Vasopressin, also known as antidiuretic hormone (ADH), is a peptide hormone produced in the hypothalamus and released by the posterior pituitary gland.
Its main functions are to:
- Conserve water in the body by reducing urine output
- Regulate blood pressure by constricting blood vessels
🧠 Where and How Is Vasopressin Made?
- Synthesized in the hypothalamus (specifically the supraoptic and paraventricular nuclei)
- Transported down nerve fibers to the posterior pituitary gland
- Released into the bloodstream in response to:
- Low blood volume or pressure
- High blood salt levels (high plasma osmolality)
💧 What Does Vasopressin Do?
🔹 1. Water Retention (Antidiuretic Effect)
- Acts on the kidneys, specifically the collecting ducts
- Increases the number of aquaporin channels, allowing more water to be reabsorbed into the bloodstream
- Result: Less water lost in urine, more concentrated urine
🔹 2. Blood Pressure Regulation
- Causes vasoconstriction — the narrowing of blood vessels
- Helps raise or stabilize blood pressure during dehydration or blood loss
🔹 3. Other Effects
- May play a role in social bonding, memory, and stress response
- Works alongside oxytocin in regulating emotional behaviors
📉 Low Vasopressin Levels Can Cause:
➤ Diabetes Insipidus
- A condition where the kidneys can’t concentrate urine properly
- Leads to:
- Excessive urination (polyuria)
- Excessive thirst (polydipsia)
- Can be central (brain doesn’t produce enough ADH) or nephrogenic (kidneys don’t respond to ADH)
📈 High Vasopressin Levels Can Lead To:
➤ SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion)
- Too much water is retained
- Causes low blood sodium levels (hyponatremia)
- Symptoms: Nausea, confusion, seizures
🧪 Medical Uses of Vasopressin (or Analogs)
- Desmopressin (DDAVP): A synthetic ADH analog used to treat:
- Diabetes insipidus
- Bedwetting
- Some bleeding disorders (like von Willebrand disease)
- Vasopressin (injection): Used in emergency settings to manage:
- Septic shock
- Cardiac arrest (sometimes)
🧠 Summary Table:
| Feature | Vasopressin (ADH) |
|---|---|
| Produced by | Hypothalamus (stored and released by posterior pituitary) |
| Type of molecule | Peptide hormone |
| Main functions | Water conservation, blood pressure regulation |
| Target organs | Kidneys (collecting ducts), blood vessels |
| Low levels cause | Diabetes insipidus |
| High levels cause | SIADH, water retention, hyponatremia |
| Medical uses | Desmopressin for DI, bleeding disorders, bedwetting |