LINE-1 and Alu Methylation Levels Among Middle Aged Women With Low Cardiovascular Risk Profile in Respect of Menopausal Hot Flashes

Vasomotor symptoms are the most common symptoms seen during climacterium. The hypoestrogenic state causes dysfunction of hypothalamic preoptic area, a thermoregulatory center. The sympathetic overactivation during the hot flashes is associated with awakening during sleep and have a negative impact on cardiac indexes and vascular reactivity. Therefore, hot flashes are accepted as subclinical cardiovascular risk factor.

The association between the severity of the hot flashes and cardiovascular risk may have an epigenetic background. Recently, methylation changes of DNA was found to be associated with clinical and subclinical cardiovascular disease risk (atherosclerosis and hypertension etc.). A transposable element in the DNA, Long interspersed nuclear elements (LINE-1), was found to be hypomethylated in cases with ischemic heart disease and stroke. Therefore, the expression of repeating elements in the DNA (LINE-1 and ALU) may be considered as a mediator in the ischemic heart disease. Until now, menopausal age, vasomotor symptoms and epigenetic and biological aging have been evaluated. However, the epigenetic impact of severe vasomotor symptoms in postmenopausal women with low cardiovascular disease risk profile has not been evaluated. In this study, we aimed to evaluate the epigenetic basis of cardiovascular disease risk for women with vasomotor symptoms which disturb sleep by assessing the methylation levels of ALU and LINE-1.

Vasomotor symptoms are the most common symptoms seen during climacterium. The hypoestrogenic state causes dysfunction of hypothalamic preoptic area, a thermoregulatory center. The variations in the range of thermoneutral zone determine the severity of the vasomotor symptoms. Sympathetic overactivation during the hot flash and decreased rate of parasympathetic control on the heart rate are the main factors contributing to the cardiovascular disease risk. The hot flashes which occur and cause awakening during sleep have negative impact on cardiac indexes and vascular reactivity. Therefore, vasomotor symptoms are accepted as subclinical cardiovascular risk factor.

Hot flashes associated with nighttime awakenings were shown to increase systolic and diastolic blood pressure and decrease pre-ejection period. Objectively recorded hot flashes and nighttime awakenings were found to be correlated white matter hyperintensities in the brain which show poor brain health. In addition, white matter hyperintensities may be considered as a cerebral small vascular disease and is associated with greater odds of having stroke and dementia.

Among postmenopausal women, cardiovascular disease is the most prevalent cause for mortality and morbidity. It results from the interaction of environmental and genetic factors. The association between the severity of hot flashes and cardiovascular risk may have an epigenetic background. The global DNA methylations were found to be decreased in postmenopausal women with high cardiovascular disease risk. Recently, methylation changes of DNA was found to be associated with clinical and subclinical cardiovascular disease risk (atherosclerosis and hypertension etc.). A transposable element in the DNA, Long interspersed nuclear elements (LINE-1), was found to be hypomethylated in cases with ischemic heart disease and stroke. Therefore, the expression of repeating elements in the DNA (LINE-1 and ALU) may be considered a mediator in the ischemic heart disease. Until now, menopausal age, vasomotor symptoms and epigenetic and biological aging have been evaluated. However, the epigenetic impact of severe vasomotor symptoms in postmenopausal women with low cardiovascular disease risk profile has not been evaluated. In this study, we aimed to evaluate the epigenetic basis of cardiovascular disease risk for women who have low cardiovascular disease risk profile at baseline and have vasomotor symptoms which disturb sleep by assessing the methylation levels of ALU and LINE-1.

Eligibility Criteria:
Inclusion Criteria:

* 45-55 years of age
* Women with serum FSH levels \>35 IU/L, serum estradiol levels \<20 pg/mL
* Women with low cardiovascular disease risk profile (Framingham score for coronary heart disease \<10%),
* Low high sensitive CRP levels (\<5 mg/L),
* Fasting glucose \<90 mg/dL,
* Fasting levels of insulin \<37.06 µIU/mL,
* Blood pressure \<140/90 mmHg (measured 2 times with 10 minutes interval),
* TSH \<4.2 mIU/L and fT4 \<1.7 ng/dL,
* Hemoglobin levels 12-16 g/dL, leucocyte count \<10.3\*10\^3/µL and neutrophil count \<4.9\*10\^3/µL; eosinophil count \<0.5\*10\^3/µL, basophil count \<0.2\*10\^3/µL

Exclusion Criteria:

* Women with high cardiovascular disease risk profile (Framingham score for coronary heart disease \>10%),
* Women who were diagnosed with a cardiovascular disease (coronary heart disease, stroke),
* Women with hypertension,
* Smokers,
* BMI \>30 kg/m2,
* Women with diabetes
* Women who were surgically postmenopausal,
* Women who used hormone therapy in the last three months,
* Women with obstructive sleep apnea
* Women who are using medicine which may cause sleep disturbances.