Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 13

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  MELATONIN
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1

Melatonin action on thyroid activity in the soft-shelled turtle, Lissemys punctata punctata

100%
Sarkar S., Sarkar N. K., Bhattacharyya S., Das P.
Folia Biologica
|
1997
|
vol. 45
109-112
EN
Adult female turtles (Lissemys punctata punctata) were treated with pineal indoleamine melatonin (100 mug/100 g) or the antithyroid agent, methylthiouracil (100 mug/100 g) or melatonin together with methylthiouracil (100 mug of each drug/100 g) for 12 days. Melatonin alone inhibited thyroid activity as evidenced by reductions in the gland weight, follicular epithelial cell height, thyroid peroxidase, and plasma thyroxine levels. Methylthiouracil caused hyperplasia of the gland, although it inhibited thyroid activity and reduced thyroid peroxidase and plasma thyroxine levels. Melatonin together with methylthiouracil produced changes similar to those obtained with melatonin alone. The results indicate that melatonin probably exerts inhibitory effects influences on both thyrotropin release from the pituitary and the activity of the thyroid itself in turtles.
2

The role of in human physiology and pathology.I. of .Involvement of melatonin in reproductive physiology.Melatonin and hypothalamic-pituitary-adrenal cortex axis

100%
Slowinska-Klecka D., Lewinski A.
Postępy Higieny i Medycyny Doświadczalnej
|
1993
|
vol. 47
|
issue 3
209-228
EN
This paper summarizes the recent knowledge on the role of in humans. The first part of the present review considers the following aspects: of , in , melatonin influence on , changes of melatonin blood concentration during the and , and the influence of on . Current views on the relationship between melatonin and the hypothalamo-pituitary-adrenal cortex axis, as well as on changes of during , and are also discussed.
3
Content available remote

Daily GnRH and LH secretion in ewes is not modified by exogenous melatonin during seasonal anestrus

100%
Romanowicz K., Misztal T., Gajewska A., Barcikowski B.
Acta Neurobiologiae Experimentalis
|
2001
|
vol. 61
|
issue 4
289-297
EN
The effect of central, short-term melatonin administration on daily GnRH and LH secretion was studied in ewes during seasonal anestrus. Melatonin, in a total dose of 32 g and the vehicle were perfused for 4 hours into the mediobasal hypothalamus/median eminence (MBH/ME). The mean GnRH concentration during perfusion with melatonin decreased significantly (P0.05), as compared to the concentration during the preceding perfusion with the vehicle only. This change resulted from high variations in GnRH concentration noted during the initial phase of perfusion rather than from an action of melatonin. Melatonin perfused into the MBH/ME did not significantly affect LH secretion. A higher dose of melatonin and vehicle were also infused intracerebroventricularly (icv.) in either intact (300 g for 3 hours) or ovariectomized (OVX) ewes (400 g for 4 hours, 100 g/100 l/h). In the intact animals, melatonin did not significantly affect LH secretion. Interestingly, melatonin significantly decreased (P0.05) the number of LH peaks in OVX ewes. These results demonstrate that melatonin delivered for a few hours directly into the central nervous system did not affect either daily hypothalamic GnRH release or pituitary LH secretion in intact ewes during seasonal anestrus, but did modify pulsatile LH secretion in ewes deprived of the negative feedback of estradiol.
4

Changes in selected blood metabolites associated with melatonin administration in dairy goats

100%
Darul K., Kruczynska H.
Folia Biologica
|
2004
|
vol. 52
|
issue 3-4
239-241
EN
In order to examine the effect of exogenous melatonin on selected blood indices, dairy goats were given pineal gland hormone at a dose of 0.1 mg/kg body weight. Next, one and four hours after the melatonin had been administered, blood samples were collected from the goats in the control and treated groups in order to determine the levels of glucose, total cholesterol, triacyloglycerides, free fatty acids, as well as alanine and aspartate aminotransferase. The pineal gland hormone caused a significant increase in the levels of glucose, total cholesterol, triacyloglycerides and the activity of alanine aminotransferase. After melatonin administration a significant decrease in the FFA:TAG and FFA:Cholesterol blood ratios was observed. Moreover, no changes in the free fatty acid concentrations and the activity of aspartate aminotransferase were observed.
5
Content available remote

Effects of melatonin infused into the III ventricle on prolactin, beta-endorphin and luteotropin secretion in ewes during the different stages of the reproductive cycle

88%
Misztal T., Romanowicz K., Barcikowski B.
Acta Neurobiologiae Experimentalis
|
1996
|
vol. 56
|
issue 3
769-778
EN
Secretion of all the pituitary hormones undergoes marked circadian and seasonal changes.The rhythmicity of these changes is controled by the circadian pacemaker system and the pineal gland transmitting daylength informatoin to the neuroendocrine axis via the secretion of melatonin.This article presents data on the effects of the short-term melatonin administratoin into the third brain ventricle on prolactin, beta-endorphin and luteotropin secretion in ewes kept under the increasing and decreasing daylenght conditions.Additional emphasis is given to dopamine and LHRH release in the madiobasal hypothalmus under the malatonin treatment by the push-pull method.The long-term and short-term actions of melatonin on the hormonal status in ewes is also discussed.
6
Content available remote

Melatonin attenuates radiation-induced learning deficit and brain oxidative stress in mice

88%
Manda K., Anzai K., Kumari S., Bhatia A. L.
|
EN
Oxidative stress has been implicated in cognitive impairment in both experimental animals and humans. This implication has led to the notion that antioxidant defence mechanisms in the brain are not sufficient to prevent oxidative damage, and that dietary intake of a variety of antioxidants might be beneficial for preserving brain function. The present study, therefore, aimed to investigate the protective effect of melatonin against radiation-induced impairment in the learning ability of mice. Twenty days oral administration of melatonin (0.1 mg/kg b.w.), followed by an acute exposure to gamma-radiation (6 Gy), inhibited the radiation-induced decline in learning ability. Biochemical estimation of brain protein carbonyls, malondialdehide (MDA) and reduced glutathione (GSH) in these mice indicated that radiation-induced augmentation of protein oxidation and lipid peroxidation had been significantly ameliorated in melatonin treated, irradiated mice. Radiation-induced deficit of glutathione was also normalized by melatonin administration, as there was no statistical difference from normal at P<0.001. Results indicate the antioxidative as well as neuroprotective properties of melatonin against the radiation. These findings support results showing melatonin as a free radical scavenger.
7
Content available remote

On light as an alerting stimulus at night

88%
Figueiro M. G., Bullough J. D., Bierman A., Fay C. R., Rea M. S.
Acta Neurobiologiae Experimentalis
|
2007
|
vol. 67
|
issue 2
171-178
EN
Light exposure at night increases alertness; however, it is not clear if light affects nocturnal alertness in the same way that it affects measures of circadian regulation. The purpose of this study was to determine if a previously established functional relationship between light and nocturnal melatonin suppression was the same as that relating light exposure and nocturnal alertness. Four levels of narrow-band blue light at the cornea were presented during nighttime sessions. The ratio of electroencephalographic alpha power density with eyes closed to eyes open (alpha attenuation coefficient, AAC) and the Norris mood scale were used. The AAC and ratings of alertness increased monotonically with irradiance and were highly correlated. Both measures of alertness were highly correlated with model predictions of nocturnal melatonin suppression for the same circadian light stimulus, consistent with the inference that the suprachiasmatic nuclei play an important role in nocturnal alertness as well as circadian regulation.
8
Content available remote

Differential endocrine response in rams to intracerebroventricular infusion of genistein

88%
Misztal T., Gorski K., Romanowicz K.
Acta Neurobiologiae Experimentalis
|
2008
|
vol. 68
|
issue 1
43-50
EN
The intracerebroventricular infusions of genistein (total 40 ?g) were made in male sheep (November) to test its influence on melatonin, growth hormone (GH) and luteinizing hormone (LH) secretion. The analysis of the results encompassed 3 similar periods: before the infusion (afternoon hours), the first (evening hours), and the second (night hours) halves of the treatment. The night plasma concentration of melatonin in genistein-infused rams was significantly lower than that noted during the respective period in vehicle-infused rams. Plasma GH concentration increased significantly in both vehicle- and genistein-infused rams during the night hours, as compared with the concentrations noted during the afternoon and evening, however, genistein significantly stimulated the amplitude of GH pulses in these latter. The LH concentration was significantly lower during the second part of genistein treatment, than in vehicle-infused rams. The frequency and amplitude of LH pulses clearly tended to decrease following genistein infusion. In conclusion, genistein, acting at the central nervous system level in sexually active rams is able to reduce the secretion of melatonin and LH and has also a slight stimulatory effect on the amplitude of GH pulses.
9
Content available remote

Melatonin as a chemical indicator of environmental light-dark cycle

75%
Zawilska J. B.
Acta Neurobiologiae Experimentalis
|
1996
|
vol. 56
|
issue 3
757-767
EN
Melatonin is an evolutionary highly conserved molecule that plays an important role in conveying the clock and calender information to all living organisms, including man.Melatonin is synthesized in the rhythmic fashion, primarily by the pineal gland, and to a lesser degree, by extrapineal tissues - namely the retina, the Harderian gland, and the gastrointestinal tract.The rhythm of the hormone production, with maximal levels occuring at night in darkness, is generated by an endogenous circadian clock(s) and is synchronized with the photoperiodic environment to which animals are exposed.This brief outline surveys data on the regulation of rhythmic melatonin biosynthesis by a circadian pacemaker and light.Additionally, possible applications of this chronobiotic compound in agriculture and in medicine in the treatment of circadian rhythm sleep disorders are discussed.
10

Time and reproductive phase-dependent effects of exogenous melatonin on the pineal gland and ovary of a nocturnal bird, the indian spotted owlet, Athene brama

75%
Guchhait P., Haldar C.
Folia Biologica
|
2000
|
vol. 48
|
issue 3-4
91-96
EN
In a tropical nocturnal bird, the Indian spotted owlet, Athene brama, the intraperitonial injection of an identical amount (20mg/ 100 g b. wt/ day) of exogenous melatonin (MEL) for 15 consecutive days increased the pineal weight and plasma MEL level in sexually active birds while it decreased them in inactive birds more potently when injected in the evening (18.30-19.30 h) rather than the morning (0500-0600 h). On the other hand, more efficiently than the morning hour treatment, the evening hour MEL injection decreased the ovary weight and plasma estradiol and progesterone levels both in sexually active and inactive birds, but more potently in active than inactive birds. Thus, the exogenous MEL showed the time and reproductive phase dependent effects on the pineal gland and the ovary of this nocturnal bird.
11
Content available remote

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
|
vol. 65
|
issue 1
1-9
EN
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.
12
Content available remote

In vitro pituitary prolactin, growth hormone and follicle stimulating hormone secretion during sexual maturation of female rats primed with melatonin

75%
Diaz_ R. E., Fernandez_ A. C., Castrillon P. O., Esquifino_ P. A. I., Diaz_ L. B.
Acta Neurobiologiae Experimentalis
|
2001
|
vol. 61
|
issue 1
27-33
EN
The influence of in vivo melatonin administration on in vitro pituitary follicle stimulating hormone (FSH), growth hormone (GH) and prolactin secretion, as well as the possible influence of dopamine (DA) were evaluated in prepubertal (31-day-old), pubertal (33-day-old) and adult female rats at diestrus phase of the sexual cycle. The in vitro pituitary hormone secretions were evaluated at basal rate for the first hour of incubation only, in Krebs Ringer phosphate (KRP) (I1) and after a second hour of incubation with KRP (I2) or with KRP+DA (I2 plus DA). I1PRL secretion was significantly higher in 33-day-old control and melatonin treated (MEL) rats as compared to I2 periods. However, in 31-day-old rats I1 secretion was higher than in the I2 or I2+DA periods, in MEL rats. In vitro GH secretion was significantly higher at I1 than during I2 periods in the control 31- and 33-day-old groups, but not in MEL rats. The only significant effect of DA was the elevation of GH in prepubertal MEL rats. In vitro FSH release was increased by melatonin in 31-and 33-day-old female rats. No differences in PRL, GH and FSH secretion were found in adult rats. In conclusion, the results show that melatonin effects upon in vitro pituitary gland activity are reproductive-stage-dependent modifying the secretory capacity of the lactotrop, gonadotrop and somatotrop during prepubertal and pubertal ages but not in adult rats studied at a quiescent phase of the sexual cycle.
13

The role of melatonin in human physiology and pathology.II.Involvement of melatonin in pathogenesis of affective and chronobiological disorders, Melatonin and aging

75%
Slowinska-Klencka D., Lewinski A.
Postępy Higieny i Medycyny Doświadczalnej
|
1993
|
vol. 47
|
issue 4
267-276
EN
In the second part of this review the role of in of and is discussed. Current views on melatonin involvement in aging are presented. Clinical experiments on the possible usefulness of melatonin in treatment of various types of cancers and hypothetical mechanisms of oncostatic influence of melatonin are also summarized.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.