Pathogenic role of melatonin in sleep disorders in menopausal women

[Insomnia in the menopause]

During the menopause transition, pathogenetic changes begin to occur in the reproductive system and they affect the quality of sleep and contribute to the development of insomnia. Given the multifactorial nature of insomnia and the special characteristics of its pathogenesis, it is necessary to adhere to an integrated approach in the treatment of patients of the older age group. In our opinion, if we have indications, a promising direction for the treatment of sleep disorders during period of menopausal syndrome is the use of hormone replacement therapy in addition to traditional methods of the treatment of insomnia.

Circadian Rhythm of Salivary Cortisol in Obese Adolescents With and Without Apnea: A Pilot Study

BACKGROUND AND OBJECTIVE

Obstructive sleep apnea (OSA) and obesity are associated with stress system activation involving the hypothalamic-pituitary-adrenal (HPA) axis in adults, but these effects in childhood and adolescence remain unclear. We examined diurnal salivary cortisol as a measurement of the HPA axis function in obese adolescents with and without OSA and the relationships between cortisol levels, body weight, and parameters of polysomnography (PSG).

METHODS

After PSG, saliva samples were collected from obese participants (with and without OSA) and lean participants four times over a 24-h period, namely, at 7:00 h (m-sCort), 13:00 h (a-sCort), 19:00 h (e-sCort), and 23:00 h (n-sCort). An enzyme-linked immunosorbent assay (ELISA) was used to measure salivary cortisol levels. The mean values of cortisol levels and fixed-time point diurnal cortisol slope (DCS) were calculated and compared among the three study groups. Correlations between parameters were analyzed using Spearman's correlation coefficients.

RESULTS

Obese OSA participants had significantly higher e-sCort and n-sCort levels than both obese non-OSA participants and lean controls. However, m-sCort and a-sCort in these patients had a pronounced upward trend. M-sCort was significantly correlated with both the lowest oxygen saturation (SpO₂) and time with SpO₂ <90%. Moreover, in the obese OSA group, DCS was significantly flatter than in the other two groups. The a-sCort in obese non-OSA participants was significantly higher than that in the lean control group and, surprisingly, was positively correlated with the apnea/hypopnea index. Additionally, m-sCort was related to body weight.

CONCLUSION

This study provided further evidence for alterations in diurnal cortisol production in obese adolescents, which may indicate a chronically stressed HPA axis. However, there were significant differences in salivary cortisol parameters between participants with and without OSA. Furthermore, patients with OSA had more associations between time-point cortisol levels and OSA-related indices. Nonetheless, this research is a pilot study, and further investigations are necessary.

8-Hydroxy-2'-Deoxyguanosine as an Oxidative Stress Marker in Insomnia

We performed comparative analysis of 8-hydroxy-2'-deoxyguanosine in women in different climax stages with and without insomnia. The study involved 90 women aged 45 to 60 years divided into perimenopausal (n=30) and postmenopausal (n=60) groups. After questioning using special sleep questionnaires (Insomnia Severity Index, Epworth Sleepiness Scale, Munich Chronotype Questionnaire), the groups were divided into subgroups with insomnia and without it (control). 8-Hydroxy-2'-deoxyguanosine was assayed in blood serum by ELISA. The higher levels of 8-hydroxy-2'-deoxyguanosine in postmenopausal women with insomnia in comparison with the control and perimenopausal patients (p<0.05) attested to oxidative DNA damage in this cohort of patients.

Circadian Melatonin Secretion In Obese Adolescents With Or Without Obstructive Sleep Apnea

Objective — To compare melatonin levels in saliva during a 24-hr day in order to identify the specificities of circadian melatonin secretion in obese adolescents with or without obstructive sleep apnea (OSA). Material and Methods — We examined 18 obese adolescents with OSA, 12 obese adolescents without OSA, and 15 healthy adolescents with a normal body weight, from whom saliva was sampled four time during the 24-hr day. Polysomnography was used to diagnose OSA. Saliva samples (n=180) were subjected to enzyme-linked immunosorbent assay. Results — Obese adolescents with OSA had higher evening melatonin levels than obese adolescents without OSA. For example, this indicator in OSA patients was 5.3 times higher than in participants without OSA, who had the lowest evening melatonin level among all groups. In both obese groups, nighttime melatonin levels were significantly lower than in the control group. A positive correlation was detected between the levels of morning and afternoon melatonin and body mass index only in obese adolescents without OSA (r=0.58; p=0.03 and r=0.68; p=0.01, respectively). It was found that evening melatonin correlated with minimum blood oxygen saturation (SaO2) in the entire sample of adolescents with OSA (r=-0.69; p=0.008), and it also correlated with time with SaO2 <90% in the group with clinical manifestations of OSA (r=0.76; p=0.003). Nighttime melatonin levels negatively correlated with the minimum SaO2 value solely in the group with clinical manifestations of OSA (r=-0.58; p=0.035). Conclusion — The circadian melatonin secretion in obese adolescents differed, depending on the presence or absence of OSA, and correlated with the level of oxygen desaturation in OSA patients, to a greater extent – in the presence of clinical manifestations.

Obesity and Circadian Cycle of Sleep and Wakefulness: Common Points and Prospects of Therapy

The prevalence of obesity in recent years has assumed the character of a non-communicable epidemic. Wherein, the standard approaches for its treatment are not always successful. Meanwhile, obesity remains one of the main causes of the formation of a number of some serious diseases, such as cardiovascular, diabetes, cancer, etc. and death from them. In search of alternative and more adequate methods of obesity treatment and preventing its complications, recent studies are aimed at further identifying new associations and revealing the pathophysiological mechanisms underlying excessive weight gain. It should be noted an increasing amount of chronobiological studies that raised awareness of the key role of the body’s circadian rhythms and its main regulator, melatonin, responsible for the temporary organization of the main physiological (including metabolism) processes throughout the 24-h day, in the development and progression of obesity. This review is devoted to the consideration of mutually directed interactions between the circadian system and metabolism; attempts have been made to explain the role of sleep-wake cycle disruptions in the excess accumulation of adipose tissue and the formation of obesity and its comorbidities, as well as detailed therapeutic principles based on normalizing disruption of body clocks using time-coordinated approaches to food intake, physical activity, the effects of non-drug methods and pharmacological substances (chronobiotics), which represents a novel and promising ways to prevent or treat obesity and associated diseases.

Performance of Metabolic Parameters in Formation of Sleep Disorders in Menopausal Women

Background. It is known that menopausal women suffer from sleep disorders. As additional diagnostic methods, it is possible to use the equations of linear classification functions.

Aim: to determine the most informative parameters among the lipid profile, the “lipid peroxidation – antioxidant protection” system parameters and the melatonin secretion chronobiological rhythms in menopausal women with sleep disorders.

Materials and methods. 56 perimenopausal women and 70 postmenopausal ones in accordance with the inclusion criteria participated in this study. Diagnoses of insomnia and obstructive sleep apnea syndrome were made according to the results of specialized somnological questionnaires and polysomnographic monitoring. Spectrophotometric methods for studying of lipid metabolism and the “lipid peroxidation – antioxidant protection” system parameters, an enzyme immunoassay method for determining melatonin were also used. A multidimensional discriminant analysis to reveal the most informative parameters among the parameters studied was used.

Results. The most informative indicators of the metabolic system for sleep disorders in perimenopausal women with insomnia are melatonin 06.00–07.00 h, melatonin 18.00–19.00 h, melatonin 23.00–00.00 h, ketodienes and conjugated trienes, oxidized glutathione; with insomnia and OSAS – melatonin 06.00–07.00 h, melatonin 12.00–13.00 h, melatonin 23.00–00.00 h, substrates with conjugated double bonds, total cholesterol; in postmenopausal women with insomnia – diene conjugates, α-tocopherol, total antioxidant capacity, active products of thiobarbituric acid, reduced glutathione; with insomnia and OSAS – total antioxidant capacity, α-tocopherol, substrates with conjugated double bonds.

Conclusions. The results obtained indicate a great strain in the antioxidant protection system in menopausal women with sleep disorders in response to changes in free radical homeostasis.

Association of 3111T/C Polymorphism of the Clock Gene with Circadian Rhythm of Melatonin in Menopausal Women with Insomnia

We carried out a comparative analysis of circadian rhythms of melatonin secretion in Caucasian menopausal women with and without insomnia depending on the 3111T/C polymorphism of the Clock gene. Melatonin levels was measured in the saliva 4 times a day (06.00-07.00, 12.00-13.00, 18.00-19.00, and 23.00-00.00 h). Carriers of the TT genotype with insomnia demonstrated significantly higher level of melatonin in the early morning hours compared to the carriers of the minor allele C (12.60±7.58 and 8.98±8.62 pg/ml, respectively, p=0.023). In the control group, no statistically significant differences were revealed. The carriers of the TT genotype with sleep disorders have higher morning melatonin level compared to control group women (12.60±7.58 and 5.48±4.74 pg/ml, respectively, p=0.005) and low nocturnal melatonin level (6.42±4.97 and 12.52±10.40 pg/ml, respectively, p=0.039).

Polymorphism T3111C of the Clock gene in ethnic groups of women from Russia and Buryatia

Biological rhythms of organisms depend on both changing conditions of the external environment and internal “biological clock”. Circadian rhythms are the response of the organism to the change of day and night. They are some of the most important biological rhythms of organisms. Circadian rhythms are regulated by the group of circadian genes. It is known that women suffer from sleep disorders more often than men. Up to 50 % of menopausal women complain of problems associated with sleeping. The study involved 403 menopausal women aged from 45 to 60 years: 214 Russians (the average age is 52.74±6.28 years) and 189 Buryats (the average age is 51.95±5.13 years) living in Eastern Siberia (Irkutsk region, Irkutsk and Republic of Buryatia, Ulan-Ude). The prevalence of genotypes and alleles of the polymorphism T3111C of the circadian rhythm gene Clock (rs1801260) was studied in these groups. To this end, we conducted genotyping of DNA samples by polymerase chain reaction. It was shown that the compared groups have statistically significant differences in genotypes frequency (р = 0.001). It was found that in the group of Russian women the frequency of the TC genotype (p = 0.004) was significantly higher and the frequency of the TT genotype (p = 0.0001) was significantly lower than those in the sample of women of Buryatia. It was shown that in the group of Russian women allele 3111C is found in 30.4 % of cases, which is statistically significantly more often than in the group of Buryat women, where the frequency of allele 3111C was 19.3 % (p = 0.014).

Association of the melatonin circadian rhythms with clock 3111T/C gene polymorphism in Caucasian and Asian menopausal women with insomnia

A comparative analysis of melatonin circadian rhythms in Caucasian (incoming population) and Asian (indigenous population) menopausal women with/without sleep disorders depending on the genotype of Clock 3111T/C gene polymorphism was realized.The melatonin level in the saliva was determined four times a day (6:00-7:00, 12:00-13:00, 18:00-19:00, 23:00-00:00 h). The Caucasian women-carriers of the TT-genotype with insomnia as compared to control group-had a higher morning melatonin level and a lower night melatonin level. The Asian women with TT-genotype and insomnia had a lower levels of melatonin as compared to control at daytime, evening and night. A significantly higher melatonin level in the early morning hours was detected in the Caucasian women-carriers of the TT-genotype with insomnia as compared to group womencarriers of the minor 3111C-allele. There were no statistically significant differences in the circadian rhythms of melatonin in the Asian women depending on the genotype of the Clock 3111T/C polymorphism. An assumption with respect to the protective role of the minor allele 3111C in the development of insomnia associated with the displacement of melatonin circadian rhythms in the representatives of the incoming population was made.

Oxidative stress in women with insomnia in different stages of menopause

Aim. To investigate of a lipid peroxidation (LPO) process and the antioxidant defense system (ADS) in peri- and postmenopausal women with insomnia. Subjects and methods. 47 perimenopausal women and 71 postmenopausal ones were examined. Each group was divided into 2 subgroups: 1) individuals with insomnia and 2) controls. LPO-ADS spectrophotometric studies were used in the investigation. Results. There was an increase in the serum levels of ketodienes and conjugated trienes and a decrease in those of α-tocopherol and retinol in postmenopause versus in perimenopause. In insomnia, there was a rise in the level of ketodienes and conjugated trienes in perimenopause; LPO substrates with conjugated double bonds, diene conjugates, and thiobarbituric acid-active products in postmenopause. The indicators of ADS do not differ from those in the controls. The integral indicator of oxidative stress assessment suggests that there is a LPO-ADS imbalance in the menopausal women with insomnia, which is most pronounced in postmenopause. Conclusion. The findings suggest that the patients with insomnia develop oxidative stress that is more marked in postmenopause.