The effects of daylight exposure on melatonin levels, Kiss1 expression, and melanoma formation in mice

Aim To determine how daylight exposure in mice affects melatonin protein expression in blood and Kiss1 gene expression in the hypothalamus. The second aim was to assess the relationship between skin cancer formation, daylight exposure, melatonin blood level, and kisspeptin gene expression level. Methods New-born mice (n = 96) were assigned into the blind group or daylight group. The blind group was raised in the dark and the daylight group was raised under 12 hours light/12 hours dark cycle for 17 weeks. At the end of the 11th week, melanoma cell line was inoculated to mice, and tumor growth was observed for 6 weeks. At the end of the experiment, melatonin level was measured from blood serum and Kiss1 expression from the hypothalamus. Results The blind group had significantly higher melatonin and lower Kiss1 expression levels than the daylight group. Tumor volume was inversely proportional to melatonin levels and directly proportional to Kiss1 expression levels. Tumor growth speed was lower in the blind than in the daylight group. Conclusion Melatonin and Kiss1 were shown to be nvolved in tumor suppression. They were affected by daylight and were mutually affected by each other

Papaverine-induced and endothelium-dependent relaxation in the isolated rat aortic strip.

In the present study, we aimed to obtain further evidence in favour of the hypothesis that nitric oxide (NO) is a major mediator of endothelium-dependent vasorelaxation and to clarify whether NO plays a role in papaverine-induced vasorelaxation. The relaxant effects of acetylcholine (Ach), acidified NaNO2 or papaverine were investigated on isolated helical strips of the rat thoracic aorta precontracted with phenylephrine in an organ bath containing Krebs solution aerated with 95% O2 and 5% CO2. The relaxation was quantified as % peak reduction of phenylephrine contracture. Saponin abolished the relaxant effects of Ach completely whereas it had no effect on the responses to acidified NaNO2 or papaverine. NG-nitro-L-arginine (L-NOARG) reduced the effects of Ach significantly, but it was ineffective on the relaxation induced by acidified NaNO2. The inhibitory action of L-NOARG was partly restored by L-arginine, but not by D-arginine. Hemoglobin, hydroxocobalamin and hydroquinone exhibited significant inhibition on the relaxation evoked by Ach and acidified NaNO2. L-NOARG, hydroxocobalamin and hydroquinone caused only limited but significant decrease in the relaxation due to papaverine. This phenomenon was also observed by increasing phenylephrine concentration leading to an enhancement in the contraction. Our findings strongly support the view that Ach-induced relaxation of rat aorta strips is mediated by free NO released from the endothelium and the results suggest that NO may indirectly contribute to papaverine-induced relaxation.</p

Possible postsynaptic action of aminoglycosides in the frog rectus abdominis.

The present study was undertaken to investigate the postsynaptic effects of aminoglycosides on contractions evoked by acetylcholine (ACh), KCl, electrical field stimulation (EFS) and Na(+)- and Ca(2+)-free Ringer solution with 0.2 mM Na2 EDTA (NaFCaFR) in the isolated frog rectus abdominis. Neomycin inhibited contraction elicited by ACh, NaFCaFR, and EFS at the higher frequencies (8 and 10 Hz) but not those elicited by KCl and EFS at the lower frequencies (2, 3 and 5 Hz). D-tubocurarine inhibited ACh-induced contractions in a concentration-dependent manner. In addition, drug reduced EFS-evoked contractions to a limited extent. Lower concentrations (10(-5), 5 x 10(-5), 10(-4), 2 x 10(-4) and 3 x 10(-4) M) but not higher concentrations (4 x 10(-4) and 5 x 10(-4) M) of methoxyverapamil exhibited a concentration-dependent inhibitory action on NaFCaFR-induced contractions. Similar inhibitions of the same type of contraction were displayed by aminoglycosides (neomycin, streptomycin, netilmycin, gentamycin and amikacin). These results suggest that in addition to their antagonistic action on nicotinic receptors in the frog rectus abdominis, aminoglycosides may exert stabilizing effects on some functional components contributing to contractions at the membrane.</p

The Role of Na⁺ Channels in Twitch Generation During Exposure of the Frog Rectus Abdominis to Ca-Free Ringer Solution with Na₂EDTA

&#8195;The aim of the study was to investigate whether Na+ channels play a role in the twitch component of the response of the isolated frog rectus abdominis to Ca2+-free Ringer solution with 0.2 mM Na2EDTA by using tetrodotoxin and some other well known drugs that exhibit a blocking action on Na+ channels. In the presence of 5 x 10-7 M tetrodotoxin, the twitch component, measured isotonically, disappeared. Although 10-7 M d-tubocurarine was found to be ineffective, a complete blockage of twitch amplitude was observed at 5 x 10-6 M concentration of the drug. The inhibitory action of d-tubocurarine on twitch response was not antagonized by 10-6 and 10-5 M carbachol. Propranolol (10-6 - 10-5 M), lidocaine (2 x 10-6 - 10-5 M), quinine (10-6 - 2 x 10-5 M) and quinidine (10-6 - 2 x 10-5 M) inhibited maximal twitch amplitude in a concentration dependent manner. These findings strongly suggest that activation of tetrodotoxin sensitive Na+ channel may play a primary role at twitch generation during exposure of the frog rectus abdominis to Ca2+-free Ringer solution with Na2 EDTA.</p

Inhibitory actions of hydroxocobalamin, cyanocobalamin, and folic acid on the ultraviolet light-induced relaxation of the frog upper oesophageal strip.

The applications of ultraviolet (UV) light (336 nm) on the upper oesophageal strips of frog elicited relaxant responses in the presence of NaNO2 (50 microM). The tissues were mounted under the tension 0.5 g in an organ bath containing Ringer solution, maintained at 25 degrees C and gassed with 100% O2. The responses were recorded on a kymograph via an isotonic lever. Antimegaloblastic agents, including hydroxocobalamin (1, 10, and 100 microM), cyanocobalamin (1, 10, 25, and 100 microM), and folic acid (1, 10, 50, 100, and 200 microM), significantly attenuated the relaxation response to UV light. Folinic acid (1, 10, 25, and 100 microM), however, enhanced the relaxation. Pyrogallol (50 microM), hydroquinone (50 microM), and diethyldithiocarbamic acid (8 mM) were found ineffective for attenuation, though FeSO4 (200, 400, and 500 microM) and hemoglobin (50 microM), respectively, exerted significant inhibition. L-arginine methylester (500 microM) did not impair UV-induced relaxation. Based on these results, we concluded that a mechanism involving undefined action(s) of antimegaloblastic drugs may cause alterations in the UV light-induced relaxation of the tissue used.</p

Inhibitory actions of hydroxocobalamin, cyanocobalamin, and folic acid on the ultraviolet light-induced relaxation of the frog upper oesophageal strip.

The applications of ultraviolet (UV) light (336 nm) on the upper oesophageal strips of frog elicited relaxant responses in the presence of NaNO2 (50 microM). The tissues were mounted under the tension 0.5 g in an organ bath containing Ringer solution, maintained at 25 degrees C and gassed with 100% O2. The responses were recorded on a kymograph via an isotonic lever. Antimegaloblastic agents, including hydroxocobalamin (1, 10, and 100 microM), cyanocobalamin (1, 10, 25, and 100 microM), and folic acid (1, 10, 50, 100, and 200 microM), significantly attenuated the relaxation response to UV light. Folinic acid (1, 10, 25, and 100 microM), however, enhanced the relaxation. Pyrogallol (50 microM), hydroquinone (50 microM), and diethyldithiocarbamic acid (8 mM) were found ineffective for attenuation, though FeSO4 (200, 400, and 500 microM) and hemoglobin (50 microM), respectively, exerted significant inhibition. L-arginine methylester (500 microM) did not impair UV-induced relaxation. Based on these results, we concluded that a mechanism involving undefined action(s) of antimegaloblastic drugs may cause alterations in the UV light-induced relaxation of the tissue used.</p

Antioxidant effect of quercetin on the nitrergic neurotansmitter in the mouse gastric fundus

WOS: 000239590003610

The impact of extracellular and intracellular Ca2+ on ethanol-induced smooth muscle contraction

WOS: 000270733600006PubMed ID: 19749788Aim: To evaluate the impact of extracellular and intracellular Ca2+ on contractions induced by ethanol in smooth muscle. Methods: Longitudinal smooth muscle strips were prepared from the gastric fundi of mice. The contractions of smooth muscle strips were recorded with an isometric force displacement transducer. Results: Ethanol (164 mmol/L) produced reproducible contractions in isolated gastric fundal strips of mice. Although lidocaine (50 and 100 mu mol/L), a local anesthetic agent, and hexamethonium (100 and 500 mu mol/L), a ganglionic blocking agent, failed to affect these contractions, verapamil (1-50 mu mol/L) and nifedipine (1-50 mu mol/L), selective blockers of L-type Ca2+ channels, significantly inhibited the contractile responses of ethanol. Using a Ca2+-free medium nearly eliminated these contractions in the same tissue. Ryanodine (1-50 mu mol/L) and ruthenium red (10-100 mu mol/L), selective blockers of intracellular Ca2+ channels/ryanodine receptors; cyclopiazonic acid (CPA; 1-10 mu mol/L), a selective inhibitor of sarcoplasmic reticulum (SR) Ca2+-ATPase; and caffeine (0.5-5 mmol/L), a depleting agent of intracellular Ca2+ stores, significantly inhibited the contractile responses induced by ethanol. In addition, the combination of caffeine (5 mmol/L) plus CPA (10 mu mol/L), and ryanodine (10 mu mol/L) plus CPA (10 mu mol/L), caused further inhibition of contractions in response to ethanol. This inhibition was significantly different from those associated with caffeine, ryanodine or CPA. Furthermore the combination of caffeine (5 mmol/L), ryanodine (10 mu mol/L) and CPA(10 mu mol/L) eliminated the contractions induced by ethanol in isolated gastric fundal strips of mice. Conclusion: Both extracellular and intracellular Ca2+ may have important roles in regulating contractions induced by ethanol in the mouse gastric fundus.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [SBAG-HD-244, 107S290]This study was supported by the Scientific and Technical Research Council of Turkey (TUBITAK) (SBAG-HD-244, 107S290). Part of this work was presented at VII National Congress of Neuroscience, Adana, Turkey, 2008

St. John's Worth Extract Induces Apoptosis and Inhibits Cancer-Related Inflamation in Basal Cell Carcinoma Cell Lines

63rd Annual Meeting of the Biophysical-Society -- MAR 02-06, 2019 -- Baltimore, MDWOS: 000460779801356…Biophys So