Animals ; Humans ; Melatonin ; physiology ; Receptors, Melatonin ; physiology ; Signal Transduction ; physiology

Circadian clock is an internal mechanism evolved to adapt to cyclic environmental changes, especially diurnal changes. Keeping the internal clock in synchronization with the external clock is essential for health. Mismatch of the clocks due to phase shift or disruption of molecular clocks may lead to circadian disorders, including abnormal sleep-wake cycles, as well as disrupted rhythms in hormone secretion, blood pressure, heart rate, body temperature, etc. Long-term circadian disorders are risk factors for various common critical diseases such as metabolic diseases, cardiovascular diseases, and tumor. To prevent or treat the circadian disorders, scientists have conducted extensive research on the function of circadian clocks and their roles in the development of diseases, and screened hundreds of thousands of compounds to find candidates to regulate circadian rhythms. In addition, melatonin, light therapy, exercise therapy, timing and composition of food also play a certain role in relieving associated symptoms. Here, we summarized the progress of both drug- and non-drug-based approaches to prevent and treat circadian clock disorders.
Circadian Rhythm ; Circadian Clocks ; Melatonin/physiology*

Animals ; Cytokines ; physiology ; Humans ; Immune System ; drug effects ; physiology ; Melatonin ; pharmacology ; Opioid Peptides ; physiology ; Receptors, Melatonin ; physiology ; Stress, Physiological ; immunology ; T-Lymphocytes ; drug effects ; physiology

AIMTo observe the role of melatonin receptor and GABAA receptor in sleeping time prolonged by melatonin in mice.

METHODSThe absence of the righting reflex was considered as the sleep onset and the duration of the loss of the righting reflex was recorded as the sleeping time. The effects of receptor agonist and antagonist on hypnotic activity of melatonin were studied in the paper.

RESULTSPrazosin hydrochloride, the blocker of melatonin 3 receptor, didn't affect the sleeping time prolonged by melatonin in mice. GABA, the endogenous agonist of GABA receptor, significantly potentiated the hypnotic activity of melatonin. When picrotoxin, the ligand of picrotoxin site on GABAA receptor, used together with melatonin, it significantly antagonized the sleeping time prolonged by melatonin, however, bicuculline, the specific antagonist of GABA binding site in GABAA receptor, didn't affect the hypnotic activity of melatonin in mice.

CONCLUSIONMelatonin does not exhibit its potentiation sleeping time in mice through melatonin 3 receptor. Hypnotic activity of melatonin may be mediated through picrotoxin site on GABAA receptor.

Animals ; Bicuculline ; pharmacology ; Male ; Melatonin ; physiology ; Mice ; Mice, Inbred Strains ; Picrotoxin ; pharmacology ; Prazosin ; pharmacology ; Receptors, GABA-A ; physiology ; Receptors, Melatonin ; physiology ; Sleep ; physiology

The aim of this study was to observe the influence of interfered circadian rhythm on pregnancy of rats and growth of neonatal rats, and to explore the relationship between the interfered circadian rhythm and the changes of melatonin and progesterone. Continuous light was used to inhibit melatonin secretion and therefore the interfered circadian rhythm animal model was obtained. The influence of interfered circadian rhythm on delivery of pregnant rats was observed. Serum was collected from rats during different stages of pregnancy to measure the concentrations of melatonin and progesterone. In order to observe the embryo resorption rate, half of pregnant rats were randomly selected to undergo a laparotomy, and the remainder was used to observe delivery and assess the growth of neonatal rats after delivery. The results showed that the interfered circadian rhythm induced adverse effects on pregnancy outcomes, including an increase of embryo resorption rate and a decrease in the number of live births; inhibited the secretion of melatonin along with decreased serum progesterone level; prolonged the stage of labor, but not the duration of pregnancy; and disturbed the fetal intrauterine growth and the growth of neonatal rats. The results suggest that interfered circadian rhythm condition made by continuous light could make adverse effects on both pregnant rats and neonatal rats. The results of our study may provide a way to modulate pregnant women's circadian rhythm and a possibility of application of melatonin on pregnant women.
Animals ; Circadian Rhythm ; Female ; Light ; Melatonin ; physiology ; Pregnancy ; Pregnancy, Animal ; Progesterone ; physiology ; Rats

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

Melatonin,an endocrine hormone synthesized by the pineal gland,plays an important role in the reproduction.The growth and development of follicles is the basis of female mammalian fertility.Follicles have a high concentration of melatonin.Melatonin receptors exist on ovarian granulosa cells,follicle cells,and oocytes.It regulates the growth and development of these cells and the maturation and atresia of follicles,affecting female fertility.This paper reviews the protective effects and regulatory mechanisms of melatonin on the development of ovarian follicles,granulosa cells,and oocytes and makes an outlook on the therapeutic potential of melatonin for ovarian injury,underpinning the clinical application of melatonin in the future.
Animals ; Female ; Melatonin/pharmacology* ; Ovarian Follicle ; Oocytes ; Granulosa Cells/physiology* ; Mammals

AIMThe effect and possible mechanism of Melatonin (MEL) on firing rate of pain neurons in lateral habenular nucleus of rats were investigated in the experiment.

METHODSSingle extracellular firing were recorded to study the firing rate changes of pain neurons and sensitivity changes to pain stimulation induced by MEL in LHb of rats. Reverse effect of naloxone on the analgesia induced by melatonin was also observed.

RESULTSMelatonin showed the effects on the firing of pain neurons in the LHb and decreased the sensitivity of pain neurons to pain stimulation, which could be reversed by naloxone.

CONCLUSIONMelatonin can change the responses of pain neurons to pain stimulation via opioid receptor in the LHb, which might be one of analgesic mechanisms by MEL.

Analgesics ; pharmacology ; Animals ; Habenula ; drug effects ; physiology ; Male ; Melatonin ; pharmacology ; Neuralgia ; physiopathology ; Neurons ; drug effects ; physiology ; Rats ; Rats, Wistar

Cardiac Surgical Procedures ; adverse effects ; Circadian Rhythm ; physiology ; Cognition Disorders ; etiology ; Humans ; Hydrocortisone ; blood ; Melatonin ; blood ; Postoperative Complications ; etiology

AIMTo study whether melatonin has effect on oocyte maturation of mouse in vitro.

METHODSMouse oocytes were cultured in maturation medium, HX-medium, or HX-medium supplemented with FSH, and the effects of MT on meiotic maturation of mouse oocyte were examined.

RESULTS(1) MT at all doses of 0.1 g/L, 0.02 g/L, 0.4 g/L or 0.8 g/L inhibited the formation of PB1 in CEO cultured in maturation medium and had no effect on GVBD. (2) MT could delay GVBD and the extrusion of PB1 in CEOs of mouse oocytes by dynamic curves. In contrast to the control, GVBD and PB1 extrusion of oocytes in the treated groups had been delayed by 8-10 hours and 3-4 hours respectively. (3) MT inhibited the effect of FSH on resumption of meiosis, but no effect on the formation of PB1. (4) MT and HX had cooperation effects on spontaneous oocyte maturation in CEO, but not in DO.

CONCLUSIONMT is able to affect mouse oocyte maturation and the regulation mechanisms may be related to cumulus cells.

Animals ; Female ; In Vitro Oocyte Maturation Techniques ; Melatonin ; pharmacology ; Mice ; Mice, Inbred Strains ; Oocytes ; drug effects ; physiology ; Oogenesis ; drug effects