Actions of GLP are all except:
**Core Concept**
Gastric inhibitory polypeptide (GIP) or glucose-dependent insulinotropic peptide (GLP) is an incretin hormone that plays a crucial role in glucose metabolism. GLP is released from the intestinal L cells in response to nutrient ingestion and stimulates insulin secretion in a glucose-dependent manner.
**Why the Correct Answer is Right**
GLP acts on the pancreas to stimulate insulin secretion, which lowers blood glucose levels. GLP also enhances glucose uptake in peripheral tissues by promoting the expression of glucose transporter type 4 (GLUT4) in adipose and muscle cells. Additionally, GLP has been shown to have a role in regulating gastric motility and emptying.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because GLP does not primarily regulate blood pressure. While GLP may have some indirect effects on blood pressure through its effects on glucose metabolism and insulin secretion, it is not a primary regulator of blood pressure.
**Option B:** This option is incorrect because GLP does not primarily regulate thyroid function. While GLP may have some indirect effects on thyroid function through its effects on glucose metabolism and insulin secretion, it is not a primary regulator of thyroid function.
**Option C:** This option is incorrect because GLP is not primarily a neurotransmitter. While GLP may have some indirect effects on neurotransmitter function through its effects on glucose metabolism and insulin secretion, it is not a primary neurotransmitter.
**Clinical Pearl / High-Yield Fact**
GLP is an important incretin hormone that plays a crucial role in glucose metabolism and insulin secretion. It is also a potential therapeutic target for the treatment of type 2 diabetes.
**Correct Answer: D.**