Why improving receptor sensitivity is important for NBE,
Regulation of hormone receptors
is very important for a normal functioning cell. There are several ways a cell regulates its hormone receptors. Below is an outline of such regulatory functions:
Regulating the expression of receptors - changing the number of receptors on the plasma membrane.
1. Up regulation - increasing the number of receptors
2. Down regulation - decreasing the number of receptors
-internalization - endocytosis of receptors
-modify transcription - inhibiting or stimulating transcription factors
-modify receptor half-life - adding groups to the receptors which will degrade them faster
is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external variable. An increase of a cellular component is called upregulation.
An example of downregulation is the cellular decrease in the number of receptors to a molecule, such as a hormone or neurotransmitter, which reduces the cell's sensitivity to the molecule. This phenomenon is an example of a locally acting negative feedback mechanism.
An example of upregulation
is the increased number of cytochrome P450 enzymes in liver cells when xenobiotic molecules such as dioxin are administered (resulting in greater degradation of these molecules).
Most receptor agonists
downregulate their respective receptor(s), while most receptor antagonists
upregulate their respective receptor(s). The disequilibrium caused by these changes often causes withdrawal when the long-term use of a medication or drug is discontinued. However, the chronic use of certain receptor antagonists may also damage receptors faster than they upregulate.
Upregulation and downregulation
can also happen as a response to toxins or hormones. An example of upregulation in pregnancy is hormones that cause cells in the uterus to become more sensitive to oxytocin.
is a chemical that binds to a receptor and activates the receptor to produce a biological response. Whereas an agonist causes an action, an antagonist
blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist.
Downregulation and upregulation
Question- what triggers tissue growth in order for NBE to work?