About VIP 10mg (Vasoactive Intestinal Peptide)

Vasoactive Intestinal Peptide (VIP) is a 28-amino acid neuropeptide with one of the broadest distribution profiles of any signalling molecule in the mammalian body. First isolated from porcine intestinal tissue by Said and Mutt in 1970, VIP was initially characterised for its potent vasodilatory properties — hence its name. However, decades of subsequent research have revealed that VIP functions far beyond the vascular system, acting as a neurotransmitter, neuromodulator, and immune regulator across the central and peripheral nervous systems, the gastrointestinal tract, the respiratory system, and the immune compartment.

VIP signals through two class B G protein-coupled receptors, VPAC1 and VPAC2, both of which couple primarily to the Gs pathway to activate adenylate cyclase and elevate intracellular cyclic AMP (cAMP). VPAC1 is expressed widely in the CNS, liver, lung, and on T lymphocytes, while VPAC2 is particularly abundant in smooth muscle, the suprachiasmatic nucleus (SCN), and pancreatic tissue. This receptor distribution underpins VIP’s remarkably diverse functional profile and makes it a compound of interest to research groups spanning neuroscience, immunology, pulmonary biology, and chronobiology.

Research Summary

VIP’s role in immune modulation has been one of the most productive areas of investigation over the past two decades. The pioneering work of Delgado and Ganea, published across a series of studies from the late 1990s onward, established VIP as a potent anti-inflammatory neuropeptide. Their research demonstrated that VIP inhibits the production of pro-inflammatory cytokines including TNF-alpha, IL-6, and IL-12 from activated macrophages, while simultaneously promoting the generation of anti-inflammatory mediators such as IL-10. In T-cell biology, VIP has been shown to shift the Th1/Th2 balance toward a Th2-dominant response and to promote the differentiation of regulatory T cells (Tregs). These properties have positioned VIP as a compound of significant interest in autoimmune disease research, with preclinical studies in models of rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis showing reduced disease severity following VIP administration.

The circadian rhythm research community has identified VIP as an essential component of the mammalian biological clock. VIP-expressing neurons in the suprachiasmatic nucleus (SCN) of the hypothalamus play a critical role in synchronising the firing patterns of individual clock neurons, maintaining coherent circadian output across the SCN network. Studies using VIP-deficient and VPAC2-knockout mouse models have demonstrated that loss of VIP signalling leads to desynchronisation of SCN neurons and disruption of behavioural circadian rhythms, including fragmented sleep-wake cycles and blunted hormonal rhythms. Aton et al. and Colwell et al. have contributed influential work in this area, establishing that VIP acts both as a synchronising signal within the clock and as a mediator of photic entrainment — the process by which the clock adjusts to environmental light-dark cycles.

VIP’s effects on the pulmonary system have attracted sustained research attention, particularly in the context of bronchodilation and airway disease. VIP is one of the most abundant neuropeptides in the lung, where it is localised to nerve fibres innervating airway smooth muscle, submucosal glands, and pulmonary vasculature. Administration of VIP produces relaxation of airway smooth muscle, and studies have reported reduced VIP levels in lung tissue from animal models of chronic airway inflammation. Research groups have explored VIP’s potential relevance to models of asthma and chronic obstructive pulmonary disease, where its dual bronchodilatory and anti-inflammatory properties represent an unusual pharmacological combination not replicated by conventional bronchodilators.

In the gastrointestinal tract — where VIP was first discovered — the peptide functions as a key regulator of smooth muscle relaxation, secretion, and blood flow. VIP is released from enteric neurons and acts as an inhibitory neurotransmitter in the gut wall, mediating the relaxation phase of peristaltic contractions. It also stimulates water and electrolyte secretion from intestinal epithelial cells and promotes pancreatic bicarbonate output. Research in this area has explored VIP’s role in functional gastrointestinal disorders, with particular interest in conditions characterised by dysmotility. Studies examining VIP neuron density and VIP receptor expression in animal models of colitis and irritable bowel-type phenotypes have provided data supporting its relevance to GI pathophysiology.

Neuroprotection represents a growing area of VIP research. Studies have demonstrated that VIP exerts protective effects on neurons exposed to a range of insults, including excitotoxicity, oxidative stress, and beta-amyloid toxicity in cell culture and animal models. Bhave and colleagues, among others, have reported that VIP promotes neuronal survival through cAMP-dependent pathways and upregulation of neurotrophic factors such as activity-dependent neuroprotective protein (ADNP). These findings have generated interest in VIP’s relevance to neurodegenerative disease models, particularly those involving Alzheimer’s-type pathology and Parkinson’s disease, where neuroinflammation and neuronal loss are central features.

Emerging research directions for VIP include its application in sepsis and systemic inflammatory response models, where its combined anti-inflammatory and vasodilatory properties have shown promise in preclinical studies examining survival, organ perfusion, and inflammatory marker profiles. Additionally, VIP’s capacity to modulate both innate and adaptive immunity has made it a subject of interest in transplantation biology, where Delgado, Ganea, and colleagues have explored its effects on graft survival and immune tolerance in animal models. The breadth of VIP’s biological activity — spanning the nervous, immune, respiratory, and gastrointestinal systems — ensures that it remains one of the most versatile neuropeptides available for preclinical investigation.