Question

Short / Long answer type questions.
How quickly do you think a steroid hormone can start to exert its effects?

Answer 1

In general, steroids are slow-acting hormones. Fast acting hormones include many of the protein hormones that bind to membrane-bound receptors. This is a relatively quick process because second messengers like cAMP amplify the cascade.

In contrast, a steroid such as testosterone must diffuse through the membrane and act on a receptor in the cytosol or nucleus of the target cell. To have its effects on the cell, testosterone must affect gene expression by regulating transcription. It does so by binding to a hormone response element on the DNA. The protein products are made from the targeted genes, leading to a cellular response. As you can imagine, it takes a relatively long time (usually hours) to make new proteins in this fashion, which is why it is slow-acting.