gamma-Preprotachykinin-(72-92)-peptide amide potentiates substance P-induced salivation

The effects of gamma-preprotachykinin-(72-92)-peptide amide [gamma-PPT-(72-92)-NH2] on salivation in the rat were investigated and were compared with salivation responses elicited by a variety of other tachykinin and related peptides. On intravenous injection or continuous infusion, gamma-PPT-(72-92)-NH2, a naturally occurring N-terminally extended derivative of neurokinin A (NKA), potently stimulated salivation. The rank order of potency of peptides that stimulated salivation was: NPK greater than gamma-PPT-(72-92)-NH2 greater than substance P greater than NKA = Asp-Ala-NKA. Moreover, gamma-PPT-(72-92)-NH2, like NPK, potentiated the effects of substance P on salivary secretion. These results indicate that the actions of gamma-PPT-(72-92)-NH2 may be pharmacologically or physiologically relevant in the actions of tachykinin peptides.