Inhibition of glycogenolysis and gluconeogenesis is caused by
**Core Concept**
The regulation of glucose metabolism is a crucial aspect of physiology and pharmacology. Glycogenolysis and gluconeogenesis are two key pathways that maintain blood glucose levels by breaking down glycogen stores and synthesizing glucose from non-carbohydrate sources, respectively.
**Why the Correct Answer is Right**
The correct answer involves the inhibition of enzymes involved in glycogenolysis and gluconeogenesis. One of the key regulators of these pathways is the glucagon-like peptide-1 (GLP-1) analogue, liraglutide, which exerts its effects through the inhibition of phosphodiesterase 3B (PDE3B) and the subsequent decrease in cyclic AMP (cAMP) levels. This decrease in cAMP reduces the activity of key enzymes involved in glycogenolysis, such as glucose-6-phosphatase, and gluconeogenesis, including the phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-bisphosphatase.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a known inhibitor of glycogenolysis and gluconeogenesis.
* **Option B:** This option is incorrect because it is a glucagon receptor antagonist, which would actually increase glucose production, not decrease it.
* **Option C:** This option is incorrect because it is a medication that primarily targets insulin resistance, not glycogenolysis and gluconeogenesis.
**Clinical Pearl / High-Yield Fact**
The inhibition of glycogenolysis and gluconeogenesis is a key mechanism by which certain medications, such as GLP-1 analogues, exert their hypoglycemic effects. This is particularly relevant in the management of type 2 diabetes mellitus.
**Correct Answer:** D. Liraglutide