The structure of steroids is as follows: one steroid, which has a lipid nature contains four carbon atoms rings. Their action in our body is hormonal, they act as “chemical messengers” and “tell” cells what to do. Read this article to know more about structure and function of steroids. Additionally, you will learn the advantages of cholesterol.
What Are Steroids?
There are probably many thoughts which appear in your mind when you think of steroids. You imagine building up huge muscles and athletes who take illegal anabolic steroids to enhance this process. Perhaps, the last thing you will think about is that our body is a steroid producer on its own. It may sound implausible, but each day natural steroids are produced in both males and females. This process is sustainable.
Read about “natural” steroids, which are synthesized by our body, their functions and constitution.
Steroid Chemical Structure
What is structure? According to encyclopedias and dictionaries, structure is the arrangement of and relations between the parts, elements or components of something more complex.
It’s possible to define steroids by analyzing their chemical structure. They have an organic origin. Their structure is rather intricate—four carbon rings, three of which are 6-sided and another that’s is 5-sided.
According to D.N. Kirk and B.A. Marples (Steroid Analysis, SpringerLink, pp 1-24), almost all steroids possess either one or, more typically, two methyl groups at “angular” or “bridgehead” positions where two rings cross.
The functional groups of varied steroids are not the same. Atom groups, located together with certain behavior are functional groups. When a connection between various functional groups and steroid rings with a basic configuration is reached, you have steroids, which operate in different ways. This issue will also be discussed here.
Steroids have an abiotic nature, subsequently, they contain carbon as a basic element. Carbohydrates, lipids, and proteins are classic organic compounds. In reality, steroidal substances belong to lipids. This is a bit strange because the basic steroidal structure and the structure of triglycerides, phospholipids, and other lipids are disparate. The main aspect which proves that steroids are lipidic compounds is that the principal components of them are carbon and atoms of hydrogen. Besides, steroids are water insoluble due to their molecular structure.
There are several functions of steroids in humans. They have hormonal activity. They influence your growth and are responsible for sexual development. Male testes and female ovaries respectively produce masculine and feminine sexual steroid hormones. These are testosterone, which is secreted by the male sex gland, and estrogen, which manages sexual maturation in women.
The adrenal cortex also produces a hormone with a steroidal nature aimed at regulating the carbohydrate metabolism and is accountable for maintaining the immune system and protecting it from inflammation.
Other types of steroids, for example, progesterone also have determinative functions. Thus, progesterone is extremely important for the female reproductive system and for the bearing of a child. Together with other hormones, it is responsible for women’s health, prepares the body for conceiving and birthing a baby, and affects the metabolism and the figure of a woman. As stated by Kim JJ and Chapman-Davis E. (Semin Reprod Med. 2010 Jan), progesterone opposes estrogen-driven growth in the endometrium, the inner epithelial layer of the mammalian and human uterus. Its deficiency may lead to hyperplasia and adenocarcinoma.
It is also important for the male body. It’s used for creating testosterone, cortisol, neurosteroids, and other hormones, it also takes part in other organismal functions.
The Importance of Cholesterol
Cholesterol (C27H46O) is the common precursor (forerunner) of all steroidal hormones. The exchange of cholesterol in tissues secreting steroids is enormously essential for the regulation of steroid biosynthesis. For instance, according to Stephen M. Eacker, Nalini Agrawal, Kun Qian et al. (Mol Endocrinol. 2008 Mar), testosterone is produced from cholesterol in Leydig cells (in the testes) under control of the pituitary gonadotropin LH.
It has been mistakenly believed that cholesterols used for steroidogenesis (the complex multienzyme process) are synthesized from acetate in cells that “manufacture” steroids. Although cholesterol synthesis does occur in these cellular systems, plasma lipoproteins that are synthesized in the liver are most probably the principal source of cholesterol used for steroidosynthesis.
The relative importance of different classes of lipoprotein substances as sources of cholesterol for this genesis depends on the animal species, but in humans, low-density lipoproteins (LDLs) play the most significant role.
Free cholesterol in steroid-producing cells, regardless of whether it originated from lipoproteins or synthesized in a cell, can be immediately used for steroidogenesis or converted to cholesterol esters. Cells that synthesize steroid hormones contain numerous cholesterolic esters in structures known as lipid droplets. Cholesterol is mainly stored in the form of esters. They are subject to hydrolysis, which transforms them into free cholesterol (used in steroidogenesis).
Higashijima M, Kato K, Nawata H, and Ibayashi H. (Endocrinol Jpn. 1987 Oct) reported that adrenocortical adenoma cells utilize plasma lipoproteins as a source of chol for steroidosynthesis during the long-lasting stimulation of steroid secretion.
The rate of the hydrolitic process covering cholesterol esters, and the capture and degradation of lipoproteins, is under the regulating influence of hormones. Thus, the delivery of free cholesterol to steroid-producing cells can be closely coordinated with the overall activity of biosynthesis processes.
Therefore, cholesterol isn’t bad for us. It can be harmful only if it is elevated.