A 69-year-old woman with Alzheimer disease is brought to the emergency department after getting lost while taking a walk in her neighborhood. Her son has been unable to contact the patient for the last 2 days, and today the police found her wandering in a park. The patient says that she drank water from a park fountain but has not had anything to eat for over 24 hours. On physical examination, she is mildly confused with dry mucous membranes. Laboratory studies show a blood glucose level of 92 mg/dL. Which of the following hormones binds to an intracellular receptor to help maintain this patient's laboratory findings within the normal range?

Question

A 69-year-old woman with Alzheimer disease is brought to the emergency department after getting lost while taking a walk in her neighborhood.  Her son has been unable to contact the patient for the last 2 days, and today the police found her wandering in a park.  The patient says that she drank water from a park fountain but has not had anything to eat for over 24 hours.  On physical examination, she is mildly confused with dry mucous membranes.  Laboratory studies show a blood glucose level of 92 mg/dL.  Which of the following hormones binds to an intracellular receptor to help maintain this patient's laboratory findings within the normal range?

Quizplus · Accepted Answer

11ec160b_36a0_0284_9249_e578c02e6cc8_MD0001_00 This patient has experienced a prolonged fast, but her blood glucose level is normal. As blood glucose levels fall in the fasting state, hypoglycemia is prevented due to suppression of insulin secretion and activation of counterregulatory hormones. Glucagon is the primary hormone secreted acutely in response to falling glucose levels; it stimulates hepatic glycogenolysis and gluconeogenesis. Concurrently, epinephrine further stimulates glycogenolysis and gluconeogenesis, increases the release of gluconeogenic substrates from muscle and fat, and limits glucose utilization by some insulin-sensitive peripheral tissues. As the fast continues, secretion of cortisol and growth hormone increases; these hormones attenuate hypoglycemia by altering transcription of key enzymes. In the inactivated state, intracellular cortisol receptors are found in the cytoplasm in association with heat shock proteins. Binding of cortisol to the carboxy terminal portion of the receptor causes the release of the heat shock proteins and allows receptor dimerization. The activated homodimers are then transported to the nucleus, where they control gene expression by binding to hormone-responsive DNA elements in the promoter region of target genes. Cortisol increases transcription of gluconeogenic enzymes as well as those involved in lipolysis and proteolysis. (Choices B, C, and F) Catecholamines (eg, epinephrine, norepinephrine) and glucagon attenuate hypoglycemia. However, they exert their metabolic effects via extracellular, transmembrane, G protein-coupled receptors that activate adenyl cyclase and increase cyclic AMP production. (Choice D) Growth hormone acts via an extracellular, transmembrane receptor that activates a JAK-STAT pathway. Growth hormone antagonizes insulin action, increases gluconeogenesis, and promotes lipolysis (provides gluconeogenic substrates). (Choice E) In addition to the production of counterregulatory hormones, the inhibition of insulin release from pancreatic beta cells plays a primary role in preventing hypoglycemia during fasting. However, insulin acts on a extracellular transmembrane receptor with intrinsic tyrosine kinase activity. Educational objective: In a fasting state, glucagon and epinephrine bind to transmembrane receptors and prevent hypoglycemia by increasing hepatic glycogenolysis and gluconeogenesis. Prolonged fasting increases the secretion of cortisol, a steroid hormone that binds to an intracellular receptor and acts to increase transcription of enzymes involved in gluconeogenesis, lipolysis, and proteolysis.

A 69-Year-Old Woman with Alzheimer Disease Is Brought to the Emergency