[EFFECT OF THE PROLYL-GLYCIL-PROLINE (PGP) AND ITS ACETYLATED FORM (N-AcPGP) ON PERMEABILITY OF SKIN VESSELS IN RATS]

Area of Science:

• Pharmacology
• Immunology
• Physiology

Background:

• Regulatory peptides like PGP and its derivatives play roles in physiological processes.
• Mast cells are key mediators of inflammatory responses, including edema and vascular permeability.

Purpose of the Study:

• To investigate the effects of peptide PGP and its acetylated form (N-AcPGP) on paw edema and skin vascular permeability in rats.
• To elucidate the mechanism underlying these effects, particularly the involvement of mast cells.

Main Methods:

• Paw edema was induced using histamine.
• Vascular permeability was assessed via intradermal injections of mast cell activators (CRH, LPS, Synacthen, histamine, compound 48/80).
• In vitro experiments measured histamine secretion from rat peritoneal mast cells pretreated with PGP or N-AcPGP.

Main Results:

• PGP administration reduced paw edema, whereas N-AcPGP exacerbated it.
• Neither PGP nor N-AcPGP altered vascular permeability when co-administered with CRH, LPS, or Synacthen.
• Vascular permeability was affected by PGP and N-AcPGP only when histamine or compound 48/80 were used as additional stimuli.
• Both peptides inhibited histamine secretion from mast cells activated by Synacthen in vitro.

Conclusions:

• The study demonstrates differential effects of PGP and N-AcPGP on edema formation.
• The peptides' influence on vascular permeability is primarily mediated through modulation of mast cell secretory activity.
• These findings highlight the complex role of regulatory peptides in inflammatory processes.