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Endogenous opioid peptides in physiological and pathological states with particular regard to kidneys

100%

Trelewicz P. , Grzeszczyk W. , Drabczyk R.

Postępy Higieny i Medycyny Doświadczalnej

1993

tom 47

nr 5

325-344

Effective stimulation of daily LH secretion by the combined treatment with melatonin and naloxone in luteal-phase ewes

75%

Misztal T. , Romanowicz K.

Acta Neurobiologiae Experimentalis

2005

tom 65

nr 1

1-9

This study was designed to test the hypothesis that melatonin would intensify daily LH release after central blockade of the opiate receptors in sexually active ewes. The intracerebroventricular infusions of vehicle (control), melatonin, naloxone and melatonin in combination with naloxone were made in ewes in the luteal phase of the estrous cycle, from 2:00 P.M. to 5:00 P.M. Blood samples were collected from 11:00 A.M. to 8:00 P.M. at 10-min intervals. The mean plasma LH concentrations were measured before, during and after the infusions. The frequency and amplitude of LH pulses were determined during the whole experimental period. The LH concentrations recorded during melatonin or naloxone infusions were significantly higher than the concomitant concentration in vehicle-infused animals. The mean LH pulse amplitude in melatonin- and naloxone-treated ewes was also significantly higher than in controls. The LH concentration measured during the combined infusion of melatonin and naloxone was significantly higher than that during vehicle infusion. The LH concentration recorded in turn after the treatment was significantly higher than the concomitant concentrations in vehicle-, melatonin- and naloxone-infused animals. The mean LH pulse amplitude in this group was significantly higher than in the vehicle-infused group. These results indicate that blockade of the opiate receptors within the CNS facilitated effective stimulation of daily LH secretion by exogenous melatonin. In conclusion, a relationship between melatonin and endogenous opioid peptides may be crucial in enabling melatonin to exhibit stimulatory action on LH secretion during the luteal phase of the estrous cycle in ewes.

Effect of exogenous opioid peptides on TNF--induced human neutrophil apoptosis in vitro

75%

Sulowska Z. , Majewska E. , Tchorzewski H. , Klink M.

Archivum Immunologiae et Therapiae Experimentalis

2003

tom 51

nr 4

267-272

Polymorphonuclear leukocytes (neutrophils) apoptosis is an important mechanism regulating the life span and some functions of neutrophils at inflamed sites. The opioid peptides are present in the peripheral circulation and their concentrations rapidly increase as the result of stress and inflammation. The effect of opioid peptides such as met-enkephalin (M-ENK) and beta-endorphin (beta-END) on tumor necrosis factor alpha (TNF-alpha)-induced apoptosis in human neutrophils in vitro was investigated. Neutrophils isolated from peripheral blood were cultured in the absence or presence of 106-1010 M of opioid peptides for 8, 12 and 18 hours. Features of apoptotic neutrophils were measured by flow cytometric method based on analysis of apoptotic nuclei (DNA content). We found that M-ENK and beta-END enhanced both non-induced and TNF-alpha-induced neutrophil apoptosis in vitro in a dose-dependent manner. The effect of opioid peptides on modulation of neutrophil apoptosis was not reversed by opioid-receptor antagonist naloxone. The results suggest that M-ENK and beta-END can regulate neutrophil life span via apoptosis and in this way may participate in resolution of inflammation.