VIP
VIP, or Vasoactive Intestinal Peptide, is a naturally occurring signaling peptide found throughout the nervous system, digestive tract, lungs, and immune system. Researchers study how it helps coordinate inflammation, blood flow, digestion, breathing, and the body’s internal clock.
VIP AT A GLANCE
WHAT IS VIP?
Vasoactive Intestinal Peptide is a naturally occurring peptide containing 28 amino acids. It was first isolated from intestinal tissue, which led to its name, but researchers later discovered that VIP is widely distributed throughout the body.
VIP acts as both a neuropeptide and a signaling molecule. It is released by nerve cells in the brain, digestive system, airways, and other tissues. Certain immune cells can also produce or respond to VIP, creating an important connection between the nervous and immune systems.
HOW DOES VIP WORK?
VIP produces many of its effects by attaching to two receptors called VPAC1 and VPAC2. These receptors are found on nerve cells, smooth-muscle cells, immune cells, and tissues throughout the digestive, respiratory, and cardiovascular systems.
When VIP activates these receptors, it commonly increases a cellular messenger called cyclic AMP. The resulting signals can relax smooth muscle, widen blood vessels, influence fluid and electrolyte secretion, and change the activity of immune cells. Its effects depend heavily on the receptor, tissue, and biological conditions involved.
Areas of Research
VIP research explores how one signaling peptide can coordinate activity across the nervous, immune, digestive, respiratory, and cardiovascular systems.
IMMUNE BALANCE AND INFLAMMATION
Studying how VIP affects immune-cell activity, inflammatory signals, and the balance between protective and excessive immune responses.
DIGESTIVE FUNCTION
Examining smooth-muscle relaxation, intestinal movement, blood flow, and the secretion of water, electrolytes, and digestive fluids.
LUNG AND BLOOD-VESSEL FUNCTION
Investigating whether VIP-related signaling can relax airways and pulmonary blood vessels while influencing inflammation within lung tissue.
BRAIN SIGNALING AND SLEEP
Exploring VIP’s role in communication between nerve cells, neurological protection, learning, behavior, and synchronization of the body’s daily rhythms.
Research Highlights
Laboratory and animal studies suggest that VIP can reduce certain inflammatory signals while encouraging immune responses associated with regulation and tissue protection. Researchers have explored these effects in models of autoimmune disease, intestinal inflammation, neurological injury, arthritis, and respiratory illness. Translating these findings into treatment has been difficult because natural VIP is rapidly broken down and can affect many systems at once.
Synthetic VIP, known as aviptadil, has been investigated in pulmonary hypertension, acute respiratory distress, and severe COVID-19. Small studies produced signs of possible respiratory or blood-vessel effects, but larger research has been less encouraging. In the randomized TESICO trial involving 461 people with COVID-19-related respiratory failure, intravenous aviptadil did not significantly improve clinical outcomes through 90 days compared with a placebo. These results show that a strong biological explanation does not always produce a meaningful benefit in human treatment.
WHAT IS VIP MOST COMMONLY RESEARCHED FOR?
VIP is most commonly researched for inflammation, immune regulation, digestive activity, airway relaxation, pulmonary blood flow, and nervous-system communication. Researchers also study its importance in circadian rhythms because VIP-producing neurons help synchronize the biological clock located within the brain. Although VIP participates naturally in all these processes, administering additional VIP has not been proven to improve them in otherwise healthy people.
HOW DOES VIP FIT INTO PEPTIDE RESEARCH?
VIP helps researchers understand the ongoing communication between nerves, organs, and immune cells. It demonstrates how a peptide released by the nervous system can influence blood vessels, digestion, inflammation, breathing, and daily biological rhythms. Its broad activity also helps scientists examine the challenge of developing peptide treatments that reach the intended tissue without producing unwanted effects elsewhere.
WHAT MAKES VIP UNIQUE?
VIP stands out because its name describes only a small part of its biological activity. Although it was discovered in the intestine and can widen blood vessels, it also acts throughout the brain, lungs, pancreas, and immune system. This unusually broad distribution allows VIP to connect biological systems that are often studied separately.
HOW IS VIP DIFFERENT FROM PACAP?
VIP and PACAP belong to the same peptide family and share many structural and biological similarities. Both can activate the VPAC1 and VPAC2 receptors and are studied for effects involving inflammation, nerve cells, blood vessels, and organ function. PACAP also activates the PAC1 receptor with much greater preference, giving it a somewhat different pattern of activity. VIP contains 28 amino acids, while the most common form of PACAP contains 38.
WHAT HAVE RESEARCHERS LEARNED ABOUT VIP SO FAR?
Researchers have learned that VIP is an important natural regulator rather than simply a digestive peptide. It influences immune signaling, smooth-muscle activity, blood flow, glandular secretion, and communication between neurons. Preclinical findings suggest several possible therapeutic applications, but VIP’s short lifespan, widespread effects, and ability to lower blood pressure or cause flushing and diarrhea have complicated treatment development. Human studies have not yet established broad clinical benefits.
IS RESEARCH ON VIP CONTINUING TODAY?
Yes. Researchers continue examining VIP and its receptors in inflammatory disease, neurological conditions, digestive disorders, lung injury, pulmonary hypertension, and circadian biology. Work is also underway on longer-lasting VIP-related molecules, targeted delivery systems, and receptor-selective treatments. These approaches may help researchers preserve a desired effect while reducing the widespread activity that has limited the usefulness of natural VIP.