Submandibular gland peptide-T (SGP-T): Modulation of endotoxic and anaphylactic shock

Abstract

This report summarizes recent studies on the antishock activities of a novel peptide, submandibular gland peptide-T (SGP-T). This heptapeptide (TDIFEGG) was isolated from the submandibular glands of rats based on the ability of extracts of these glands to reduce the severity of the hypotension induced by lipopolysaccharide. SGP-T was also found to reduce the severity of anaphylactic shock in ovalbumin-sensitized rats. Structure–activity relationship studies revealed that the inhibition of intestinal anaphylaxis in vitro only required a portion of SGP-T, i.e., the tripeptide FEG, localized at the carboxy terminal of the parent heptapeptide. Both FEG and its d-isomeric form, feG, inhibited anaphylactic hypotension when administered intravenously prior to exposure to the antigen. The peptide feG also inhibited anaphylactic hypotension when given orally 1 h before exposure to the antigen. SGP-T may be a prototype to a family of small peptides that modulate the immunological and smooth muscle reactions to severe inflammatory (endotoxic and anaphylactic) reactions. Drug Dev. Res. 42:164–171, 1997. © 1997 Wiley-Liss, Inc.