Methyl-β-cyclodextrin suppresses the monocyte-endothelial adhesion triggered by lipopolysaccharide (LPS) or oxidized low-density lipoprotein (oxLDL)

ContextRecent studies demonstrated the anti-atherosclerotic efficacy of cyclodextrin. However, it remains unclear whether cyclodextrin exerts the anti-atherosclerotic effect via regulating monocyte-endothelial adhesion.ObjectiveTo answer that question by recruiting methyl-β-cyclodextrin (MβCD) as a cyclodextrin representative.Materials and methodsHuman umbilical vein endothelial cells (HUVECs) were not treated, or treated with 1 µg/mL liposaccharide (LPS) or 50 µg/mL oxidized low-density lipoprotein (oxLDL) for 12 h, 5 mM MβCD for 1 h, and LPS/oxLDL (1 and 50 µg/mL, respectively for 12 h) plus MβCD (5 mM for 1 h), respectively. The effects of MβCD on LPS/oxLDL-triggered monocyte-endothelial adhesion and related molecules in signalling pathways were evaluated via confocal microscopy, flow cytometry, RT-PCR, western blotting, and cell adhesion assay.ResultsMβCD with an IC₅₀ of 27.66 mM (1 h treatment) exerted no significant cytotoxicity at ≤5 mM for ≤2 h. Compared with the control, both LPS and oxLDL induced an ∼2–3-fold increase in adhesion molecule expression (ICAM-1 and VCAM-1 at protein and mRNA levels) and NF-κB phosphorylation (p-NF-κB/pP65), an increase in IκB kinase (IKK), and a decrease in phosphorylated protein kinase B (p-Akt), respectively. Moreover, more monocytes (2-fold higher for LPS and 15% higher for oxLDL) were attached on LPS/oxLDL-stimulated HUVECs. 5 mM MβCD reversed the LPS/oxLDL-induced changes back to the control levels.ConclusionsMβCD significantly suppresses the LPS/oxLDL-triggered monocyte-endothelial adhesion by downregulating adhesion molecule expression probably via LPS-IKK-NF-κB or oxLDL-Akt-NF-κB pathway. This study demonstrates a potential mechanism of the anti-atherosclerotic efficacy of cyclodextrin from the angle of monocyte-endothelial adhesion.     

Preparation,characterization, dissolution,and permeation of flibanserin − 2-HP-β-cyclodextrin inclusion complexes

Flibanserin (FLB), an antiserotonin drug, is used to treat women with hypoactive sexual appetite disorder. FLB shows low bioavailability (~33%) probably due to its low water solubility. The current study investigated the impact of hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium lauryl sulfate (SLS) on the dissolution and permeation of FLB. HP-β-CD–FLB inclusion complexes were prepared using physical mixing and kneading at 1:1 and 1:2 M ratios and characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy, and powder X-ray diffractometry. The dissolution and permeation of the complexes through a cellophane membrane were performed in, 0.1, 0.3 and 0.5% SLS in phosphate buffer (pH 6.8).Derived from the slope of the linear phase solubility diagram, the apparent stability constant (K_1:1) was 372.54 M⁻¹. Kneading changed the crystalline form of FLB to an amorphous appearance characterized by minimal crystalline peaks, indicating successful inclusion complex formation. In addition, the HP-β-CD–FLB inclusion complexes showed twofold increased dissolution efficiency at 6 h. The cumulative FLB amount permeated at 6 h increased from 14.1% to 21.88% and 34.56% in the presence of 0.1% and 0.3% of SLS, respectively. However, increasing SLS to 0.5% did not show an increase in FLB permeation. Therefore, the HP-β-CD–FLB inclusion complex has an improved dissolution rate compared to FLB alone. The presence of SLS in the dissolution medium increases the dissolution rate of pure FLB and its complex with HP-β-CD. kneaded 1:1 complex was formulated bioadhesive buccal tablets and showed enhanced drug release.     

Differential modulation of rat neuronal nicotinic receptor subtypes by acute application of ethanol

1. We have studied the effects of acute ethanol (EtOH) exposure on the agonist responses of rat neuronal nicotinic receptors expressed in Xenopus oocytes by means of voltage clamp techniques.
2. In some cells, agonist-induced current responses with the α3β4 subunit combination could be either significantly potentiated or inhibited (range 25% to 237% of control response) by low ethanol concentrations (1–30 mM). At high ethanol concentrations (100–300 mM) robust potentiations were observed (range 135% to 305% of control).
3. The low EtOH concentration effects on the α3β4 subtype exhibited tolerance with repeated EtOH exposure.
4. In general, the α3β2, α4–1β2 and α4–1β4 subunit combinations were less sensitive to low concentrations of ethanol, but respectively showed potentiations of up to 178%, 226% and 154% at high EtOH concentrations.
5. The α7 homomeric receptor was also relatively insensitive at low EtOH concentrations. At high EtOH concentrations, potentiations, inhibitions or no alteration of control agonist response were observed (range 88% to 141% of control).
6. We conclude that all the neuronal nicotinic receptor subunit combinations tested here can be modulated by high concentrations of EtOH in a rapidly reversible manner. This modulation may underlie some of the behavioural effects of ethanol. The α3β4 subunit combination may be especially sensitive to modulation by low EtOH concentrations. This remarkable sensitivity and plasticity of nicotinic receptors may contribute to a process of mutual reinforcement in nicotine and alcohol addiction.

     

Preparation,characterization, and antibacterial activity of plaunotol and plaunoi extracts complexed with hydroxypropyl-β-cyclodextrin

Croton stellatopilosus (Plaunoi) leaves accumulate several diterpenes and possess various pharmacological activities. The present study aimed to prepare, characterize and assess the antibacterial activity of inclusion complexes prepared by mixing plaunotol (PL) or plaunoi extract (PE) with cyclodextrins (CD), including α-CD, β-CD, γ-CD, and hydroxypropyl-β-cyclodextrin (HP-β-CD). The inclusion complexes were characterized using SEM, XRD, DSC, and FT-IR and evaluated for aqueous solubility and thermal stability. The PL and PE lyophilized complexes with HP-β-CD were further evaluated for their antibacterial activity against acne-causing bacteria. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of PL, PE, and the inclusion complexes evaluated using the agar dilution method revealed that the MIC and MBC values of the inclusion complexes were lower than those of PL or PE alone. Interestingly, the complexes had a synergistic activity with clindamycin after testing with checkerboard assay. The hydrogel containing the inclusion complex and clindamycin were assessed for antibacterial activity using the agar well diffusion method. The results indicated that the hydrogels showed significant inhibition of bacterial growth. In conclusion, the prepared solid dispersion of PL or PE with HP-β-CD could enhance antibacterial activity by increasing the drug solubility. The hydrogels containing PL or PE complex and clindamycin could be considered as a candidate for the treatment of acne vulgaris.     

α-Galactosylceramide suppresses murine eosinophil production through interferon-γ-dependent induction of NO synthase and CD95

Background and Purpose

α-Galactosylceramide (α-GalCer), a pleiotropic immunomodulator with therapeutic potential in neoplastic, autoimmune and allergic diseases, activates invariant natural killer T-cells throughCD1-restricted receptors for α-GalCer on antigen-presenting cells, inducing cytokine secretion. However the haemopoietic effects of α-GalCer remain little explored.

Experimental Approach

α-GalCer-induced modulation of eosinophil production in IL-5-stimulated bone marrow cultures was examined in wild-type (BALB/c, C57BL/6) mice and their mutants lacking CD1, inducible NOS (iNOS), CD95 and IFN-γ, along with the effects of lymphocytes; IFN-γ; caspase and iNOS inhibitors; non-steroidal anti-inflammatory drugs (NSAIDs) and LTD₄; and dexamethasone.

Key Results

α-GalCer (10⁻⁶–10⁻⁸M) suppressed IL-5-stimulated eosinopoiesis by inducing apoptosis. α-GalCer pretreatment in vivo (100 μg·kg⁻¹, i.v.) suppressed colony formation by GM-CSF-stimulated bone marrow progenitors in semi-solid cultures. α-GalCer and dexamethasone synergistically promoted eosinophil maturation. Suppression of eosinophil production by α-GalCer was prevented by aminoguanidine and was undetectable in bone marrow lacking iNOS, CD95, CD28; or CD1d. Separation on Percoll gradients and depletion of CD3+ cells made bone marrow precursors unresponsive to α-GalCer. Responsiveness was restored with splenic lymphocytes. Experiments with (i) IFN-γ-deficient bone marrow, alone or co-cultured with spleen T-cells from wild-type, but not from CD1d-deficient, donors; (ii) IFN-γ neutralization; and (iii) recombinant IFN-γ, showed that these effects of α-GalCer were mediated by IFN-γ. Effects of α-GalCer on eosinophil production were blocked by LTD₄ and NSAIDs.

Conclusions and Implications

α-GalCer activation of IFN-γ-secreting, CD1d-restricted lymphocytes induced iNOS-CD95-dependent apoptosis in developing eosinophils. This pathway is initiated by endogenous regulatory lymphocytes, antagonised by LTD₄, NSAIDs and aminoguanidine, and modified by dexamethasone.     

Rheological Characterization of an Acetaminophen Jelly

The aim of this study was to prepare an inclusion complex of acetaminophen and β-cyclodextrin (molar ratio of 1:1). A jelly with inclusion complexes formed by kneading was prepared. The formation of inclusion complexes was assessed by powder X-ray diffraction patterns and Fourier transform-infrared spectroscopy. Jellies were prepared with xanthan gum, gelatin, and κ-carrageenan. The concentration of each jelling agent was 0.5, 1.0, and 1.5% w/v. Viscoelasticity and dissolution characteristics were determined and osmometry was performed. PGWater^™, a commercial jelly for fluid replacement, served as a reference for viscoelastic characteristics and dissolution. Powder X-ray diffraction measurement revealed a different diffraction pattern for the kneading than for acetaminophen and β-cyclodextrin. Fourier transform-infrared spectroscopy revealed an absorption peak (at around 1655 cm⁻¹) due to the carbonyl group and benzene ring (at around 1610 cm⁻¹) of acetaminophen. In contrast, the kneaded mixture (1:1) had a shift in the absorption peak due to the carbonyl group (at around 1650 cm⁻¹) in acetaminophen''s molecular structure, and the formation of an inclusion complex was noted. The viscosity of xanthan gum-1.0, gelatin-1.5, and carrageenan-0.5 resembled the viscoelasticity of PGWater^™. The acetaminophen in gelatin-1.0 and carrageenan-0.5 had dissolution behavior similar to that of commercial acetaminophen preparations. The osmolality of jellies prepared in different concentrations ranged from about 20-50 mOsm/kg. Results suggested that carrageenan-0.5 could serve as a useful jelly vehicle for acetaminophen.     

Clinical pharmacology of AMG 181, a gut-specific human anti-α4β7 monoclonal antibody,for treating inflammatory bowel diseases

Aims

AMG 181 pharmacokinetics/pharmacodynamics (PK/PD), safety, tolerability and effects after single subcutaneous (s.c.) or intravenous (i.v.) administration were evaluated in a randomized, double-blind, placebo-controlled study.

Methods

Healthy male subjects (n= 68) received a single dose of AMG 181 or placebo at 0.7, 2.1, 7, 21, 70 mg s.c. (or i.v.), 210 mg s.c. (or i.v.), 420 mg i.v. or placebo. Four ulcerative colitis (UC) subjects (n= 4, male : female 2:2) received 210 mg AMG 181 or placebo s.c. (3:1). AMG 181 concentration, anti-AMG 181-antibody (ADA), α₄β₇ receptor occupancy (RO), target cell counts, serum C-reactive protein, fecal biomarkers and Mayo score were measured. Subjects were followed 3–9 months after dose.

Results

Following s.c. dosing, AMG 181 was absorbed with a median t_max ranging between 2–10 days and a bioavailability between 82% and 99%. C_max and AUC increased dose-proportionally and approximately dose-proportionally, respectively, within the 70–210 mg s.c. and 70–420 mg i.v. ranges. The linear β-phase t_1/2 was 31 (range 20–48) days. Target-mediated disposition occurred at serum AMG 181 concentrations of less than 1 μg ml⁻¹. The PD effect on α₄β₇ RO showed an EC₅₀ of 0.01 μg ml⁻¹. Lymphocytes, eosinophils, CD4+ T cells and subset counts were unchanged. AMG 181-treated UC subjects were in remission with mucosal healing at weeks 6, 12 and/or 28. The placebo-treated UC subject experienced colitis flare at week 6. No ADA or AMG 181 treatment-related serious adverse events were observed.

Conclusions

AMG 181 has PK/PD, safety, and effect profiles suitable for further testing in subjects with inflammatory bowel diseases.     

Formulation and characterization of eprosartan mesylate and β-cyclodextrin inclusion complex prepared by microwave technology

The goal of this work was to improve the aqueous solubility and dissolution rate of eprosartan mesylate by preparing inclusion complex of drug with β-cyclodextrin (β-CD) by microwave technique. In order to determine the solubility of eprosartan, phase solubility was determined and dissolution study was also conducted. Further, analytical techniques for instance, particle size distribution, differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy were used for the characterization of inclusion complex. In addition, the binding pattern of eprosartan with the β-CD was investigated by molecular modeling study. Phase solubility study revealed that approximately 4.48 folds improvement in the solubility of drug was noted with β-CD (10 mM). The estimated stability constant (K_c) values for eprosartan:β-CD binary mixture was found to be 280.78 M^–1. The prepared inclusion complex of drug with β-CD presented better drug release profile (62.96 ± 2.01% in 1 h) as compared to their physical mixture (41.41 ± 1.77% in 1 h) or drug per se (29.97 ± 3.13%). The inclusion complex demonstrated different features and properties from pure drug, and we inferred that this could be due to the inclusion of drug into cyclodextrin cavity that confirmed by different analytical method. Molecular modeling study demonstrated a good affinity of eprosartan to entangle to β-CD. The outcomes have shown that guest molecule has many significant interactions with the host molecule. These observations are very interesting and may be a valuable approach to improve the solubility and in turn the bioavailability of eprosartan.     

Evidence that Behavioral Phenotypes of Morphine in β-arr2?/? Mice Are Due to the Unmasking of JNK Signaling

The altered behavioral effects of morphine, but not most other mu agonists, in mice lacking β-arrestin 2, suggest that this scaffolding protein regulates the signaling cascade of this commonly used analgesic. One of the cascades that could be regulated by β-arrestin 2 is cJun-N-terminal kinase (JNK), which binds with β-arrestin 2 and modulates the analgesic effects of morphine. Using neurons lacking β-arrestin 2 (β-arr2−/−) to examine this interaction, we found that β-arr2−/− neurons show altered intracellular distribution of JNK and cJun, and that morphine, but not fentanyl, increased the nuclear localization of the phosphorylated, therefore activated, form of cJun, a JNK target in dorsal root ganglia neurons. This suggests that deleting β-arrestin 2 affects the JNK cascade. We therefore examined whether some of the behavioral phenotypes of mice lacking β-arrestin 2 could be a result of altered JNK signaling. Indeed, two different JNK inhibitors reversed the enhanced analgesic effect of morphine, a known phenotype of β-arr2−/− mice, to +/+ levels. Both the reduced locomotor effect of morphine and the psychomotor sensitization to repeated morphine administration in β-arr2−/− mice were also returned to +/+ levels by inhibiting JNK. In contrast, the behavioral effects of fentanyl were neither genotype-dependent nor affected by JNK inhibition. Furthermore, a PKC inhibitor had a similar effect as inhibiting JNK in reducing the enhanced analgesic effect of morphine in β-arr2−/− mice to +/+ levels. In summary, removing β-arrestin 2 reveals mu receptor activation of the JNK cascade in a ligand-specific manner explaining several behavioral phenotypes of β-arr2−/− mice.     

β-adrenoceptor blockers and pulmonary function in the general population: the Rotterdam Study

Aim

β-adrenoceptor blockers have been used with caution in patients with obstructive lung diseases such as asthma or chronic obstructive pulmonary disease (COPD), due to the potentially increased airway reactivity and risk of bronchial obstruction. Cardioselective β-adrenoceptor blockers have a more beneficial profile than non-cardioselective β-adrenoceptor blockers and can be safely prescribed to patients with both cardiovascular disease and COPD. We hypothesized that cardioselective β-adrenoceptor blockers also affect pulmonary function.

Methods

This study was performed within the Rotterdam Study, a prospective population-based cohort study. Effects of cardioselective and non-cardioselective β-adrenoceptor blockers on pulmonary function were analysed using regression techniques with multivariable adjustment for potential confounders.

Results

Current use of non-cardioselective β-adrenoceptor blockers was significantly associated with a lower forced expiratory volume in 1 s (FEV₁) of −198 ml (95% CI −301, −96), with a lower forced vital capacity (FVC) of −223 ml (95% CI −367, −79) and with a decreased FEV₁ : FVC of −1.38% (95% CI −2.74, −0.13%). Current use of cardioselective β-adrenoceptor blockers was significantly associated with a lower FEV₁ of −118 ml (95% CI −157, −78) and with a lower FVC of −167 ml (95% CI −222, −111), but did not affect FEV₁ : FVC. After exclusion of patients with COPD, asthma and heart failure the effects of cardioselective β-adrenoceptor blockers remained significant for FEV₁ (−142 ml [95% CI −189, −96]) and for FVC (−176 ml [95% CI −236, −117]).

Conclusion

In our study both non-cardioselective and cardioselective β-adrenoceptor blockers had a clinically relevant effect on both FEV₁ and FVC. In contrast to cardioselective β-adrenoceptor blockers, use of non-cardioselective β-adrenoceptor blockers was associated with a significantly lower FEV₁ : FVC.     

Histamine mediates behavioural and metabolic effects of 3-iodothyroacetic acid,an endogenous end product of thyroid hormone metabolism

BACKGROUND AND PURPOSE

3-Iodothyroacetic acid (TA1) is an end product of thyroid hormone metabolism. So far, it is not known if TA1 is present in mouse brain and if it has any pharmacological effects.

EXPERIMENTAL APPROACH

TA1 levels in mouse brain were measured by HPLC coupled to mass spectrometry. After i.c.v. administration of exogenous TA1 (0.4, 1.32 and 4 μg·kg⁻¹) to mice, memory acquisition-retention (passive avoidance paradigm with a light-dark box), pain threshold to thermal stimulus (51.5°C; hot plate test) and plasma glucose (glucorefractometer) were evaluated. Similar assays were performed in mice pretreated with s.c. injections of the histamine H₁ receptor antagonist pyrilamine (10 mg·kg⁻¹) or the H₂ receptor antagonist zolantidine (5 mg·kg⁻¹). TA1 (1.32 and 4 μg·kg⁻¹) was also given i.c.v. to mice lacking histidine decarboxylase (HDC^−/−) and the corresponding WT strain.

KEY RESULTS

TA1 was found in the brain of CD1 but not of HDC mice. Exogenous TA1 induced amnesia (at 0.4 μg·kg⁻¹), stimulation of learning (1.32 and 4 μg·kg⁻¹), hyperalgesia (0.4, 1.32 and 4 μg·kg⁻¹) and hyperglycaemia (1.32 and 4 μg·kg⁻¹). All these effects were modulated by pyrilamine and zolantidine. In HDC^−/− mice, TA1 (1.32 and 4 μg·kg⁻¹) did not increase plasma glucose or induce hyperalgesia.

CONCLUSIONS AND IMPLICATIONS

Behavioural and metabolic effects of TA1 disclosed interactions between the thyroid and histaminergic systems.     

Action potential shortening through the putative β4-adrenoceptor in ferret ventricle: comparison with β1- and β2-adrenoceptor-mediated effects

The electrophysiological responses to (−)-CGP 12177 ((−)-4-(3-tertiarybutylamino-2-hydroxypropoxy) benzimidazol-2-one), an agonist for the putative β₄-adrenoceptor, were investigated on isolated perfused ferret hearts paced at 100 min⁻¹ and compared to those of (−)-noradrenaline and (−)-adrenaline, mediated through β₁- and β₂-adrenoceptors respectively. The three agonists decreased ventricular monophasic action potential duration but prolonged the action potential plateau; β₃-adrenoceptor-selective agonists had no effect. (−)-CGP 12177 was the most potent, but (−)-noradrenaline the most efficacious; both agonists caused ventricular extra-systoles. Because only (−)-noradrenaline but not (−)-CGP 12177 elicited shortening of the refractory period, the mechanism of arrhythmias mediated through β₁- and putative β₄-adrenoceptors may be different.     

Effects of the α subunit on imidacloprid sensitivity of recombinant nicotinic acetylcholine receptors

1. Imidacloprid is a new insecticide with selective toxicity for insects over vertebrates. Recombinant (α4β2) chicken neuronal nicotinic acetylcholine receptors (AChRs) and a hybrid nicotinic AChR formed by co-expression of a Drosophila melanogaster neuronal α subunit (SAD) with the chicken β2 subunit were heterologously expressed in Xenopus oocytes by nuclear injection of cDNAs. The agonist actions of imidacloprid and other nicotinic AChR ligands ((+)-epibatidine, (−)-nicotine and acetylcholine) were compared on both recombinant nicotinic AChRs by use of two-electrode, voltage-clamp electrophysiology.
2. Imidacloprid alone of the 4 agonists behaved as a partial agonist on the α4β2 receptor; (+)-epibatidine, (−)-nicotine and acetylcholine were all full, or near full, agonists. Imidacloprid was also a partial agonist of the hybrid Drosophila SAD chicken β2 receptor, as was (−)-nicotine, whereas (+)-epibatidine and acetylcholine were full agonists.
3. The EC₅₀ of imidacloprid was decreased by replacing the chicken α4 subunit with the Drosophila SAD α subunit. This α subunit substitution also resulted in an increase in the EC₅₀ for (+)-epibatidine, (−)-nicotine and acetylcholine. Thus, the Drosophila (SAD) α subunit contributes to the greater apparent affinity of imidacloprid for recombinant insect/vertebrate nicotinic AChRs.
4. Imidacloprid acted as a weak antagonist of ACh-mediated responses mediated by SADβ2 hybrid receptors and as a weak potentiator of ACh responses mediated by α4β2 receptors. This suggests that imidacloprid has complex effects upon these recombinant receptors, determined at least in part by the α subunit.

     

Microcalorimetric investigation on the formation of supramolecular nanoassemblies of associative polymers loaded with gadolinium chelate derivatives

In this study, isothermal titration microcalorimetry (ITC) and molecular modeling were used to investigate the mechanism of formation of supramolecular nanoassemblies prepared by mixing aqueous solutions of two associative polymers (i.e. polymerised β-CD (pβ-CD) and dextran grafted with lauryl side chains (MD)). Their capacity to entrap a contrast agent for magnetic resonance imaging (a gadolinium (Gd³⁺) derivative) has been determined by the same methods. ITC experiments have been employed to evaluate the stoichiometry of interaction (N), association constants (K) and thermodynamic parameter variation associated with complexation between hosts and guests involved in this system. The inclusion compounds studied were: as hosts, β-CD and pβ-CD, and as guests, MD, adamantyl amine, and a Gd³⁺ complex functionalized with adamantane. It has been demonstrated that pβ-CD cavities tend to interact more favourably with MD (K = 25,000 M⁻¹) than with adamantly amine (K = 3650 M⁻¹) and Gd³⁺ complex (K = 1460 M⁻¹), forming 1:1 complexes, as also confirmed by molecular modeling. Noteworthy, the Gd³⁺ derivatives, although incorporated in the supramolecular nanoassemblies (by inclusion into the β-CD cavities of pβ-CD), did not destabilize the pβ-CD–MD inclusion complexes, probably because the interaction between pβ-CD and MD was stronger. Finally, the analysis of thermodynamic parameters revealed that the interaction between MD and pβ-CD was entropy driven (|ΔH| < |TΔS|) while the interactions of adamantly amine and Gd³⁺ complex with β-CD and pβ-CD were enthalpy driven and dominated by van der Walls forces (|ΔH| > |TΔS|).     

Impaired IL-1β-induced neutrophil accumulation in tachykinin NK1 receptor knockout mice

Tachykinin NK₁ receptors play an important role in the development of neurogenic inflammatory responses. We have used the murine air-pouch model to investigate whether the neurogenic component of the cellular inflammatory response to interleukin-1β (IL-1β, 10 ng into the air-pouch) is altered in NK₁ receptor knockout mice compared to wild type controls. Air-pouches were washed following a 4 h IL-1β treatment, the wash collected and neutrophil number estimated using a Neubauer haemocytometer. The response to IL-1β was significantly attenuated in NK₁ receptor +/− (40% reduction) and −/− mice (62% reduction) compared to wild type controls (+/+), whilst the response to cytokine-induced neutrophil chemoattractant (CINC, 0.3 μg) was unaffected. The response to substance P (7.5 nmol) was attenuated by approximately 50% in both NK₁ receptor +/− and −/− mice compared to wild type controls. In conclusion NK₁ receptors play a significant role in the cellular response to IL-1β in a model of inflammation.     

Inotropy and L-type Ca2+ current,activated by β1- and β2-adrenoceptors,are differently controlled by phosphodiesterases 3 and 4 in rat heart

Background and purpose

β₁- and β₂-adrenoceptors coexist in rat heart but β₂-adrenoceptor-mediated inotropic effects are hardly detectable, possibly due to phosphodiesterase (PDE) activity. We investigated the influence of the PDE3 inhibitor cilostamide (300 nmol·L⁻¹) and the PDE4 inhibitor rolipram (1 µmol·L⁻¹) on the effects of (−)-catecholamines.

Experimental approach

Cardiostimulation evoked by (−)-noradrenaline (ICI118551 present) and (−)-adrenaline (CGP20712A present) through β₁- and β₂-adrenoceptors, respectively, was compared on sinoatrial beating rate, left atrial and ventricular contractile force in isolated tissues from Wistar rats. L-type Ca²⁺-current (I_Ca-L) was assessed with whole-cell patch clamp.

Key results

Rolipram caused sinoatrial tachycardia. Cilostamide and rolipram did not enhance chronotropic potencies of (−)-noradrenaline and (−)-adrenaline. Rolipram but not cilostamide potentiated atrial and ventricular inotropic effects of (−)-noradrenaline. Cilostamide potentiated the ventricular effects of (−)-adrenaline but not of (−)-noradrenaline. Concurrent cilostamide + rolipram uncovered left atrial effects of (−)-adrenaline. Both rolipram and cilostamide augmented the (−)-noradrenaline (1 µmol·L⁻¹) evoked increase in I_Ca-L. (−)-Adrenaline (10 µmol·L⁻¹) increased I_Ca-L only in the presence of cilostamide but not rolipram.

Conclusions and implications

PDE4 blunts the β₁-adrenoceptor-mediated inotropic effects. PDE4 reduces basal sinoatrial rate in a compartment distinct from compartments controlled by β₁- and β₂-adrenoceptors. PDE3 and PDE4 jointly prevent left atrial β₂-adrenoceptor-mediated inotropy. Both PDE3 and PDE4 reduce I_Ca-L responses through β₁-adrenoceptors but the PDE3 component is unrelated to inotropy. PDE3 blunts both ventricular inotropic and I_Ca-L responses through β₂-adrenoceptors.     

Association of Impulsivity With Food,Nutrients, and Fitness in a Longitudinal Birth Cohort Study

BackgroundImpulsivity is a psychiatric vulnerability factor strongly associated with substance abuse but also with unhealthy diet. Whether these associations extend to specific nutrients is largely unknown. Therefore, we investigated the longitudinal association between diet, cardiorespiratory fitness, and 2 impulsivity dimensions in a representative sample of south Estonian adolescents and young adults. Impulsivity and dietary intake were measured 3 times in 2 birth cohorts at regular intervals in individuals aged 15 to 33 years.MethodsThe sample included 2 birth cohorts of the longitudinal Estonian Children Personality Behaviour and Health Study. The analytic sample size consisted of 2883 observations (56.4% females). The primary outcomes were adaptive and maladaptive impulsivity scores measured by an original 24-item Likert-type questionnaire. Impulsivity scores were predicted from the food diaries data converted into nutrient categories. A linear mixed-effects approach was used to model the time dependence between observations.ResultsLower maladaptive impulsivity was associated with higher cardiorespiratory fitness (β = −.07; 95% CI = −0.12; −0.03). Higher maladaptive impulsivity was associated with lower dietary intake of zinc (β = −.10; −0.15; −0.06) and vegetables (β = −.04; −0.07; −0.01) and higher intake of sodium (β = .06; 0.02; 0.10). Vitamin B6 was positively associated with adaptive impulsivity (β = .04; 0.01; 0.07). Additionally, some of the adjusted models showed significant but weak associations with selenium, alcohol, fish, and cereal products.ConclusionsFood choice may affect the neurochemistry and therefore regulate the manifestations of impulsivity. We identified associations between several (micro)nutrients and maladaptive impulsivity.     

Release of granulocyte-macrophage colony stimulating factor by human cultured airway smooth muscle cells: suppression by dexamethasone

Smooth muscle cells represent a significant percentage of the total cells in the airway but their contribution to the inflammatory response seen in airway disease has not been studied. Hence, we have looked at the release of the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF) in response to bacterial lipopolysaccharide (LPS) and the pro-inflammatory cytokines interleukin-1β (IL-1β), tumour necrosis factor α (TNFα) and interferon γ (IFNγ). Human airway smooth muscle (HASM) cells released GM-CSF under basal conditions (45.4±13.1 pg ml⁻¹) that was significantly enhanced by IL-1β and TNFα with a maximal effect seen at 10 ng ml⁻¹ (1.31±0.07 ng ml⁻¹ and 0.72±0.16 ng ml⁻¹, respectively). In contrast, neither LPS nor IFNγ produced a significant increase in GM-CSF release. However, HASM cells exposed to IL-1β, TNFα and IFNγ generated more GM-CSF than that evoked by any cytokine alone (2.2±0.15 ng ml⁻¹). The release of GM-CSF elicited by the cytokine mixture was inhibited by cycloheximide and dexamethasone. These data suggest that HASM cells might play an active part in initiating and/or perpetuating airway inflammation in addition to controlling airway calibre.     

The influence of antibodies to TNF-α and IL-1β on haemodynamic responses to the cytokines,and to lipopolysaccharide,in conscious rats

1. Male, Long Evans rats (350–450 g) were anaesthetized and had pulsed Doppler probes and intravascular catheters implanted to allow monitoring of regional (renal, mesenteric and hindquarters) haemodynamics in the conscious state. Our main objectives were to:- assess the effects of administering human recombinant tumour necrosis factor (TNF)-α and human recombinant interleukin-1 (IL-1)β, alone and together; determine the influence of pretreatment with a mixture of antibodies to TNF-α and IL-1β on responses to co-administration of the cytokines; ascertain if pretreatment with a mixture of the antibodies to TNF-α and IL-1β had any influence on the responses to lipopolysaccharide (LPS).
2. TNF-α (10, 100 and 250 μg kg⁻¹, in separate groups, n=3, 9 and 8, respectively) caused tachycardia (maximum Δ, +101±9 beats min⁻¹) and modest hypotension (maximum Δ, −10±2 mmHg), accompanied by variable changes in renal and mesenteric vascular conductance, but clear increases in hindquarters vascular conductance; only the latter were dose-related (maximum Δ, +6±6, +27±9, and +61±12% at 10, 100 and 250 μg kg⁻¹, respectively).
3. IL-1β (1, 10, and 100 μg kg⁻¹ in separate groups, n=8, 8 and 9, respectively) evoked changes similar to those of TNF-α (maximum Δ heart rate, +69±15 beats min⁻¹; maximum Δ mean blood pressure, −14±2 mmHg; maximum Δ hindquarters vascular conductance, +49±17%), but with no clear dose-dependency.
4. TNF-α (250 μg kg⁻¹) and IL-1β (10 μg kg⁻¹) together caused tachycardia (maximum Δ, +76±15 beats min⁻¹) and hypotension (maximum Δ, −24±2 mmHg) accompanied by increases in renal, mesenteric and hindquarters vascular conductances (+52±6%, +23±8%, and +52±11%, respectively). Thereafter, blood pressure recovered, in association with marked reductions in mesenteric and hindquarters vascular conductances (maximum Δ, −50±3% and −58±3%, respectively). Although bolus injection of LPS (3.5 mg kg⁻¹) caused an initial hypotension (maximum Δ, −27±11 mmHg) similar to that seen with co-administration of the cytokines, it did not cause mesenteric or hindquarters vasodilatation, and there was only a slow onset renal vasodilatation. The recovery in blood pressure following LPS was less than after the cytokines, and in the former condition there was no mesenteric vasoconstriction. By 24 h after co-administration of TNF-α and IL-1β or after bolus injection of LPS, the secondary reduction in blood pressure was similar (−16±2 and −13±3 mmHg, respectively), but in the former group the tachycardia (+117±14 beats min⁻¹) and increase in hindquarters vascular conductance (+99±21%) were greater than after bolus injection of LPS (+54±16 beats min⁻¹ and +43±9%, respectively).
5. Pretreatment with antibodies to TNF-α and IL-1β (300 mg kg⁻¹) blocked the initial hypotensive and mesenteric and hindquarters vasodilator responses to co-administration of the cytokines subsequently. However, tachycardia and renal vasodilatation were still apparent. Premixing antibodies and cytokines before administration prevented most of the effects of the latter, but tachycardia was still present at 24 h.
6. Pretreatment with antibodies to TNF-α and IL-1β before infusion of LPS (150 μg kg⁻¹ h⁻¹ for 24 h) did not affect the initial fall in blood pressure, but suppressed the hindquarters vasodilatation and caused a slight improvement in the recovery of blood pressure. However, pretreatment with the antibodies had no effect on the subsequent cardiovascular sequelae of LPS infusion.
7. The results indicate that although co-administration of TNF-α and IL-1β can evoke cardiovascular responses which, in some respects, mimic those of LPS, and although antibodies to the cytokines can suppress most of the cardiovascular effects of the cytokines, the antibodies have little influence on the haemodynamic responses to LPS, possibly because, during infusion of LPS, the sites of production and local action of endogenous cytokines, are not accessible to exogenous antibodies.