As Hormone synthesis is the term used to describe the manufacturing process of hormones. Hormones are biochemical messenger substances that are released by hormone-producing cells and cause certain effects on target cells.
The process of making hormones is called hormone synthesis. Illustration shows the release of insulin from the pancreas.
A wide variety of hormones are formed in the course of hormone synthesis. According to their basic chemical structure, two large groups of hormones can be distinguished. On the one hand there are the peptide hormones and on the other hand the steroid hormones.
Steroid hormones are only very poorly soluble in water and must therefore be bound to carrier proteins for transport in the blood. The mechanism of action is only triggered in the target cell itself. Peptide hormones are readily soluble in water and do not have to be bound to proteins for transport. They bind directly to the cell surface of their target cell through specific receptors and trigger the mechanism of action there.
The hormone synthesis is very different in the two groups. In hormone synthesis, autocrine, endocrine and paracrine hormones are produced. Hormones are called autocrine when they work within the same cell. If neighboring cell aggregates are controlled by the hormone produced, one speaks of a paracrine hormone. If the hormone reaches the target cell via the bloodstream, it is an endocrine hormone.
Peptide hormones are made up of amino acids. Amino acids are the smallest building blocks of proteins. The structure of the peptide hormones is genetically coded. Hormone production takes place in the endoplasmic reticulum of the hormone-producing cell. The endoplasmic reticulum is a small system of channels within the cell.
In many cells, peptide hormones are produced in intermediate stages. These intermediate stages are also known as pre- or prohormones. They are stored in the Golgi apparatus of the cell or in small vesicles and activated when necessary and converted into the final hormone. In this way, larger quantities of the respective hormone can be produced quickly.
The peptide hormones include, for example, insulin, somatostatin or glucagon. With insulin and glucagon in particular, it is important that sufficient amounts of hormones can be released quickly if necessary. Otherwise, hypoglycemia or hypoglycemia will occur after eating or in physical stressful situations.
Steroid hormones are usually made from cholesterol. The thyroid hormones are an exception. These are counted among the steroid hormones, but are synthesized from so-called tyrosines. The cholesterol for the steroid hormones comes primarily from the liver. The production of hormones takes place in the mitochondria of the hormone-producing cells. Mitochondria are also called the "power plants of the cell" because they supply the cells with energy. Steroid hormones are primarily produced in the adrenal cortex. Examples of steroid hormones are mineralocorticoids such as aldosterone or glucocorticoids such as cortisol.
The production of steroid hormones in the adrenal cortex is strongly influenced by a transport protein, the Steroidogenic Acute Regulatory Protein (StAR). This protein quickly makes cholesterol available for hormone synthesis when there is an increased need. Rapid hormone synthesis by glucocorticoids must be guaranteed, especially in the case of acute stress reactions. Glucocorticoids are also known as stress hormones. They ensure that the body's energy reserves are released. Vitamin D and vitamin A, which are incorrectly assigned to vitamins, actually belong to the steroid hormones.
The hormone synthesis is controlled by feedback. With negative feedback, hormone synthesis is stopped or reduced as soon as the target cell shows the desired reaction. With positive feedback, the target cell's response enhances hormone synthesis. This is especially the case with sex hormones. Important control organs of hormone synthesis are the pituitary gland and the hypothalamus.
Disorders of hormone synthesis can occur with any hormone. The symptoms can be very diverse, depending on which hormone is affected by the synthesis disorder. Disorders of hormone synthesis are often caused by diseases of the hormone-producing organ.
In type 1 diabetes mellitus, the hormone synthesis of insulin is disturbed. It is an autoimmune disease in which the body's own immune cells destroy the insulin-producing cells in the pancreas. Insulin synthesis is only possible to a limited extent or not at all. As a result, the sugar from the blood can no longer be transported into the cells. The result is an excess of sugar with typical symptoms such as increased thirst, frequent urination and weight loss. If left untreated, there is a risk of ketoacidosis, a dangerous derailment of the metabolism.
A disruption in the synthesis of thyroid hormones can result in an underactive thyroid. The synthesis disorder can be congenital, caused by iodine deficiency or an autoimmune disease such as Hashimoto's thyroiditis. If the hormone synthesis of the thyroid gland is stimulated too strongly, the thyroid gland becomes overactive. Here too, an autoimmune disease, Graves' disease, can be the cause. Typical symptoms of an overactive thyroid are increased sweating, nervousness, diarrhea and hair loss.