Effects of cyclopiazonic acid and dexamethasone on serotonin-induced calcium responses in vascular smooth muscle cells

Duloxetine HCl Alleviates Asthma Symptoms by Regulating PI3K/AKT/mTOR and Nrf2/HO-1 Signaling Pathways

Asthma is an inflammatory disease characterized by airway hyperresponsiveness, airway remodeling, and airway inflammation. In recent years, the prevalence of asthma has been increasing steadily and the pathogenesis of asthma varies from person to person. Due to poor compliance or resistance, existing drugs cannot achieve the desired therapeutic effect. Therefore, developing or screening asthma therapeutic drugs with high curative effects, low toxicity, and strong specificity is very urgent. Duloxetine HCl (DUX) is a selective serotonin and norepinephrine reuptake inhibitor, and it was mainly used to treat depression, osteoarthritis, and neuropathic pain. It was also reported that DUX has potential anti-infection, anti-inflammation, analgesic, antioxidative, and other pharmacological effects. However, whether DUX has some effects on asthma remains unknown. In order to investigate it, a series of ex vivo and in vivo experiments, including biological tension tests, patch clamp, histopathological analysis, lung function detection, oxidative stress enzyme activity detection, and molecular biology experiments, were designed in this study. We found that DUX can not only relax high potassium or ACh precontracted tracheal smooth muscle by regulating L-type voltage-dependent Ca2+ channel (L-VDCC) and nonselective cation channel (NSCC) ion channels but also alleviate asthma symptoms through anti-inflammatory and antioxidative response regulated by PI3K/AKT/mTOR and Nrf2/HO-1 signaling pathways. Our data suggests that DUX is expected to become a potential new drug for relieving or treating asthma.

Immunosuppressive effects of a novel potassium channel toxin Ktx-Sp2 from Scorpiops Pocoki

Background

The cDNA Library of venomous animals could provide abundant bioactive peptides coding information and is an important resource for screening bioactive peptides that target and regulate disease-related ion channels. To further explore the potential medicinal usage of the transcriptome database of Scorpiops Pocoki’s venom gland, this research identified the function of a new potassium channel toxin Ktx-Sp2, whose gene was screened from the database by sequence alignment.

Results

The mature peptide of Ktx-Sp2 was obtained by genetic engineering. Whole-cell patch-clamp experiment showed that Ktx-Sp2 peptide could effectively block three types of exogenous voltage-gated potassium channels—Kv1.1, Kv1.2 and Kv1.3, among which, the blocking activity for Kv1.3 was relatively high, showing selectivity to some extent. Taking Jurkat T cells as the cell model, this study found that Ktx-Sp2 peptide could also effectively block endogenous Kv1.3, significantly reduce the free calcium concentration in Jurkat T cells, inhibit the activation of Jurkat T cells and reduce the release of inflammatory cytokines IL-2, showing a strong immunosuppressant effect.

Conclusions

This study further proves that the transcriptome database of the Scorpiops Pocoki venom gland is an important resource for discovery of novel bioactive polypeptide coding genes. The newly screened Kv1.3 channel blocker Ktx-Sp2 expanded the range of leading compounds for the treatment of autoimmune diseases and promoted the development and application of scorpion toxin peptides in the field of biomedicine.

The Flavone Luteolin, an Endocrine Disruptor, Relaxed Male Guinea Pig Gallbladder Strips

Background

Luteolin (3',4',5,7-tetrahydroxyflavone) is a flavone with a yellow crystalline appearance present in numerous plants such as broccoli, green chili, and carrot. Luteolin is considered to be an endocrine disruptor with potent estrogen agonist activity and potent progesterone antagonist activity. Luteolin has effects on smooth muscle. Luteolin relaxed guinea pig trachea smooth muscle as it inhibited both phosphodiesterase and reduced intracellular Ca²⁺. Luteolin also caused vasorelaxation in rat thoracic aorta smooth muscle by inhibiting intracellular Ca²⁺ release, inhibition of sarcolemmal Ca²⁺ channels, and activation of K⁺ channels. Luteolin or its glycosides from artichoke extracts may have an ameliorating effect on irritable bowel syndrome. The purpose of this study was to determine if luteolin had an effect on gallbladder motility.

Methods

An in vitro pharmacologic technique was utilized. Either cholecystokinin octapeptide (CCK) or KCl were used to induce tension in male guinea pig gallbladder strips maintained in Sawyer-Bartlestone chambers. Luteolin relaxed either the CCK- or KCl-induced tension in a concentration dependent manner. Various blockers were added to the chambers to determine which second messenger system(s) mediated the observed relaxation. Paired t-tests were used for statistical analysis. Differences between mean values of P < 0.05 were considered significant.

Results

Treatment of the gallbladder strips with luteolin prior to either KCl or CCK significantly (P < 0.001) decreased the amount of either KCl- or cholecystokinin-induced tension. The 2-aminoethoxydiphenylborane was used to ascertain if the release of intracellular Ca²⁺ mediated the luteolin-induced relaxation. It significantly (P < 0.001) decreased the amount of luteolin-induced relaxation. To ascertain if PKA mediated the luteolin-induced relaxation, PKA inhibitor 14-22 amide myristolated was used. It significantly (P < 0.01) reduced the amount of luteolin-induced relaxation. Neither KT5823, N^G-methyl-L-arginine acetate salt, genistein, tetraethylammonium, nor fulvestrant had a significant effect. To ascertain if PKC mediated the luteolin-induced relaxation, the PKC inhibitors bisindolymaleimide IV and chelerythrine Cl^- were used together. They had no significant effect.

Conclusions

Luteolin relaxed cholecystokinin- or KCl-induced tension by blocking extracellular Ca²⁺ entry as well as intracellular Ca²⁺ release. In addition, the actions of PKA are also involved in mediating the luteolin effect.

Effect of Sphingosine-1-Phosphate on Intracellular Free Ca²⁺ in Cat Esophageal Smooth Muscle Cells

A comprehensive collection of proteins senses local changes in intracellular Ca²⁺ concentrations ([Ca²⁺]_i) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular Ca²⁺ concentrations in cat esophageal smooth muscle cells. To measure [Ca²⁺]_i levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in [Ca²⁺]_i in the cells. Pretreatment with EGTA, an extracellular Ca²⁺ chelator, decreased the S1P-induced increase in [Ca²⁺]_i, and an L-type Ca²⁺-channel blocker, nimodipine, decreased the effect of S1P. This indicates that Ca²⁺ influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an InsP₃ receptor blocker, the S1P-evoked increase in [Ca²⁺]_i was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of G_i-protein, suppressed the increase in [Ca²⁺]_i evoked by S1P. These results suggest that the S1P-induced increase in [Ca²⁺]_i in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of Ca²⁺ from the InsP₃-sensitive Ca²⁺ pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular Ca²⁺ via the L type Ca²⁺ channel, which was dependent on activation of the S1P₄ receptor coupled to PTX-sensitive G_i protein, via phospholipase C-mediated Ca²⁺ release from the InsP₃-sensitive Ca²⁺ pool in cat esophageal smooth muscle cells.