Lecture 10: Hormone Actions

How are hormone secretion patterns described

Amplitude (how much) and frequency (how often)

Describe an episodic pattern of hormone secretion

High amplitude, low frequency

What type of pattern is surge release

Episodic

Describe a basal pattern of hormone release

Low amplitude, high frequency

What type of pattern is tonic release

Basal

Describe a sustained pattern of hormone release

High amplitude, high frequency

What pattern is associated with steroid hormone release

Sustained

What type of hormones can only utilize plasma membrane receptors

Peptide, glycoprotein, and eicosanoid hormones

Why can’t peptide, glycoprotein, and eicosanoid hormones enter the cell

They aren’t lipid soluble, and can’t make it through the lipid bilayer

What type of hormones can utilize plasma membrane, cytoplasmic, and nuclear receptors

Steroid

Describe how a hormone binding to a PM receptor works

Hormone binds to receptor triggers a second messenger system within the cell

Describe how a hormone binding to an intracellular receptor works

The steroid hormone-receptor complex becomes a transcription factor

What is the universal second messenger

Cyclic adenosine monophosphate (cAMP)

Describe cAMP signal transduction pathway

Hormone binds to ligand→ G protein activates and dissociates→ activates adenylyl (adenylate) cyclase→ converts 1 ATP into 3 cAMP → binds and activates protein kinase→ phosphorylates proteins, triggers new protein synthesis

How are peptide and glycoprotein hormones inactivated

After they lose glycosylation, they are engulfed by hepatocytes and degraded, to be excreted in waste

How are eicosanoid hormones inactivated

Broken down by dehydrogenases in hepatocytes, or on contact with O2 in the lungs

How are steroid hormones inactivated

Steroids are solubilized by carrier proteins, carried in blood to liver. Hepatocytes make the steroid water soluble by adding on an ionic compound. Steroid-ion complex reenters blood, and is filtered out by kidneys

List the steroid carrier proteins and what they bind to

* Albumin: everything
* Sex-hormone binding globulin: androgens, estrogens
* Transcortin/SerpinA6: progestagens