3-isobutyl-1-methylxanthine Research Articles

Supplementation of Freezing Media with Cyclic Adenosine Monophosphate Analog and Isobutylmethylxanthine on Sperm Quality

Background: This study aimed to explore whether the addition of a cyclic adenosine monophosphate (cAMP) analog and isobutylmethylxanthine (IBMX) in freezing media improved sperm quality and what role cAMP has in this recovery. Materials and methods: ach semen sample was cryopreserved into four groups: fresh semen sample, as a control group, freezing medium + 2.5 mM cAMP analog and 0.2 mM IBMX, freezing medium + 12.5 mM cAMP analog and 0.2 mM IBMX, and freezing medium + 25 mM cAMP analog and 0.2 mM IBMX. Sperm parameters after post-thaw were analyzed according to WHO instruction (2010). Viability, acrosome reaction, and DNA damage levels of the samples were evaluated. Results: Our results indicated that the effective concentrations of 12.5 and 25 mM cAMP analog and 0.2 mM IBMX significantly improved the total motility, progressive motility, and viability of the frozen-thawed (P<0.05). However, non-progressive motility and immotile were significantly reduced in the 12.5 and 25 mM cAMP analogs and 0.2 mM IBMX groups after thawing (P<0.05). During freezing the spermatozoa, the high concentration of the cAMP analog increased acrosome reaction after thawing in the 25 mM and 0.2 mM IBMX treated samples (P<0.05). DNA fragmentation in 25 mM cAMP analog and 0.2 mM (IBMX) supplementation was significantly lower compared to the other groups (P<0.05). Conclusions: Our findings revealed that in vitro cAMP analog and IBMX supplementation in freezing media play an important role in preventing cryodamage by maintaining the sperm functional parameters.

Evaluation of the Antidiabetic and Insulin Releasing Effects of A. squamosa, Including Isolation and Characterization of Active Phytochemicals.

Annona squamosa is generally referred to as a ‘custard apple’. Antidiabetic actions of hot water extract of Annona squamosa (HWAS) leaves together with isolation of active insulinotropic compounds were studied. Insulin release, membrane potential and intracellular Ca2+ were determined using BRIN-BD11 cells and isolated mouse islets. 3T3L1 adipocytes and in vitro models were used to determine cellular glucose uptake, insulin action, starch digestion, glucose diffusion, DPP-IV activity and glycation. Glucose intolerant high-fat fed rats were used for in vivo studies. Active compounds were isolated and characterized by HPLC, LCMS and NMR. HWAS stimulated insulin release from clonal β-cells and mouse islets. Using fluorescent indicator dyes and modulators of insulin secretion, effects could be attributed to depolarization of β-cells and influx of Ca2+. Secretion was stimulated by isobutylmethylxanthine (IBMX), tolbutamide or 30 mM KCl, indicating additional non-KATP dependent pathways. Extract stimulated cellular glucose uptake and insulin action and inhibited starch digestion, protein glycation, DPP-IV enzyme activity and glucose diffusion. Oral HWAS improved glucose tolerance and plasma insulin in high-fat fed obese rats. Treatment for 9 days with HWAS (250 mg/5 mL/kg), partially normalised energy intake, body weight, pancreatic insulin content, and both islet size and beta cell mass. This was associated with improved oral glucose tolerance, increased plasma insulin and inhibition of plasma DPP-IV activity. Isolated insulinotropic compounds, including rutin (C27H30O16), recapitulated the positive actions of HWAS on beta cells and in vivo glucose tolerance and plasma insulin responses. Annona squamosa is attractive as a dietary adjunct in treatment of T2DM and as a source of potential antidiabetic agents including rutin.

Molecular Mechanisms Involved in Neural Substructure Development during Phosphodiesterase Inhibitor Treatment of Mesenchymal Stem Cells.

Stem cells are highly important in biology due to their unique innate ability to self-renew and differentiate into other specialised cells. In a neurological context, treating major injuries such as traumatic brain injury, spinal cord injury and stroke is a strong basis for research in this area. Mesenchymal stem cells (MSC) are a strong candidate because of their accessibility, compatibility if autologous, high yield and multipotency with a potential to generate neural cells. With the use of small-molecule chemicals, the neural induction of stem cells may occur within minutes or hours. Isobutylmethyl xanthine (IBMX) has been widely used in cocktails to induce neural differentiation. However, the key molecular mechanisms it instigates in the process are largely unknown. In this study we showed that IBMX-treated mesenchymal stem cells induced differentiation within 24 h with the unique expression of several key proteins such as Adapter protein crk, hypoxanthine-guanine phosphoribosyltransferase, DNA topoisomerase 2-beta and Cell division protein kinase 5 (CDK5), vital in linking signalling pathways. Furthermore, the increased expression of basic fibroblast growth factor in treated cells promotes phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK) cascades and GTPase–Hras interactions. Bioinformatic and pathway analyses revealed upregulation in expression and an increase in the number of proteins with biological ontologies related to neural development and substructure formation. These findings enhance the understanding of the utility of IBMX in MSC neural differentiation and its involvement in neurite substructure development.

The Phosphodiesterase Inhibitor, Isobutyl-1-Methylxanthine Prevents the Sudden Drop in Cyclic Adenosine Monophosphate Concentration and Modulates Glucose Metabolism of Equine Cumulus–Oocyte Complexes Matured in Vitro

Spontaneous nuclear maturation of mammalian oocytes can occur when physically removed from the ovarian follicle during in vitro oocyte maturation (IVM), largely because of a decrease in cyclic adenosine monophosphate (cAMP) concentration. Modulation of oocyte cAMP during IVM by using phosphodiesterase inhibitors has been shown to maintain elevated oocyte cAMP concentrations and control meiotic resumption of bovine and ovine oocytes. This study determined the effect of inclusion of isobutyl-1-methylxanthine (IBMX) during collection and the first 12 hours of incubation of equine oocytes on cAMP concentration and glucose metabolism of cumulus–oocyte complexes (COCs). Abattoir-derived COCs were collected in aspiration medium with (Asp-IBMX) or without (Asp) IBMX. Cumulus–oocyte complexes were then incubated for 12 hours in IVM medium with (Mat-IBMX) or without (Mat) IBMX, followed by additional 24 hours in Mat medium. The cAMP concentration, glucose consumption, lactate production, and metaphase II rates of the COCs were assessed. Cumulus–oocyte complexes aspirated into Asp-IBMX (62.2 ± 2.6 fmol per COC) medium had higher cAMP concentration than Asp (31.8 ± 2.8 fmol per COC) control group (P < .05). Likewise, at 12 hours of IVM, Mat-IBMX group (33.2 ± 2.1 fmol per COC) had higher cAMP concentration than the Mat group (7.68 ± 0.5 fmol per COC; P < .05). Glucose consumption and lactate production were lower during the first 12 hours of incubation in COCs cultured in Mat-IBMX (P < .05). Isobutyl-1-methylxanthine prevented the rapid drop in cAMP concentration and altered metabolism of glucose by the COC. Preventing the sudden drop in cAMP prevents the premature nuclear maturation of in vitro–matured oocytes causing poor developmental competence.

Methylxanthines Inhibit Primary Amine Oxidase and Monoamine Oxidase Activities of Human Adipose Tissue.

Background: Methylxanthines including caffeine and theobromine are widely consumed compounds and were recently shown to interact with bovine copper-containing amine oxidase. To the best of our knowledge, no direct demonstration of any interplay between these phytochemicals and human primary amine oxidase (PrAO) has been reported to date. We took advantage of the coexistence of PrAO and monoamine oxidase (MAO) activities in human subcutaneous adipose tissue (hScAT) to test the interaction between several methylxanthines and these enzymes, which are involved in many key pathophysiological processes. Methods: Benzylamine, methylamine, and tyramine were used as substrates for PrAO and MAO in homogenates of subcutaneous adipose depots obtained from overweight women undergoing plastic surgery. Methylxanthines were tested as substrates or inhibitors by fluorimetric determination of hydrogen peroxide, an end-product of amine oxidation. Results: Semicarbazide-sensitive PrAO activity was inhibited by theobromine, caffeine, and isobutylmethylxanthine (IBMX) while theophylline, paraxanthine, and 7-methylxanthine had little effect. Theobromine inhibited PrAO activity by 54% at 2.5 mM. Overall, the relationship between methylxanthine structure and the degree of inhibition was similar to that seen with bovine PrAO, although higher concentrations (mM) were required for inhibition. Theobromine also inhibited oxidation of tyramine by MAO, at the limits of its solubility in a DMSO vehicle. At doses higher than 12 % v/v, DMSO impaired MAO activity. MAO was also inhibited by millimolar doses of IBMX, caffeine and by other methylxanthines to a lesser extent. Conclusions: This preclinical study extrapolates previous findings with bovine PrAO to human tissues. Given that PrAO is a potential target for anti-inflammatory drugs, it indicates that alongside phosphodiesterase inhibition and adenosine receptor antagonism, PrAO and MAO inhibition could contribute to the health benefits of methylxanthines, especially their anti-inflammatory effects.

Airway Ciliary Beating Affected by the Pcp4 Dose-Dependent [Ca2+]i Increase in Down Syndrome Mice, Ts1Rhr

In Ts1Rhr, a Down syndrome model mouse, the airway ciliary beatings are impaired; that is, decreases in ciliary beat frequency (CBF) and ciliary bend angle (CBA, an index of ciliary beat amplitude)). A resumption to two copies of the Pcp4 gene on the Ts1Rhr trisomic segment (Ts1Rhr:Pcp4+/+/-) rescues the decreases in CBF and CBA that occur in Ts1Rhr. In airway cilia, upon stimulation with procaterol (a β2-agonist), the CBF increase is slower over the time course than the CBA increase because of cAMP degradation by Ca2+/calmodulin-dependent phosphodiesterase 1 (PDE1) existing in the metabolon regulating CBF. In Ts1Rhr, procaterol-stimulated CBF increase was much slower over the time course than in the wild-type mouse (Wt) or Ts1Rhr:Pcp4+/+/-. However, in the presence of 8MmIBMX (8-methoxymethyl isobutylmethyl xanthine, an inhibitor of PDE1) or calmidazolium (an inhibitor of calmodulin), in both Wt and Ts1Rhr, procaterol stimulates CBF and CBA increases over a similar time course. Measurements of cAMP revealed that the cAMP contents were lower in Ts1Rhr than in Wt or in Ts1Rhr:Pcp4+/+/-, suggesting the activation of PDE1A that is present in Ts1Rhr airway cilia. Measurements of the intracellular Ca2+ concentration ([Ca2+]i) in airway ciliary cells revealed that temperature (increasing from 25 to 37 °C) or 4αPDD (a selective transient receptor potential vanilloid 4 (TRPV4) agonist) stimulates a larger [Ca2+]i increase in Ts1Rhr than in Wt or Ts1Rhr:Pcp4+/+/-. In airway ciliary cells of Ts1Rhr, Pcp4-dose dependent activation of TRPV4 appears to induce an increase in the basal [Ca2+]i. In early embryonic day mice, a basal [Ca2+]i increased by PCP4 expressed may affect axonemal regulatory complexes regulated by the Ca2+-signal in Ts1Rhr, leading to a decrease in the basal CBF and CBA of airway cilia.

Caffeic Acid Phenethyl Ester and Its Fluorinated Derivative as Natural Anti-obesity Agents (P06-089-19)

ObjectivesCaffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives, is well studied for its beneficial effects on cancer, inflammation and diabetes. There are however limited studies investigating the effects of CAPE on obesity. Currently, several natural products are under investigation for their effects on adipocyte life cycle. A multi-targeted approach for prevention and treatment of obesity includes targeting adipocytes at all the stages of life cycle by decreasing adipocyte differentiation, inducing lipolysis and/or by inducing adipocyte apoptosis. In this study, we examined the effects of CAPE on preadipocyte viability, adipogenesis and lipolysis. Earlier reports on CAPE indicate that CAPE is liable to enzymatic hydrolysis in vivo making this compound unstable for therapeutic applications. In the current study, we compared the anti-adipogenic effects of CAPE with its novel fluorinated derivative (FCAPE), a more stable compound. Methods3T3-L1 pre-adipocytes were differentiated using a cocktail consisting of insulin, dexamethasone, and isobutyl methyl xanthine in DMEM supplemented with 10% FBS following adipogeneic differentiation. Pre- and mature adipocytes were incubated with CAPE or FCAPE for 24–48 hours and their effects on viability, lipolysis, and adipogenesis was tested using Prestoblue, Lipolysis assay (Zen-Bio) and AdipoRed assay respectively. ResultsOur results indicate that neither CAPE nor FCAPE significantly altered preadipocyte viability within the tested dose range. Although both CAPE and FCAPE significantly decreased adipogenesis compared to control, FCAPE decreased lipid content by 73.6 ± 1.6% while CAPE reduced lipid content by only 36.8 ± 9.1% at 25 μM concentration. In contrast to adipogenesis data, our preliminary results with lipolysis assay indicate that only CAPE, but not FCAPE induces lipolysis in mature adipocytes. ConclusionsThese findings suggest that both CAPE and FCAPE possess anti-adipogenic properties. Further studies are needed to elucidate their differential effects on adipogenesis and lipolysis. Funding SourcesThis study was funded by the Department of Research, PCOM.

Pharmacological and molecular dynamics analyses of differences in inhibitor binding to human and nematode PDE4: Implications for management of parasitic nematodes

Novel chemical controls are needed that selectively target human, animal, and plant parasitic nematodes with reduced adverse effects on the host or the environment. We hypothesize that the phosphodiesterase (PDE) enzyme family represents a potential target for development of novel nematicides and anthelmintics. To test this, we identified six PDE families present in the nematode phylum that are orthologous to six of the eleven human PDE families. We characterized the binding interactions of family-selective PDE inhibitors with human and C. elegans PDE4 in conjunction with molecular dynamics (MD) simulations to evaluate differences in binding interactions of these inhibitors within the PDE4 catalytic domain. We observed that roflumilast (human PDE4-selective inhibitor) and zardaverine (selective for human PDE3 and PDE4) were 159- and 77-fold less potent, respectively, in inhibiting C. elegans PDE4. The pan-specific PDE inhibitor isobutyl methyl xanthine (IBMX) had similar affinity for nematode and human PDE4. Of 32 residues within 5 Å of the ligand binding site, five revealed significant differences in non-bonded interaction energies (van der Waals and electrostatic interaction energies) that could account for the differential binding affinities of roflumilast and zardaverine. One site (Phe506 in the human PDE4D3 amino acid sequence corresponding to Tyr253 in C. elegans PDE4) is predicted to alter the binding conformation of roflumilast and zardaverine (but not IBMX) into a less energetically favorable state for the nematode enzyme. The pharmacological differences in sensitivity to PDE4 inhibitors in conjunction with differences in the amino acids comprising the inhibitor binding sites of human and C. elegans PDE4 catalytic domains together support the feasibility of designing the next generation of anthelmintics/nematicides that could selectively bind to nematode PDEs.

Anti-melanogenesis potential of a new series of Morita-Baylis-Hillman adducts in B16F10 melanoma cell line

Melanin is a natural polymer pigment which provides skin photoprotection against ultraviolet radiation. An excessive synthesis of melanin leads to hyperpigmentation disorders. Tyrosinase catalyzes the rate limiting steps on melanogenesis. Therefore, tyrosinase inhibitors have potential applications in medicine and cosmetic fields. We carried out herein the screening of a family of cyclic Morita-Baylis-Hillman adducts (MBH) to find out their effects on tyrosinase activity and on melanogenesis in murine melanoma B16F10 cell line. Kinetic analysis of tyrosinase inhibition showed that compounds 1a (2-hydroxymethyl) cyclohex-2-enone) and 3f (diethyl (1-(6-oxocyclohex-1-en-1-yl) ethyl-phosphonate) were competitive inhibitors, whereas the compound 2b (6-oxocyclohex-1-en-1-yl) ethyl acetate) was a non-competitive one. Additionally we have found that (1a, 2b and 3f) compounds had a strong melanogenesis inhibition effect in isobutylmethylxanthine (IBMX)-treated murine melanoma B16F10 cells when tested at low and non cytotoxic dose (10–50 µM), by attenuating the melanin production, intracellular tyrosinase activity and tyrosinase expression. Thus, we suggest that these compounds could be used as effective skin-whitening agents.

PO-119 Adrenergic Receptor β3 Up-regulates Uncoupling Protein 1 and Cyclooxygenase 2 Expressions in The Brown Adipocyte

Objective Brown adipose tissues (BAT) activation is important for losing weight as its high energy expenditure in Mammalian. Recent studies showed that exercise may also be essential for BAT activation. Uncoupling protein 1 (UCP1), specifically expressed in BAT's mitochondria, uncouples oxidative phosphorylation and dissipates energy from Free Fatty Acids into heat. Activating the Adrenergic Receptor β3 (Adrβ3) provides fuel for mitochondrial heat production and up-regulates Cyclooxygenase 2 (COX2), which is a key factor of UCP1 synthesis. Sympathetic nerve excitement stimulated by exercise can release norepinephrine as a neurotransmitter, which can affect Adrβ3. Brown adipocyte (BAC) is a kind of adipocyte in vitro as a model to study heat production. Isoprenaline Hydrochloride (ISO) is a widely used as an Adrβ agonist. In this research, we tried to figure out the response of BAC to Adrβ3 activations with different time points and whether ISO can be used as a BAC activator.&#x0D; Methods C3H10T1/2 cells were maintained in a humidified, 37°C, 5% CO2 incubator in DMEM/F12 medium with 10% fetal bovine serum (FBS). For brown adipogenesis, cells were first split into differentiation medium (DMEM/F12 containing 10% FBS, 20nM insulin, 1nM 3,3’5-Triiodo-L-thyronine(T3)) for 4 days, the medium was changed every other day. Confluent cells were treated for 2 days with brown adipose adipogenesis cocktails (differentiation medium containing 2µg/mL dexamethasone, 0.5mM isobutylmethylxanthine (IBMX), 0.125mM indomethacin and 1µM rosiglitazone) on day 4. Then the medium was replaced by differentiation medium and changed every other day. At day 10, the full differentiation adipocytes were treated with 10µM ISO for 0 (as control), 1, 3, 6, 12 and 24 hours. For the lipid droplets staining, the cells were fixed by 4% paraformaldehyde solution then stained with Oil Red O. The cells were harvested and the total cell lysates were extracted for protein analysis after each time point. The UCP1, COX2, and Adrβ3 expression levels were detected by western blot, using Actin as the internal protein. The results were expressed as the mean ± standard error of the mean (SEM). Group comparisons were performed using two-way ANOVA and LSD’s post-hoc tests.&#x0D; Results After differentiation, the cell shapes converted from fibroblastic to a spherical shape. Dispersed small lipid droplets were observed in the cells. After ISO treatment, the red color after Oil Red Staining became lighter and the size of the lipid droplets turned to smaller. The Adrβ3 protein expressions were 1.00±0.00, 1.34±0.32, 1.07±0.50, 4.65±1.84*, 2.44±0.73, and 3.43±1.09 at 0h, 1h, 3h, 6h, 12h, and 24h after ISO treatment, respectively. After introduced to ISO, the UCP1 expression levels were 1.00±0.00, 1.95±0.39, 2.72±0.57, 5.68±1.82*, 3.49±0.92, and 2.79±1.05 at 0h, 1h, 3h, 6h, 12h, and 24h, respectively. And for COX2, the protein expressions were 1.00±0.00, 2.13±0.67, 1.82±0.33, 4.67±1.82*, 2.88±0.44, and 2.65±0.54, respectively. The * means p ˂ 0.05, compared with oh controls. The proteins expressions were reached to peak after 6 hours ISO treatment from the above results.&#x0D; Conclusions UCP1 and COX2 protein expressions were increased in BAC according to Adrβ3's expression in different time points, indicating that Adrβ3 may induce adipolysis in BAC and help to burn fat and produce heat.

The Phosphodiesterase Inhibitor, Isobutyl-1-methylxanthine (IBMX) Prevents the Sudden Drop in cAMP Concentration and Modulates Glucose Metabolism of Equine COCs Matured In Vitro

Sperm cryopreservation is an effective method of preserving male fertility in humans, as well as domestic and experimental animals. However, various factors such as ice crystal formation, osmotic stress, and oxidative stress, negatively influence the motility and viability of post-thawed spermatozoa. Betaine, which works as an osmoprotectant is known to work as a nontoxic cryoprotectant. However, the protective effects during mouse sperm cryopreservation are still unclear. Thus, the purpose of this study was to investigate whether betaine has protective effects during the process of mouse sperm cryopreservation. In this study, betaine was found to be effective in maintaining sperm motility during the freezing procedure and 1% (85.4 mM) betaine was identified as the optimal concentration to be added to cryopreservation solutions. It was also found that betaine improves the integrity of the plasma membranes of sperm tails, suggesting that betaine has a positive effect on sperm motility.

Calcium: A novel and efficient inducer of differentiation of adipose-derived stem cells into neuron-like cells.

This study comparatively investigated the effectiveness of calcium and other well-known inducers such as isobutylmethylxanthine (IBMX) and insulin in differentiating human adipose-derived stem cells (ADSCs) into neuronal-like cells. ADSCs were immunophenotyped and differentiated into neuron-like cells with different combinations of calcium, IBMX, and insulin. Calcium mobilization across the membrane was determined. Differentiated cells were characterized by cell cycle profiling, staining of Nissl bodies, detecting the gene expression level of markers such as neuronal nuclear antigen (NeuN), microtubule associated protein 2 (MAP2), neuron-specific enolase (NSE), doublecortin, synapsin I, glial fibrillary acidic protein (GFAP), and myelin basic protein (MBP) by quantitative real-time polymerase chain reaction (quantitative real-time polymerase chain reaction (qRT-PCR) and protein level by the immunofluorescence technique. Treatment with Ca + IBMX + Ins induced neuronal appearance and projection of neurite-like processes in the cells, accompanied with inhibition of proliferation and halt in the cell cycle. A significantly higher expression of MBP, GFAP, NeuN, NSE, synapsin 1, doublecortin, and MAP2 was detected in differentiated cells, confirming the advantages of Ca + IBMX + Ins to the other combinations of inducers. Here, we showed an efficient protocol for neuronal differentiation of ADSCs, and calcium fostered differentiation by augmenting the number of neuron-like cells and instantaneous increase in the expression of neuronal markers.

Voltage-dependent inward currents in smooth muscle cells of skeletal muscle arterioles.

Voltage-dependent inward currents responsible for the depolarizing phase of action potentials were characterized in smooth muscle cells of 4th order arterioles in mouse skeletal muscle. Currents through L-type Ca2+ channels were expected to be dominant; however, action potentials were not eliminated in nominally Ca2+-free bathing solution or by addition of L-type Ca2+ channel blocker nifedipine (10 μM). Instead, Na+ channel blocker tetrodotoxin (TTX, 1 μM) reduced the maximal velocity of the upstroke at low, but not at normal (2 mM), Ca2+ in the bath. The magnitude of TTX-sensitive currents recorded with 140 mM Na+ was about 20 pA/pF. TTX-sensitive currents decreased five-fold when Ca2+ increased from 2 to 10 mM. The currents reduced three-fold in the presence of 10 mM caffeine, but remained unaltered by 1 mM of isobutylmethylxanthine (IBMX). In addition to L-type Ca2+ currents (15 pA/pF in 20 mM Ca2+), we also found Ca2+ currents that are resistant to 10 μM nifedipine (5 pA/pF in 20 mM Ca2+). Based on their biophysical properties, these Ca2+ currents are likely to be through voltage-gated T-type Ca2+ channels. Our results suggest that Na+ and at least two types (T- and L-) of Ca2+ voltage-gated channels contribute to depolarization of smooth muscle cells in skeletal muscle arterioles. Voltage-gated Na+ channels appear to be under a tight control by Ca2+ signaling.

Effects of phosphorylation state on perilipin 5 localization and trafficking.

Perilipins are a family of five proteins found on the surface of lipid storage droplets in nearly all tissues. These proteins act as cofactors for lipases and scaffolding for other proteins involved in lipid metabolism. In addition to the lipid droplet surface, members of the perilipin family have been found in the cytosol, endoplasmic reticulum, plasma membrane and mitochondria. The localization of these proteins is in part determined by their phosphorylation state. Recently perilipin 5 has been shown to localize to the nucleus when phosphorylated by PKA on serine 155 and interact with the peroxisome proliferator‐activated receptor gamma coactivator alpha (PGC‐1a). In silico analysis of a phosphomimetic mutant (Ser155Asp) indicate that this site may contain a nuclear localization sequence. Using a CHO model cell line we observed that translocation to the nucleus could be stimulated by treatment with forskolin and isobutylmethylxanthine (IBMX) and occurred independent of treating cells with oleic acid to promote triacylglycerol deposition. We are currently investigating the affects of stimulating other phosphorylation pathways to determine if they also phosphorylate perilipin 5 and affect subcellular localization. These data have the potential to gain insights to the regulation of perilipin 5 trafficking into the nucleus and therefore interacting with PGC‐1a regulating mitochondrial biogenesis.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Porcine Epidemic Diarrhea Virus, a Member of the Coronaviridae Family, Increases Epithelial Secretion in the Jejunum by Up‐regulation of KCNN4

The porcine epidemic diarrhea virus (PEDV), an alphacoronavirus affects the small intestine of suckling piglets causing acute watery diarrhea. Here, the effects on agonist‐induced electrogenic secretory response by PEDV was assessed to determine its role in the diarrheal disease. Jejunal tissues were compared in healthy (n=12) and diseased (n=20) one‐week‐old crossbred Yorkshire x Landrace piglets in Ussing chambers. Diseased jejunal tissues displayed elevated changes in Isc following agonist addition compared to control. Activation of cAMP driven secretion via isoproterenol (adrenergic agonist) and forskolin/3‐isobutyl‐1‐methylxanthine (IBMX) demonstrated a significantly increased change in short‐circuit current (Isc). Cholinergic activation of secretion via carbachol revealed no significant difference in Isc, however, 9/20 diseased jejunal tissues had a negative change in Isc while the remaining 11/20 had a positive change in Isc. Bumentanide inhibitable Isc was not significantly different in diseased tissues compared to controls. Inhibition of cAMP induced secretion via glibenclamide revealed a significant increase in Isc, while niflumic acid, a potent inhibitor of calcium‐activated chloride channels, had no significant effect. Non‐selective potassium channel blocker tetraethylammonium chloride (TEA) revealed a significant decrease in the Isc of diseased animals compared to control. Furthermore, significant decrease in transepithelial electrical resistance (TEER) was noted in jejunal tissues infected with PED virus compared to controls. RT‐qPCR was conducted to determine if elevated chloride and potassium channel gene transcripts were responsible for the increase in cAMP induced secretion. Inflammatory cytokines were also assessed to determine their role in ion channel modulation. mRNA expression of the Cystic Fibrosis transmembrane conductance regulator (CFTR) in the jejunum of PEDV infected piglets was not significantly different than control, while potassium voltage‐gated channel subfamily Q member 1 (KCNQ1) was significantly down‐regulated in diseased animals. However, mRNA expression of potassium calcium‐activated channel subfamily N member 4 (KCNN4) and Transmembrane member protein 16A (TMEM16A) were significantly up‐regulated 3‐fold (P &lt; 0.05) and 5‐fold (P &lt; 0.05) respectively in the jejunum of diseased pigs compared to control. Furthermore, gene expression of proinflammatory cytokines was determined to be significantly elevated in the jejunum of diseased piglets. Collectively, these findings suggest that upregulation of KCNN4 by proinflammatory cytokines is responsible for the increased change in agonist induced Isc by driving chloride secretion via CFTR and TMEM16A.Support or Funding InformationThis research was supported by Genome Alberta GAB‐PEDH ‐ U of S – 344078, the Saskatchewan Agricultural Development Fund (ADF) Project 20140215, and the National Sciences and Engineering Research Council of Canada Discovery Grant 371364‐2010 (M.E.L.)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Embryonic cholesterol esterification is regulated by a cyclic AMP-dependent pathway in yolk sac membrane-derived endodermal epithelial cells.

During avian embryonic development, endodermal epithelial cells (EECs) absorb yolk through the yolk sac membrane. Sterol O-acyltransferase (SOAT) is important for esterification and yolk lipid utilization during development. Because the major enzyme for yolk sac membrane cholesteryl ester synthesis is SOAT1, we cloned the avian SOAT1 promoter and elucidated the cellular functions of SOAT1. Treatments with either glucagon, isobutylmethylxanthine (IBMX), an adenylate cyclase activator (forskolin), a cAMP analog (dibutyryl-cAMP), or a low glucose concentration all increased SOAT1 mRNA accumulation in EECs from Japanese quail, suggesting that SOAT1 is regulated by nutrients and hormones through a cAMP-dependent pathway. Activity of protein kinase A (PKA) was increased by IBMX, whereas co-treatment with the PKA inhibitor, H89 negated the increase in PKA activity. Cyclic AMP-induced EECs had greater cholesterol esterification than untreated EECs. By promoter deletion and point-mutation, the cAMP-response element (-349 to -341 bp) was identified as critical in mediating transcription of SOAT1. In conclusion, expression of SOAT1 was regulated by a cAMP-dependent pathway and factors that increase PKA will increase SOAT1 to improve the utilization of lipids in the EECs and potentially modify embryonic growth.

Optogenetic Analysis of Depolarization-Dependent Glucagonlike Peptide-1 Release.

Incretin hormones play an important role in the regulation of food intake and glucose homeostasis. Glucagonlike peptide-1 (GLP-1)–secreting cells have been demonstrated to be electrically excitable and to fire action potentials (APs) with increased frequency in response to nutrient exposure. However, nutrients can also be metabolized or activate G-protein–coupled receptors, thus potentially stimulating GLP-1 secretion independent of their effects on the plasma membrane potential. Here we used channelrhodopsins to manipulate the membrane potential of GLUTag cells, a well-established model of GLP-1–secreting enteroendocrine L cells. Using channelrhodopsins with fast or slow on/off kinetics (CheTA and SSFO, respectively), we found that trains of light pulses could trigger APs and calcium elevation in GLUTag cells stably expressing either CheTA or SSFO. Tetrodotoxin reduced light-triggered AP frequency but did not impair calcium responses, whereas further addition of the calcium-channel blockers nifedipine and ω-conotoxin GVIA abolished both APs and calcium transients. Light pulse trains did not trigger GLP-1 secretion from CheTA-expressing cells under basal conditions but were an effective stimulus when cyclic adenosine monophosphate (cAMP) concentrations were elevated by forskolin plus 3-isobutyl 1-methylxanthine. In SSFO-expressing cells, light-stimulated GLP-1 release was observed at resting and elevated cAMP concentrations and was blocked by nifedipine plus ω-conotoxin GVIA but not tetrodotoxin. We conclude that cAMP elevation or cumulative membrane depolarization triggered by SSFO enhances the efficiency of light-triggered action potential firing, voltage-gated calcium entry, and GLP-1 secretion.

Simultaneous estimation of lisofylline and pentoxifylline in rat plasma by high performance liquid chromatography-photodiode array detector and its application to pharmacokinetics in rat.

Lisofylline (LSF) is an anti-inflammatory and immunomodulatory agent with proven activity in serious infections associated with cancer chemotherapy, hyperoxia-induced acute lung injury, autoimmune disorders including type-1 diabetes (T1DM) and islet rejection after islet transplantation. It is also an active metabolite of another anti-inflammatory agent, Pentoxifylline (PTX). LSF bears immense therapeutic potential in multiple pharmacological activities and hence appropriate and accurate quantification of LSF is very important. Although a number of analytical methods for quantification of LSF and PTX have been reported for pharmacokinetics and metabolic studies, each of these have certain limitations in terms of large sample volume required, complex extraction procedure and/or use of highly sophisticated instruments like LC-MS/MS. The aim of current study is to develop a simple reversed-phase HPLC method in rat plasma for simultaneous determination of LSF and PTX with the major objective of ensuring minimum sample volume, ease of extraction, economy of analysis, selectivity and avoiding use of instruments like LC-MS/MS to ensure a widespread application of the method. A simple liquid-liquid extraction method using methylene chloride as extracting solvent was used for extracting LSF and PTX from rat plasma (200μL). Samples were then evaporated, reconstituted with mobile phase and injected into HPLC coupled with photo-diode detector (PDA). LSF, PTX and 3-isobutyl 1-methyl xanthine (IBMX, internal standard) were separated on Inertsil® ODS (C18) column (250×4.6mm, 5μm) with mobile phase consisting of A-methanol B-water (50:50v/v) run in isocratic mode at flow rate of 1mL/min for 15min and detection at 273nm. The method showed linearity in the concentration range of 50-5000ng/mL with LOD of 10ng/mL and LLOQ of 50ng/mL for both LSF and PTX. Weighted linear regression analysis was also performed on the calibration data. The mean absolute recoveries were found to be 80.47±3.44 and 80.89±3.73% for LSF and PTX respectively. The method was successfully applied for studying the pharmacokinetics of LSF and PTX after IV bolus administration at dose of 25mg/kg in Wistar rat. In conclusion, a simple, sensitive, accurate and precise reversed-phase HPLC-UV method was established for simultaneous determination of LSF and PTX in rat plasma.

Sperm capacitation pretreatment positively impacts bovine intracytoplasmic sperm injection.

The efficiency of intracytoplasmic sperm injection (ICSI) in bovines is low compared to other species due in part to inadequate egg activation and sperm nucleus decondensation after injection. We hypothesized that this low efficiency is due to the lack of complete sperm capacitation, so we evaluated the effects of isobutylmethylxanthine (IBMX) and methyl-β-cyclodextrin (MβCD) on bovine sperm capacitation and on the preimplantation developmental potential of bovine embryos generated by ICSI. Treatment with IBMX and MβCD decreased sperm viability (between 13-30%); nevertheless, 0.4 mM IBMX and 1 mM MβCD increased (p < 0.05) capacitation metrics-that is, acrosome exocytosis, intracellular calcium level, plasma membrane fluidity, and tyrosine phosphorylation-compared to the control. After ICSI, embryos injected with IBMX- and MβCD-treated sperm showed similar cleavage to the untreated group (range 82-88%). Pronucleus formation rate was higher with MβCD-pretreatment (54%) compared to the control group (25%), and blastocyst rate was significantly improved with MβCD-pretreatment (24%) compared to the IBMX (18%) and control (17%) groups. Importantly, embryo quality-as assessed by the total number of cells, cell allocation, and apoptotic cell index-was not affected by the sperm treatments. In conclusion, MβCD pretreatment of sperm improved the efficiency of blastocyst production in bovine ICSI.

Glucocorticoid‐induced inhibition of AKT leads to CREB phosphorylation and increased myostatin expression via a PDE/cAMP/PKA pathway in skeletal muscle

Muscle atrophy in diseases like chronic kidney disease and diabetes is associated with dysfunctional regulation of insulin/Akt/FoxO3 and myostatin‐SMAD3 signaling pathways. We recently found CREB, a transcription factor that regulates maintenance and regeneration of skeletal muscle, is phosphorylated in wasting conditions. In silico analysis identifies a CREB binding site in the myostatin promoter. This study investigated the mechanism by which atrophy‐inducing conditions regulate CREB phosphorylation and its impact on myostatin expression. Differentiated C2C12 myotubes were incubated with combinations of dexamethasone (Dex), LY294002 (PI‐3 kinase inhibitor), H89 (protein kinase A inhibitor), isobutylmethyl xanthine (IBMX, a general phosphodiesterase (PDE) inhibitor), milrinone (PDE3 inhibitor), or rolipram (PDE4 inhibitor) for up to 24 h. Cells were harvested for analysis of proteins or mRNAs. Treatment of myotubes with Dex for 6–24h increased CREB phosphorylation (pCREB) within 3 h and sustained the increase over 24h. Dex also inhibited Akt phosphorylation (pAkt) over a similar time frame. Inhibition of pAkt by LY294002 mimicked Dex by increasing pCREB; the actions of LY294002 and Dex on pCREB were not additive. Since Akt can activate PDE3/PDE4 and reduce cAMP/PKA signaling in non‐muscle cells, we tested whether Dex‐induced inhibition of PDE3/4 increases pCREB. Without Dex, IBMX, milrinone, and rolipram increased pCREB. The Dex‐induced increase in pCREB was attenuated by the PKA inhibitor H89. When added individually, Dex, milrinone, rolipram and IBMX increase myostatin mRNA and protein significantly. Our study identifies a new mechanism by which atrophy‐inducing conditions activate CREB and contribute to myostatin expression. Signals that attenuate insulin/Akt signaling reduce the PDE3/4 activity. This leads to an increase in cAMP, PKA activity, CREB phosphorylation and myostatin expression.Support or Funding InformationFunded by NIH RO1 DK95610 and VA Merit X01BX001456