Release of histamine by substance P

Area of Science:

• Neuroscience
• Pharmacology
• Immunology

Background:

• Substance P is a neuropeptide implicated in inflammatory responses.
• The role of Substance P in mast cell activation and histamine release requires further elucidation.

Purpose of the Study:

• To investigate the effect of Substance P on histamine release from rat mast cells.
• To compare the effects of Substance P with related peptides, eledoisin and physalaemin.
• To explore the role of Substance P in neurogenic inflammation in vivo.

Main Methods:

• In vitro studies using rat peritoneal mast cells.
• In vivo experiments involving infusion of peptides into rat hindquarter preparations.
• Measurement of histamine and serotonin (5-HT) levels in venous outflow and paw skin.

Main Results:

• Substance P, but not eledoisin or physalaemin, induced histamine release from mast cells in vitro.
• Infusion of Substance P significantly increased histamine levels in the venous outflow of rat hindquarters.
• Substance P infusion led to histamine depletion in paw skin, suggesting mast cell activation.

Conclusions:

• Substance P is a potent stimulator of histamine release from peripheral mast cells.
• This mechanism likely contributes to neurogenic vasodilatation and plasma extravasation.
• Substance P plays a significant role in neurogenic inflammatory processes.