Steroids

Steroids, or steroid hormones, are fat-soluble molecules whose chemical structures are derived from cholesterol. Found in both plants and animals, these small molecules regulate many developmental and physiological processes within the organism. They function by binding to and activating proteins called hormone receptors located in the nucleus of the cell. These activated receptor proteins then bind to DNA, turning on or off specific genes within the cell.

There are five major classes of steroids in the human body: progestagens, androgens, and estrogens, also known as sex hormones, affect sexual development and function; glucocorticoids regulate carbohydrate and lipid metabolism and have an inhibitory effect on inflammation; and mineralocorticoids help regulate the balance of electrolytes in the body and affect blood pressure through regulation of the fluid amounts in the body and vasculature.

Fat storage cells, also known as adipose tissue, play an important role in metabolizing steroid hormones, [Page 714]interconverting them between different forms. A high proportion of fat to muscle in the body can therefore disrupt the normal balance of steroids in the body.

A high proportion of fat to muscle in the body can disrupt the normal balance of steroids in the body.

Glucocorticoids such as cortisol increase the uptake of lipids into fat cells by increasing the expression of lipoprotein lipase (LPL), an enzyme found on the cell's surface that helps remove fatty acids from lipoproteins circulating in the blood. Excess glucocorticoid levels lead to a redistribution of body fat, mostly in the abdomen but also in the face, producing a “moon face” characteristic of Cushing syndrome. The sex steroid hormones are believed to act in an opposite manner, decreasing lipid uptake into adipose tissue. Testosterone in particular has a strong effect, leading to lower body fat content in men.

The reduction of sex hormone levels that occurs with age is associated with an increase in obesity, bringing with it risks for cardiovascular disease and Type 2 diabetes. Hormone replacement therapies in older women and men can alleviate this problem, but have side effects which limit their use.

Medically, steroids are used to reduce swelling, increase the level of red blood cells, ease breathing, and replace low levels of hormones in the body as well as for treatment for delayed puberty, impotence, or in conditions such as acquired immunodeficiency syndrome (AIDS) or cancer. Side effects of steroid use include an increased appetite, bitter taste in the mouth, and cellular swelling. This may cause a transient rise in a person's weight.

Anabolic steroids, also known as roids, are derived from testosterone and promote the development of muscle mass and enhance bone structure. They have many legitimate medical uses, but have received a bad reputation due to their controversial use in competitive sports. These hormones are often used by athletes to increase muscle mass and strength, but have serious side effects, including virilization (the development of male secondary sexual characteristics in women), severe acne, increased blood pressure, elevated cholesterol levels, and possibly liver damage.