Downregulation is defined as which of the following?

Downregulation is defined as which of the following?

• A. Inability of hormones to react to receptors
• B. Increased receptor sensitivity
• C. Increased hormone production
• D. Decreased hormone release

Answer: (A)

Downregulation happens when target cells reduce their responsiveness to a hormone after prolonged exposure. This occurs through fewer receptors or receptors becoming less sensitive, so the signal from the hormone is weaker and the cellular response is diminished. In this light, the idea of an inability of the hormone to react with its receptors captures the outcome: the hormone can’t elicit the same effect because the receptors aren’t presenting the same level of responsiveness. The other options describe changes in hormone production or release, or an opposite effect (increased receptor sensitivity), which would not explain the reduced response characteristic of downregulation.

Downregulation happens when target cells reduce their responsiveness to a hormone after prolonged exposure. This occurs through fewer receptors or receptors becoming less sensitive, so the signal from the hormone is weaker and the cellular response is diminished. In this light, the idea of an inability of the hormone to react with its receptors captures the outcome: the hormone can’t elicit the same effect because the receptors aren’t presenting the same level of responsiveness. The other options describe changes in hormone production or release, or an opposite effect (increased receptor sensitivity), which would not explain the reduced response characteristic of downregulation.