the ability of stress to induce these cytokines is prevented by treatment with the anxiolytic chlordiazepoxide. The findings suggest that stress enhances the production of immunosuppressive cytokines, which may impact on stress-related disease processes.

Rabbit, a relevant model for the study of cardiac beta 3-adrenoceptors.

The beta(3)-adrenoceptors (beta(3)-ARs) have been identified and characterized in the human heart. Specific beta(3)-AR stimulation, unlike beta(1)-AR or beta(2)-AR stimulation, decreases cardiac contractility, partly via the G(i)-NO pathway. However, the precise role of cardiac beta(3)-ARs is not yet completely understood. Indeed, under normal conditions, the beta(3)-AR response is present only to a very low degree in rats and mice. Therefore, we evaluated whether beta(3)-ARs were present and functional in rabbit ventricular cardiomyocytes, and whether the rabbit could serve as a relevant model for the study of cardiac beta(3)-ARs. We used RT-PCR and Western blot to measure the beta(3)-AR transcripts and protein levels in rabbit ventricular cardiomyocytes. We also analysed the effect of beta(3)-AR stimulation using isoproterenol in combination with nadolol or SR 58611A on cardiomyocyte shortening, Ca(2+) transient, L-type Ca(2+) current (I(Ca,L)), delayed rectifier potassium current (I(Ks)) and action potential duration (APD). For the first time, we show that beta(3)-ARs are expressed in rabbit ventricular cardiomyocytes. The mRNA and protein sequences present a high homology to those of rat and human beta(3)-ARs. Furthermore, beta(3)-AR stimulation decreases cardiomyocyte shortening, Ca(2+) transient and I(Ca,L) amplitudes, via a G(i)-NO pathway. Importantly, beta(3)-AR stimulation enhances I(Ks) amplitude and shortens the APD. Taken together, our results indicate that the rabbit provides a relevant model, easily used in laboratories, to study the roles of cardiac beta(3)-ARs in physiological conditions.

Effect of nadolol injected prior to CRH on stress-induced plasma corticosterone level in rat.

The proposed research is the part of our investigation of the role of catecholamines in the alterations provoked by stress. Especially, we elucidate if Nadolol injected prior to CRH ICV has some effect on plasma corticosterone level. 15 mg/kg of Nadolol (the dose sufficient to prevent CRH-induced increases in heart-rate for 2 hr), dissolved in saline was administered intraperitoneally, 30 minutes prior to CRH (The dose of interest for CRH - 1 mkg/kg - was determined earlier, as provoking the maximal increase of plasma corticosterone level after 20 minutes of its ICV injection). Whole blood was collected at 11.00 am, via indwelling jugular catheter at 0 (control) and 15 minutes after Nadolol injection, also 30 and 60 min after CRH injection. After centrifugation the plasma level of corticosterone was essayed using ELISA method. 15 minutes after Nadolol injection the level of plasma corticosterone in comparing with control wasn't changed, at subsequent time-points plasma corticosterone level was increased but significant difference was observed only after 30 minutes. Thus, according our results, 30 min after injection, the dose of Nadolol, sufficient to prevent CRH-induced increase in heart rate, doesn't preclude the CRH-induced increase of plasma corticosterone - one of key signs of the stress-axis activation. The results were discussed.

The behaviour of some antihypertension drugs on human serum paraoxonase-1: an important protector enzyme against atherosclerosis.

OBJECTIVES: Paraoxonase-1 (PON1) enzyme is related to high-density lipoprotein (HDL), which is calcium dependent. It has essential roles such as protecting LDL against oxidation and detoxification of highly toxic substances. It is a significant risk to reduce the levels of this enzyme in patients with diabetes mellitus, cardiovascular diseases, hyperthyroidism and chronic renal failure. METHODS: Here, it was reported that the purification of human serum PON1 using straightforward methods and determination of the interactions between some antihypertension drugs and the enzyme. KEY FINDING: It was found that these drugs exhibit potential inhibitor properties for human serum PON1 with IC50 values in the range of 131.40-369.40 µm and Ki values in the range of 56.24 ± 6.75-286.74 ± 28.28 µm. These drugs showed different inhibition mechanisms. It was determined that midodrine and nadolol were exhibited competitive inhibition, but atenolol and pindolol were exhibited non-competitive inhibition. CONCLUSION: Usage of these drugs would be hazardous in some cases.