Mechanism 2 of Hormonal Action

Endocrine Glands secrete and produce body molecules called Hormones. These body molecules called hormones are released to our blood stream and are then distributed to the other parts of the body where they bring out physiologic responses from specific cells.

There are 2 mechanisms of Hormonal Action: the 1^st mechanism involves non-steroid hormones like peptides, amino acids and sphingolipids, and the 2^nd mechanism involves generally steroid hormones like testosterone and estrogen.

Steroid hormones contain structures that are lipid-soluble and synthesized or derived from cholesterol. with the basic nucleus which is CPPP (cyclopentanoperhydrophenanthrene). Steroid hormones pass through the target cell’s cell membrane which can cause changes within the cell. Unlike non-steroid hormones, steroid hormones can do this because they are fat-soluble. Cells membrane contains phospholipid bilayer which forbids fat-insoluble molecules from diffusing into the cell.

Steroid Hormone Mechanism of Action

The steroid hormone mechanism of action can be summarized as follows:

1. It first passes through the cell membrane of the target cell.
2. It binds with the cytoplasm in a specific receptor site.
3. The receptor bound steroid hormone goes inside the nucleus and binds on the chromatin with another specific site.
4. Then the production of proteins takes place when the steroid hormone-receptor complex calls for the production of messenger RNA (mRNA) molecules.
   

References:

Henry’s Clinical Diagnosis and Management by Laboratory Methods,21^st edition; edited by Richard A. McPherson and Matthew R. Pincus

http://wwwences/LifeScience/GeneralBiology/Physiology/EndocrineSystem/MechanismsHormone/MechanismsHormone.htm