Melatonin receptor 1B (MT2, encoded by the MTNR1B gene), a high-affinity receptor for melatonin, is associated with glucose homeostasis including glucose uptake and transport. The rs10830963 variant in the MTNR1B gene is linked to glucose metabolism disorders including gestational diabetes mellitus (GDM); however, the relationship between MT2-mediated melatonin signaling and a high birth weight of GDM infants from maternal glucose abnormality remains poorly understood. This article aims to investigate the relationship between rs10830963 variants and GDM development, as well as the effects of MT2 receptor on glucose uptake and transport in trophoblasts. TaqMan-MGB (minor groove binder) probe quantitative real-time polymerase chain reaction (qPCR) assays were used for rs10930963 genotyping. MT2 expression in the placenta of GDM and normal pregnant women was detected by immunofluorescence, western blot, and qPCR. The relationship between MT2 and glucose transporters (GLUTs) or peroxisome proliferator-activated receptor γ (PPARγ) was established by western blot, and glucose consumption of trophoblasts was measured by a glucose assay kit. The results showed that the genotype and allele frequencies of rs10830963 were significantly different between GDM and normal pregnant women (P<0.05). The fasting, 1-h and 2-h plasma glucose levels of G-allele carriers were significantly higher than those of C-allele carriers (P<0.05). Besides, the protein and messenger RNA (mRNA) expression of MT2 in the placenta of GDM was significantly higher than that of normal pregnant women (P<0.05). Melatonin could stimulate glucose uptake and GLUT4 and PPARγ protein expression in trophoblasts, which could be attenuated by MT2 receptor knockdown. In conclusion, the rs10830963 variant was associated with an increased risk of GDM. The MT2 receptor is essential for melatonin to raise glucose uptake and transport, which may be mediated by PPARγ.
Female ; Humans ; Pregnancy ; Blood Glucose/metabolism* ; Diabetes, Gestational/metabolism* ; Glucose/metabolism* ; Melatonin/metabolism* ; Polymorphism, Genetic ; PPAR gamma ; Receptor, Melatonin, MT2/genetics*

Animals ; Antioxidants ; metabolism ; Diabetes Mellitus, Experimental ; metabolism ; Melatonin ; metabolism ; Physical Conditioning, Animal ; Rats

OBJECTIVETo observe the effects of electroacupuncture (EA) on circadian rhythm of temperature and melatonin (MT) in depression rats model induced by chronic stress, so as to explore the biological mechanism of EA for depression.

METHODSTwenty-four SD rats were randomly divided into a control group, a model group and an EA group, 8 cases in each one. Rats in the control group were treated with normal diet for 21 days without any treatment. In the model and EA group, rat model was established by chronic unpredictable stress combined with solitarily feeding method, and rats in the EA group was treated with EA at "Baihui" (GV 20), "Yintang" (GV 29) 1 h before stress stimulation everyday, 2 Hz in frequency and intensity was favorable with the head of rat slightly shivering. The needles were retained for 20 min, once a day for totally 21 days. After EA treatment, open-field experiment was adopted to observe the behavioral improvement; the rats temperatures were monitored at six time points (2:00, 6:00, 10:00, 14:00, 18:00, 22:00) and orbital blood sampling was collected. The level of serum MT was tested by enzyme linked immunosorbent assay. The circadian rhythm changes of temperature and serum MT in each group were compared.

RESULTSThe numbers of horizontal movement and vertical movement in the model group were obviously lower than those in the control group (both P < 0.05), while those in the EA group were significantly improved compared with those in the model group (both P < 0.01). The circadian rhythm of temperature and MT disappeared in the model group, which was improved into normal level after EA treatment.

CONCLUSIONThe electroacupuncture has regulation effects on circadian rhythm of temperature and melatonin in depression rat model induced by chronic stress.

Animals ; Circadian Rhythm ; Depression ; metabolism ; physiopathology ; therapy ; Electroacupuncture ; Humans ; Male ; Melatonin ; metabolism ; Rats ; Rats, Sprague-Dawley

Melatonin (N-acetyl-5-methoxytryptamine, MT) is a hormone synthesized and secreted by the pineal gland. Recent studies show that melatonin plays an essential role in the pathogenesis of many reproductive processes. High-concentration melatonin exists in human preovulatory follicular fluid and melatonin receptors are present in ovarian granulosa cells, which indicates the direct effects of melatonin on ovarian function. Reactive oxygen species are involved in a number of reproductive events, including folliculogenesis, follicular atresia, ovulation, oocyte maturation, and corpus luteum formation. Melatonin and its metabolites, as powerful antioxidants and free radical scavengers, can potentially inhibit premature ovarian failure. Literature published in recent years shows the essential roles of melatonin in improving human ovarian function and oocyte quality as well as in the management of infertility. Researches on the action mechanisms of melatonin may provide a theoretical basis for the prevention and treatment of some clinical diseases.
Female ; Granulosa Cells ; metabolism ; physiology ; Humans ; Melatonin ; metabolism ; physiology ; Ovarian Follicle ; growth & development ; metabolism ; Ovary ; physiology ; Reactive Oxygen Species ; metabolism

OBJECTIVETo detect the concentrations of melatonin(MLT) in the seminal plasma of fertile and infertile men.

METHODSSerum and semen were collected from 18 fertile men aged 26-36 and 99 infertile men aged 23-36, and the latter were divided into five groups: normozoospermia (13 cases), oligozoospermia (27 cases), asthenozoospermia (31 cases), oligoasthenozoospermia (17 cases) and oligoasthenoteratozoospermia (11 cases). Concentrations of MLT in the serum and seminal plasma of the subjects were detected by ELISA.

RESULTSConcentrations of MLT in the serum showed no significant difference between the fertile and infertile men, and concentrations of MLT in the seminal plasma were lower than in the serum. Concentrations of MLT in the seminal plasma of the fertile men were not significantly different from those of the infertile men. Concentrations of MLT in the seminal plasma of the oligoasthenozoospermic and oligoasthenoteratozoospermic men were relatively lower than the fertile men, but the difference was not statistically significant (P > 0.05).

CONCLUSIONSMLT of seminal plasma may have certain effect on sperm function, but it is necessary to further study and clarify its mechanism.

Adult ; Humans ; Infertility, Male ; metabolism ; Male ; Melatonin ; analysis ; blood ; Semen ; chemistry

OBJECTIVE: To investigate the effects of melatonin on the growth and metastasis of MDA-MB-231 breast cancer cells and explore the mechanism. METHODS: MDA-MB-231 cells were treated with 1, 3 or 5 mmol/L melatonin, and the changes in cell proliferation were examined using CCK-8 assay. Colony-forming assay and wound healing assay were used to assess the effects of melatonin treatmnent on colony-forming ability and migration of the cells. Flow cytometry and immunofluoresnce assay were employed to examine apoptosis and positive staining for autophagy-related proteins in the cells treated with 3 mmol/L melatonin. The effects of melatonin treatment alone or in combination with 3-methyladenine (3-MA) on the expressions of the proteins associated with autophagy (LC3, P62 and Beclin1), apoptosis (Bcl2 and Bax) and epithelial-mesenchymal transition (E-cadherin and Snail) were examined with Western blotting. RESULTS: Melatonin treatment significantly inhibited the proliferation of breast cancer cells in a concentration- and time-dependent manner (P < 0.05), suppressed colony-forming ability and migration (P < 0.01), and promoted apoptosis of the cells (P < 0.01). Melatonin treatment alone significantly increased the expressions of Bax (P < 0.05), E-cadherin, LC3-II/LC3-I, and Beclin1 and lowered the expressions of Bcl2 (P < 0.05), Snail, P62 (P < 0.05), and Bcl2/Bax ratio (P < 0.01) in the cells, and caused enhanced positive staining of Beclin1 protein and attenuated staining of P62 protein. Compared with melatonin treatment alone, melatonin treatment combined with 3-MA significantly decreased the expressions of Beclin1 (P < 0.001), LC3-II/LC3-I (P < 0.05), Bax (P < 0.01), and E-cadherin (P < 0.001) and increased the expressions of Bcl2 (P < 0.05), Snail, and Bcl2/Bax ratio (P < 0.01). CONCLUSION Melatonin can induce autophagy of MDA-MB-231 breast cancer cells to inhibit cell proliferation and metastasis and promote cell apoptosis, and suppressing autophagy can weaken the inhibitory effect of melatonin on the growth and metastasis of breast cancer cells.
Autophagy ; Autophagy-Related Proteins/metabolism* ; Breast Neoplasms ; Cell Line, Tumor ; Female ; Humans ; Melatonin/pharmacology*

OBJECTIVETo investigate the protective effect of melatonin on residual hair follicle cells of scald rats at early stage.

METHODSEighteen male Sprague-Dawley rats were randomly divided into scald group, treatment group, sham group , with 6 rats in each group. The rats in scald group and treatment group were subjected to 30% TBSA partial thickness scald on the back, and were resuscitated with balanced solution after 1 hour, while those in sham group were immersed in water at 37 degrees C for 25 s to simulate scald, and did not receive fluid replacement. Rats in treatment group were intraperitoneally injected with 10 mg/kg melatonin solution at 1 minute, 8 hours and 12 hours after scald, while those in sham group and scald group were given equal volume of 1% alcohol sodium-isotonic saline instead. Tissue samples were harvested at 6, 12 and 24 post scald hours (PSH) for determination of MDA and GSH levels. Apoptosis of residul hair follicle was detected by TUNEL method and immunohistochemistry of caspase-3.

RESULTSThe level of MDA in scald group at each time point was much higher than that in sham group (P < 0.01) and treatment group (P < 0.05), and it peaked at 12 PSH. The changes in GSH were just opposite to that of MDA. Under fluorescence microscope, the residual hair follicle cells were blue, and the apoptotic cells appeared green. The apoptosis rate in scald group at 6, 12, 24 PSH was obviously higher than that in sham (P < 0.01) and treatment groups (P < 0.05), which was (20.2 +/- 3.4)% vs (4.3 +/- 2.3)% vs (10.9 +/- 3.2)%, (31.2 +/- 3.6)% vs (5.1 +/- 2.5)% vs (19.1 +/- 3.7)%, (22.4 +/- 2.7)% vs (4.1 +/- 2.4)% vs (13.1 +/- 3.4)%, respectively. The score of caspase-3 positive cell in scald group was higher than those in sham group (P < 0.01) and treatment group (P < 0.05).

CONCLUSIONSThere is obvious correlation between oxidative stress and apoptosis rate of hair follicle cells in rats with partial thickness scald. Early administration of melatonin may have anti-apoptosis ability for residual hair follicle cells by attenuation of oxidative stress.

Animals ; Apoptosis ; Burns ; drug therapy ; metabolism ; Hair Follicle ; cytology ; metabolism ; Male ; Melatonin ; therapeutic use ; Oxidative Stress ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: Melatonin, which is secreted by pineal gland play an important role in the regulation of ovarian function via seasonal rhythm and sleep in most mammals. It also has a role in the protection of cells by removing toxic oxygen free radicals brought about by metabolism. In the present study, effects of melatonin on the mouse oocyte maturation were examined using two different culture conditions provided with 5% or 21% oxygen concentration. MATERIAL AND METHOD: Immature mouse oocytes were obtained from the ovarian follicles of 3~4 weeks old ICR strain mice intraperitoneally injected with 5 I.U. PMSG 44 hour before. Under stereomicroscope, morphologically healthy oocytes with distinct germinal vesicle (GV) were liberated from the graafian follicles and collected using mouth-controlled micropipette. They were then cultured for 17 hour at 37degrees C, 5% CO2 and 21% O2 (95% air) or 5% CO2, 5% O2 and 90% N2. New modified Hank's balanced salt solution (New MHBS) was used as a culture medium throughout the experiments. Effects of melatonin were examined at a concentration of 0.0001 micrometer, 0.01 micrometer or 1.0 micrometer. For the prevention of spontaneous maturation of immature oocytes during culture, dibutyryl cyclic AMP (dbcAMP) and/or hypoxanthine were included in the medium. RESULTS: Under 21% oxygen condition, oocytes cultured in the presence of 0.01 micrometer melatonin showed a significantly higher maturation rates, in terms of germinal vesicle breakdown (95.0% vs 89.0%) and polar body formation (88.1% vs 75.4%), compared to those cultured with 0.0001 micrometer or 1.0 micrometer melatonin. However, no difference was observed in oocytes cultured under 5% oxygen whether they were treated with melatonin or not. In the presence of 0.01 micrometer melatonin, oocytes either cultured under 21% or 5% oxygen exhibited no difference in the polar body formation (85.6% vs 86.7%). However, in the absence of melatonin, oocytes cultured under 21% oxygen exhibited lower polar body formation (74.7%). When oocytes were cultured in the presence of dbcAMP alone or with varying concentrations of melatonin, those treated with both compounds always showed better maturation, i.e., germinal vesicle breakdown and polar body formation, compared to those cultured with dbcAMP alone. At the same concentration of melatonin, however, oocytes exposed to 21% oxygen showed poor maturation than those to 5% oxygen. Similar results were obtained from the experiments using hypoxanthine instead of dbcAMP. CONCLUSION: Based upon these results, it is suggested that melatonin could enhance the meiotic maturation of mouse oocytes under 21% oxygen concentration, and release oocytes from the meiotic arrest by dbcAMP or hypoxanthine regardless of the concentration of oxygen, probably via the removal of oxygen free radicals.
Animals ; Bucladesine ; Female ; Free Radicals ; Hypoxanthine ; Mammals ; Melatonin* ; Metabolism ; Mice* ; Oocytes* ; Ovarian Follicle ; Oxygen ; Pineal Gland ; Polar Bodies ; Seasons

PURPOSE: Neonatal hyperbilirubinema, the single most common abnormal physical finding in the first week of life, is seen in 60-80% of newborn infants. It is commonly managed by phototherapy, which has been associated with an increased incidence of hypocalcemia. As one of the mechanisms of the phototherapy-induced hypocalcemia, it was hypothesized that phototherapy dicreases the secretion of melatonin and the low serum concentration of melatonin permits the unopposed uptake of calcium by bone. The aim of the bony uptake of calcium by assessing the effect of phototherapy on the bone mineral density. METHODS: Newborn male rats were exposed to blue fluorescent light (420-470 nm wave length) intermittently at 12-hours intervals for 4 weeks from the second day of life. The newborn rats were sacrified and the blood was obtained by a direct puncture of heart at first , second, third, and fourth weeks, respectively. Total bone mineral contents and bone mineral concentration were measured by QDR 4500 FAN BEAM X-Ray densitometer, and serum intact parathyroid hormone levels by a radioimmunoassay. RESULTS: 1) There were no significant differences in total bone mineral contents between the photo-treated groups and control groups, except those between a 1-week photo-treated and its groups. 2) Bone mineral concentrations in photo-treated grups were similar to those of control groups.3) Although the levels of intact parathyroid hormone tend to be lower in all of the photo-treated groups than in control groups. it was statistically significant only in the 1-week photo-treated group (P<0.05). CONCLUSION: These results are inconsistent with previous hypothesis that phototherapy-induced hypocalcemia results from the unopposed uptake of calcium by bone due to decreased secretion of melatonin and suggest that decreased secretion of parathyroid hormone may be one of the causes for phototherapy-induced hypocalcemia.
Animals ; Bone Density ; Calcium ; Heart ; Humans ; Hypocalcemia ; Incidence ; Infant, Newborn* ; Male ; Melatonin ; Metabolism* ; Parathyroid Hormone ; Phototherapy* ; Punctures ; Radioimmunoassay ; Rats*

PURPOSE: Neonatal hyperbilirubinema, the single most common abnormal physical finding in the first week of life, is seen in 60-80% of newborn infants. It is commonly managed by phototherapy, which has been associated with an increased incidence of hypocalcemia. As one of the mechanisms of the phototherapy-induced hypocalcemia, it was hypothesized that phototherapy dicreases the secretion of melatonin and the low serum concentration of melatonin permits the unopposed uptake of calcium by bone. The aim of the bony uptake of calcium by assessing the effect of phototherapy on the bone mineral density. METHODS: Newborn male rats were exposed to blue fluorescent light (420-470 nm wave length) intermittently at 12-hours intervals for 4 weeks from the second day of life. The newborn rats were sacrified and the blood was obtained by a direct puncture of heart at first , second, third, and fourth weeks, respectively. Total bone mineral contents and bone mineral concentration were measured by QDR 4500 FAN BEAM X-Ray densitometer, and serum intact parathyroid hormone levels by a radioimmunoassay. RESULTS: 1) There were no significant differences in total bone mineral contents between the photo-treated groups and control groups, except those between a 1-week photo-treated and its groups. 2) Bone mineral concentrations in photo-treated grups were similar to those of control groups.3) Although the levels of intact parathyroid hormone tend to be lower in all of the photo-treated groups than in control groups. it was statistically significant only in the 1-week photo-treated group (P<0.05). CONCLUSION: These results are inconsistent with previous hypothesis that phototherapy-induced hypocalcemia results from the unopposed uptake of calcium by bone due to decreased secretion of melatonin and suggest that decreased secretion of parathyroid hormone may be one of the causes for phototherapy-induced hypocalcemia.
Animals ; Bone Density ; Calcium ; Heart ; Humans ; Hypocalcemia ; Incidence ; Infant, Newborn* ; Male ; Melatonin ; Metabolism* ; Parathyroid Hormone ; Phototherapy* ; Punctures ; Radioimmunoassay ; Rats*