Quantitation of N-terminally extended tachykinins in cerebrospinal fluid from healthy subjects

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.

Gradients of CSF monoamine metabolites: a comparison between male and female volunteers

Lumbar puncture at the L4-5 level was performed on 12 healthy male and 12 healthy female volunteers. Confirming previous results, we found pronounced gradients in cerebrospinal fluid (CSF) 5-HIAA and HVA (5-hydroxyindoleacetic acid and homovanillic acid). We also found a gradient in 4-hydroxy-3-methoxyphenylglycol (HMPG), but only in the male volunteers. We also found that tapping-time was significantly longer in females than in males. One reason for this discrepancy may be that an estimate of the spinal distance was greater in males, which might indicate that a hydrodynamic factor plays a role. On taking tapping-time into consideration, the 5-HIAA and HMPG concentrations were significantly higher in males than in females.