Which hormones are responsible for gluconeogenesis and lipolysis?

SGPGI Nursing Officer-2022

Biochemistry & Nutrition

Easy

Appeared in: SGPGI Nursing Officer-2022

Explanation

Epinephrine and glucagon are key counter-regulatory hormones that work to raise blood glucose levels.
Both hormones potently stimulate gluconeogenesis in the liver, which is the synthesis of new glucose.
Both hormones also stimulate lipolysis in adipose tissue, which is the breakdown of stored fat into fatty acids and glycerol.
This dual action ensures that the body can produce glucose and utilize fat for energy during times of fasting, exercise, or stress.

Option A: While glucagon is correct, thyroxine's primary role is regulating the basal metabolic rate. It does stimulate lipolysis but is not a primary, acute driver of gluconeogenesis like epinephrine is.
Option B: This option is incorrect because insulin has the opposite effect; it inhibits both gluconeogenesis and lipolysis. Insulin is a storage hormone, not a mobilization hormone.
Option D: Cortisol and thyroxine both influence these pathways, but not as the primary acute stimulators. Cortisol has a slower, permissive effect on gluconeogenesis and lipolysis, meaning it supports the actions of other hormones. Thyroxine mainly affects the overall metabolic rate.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of metabolism as background academic context rather than a clinical decision trigger.
Understanding these hormonal actions is crucial for managing diabetes mellitus. In uncontrolled Type 1 diabetes, the absence of insulin leads to unopposed action of glucagon and epinephrine, causing severe hyperglycemia (from gluconeogenesis) and ketoacidosis (from excessive lipolysis and ketone body formation).
Stress hyperglycemia can occur in critically ill patients due to high levels of stress hormones like epinephrine and cortisol, leading to elevated blood glucose even in non-diabetic individuals.
What if? If a patient is experiencing hypoglycemia (low blood sugar), the body's natural response is to release glucagon and epinephrine to stimulate gluconeogenesis and glycogenolysis to raise blood glucose back to normal levels. This is a vital protective mechanism.

How to Approach the Question

First, understand the definitions of the key terms: 'gluconeogenesis' (making new glucose) and 'lipolysis' (breaking down fat). Both are processes that increase available energy substrates in the blood.
Next, recall the primary function of each hormone listed in the options. Think about which hormones raise blood glucose and which lower it.
Evaluate each option pair. The correct pair must contain two hormones that both stimulate gluconeogenesis AND lipolysis.
Eliminate the option containing insulin, as it is a storage hormone that inhibits both processes.
Compare the remaining pairs. Epinephrine and glucagon are known for their rapid, potent effects on glucose and fat mobilization. Cortisol and thyroxine have more chronic or permissive roles, making them less likely to be the primary answer for acute stimulation.

Concept Tested & Keywords

QkclcxWNbd8irG9_knLc71

E6 Physiology Guyton 4SAE Part 3 p. 5-7

E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) p. 305-307