Detection of stable N-terminal protachykinin A immunoreactivity in human plasma and cerebrospinal fluid.
Substance P (SP) is a neuropeptide that is released from sensory nerves and several types of immune cells. It is involved in the transmission of pain and has a number of pro-inflammatory effects. Like other neuropeptides, SP is derived from a large precursor peptide, protachykinin A (PTA). Alternative splicing results in the production of four distinct PTA molecules that all contain the sequence of SP and a common N-terminal region consisting of 37 amino acids. We have developed a sandwich immunoassay using antibodies against the N-terminal part of PTA. Here we demonstrate that N-terminal PTA immunoreactivity is present in human circulation and cerebrospinal fluid (CSF). The concentration was about 90 times higher in CSF than in EDTA-plasma. Analytical reversed phase HPLC revealed that NT-PTA 1-37 is the main immunoreactivity in human circulation and CSF. Moreover, compared to the low in vitro stability of SP of less than 12 min, NT-PTA immunoreactivity is absolutely stable in EDTA-plasma and CSF for more than 48 h. As NT-PTA 1-37 is produced in stoichiometric amounts and is theoretically co-released with SP, we suggest the measurement of NT-PTA immunoreactivity as surrogate molecule for the release of bioactive SP.
Ernst
Andrea
A
SphingoTec GmbH, Tulpenweg 6, D-16556 Borgsdorf, Germany. ernst310577@gmx.de
Suhr
Jennifer
J
Köhrle
Josef
J
Bergmann
Andreas
A
D000595:Amino Acid Sequence; D002614:Chelating Agents / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004492:Edetic Acid / Q000097:blood; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000737:chemistry / Q000276:immunology*; D015320:Tachykinins / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000737:chemistry / Q000276:immunology*; D013997:Time Factors
D002614:Chelating Agents; D011498:Protein Precursors; D015320:Tachykinins; C054618:protachykinin; D004492:Edetic Acid