A morpholinocatechol compound (UK42620) with clonidine- and tyramine-like actions

1. The actions of a morpholinocatechol (UK42620) were studied in rat isolated atria preparations consisting of spontaneously beating left and right atrial pairs. 2. UK42620 produced positive inotropic and chronotropic responses and, in atria that were incubated with [(3)H]-noradrenaline, it also produced a massive increase in the release of radioactivity. 3. These actions of UK42620 were similar to those of tyramine and were blocked by the beta-adrenoceptor antagonist propranolol (0.3 microM) and by the neuronal uptake blocker desipramine (1 microM). 4. In the presence of desipramine, UK42620 but not tyramine produced a decrease in the stimulation-induced efflux of radioactivity that was antagonized by idazoxan. 5. Thus, UK42620 had prejunctional alpha(2)-adrenoceptor activity like that of clonidine- and tyramine-like activity releasing large amounts of noradrenaline.     

Pharmacokinetic actions of exendin‐4 in the rat: Comparison with glucagon‐like peptide‐1

Exendin‐4, originally isolated from saliva of the lizard Heloderma suspectum, shares 53% sequence homology and several potentially antidiabetic actions with the mammalian hormone glucagon‐like peptide‐1(7‐36)amide (GLP‐1). It shows a higher potency and longer duration of effect in vivo, which may be partly attributed to pharmacokinetic properties. The present study compares the pharmacokinetics of GLP‐1 and exendin‐4 in rats after intravenous (iv), subcutaneous (sc), or intraperitoneal (ip) administration. Samples were assayed for active GLP‐1 (7‐36) amide using an enzyme‐linked immunosorbent assay that does not detect GLP‐1 (1‐36‐amide), (1‐37), (9‐36‐amide) or (9‐37). In parallel experiments, samples were assayed for exendin‐4 using a two‐site immunoradiometric assay that reacts specifically with full‐length exendin‐4. The estimated half‐life for GLP‐1 and exendin‐4 were 0.8–4.7 min and 18–41 min for iv bolus, and 4.6–7.1 min and 90–216 min for SC administration, respectively. Half‐lives after ip injection were 0.6–13.5 min for GLP‐1 and 125–174 min for exendin‐4. Bioavailability for GLP‐1 and exendin‐4 was 44–71% and 65–75%, respectively, for sc injection. For ip injection, bioavailability for GLP‐1 and exendin‐4 was 36–67% and 74–76%, respectively. Plasma clearance, as determined from iv infusion data, was 35–38 ml/min for GLP‐1 and 4‐8 ml/min for exendin‐4. Both Co/C_max and AUC values were proportional to dose with each route of administration. Plasma clearance of exendin‐4 was reduced by 4.4‐fold in nephrectomized animals. In conclusion, exendin‐4 exhibited a much longer plasma half‐life than GLP‐1 in rats after iv, sc, or ip injection, which may contribute in some part to reported differences in duration of biological action of the two peptides. Drug Dev. Res. 53:260–267, 2001. © 2001 Wiley‐Liss, Inc.     

The influences of extremely low frequency magnetic fields on clonidine‐induced sleep in 2‐day‐old chicks

1 It has been shown that magnetic fields (MFs) affect a variety of biological effects in animal brains. There have been few experiments on the effects of MFs on sleep. Therefore, we investigated whether extremely low frequency (ELF) MFs affect the sleep induced by clonidine, a central α₂‐adrenoceptor agonist. Clonidine produced dose‐related increase of the sleeping time and dose‐related decrease of the onset time in 2‐day‐old chicks. 2 Exposure of chicks to MFs (5, 10, 20 G; for 3, 6, 9, 12 h) significantly increased the clonidine‐induced sleep time as a direct function of intensity and duration of MF application. Clonidine reduced noradrenaline or tyrosine in the brain, an effect which was not further changed in animals exposed to MF. 3 To determine whether the gamma amino butyric acid A (GABA_A)/benzodiazepine (BZD) receptor system is involved in the decrease in clonidine‐induced sleep caused by activation of central α₂‐adrenergic systems, we examined exposure of chicks to the effects of the BZD receptor antagonist flumazenil (0.5 mg kg^?1, i.p.) and GABA_A antagonist bicuculline (0.1 mg kg^?1, i.p.) on clonidine‐induced sleep. Bicuculline and flumazenil inhibited the increase of clonidine‐induced sleep time by MFs. Clonidine or MFs did not change GABA levels in the brain. 4 These results suggest that MFs can increase clonidine‐induced sleep via a change of GABA_A and BZD receptor system irrespective of the concentration of GABA or noradrenaline in the brain of 2‐day‐old chicks.     

A napin‐like polypeptide with translation‐inhibitory,trypsin‐inhibitory,antiproliferative and antibacterial activities from kale seeds

Abstract: A heterodimeric napin‐like polypeptide with translation‐inhibiting and antibacterial activities has been isolated from kale seeds. The purification procedure entailed ion‐exchange chromatography on dielthylaminoethyl (DEAE)‐cellulose, affinity chromatography on Affi‐gel blue gel, ion‐exchange chromatography by fast protein liquid chromatography (FPLC) on Mono S, and gel filtration by FPLC on Superdex 75. The napin‐like polypeptide was unadsorbed on DEAE‐cellulose but adsorbed on Affi‐gel blue gel and Mono S. Its 7‐kDa large subunit differs in N‐terminal amino acid sequence from the 4‐kDa small subunit. The polypeptide inhibited translation in the rabbit reticulocyte lysate system with an IC₅₀ of 37.5 nm . This activity was preserved between pH 5 and pH 11, and between 10 and 40 °C. It fell to a low level at pH 3 and pH 13 and at 70 °C. Antibacterial activity against Bacillus, Megabacterium, and Pseudomonas species and antiproliferative activity against leukemia L1210 cells were observed. However, the polypeptide did not exert antifungal, ribonuclease, or protease activity.     

Novel markers to detect recombinant human insulin‐like growth factor‐I (rhIGF‐I)/rhIGF binding protein‐3 (rhIGFBP‐3) misuse in athletes

Insulin‐like growth factor‐I (IGF‐I) is abused by elite athletes for its metabolic and anabolic effects. We have previously shown that it is possible to detect IGF‐I misuse by measuring serum IGF‐I and procollagen type III amino‐terminal propeptide (P‐III‐NP) but a pilot study suggested measuring IGF‐II, IGF binding protein‐2 (IGFBP‐2) and acid‐labile subunit (ALS) may improve the detection of IGF‐I administration. The aim of the study was to assess this in a randomized controlled trial. Twenty‐six female and 30 male recreational athletes were randomized to 28 days’ treatment with placebo or recombinant human (rh)IGF‐I/rhIGF binding protein‐3 (IGFBP‐3) complex (30 mg/day or 60 mg/day), followed by 56 days’ washout. IGF‐II, IGFBP‐2 and ALS (women only) were measured using commercial immunoassays. IGFBP‐2 increased and IGF‐II decreased in response to both low and high dose rhIGF‐I/rhIGFBP‐3 in both women and men while ALS decreased in women in response to high dose rhIGF‐I/rhIGFBP‐3. Two days after discontinuing treatment, significant differences remained between the three treatment groups in IGFBP‐2 and IGF‐II, but not ALS. Thereafter there were no significant differences between the three treatment groups in any of the markers. Combining IGF‐I with IGF‐II and/or IGFBP‐2 improved the performance of the test to detect rhIGF‐I/rhIGFBP‐3 administration in both women and men. Copyright © 2016 John Wiley & Sons, Ltd.     

The role of Toll‐like receptor 4 (TLR4) in cardiac ischaemic‐reperfusion injury,cardioprotection and preconditioning

Cardiac ischaemic‐reperfusion injury (IRI) remains the primary cause of mortality throughout the developed world. Molecular mechanisms underlying IRI are complex and are often interlinked with each other driving a synergistic response. Toll‐like receptor 4 (TLR4), an immunosurveillance receptor, is known to enhance tissue injury during IRI by enhancing the inflammatory response. The release of endogenous components during IRI bind onto TLR4 leading to the activation of multiple signalling kinases. Once this event occurs these proteins are defined as danger associated molecular patterns molecules (DAMPs) or alarmins. Examples include heat shock proteins, high mobility group box one (HMGB1) and extracellular matrix proteins, all of which are involved in IRI. However, literature in the last two decades suggests that transient stimulation of TLR4 may suppress IRI and thus improve cardiac recovery. Furthermore, it remains to be seen what role TLR4 plays during ischaemic‐preconditioning where acute bouts of ischaemia, preceding a harmful bout of ischaemic‐reperfusion, is cardioprotective. The other question which also needs to be considered is that if transient TLR4 signalling drives a preconditioning response then what are the ligands which drive this? Hence the second part of this review explores the possible TLR4 ligands which may promote cardioprotection against IRI.     

Purification and characterization of charantin,a napin‐like ribosome‐inactivating peptide from bitter gourd (Momordica charantia) seeds

Abstract: A peptide designated charantin, with a molecular mass of 9.7 kDa, was isolated from bitter gourd seeds. The procedure comprised affinity chromatography on Affi‐gel blue gel, ion‐exchange chromatography on Mono S and gel filtration on Superdex 75. The N‐terminal sequence of charantin exhibited marked similarity to that of the 7.8‐kDa napin‐like peptide previously isolated from bitter gourd seeds. Charantin inhibited cell‐free translation in a rabbit reticulocyte lysate system with an IC₅₀ of 400 nm , a potency lower than that of the previously reported small ribosome‐inactivating protein γ‐momorcharin (IC₅₀ = 55 nm ) which also exhibited an abundance of arginine and glutamate/glutamine residues. Charantin reacted positively in the N‐glycosidase assay, yielding a band similar to that formed by the small ribosome‐inactivating proteins γ‐momorcharin and luffin S.     

Effects of gastric inhibitory polypeptide,glucagon‐like peptide‐1 and glucagon‐like peptide‐1 receptor agonists on Bone Cell Metabolism

The relationship between gut and skeleton is increasingly recognized as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1) are secreted from the intestine in response to nutrient intake and exhibit several physiological functions including regulation of islet hormone secretion and glucose levels. A number of GLP‐1 receptor agonists (GLP‐1RAs) are currently used in treatment of type 2 diabetes and obesity. However, GIP and GLP‐1 cognate receptors are widely expressed suggesting that incretin hormones mediate effects beyond control of glucose homeostasis, and reports on associations between incretin hormones and bone metabolism have emerged. The aim of this MiniReview was to provide an overview of current knowledge regarding the in vivo and in vitro effects of GIP and GLP‐1 on bone metabolism. We identified a total of 30 pre‐clinical and clinical investigations of the effects of GIP, GLP‐1 and GLP‐1RAs on bone turnover markers, bone mineral density (BMD), bone microarchitecture and fracture risk. Studies conducted in cell cultures and rodents demonstrated that GIP and GLP‐1 play a role in regulating skeletal homeostasis, with pre‐clinical data suggesting that GIP inhibits bone resorption whereas GLP‐1 may promote bone formation and enhance bone material properties. These effects are not corroborated by clinical studies. While there is evidence of effects of GIP and GLP‐1 on bone metabolism in pre‐clinical investigations, clinical trials are needed to clarify whether similar effects are present and clinically relevant in humans.     

Isotopic labeling of 2‐desoxoparaherquamide A (PNU‐141962) with deuterium

Modifications of marcfortine A and paraherquamide A led to the discovery of 2‐desoxoparaherquamide A (PNU‐141962, 3 ) which is as active as paraherquamide A and has an improved safety profile. In order to do preclinical studies, we wished to synthesize isotope‐labeled PNU‐141962. This account will describe the synthesis of [CD₃]‐2‐desoxoparaherquamide A ( 4 ). The deuterium product was prepared in anticipation of using a similar synthesis for the preparation of the corresponding ¹⁴C‐ and ³H‐labeled products. Copyright © 2002 John Wiley & Sons, Ltd.     

Agmatine Reverses Sub‐chronic Stress induced Nod‐like Receptor Protein 3 (NLRP3) Activation and Cytokine Response in Rats

The activation of Nod‐like receptor protein 3 (NLRP3) has lately been implicated in stress and depression as an initiator mechanism required for the production of interleukin (IL)‐1β and IL‐18. Agmatine, an endogenous polyamine widely distributed in mammalian brain, is a novel neurotransmitter/neuromodulator, with antistress, anxiolytic and antidepressant‐like effects. In this study, we examined the effect of exogenously administered agmatine on NLRP3 inflammasome pathway/cytokine responses in rats exposed to restraint stress for 7 days. The rats were divided into three groups: stress, stress+agmatine (40 mg/kg; i.p.) and control groups. Agmatine significantly down‐regulated the gene expressions of all stress‐induced NLRP3 inflammasome components (NLRP3, NF‐κB, PYCARD, caspase‐1, IL‐1β and IL‐18) in the hippocampus and prefrontal cortex (PFC) and reduced pro‐inflammatory cytokine levels not only in both brain regions, but also in serum. Stress‐reduced levels of IL‐4 and IL‐10, two major anti‐inflammatory cytokines, were restored back to normal by agmatine treatment in the PFC. The findings of the present study suggest that stress‐activated NLRP3 inflammasome and cytokine responses are reversed by an acute administration of agmatine. Whether antidepressant‐like effect of agmatine can somehow, at least partially, be mediated by the inhibition of NLRP3 inflammasome cascade and relevant inflammatory responses requires further studies in animal models of depression.     

Characteristics of metabolic stability and the cell permeability of 2‐pyrimidinyl‐piperazinyl‐alkyl derivatives of 1H‐imidazo[2,1‐f]purine‐2,4(3H,8H)‐dione with antidepressant‐ and anxiolytic‐like activities

A series of 2‐pyrimidinyl‐piperazinyl‐alkyl derivatives of 1H‐imidazo[2,1‐f]purine‐2,4(3H,8H)‐dione has been synthesized in an attempt to discover a new class of psychotropic agents. Compounds were evaluated for their in vitro affinity for serotonin 5‐HT_1A, 5‐HT₇, and phosphodiesterases PDE4 and PDE10. The most potent compound 2‐pyrimidinyl‐1‐piperazinyl‐butyl‐imidazo[2,1‐f]purine‐2,4‐dione ( 4b ) behaved as strong and selective antagonist of 5‐HT_1A. Molecular modeling studies revealed differences in binding mode between compound 4b and buspirone, which might reflect variation of the ligands’ affinity and potency in the 5‐HT_1A receptor. Compound 4b in silico models demonstrated drug‐likeness properties and, contrary to buspirone, showed a metabolic stability in mouse liver microsomes system. Experimentally obtained value of apparent permeability coefficient P_app for 4b in parallel artificial permeability assay indicates the possibility of binding weakly to plasma proteins and high intestinal absorption fraction. Evaluation of the antidepressant‐ and anxiolytic‐like activities of 4b revealed both activities at the same dose of 1.25 mg/kg and seemed to be specific. The antidepressant and/or anxiolytic properties of 4b may be related to its first‐pass effect.     

Protective effects of melatonin and glucagon‐like peptide‐1 receptor agonist (liraglutide) on gastric ischaemia–reperfusion injury in high‐fat/sucrose‐fed rats

Ischaemia–reperfusion (I–R) injury is a serious pathology that is often encountered with thrombotic events, during surgery when blood vessels are cross‐clamped, and in organs for transplantation. Increased oxidative stress is the main pathology in I–R injury, as assessed in studies on the heart, kidney, and brain with little data available on gastric I–R (GI–R). Liraglutide is a GLP‐1 receptor agonist that has insulinotropic and weight reducing actions, and melatonin that has been much studied as a chronotropic hormone; have also studied as being anti‐oxidative stress agents. Herein, we aimed to explore the effects of liraglutide and melatonin on GI–R injury with high‐fat/sucrose diet. Rats were divided into six groups; two diet‐control, two melatonin‐ and two liraglutide‐pretreated groups. All rats were subjected to 30 minutes of gastric ischaemia followed by 1 hour of reperfusion. Gastric tissues were assessed for the percentage of DNA fragmentation, myeloperoxidase activity, total oxidant status, total antioxidant capacity, oxidative stress index, BMI and histopathological examination. We showed that high‐fat feeding for four weeks prior to GI–R significantly increased BMI, oxidative stress indices and decreased total antioxidant capacity, with a neutral effect on apoptosis compared to controls. Pretreatment with either melatonin (10 mg/kg per day orally) or liraglutide (25 μg/kg per day ip) reverses these effects. Furthermore, both drugs reduced weight only in HFS‐fed rats. Both liraglutide and melatonin have nearly similar protective effects on gastric I–R injury through decreasing the oxidative stress and apoptosis.     

Cyanidin‐3‐glucoside inhibits inflammatory activities in human fibroblast‐like synoviocytes and in mice with collagen‐induced arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint tissue inflammation. Cyanidin‐3‐glucoside (C3G) is a major component in the flavonoid family and has shown anti‐inflammatory, anti‐oxidant and anti‐tumour activity. In this study, we investigated the effects of C3G on lipopolysaccharides (LPS)‐induced inflammation on human rheumatoid fibroblast‐like synoviocytes (FLS) and on collagen‐induced arthritis (CIA) mice model. We treated FLS with C3G followed by LPS induction, the expressions of tumour necrosis factor alpha (TNF‐α), interleukin 1 beta (IL‐1β) and IL‐6 and the activation of nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) and mitogen‐activated protein kinase (MAPK) signalling pathway were analyzed. CIA was induced in mice and the arthritic mice were treated with C3G for 3 weeks. The disease severity was compared between control and C3G treated mice. The serum levels of TNF‐α, IL‐1β and IL‐6 were analyzed by ELISA. C3G inhibited LPS‐induced TNF‐α, IL‐1β and IL‐6 expression in FLS. Moreover, C3G inhibited LPS‐induced p65 production and IκBa, p38, ERK and JNK phosphorylation. Administration of C3G significantly attenuated disease in mice with CIA and decreased the serum level of TNF‐α, IL‐1β and IL‐6. C3G inhibited LPS‐induced inflammation in human FLS by inhibiting activation of NF‐κB and MAPK signalling pathway. C3G exhibited therapeutic effects in mice with CIA.