Antagonistic analogs of luteinizing hormone-releasing hormone are mast cell secretagogues.

The histamine-releasing activity of luteinizing hormone-releasing hormone (LHRH) antagonistic analogs has been documented. Antagonists of LHRH elicited in vitro histamine release from mast cells obtained from previously unexposed rats. Intradermal injection of the antagonists caused increased local skin permeability. Anaphylactoid reactions followed subcutaneous injection of the antagonists and in some cases these edematous reactions were accompanied by increased serum histamine levels. These studies show that these small peptides can cause mast cell degranulation and suggest that the neuropeptide, LHRH, may have modulating effects on the immune system.