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Changes in melatonin content in conditioned corn (Zea mays L.) and cucumber (Cucumis sativus L.) seeds

100%
Rakowiec M., Parczewska A., Szewczyk R., Kolodziejczyk I., Posmyk M. M.
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
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2013
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tom 94
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nr 3
2
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Exogenous melatonin delays gastric emptying rate in rats: role of CCK2 and 5-HT3 receptors

100%
Kasimay O., Cakir B., Devseren E., Yegen B. C.
Journal of Physiology and Pharmacology
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2005
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tom 56
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nr 4
Pineal hormone melatonin is proposed as a potential treatment for severe sleep disturbances, and various gastrointestinal disorders. It was shown that melatonin increases intestinal motility and influences the activity of myoelectric complexes of the gut. The aim of the study was to evaluate the mechanisms of the effect of exogenous melatonin on gastric emptying rate. Male Sprague-Dawley rats were fitted with gastric cannulas under anesthesia. The rate of gastric emptying of saline was determined after instillation into the gastric fistula, from the volume and phenol red concentrations recovered after 5 min. Melatonin injected intraperitoneally (ip; 0.001-100 mg/kg) delayed gastric emptying rate of saline at 3 and 10 mg/kg doses. When administered ip 15 min before melatonin (10 mg/kg) injections, CCK2 (L-365,260, 1 mg/kg) or 5-HT3 receptor (ramosetrone, 50 µg/kg) blockers abolished melatonin-induced delay in gastric emptying rate, while the blockade of sympathetic ganglia (bretylium tosylate, 15 mg/kg) significantly reduced the delay in gastric emptying rate. CCK1 receptor blocker (L-364,718, 1 mg/kg) had no significant effect on the delaying action of melatonin. Our results indicate that pharmacological doses of melatonin delay gastric emptying via mechanisms that involve CCK2 and 5-HT3 receptors. Moreover, it appears that exogenous melatonin inhibits gastric motility in part by activating sympathetic neurons.
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Melatonin-induced protein synthesis in the rat parotid gland

80%
Cevik-Aras H., Godoy T., Ekstrom J.
Journal of Physiology and Pharmacology
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2011
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tom 62
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nr 1
Melatonin occurs in large amounts in the intestinal mucosa and is released during a meal. Recent studies of ours reveal that exogenous melatonin evokes the in vivo secretion of protein and amylase from the rat parotid gland. The aim of the present study was to investigate the effect of melatonin on the protein synthesis of the parotid gland of pentobarbitone-anaesthetised rats as estimated by the rate of incorporation of [3H]leucine into trichloroacetic acid-insoluble material of the gland. Compared with the parotid protein synthesis (set at 100%) of those rats exposed to an intravenous infusion of melatonin (25 mg/kg during 1 hour), under muscarinic and - and ß-adrenoceptor blockade, the synthesis in the corresponding glands of saline-treated control rats was less (by 25%). The synthesis was also less when the melatonin administration was combined with the melatonin 2-preferring receptor antagonist luzindole (24%), the non-selective nitric oxide synthase inhibitor L-NAME (18%) and the neuronal nitric oxide synthase inhibitor N-PLA (21%). Almost all the melatonin receptor-mediated effect was due to nitric oxide generation via the activity of neuronal type nitric oxide synthase. The present findings lend further weight to the idea that salivary glandular activity associated with food intake is hormonally influenced and they also suggest clinical implications for melatonin in the treatment of xerostomia. Since melatonin is known to exert anti-inflammatory actions in the oral cavity, the stimulatory effect of melatonin may include the synthesis of proteins of importance for the oral defence.
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The effect of exogenous melatonin on the pinealocyte ultrastructure in the domestic pig [Sus domesticus] depends on the time of its administration

80%
Lewczuk B., Przybylska-Gornowicz B.
Polish Journal of Veterinary Sciences
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2000
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tom 03
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nr 1
Melatonin secretion is not regulated via simple negative feedback inhibition. However some results show that melatonin may influence its own synthesis and secretion as well as other processes in the pineal gland. The present study was undertaken to check the effects of melatonin administered at different times of day on the ultrastructure of pig pinealocytes. The study was performed in summer under natural photoperiod. Gilts, aged 4 months, received lmg or 3 x lmg melatonin (i.m.) daily for four consecutive days, at different times of day. Point count analysis was used in quantitative studies of pinealocyte substructures. The administration of melatonin caused clear changes in the pinealocyte ultrastructure and the effects were closely dependent on the time of hormone injection. The most visible changes were observed in pinealocytes of pigs which received one injection of melatonin per 24 hr, at the end of the light phase. This schedule of melatonin administration resulted in a decrease in the relative volume of mitochondria and dense bodies of type MBB-1 (specific structures of the pig pinealocytes) as well as an increase in the relative volume of Golgi apparatus and numerical density of multivesicular bodies. The melatonin administration three times per 24 hr (in the morning, in the early afternoon and in the evening) caused a decrease in the relative volume of mitochondria and Golgi apparatus as well as an increase in the relative volume of MBB-1. Treatment with melatonin once per 24 hr in the morning resulted in a decrease in the relative volume of mitochondria.
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