Introduction of hormones
Hormones are a highly effective biologically active substance secreted by endocrine glands or endocrine cells, which act as a messenger in the body to regulate the physiological processes of the body. It plays an important role in regulating the body's metabolism, growth, development, reproduction, gender and so on. The secretion of hormones is extremely small, at the level of nanograms, but its regulation is extremely obvious. The mechanism of action of hormones is to introduce information into cells by binding to specific receptor proteins on the cell membrane or in the cytoplasm, causing a series of corresponding linkage changes in the cells, and finally expressing the physiological effects of hormones. The physiological role of hormones is mainly to regulate the metabolism of proteins, sugars and fats and the metabolism of water and salt, maintain the balance of metabolism, provide energy for physiological activities, promote cell division and differentiation, and ensure the normal growth, development and maturity of tissues and organs, and affect the aging process; affect the development of the nervous system and its activities; promote the development and maturity of the reproductive organs, regulate the reproductive process; closely cooperate with the nervous system, so that the body can better adapt to environmental changes. Hormones have a wide range of effects, but do not participate in specific metabolic processes, only regulate specific metabolic and physiological processes, regulate the speed and direction of metabolism and physiological processes, so that the activities of the body are more suitable for changes in internal and external environments. According to previous research, hormones and cardiovascular diseases are closely related. For example, sex hormones play an important role in atherosclerosis (AS); Growth hormone can promote myocardial tissue growth and improve cardiac function; the target organ of thyroxine is the heart; the research of natriuretic peptide has progressed to the molecular level.
The relationship of hormones and cardiovascular
In hormone and cardiovascular research, researchers found that hormone secretions such as sex hormones, growth hormones, thyroid hormones, and natriuretic peptides have a significant effect on cardiovascular disease.
Estradiol is the main component of estrogen (E). Ovarian function is severely degraded, and the E2 level is reduced to more than 2/3 of that before menopause, and the cardiovascular protection of women is lost. Postmenopausal women have elevated levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein-cholesterol (LDL-C), and decreased levels of high-density lipoprotein-cholesterol (HDL-C) are associated with E2 deficiency. It is one of the main mechanisms leading to abnormal lipid metabolism and an increased incidence of coronary heart disease and mortality. Sack and other studies have confirmed that E2 can accelerate the oxidative decomposition of LDL-C and increase the level of HDL-C. Its anti-atherosclerosis (AS) effect is independent. Some studies have shown that E2 has the effect of directly expanding coronary vascular smooth muscle. It can directly act on the vascular endothelium, indirectly causing endothelial cells to release the vasodilator (nitric oxide) and prevent endothelial cells from producing the vasoconstrictor (acetylcholine). E deficiency has just led to coronary dysfunction. Williams and colleague's animal experiments proved that coronary injection of acetylcholine lead to contraction, and then the coronary artery expansion after intravenous injection of E for 20 minutes. So E is beneficial for the protection of cardiovascular diseases. Decreased E level is one of the important factors for coronary heart disease in postmenopausal women. In the clinical field, estrogen replacement therapy (ERT): long-term use of E can increase the risk of endometrial cancer. In order to prevent the occurrence of coronary heart disease, ERT should be adopted in postmenopausal women with severely reduced E2 levels.
There are a variety of androgen in the male body, the testosterone is important in cardiovascular. It has a beneficial effect on vascular endothelial function through a variety of pathology, which can prevent the occurrence of thrombotic diseases. Studies have found that men with low sexual function are prone to thromboembolic disease, and taking androgen can counteract this effect. Androgen can lower blood lipid levels, inhibit multiple parts of AS, and reduce coronary smooth muscle spasm. Herrington et al found that decreased plasma testosterone levels can cause AS to occur; elevated testosterone levels delay AS. Wu et al found that increasing plasma testosterone levels alleviated AS angina and myocardial ischemia. In clinical treatment, low-dose testosterone can reduce exercise-induced myocardial ischemia, improve quality of life, and increase angina threshold in men with chronic stable angina.
Growth hormone (GH)
Growth hormone also plays a role in promoting myocardial tissue growth, changing wall thickness and adjusting the tension in the cardiovascular system. It is the main mechanism of action to improve cardiac function in patients with heart failure. Studies have shown that GH can improve the long-term prognosis of patients with heart failure, and increase the function of cardiac. It is beneficial for end-stage heart failure with reduced energy reserve. Clinically relevant research is still in progress.
The heart is the most important target organ of thyroxine. It can enhance ventricular systolic and diastolic function, reduce peripheral vascular resistance, and reduce cardiovascular stimulating response to adrenaline. In recent years, researchers has discovered that extracorporeal circulation, acute myocardial infarction, and congestive heart failure, patients with heart transplantation, and sudden cardiac death has shown a lower level of thyroxine. Katzcff et al. in a study of experimental animals with hypothyroxin syndrome found that the application of low doses of thyroxine significantly improved cardiac systolic and diastolic function in animals. Therefore, thyroxine is expected to become a new drug for the treatment of cardiovascular diseases.
Natriuretic peptide is a cardiovascular hormone secreted by the heart. It can excrete sodium and diuretic, expand blood vessels and inhibit aldosterone secretion. Four types are currently found: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), type C natriuretic peptide (CNP), and dendroaspis natriuretic peptide (DNP). Studies have shown that ventricular expression of ANP is a sign of cardiac hypertrophy. BNP and CNP have the ability to inhibit mast cell and fibroblast growth factors. When faced with hemodynamic stress, such as ischemia. The heart uses a series of intrinsic reactions in an effort to maintain homeostasis. Role of natriuretic peptide is to dilate blood vessels and inhibit the response of mast cells, the reaction of fibroblasts and vascular smooth muscle cells to growth factors and mechanical traction, and inhibits neutrophil-mediated cell damage and AS formation. Natriuretic peptide is released from dying muscle cells. It has a strong function of central regulation and can be used as an indicator of severe myocardial ischemia.