Regional distribution of neuropeptide gamma and other tachykinin peptides derived from the substance P gene in the rat.

Substance P (SP) and multiple neurokinin A (NKA)-related peptides can be derived from alpha-, beta- and/or gamma-preprotachykinin (PPT) mRNAs. In this study, the relative concentrations of the tachykinin peptides derived from the SP gene in rat brain, duodenum, jejunum, submandibular gland, parotid gland, urinary bladder and vas deferens was determined using high-performance liquid chromatography (HPLC) and radioimmunoassays (RIAs). In all tissues, SP levels were the highest. The relative abundance of NKA-related peptides was NKA greater than neuropeptide gamma (NP gamma) = neuropeptide K (NPK) greater than NKA(3-10). These results demonstrate that multiple tachykinin peptides are present in tissues where the SP gene is expressed, and that the NKA portion of the beta- and gamma-PPT precursors can be differentially processed posttranslationally in rat tissues into NKA, NPK, NP gamma and/or NKA(3-10).