ELEVATED CEREBROSPINAL-FLUID LEVEL OF SUBSTANCE-P AND DECREASED UNDECAPEPTIDASE ACTIVITY AT TERM PREGNANCY

This paper reports a study of substance P and its converting enzyme su bstance P endopeptidase (SPE) in cerebrospinal fluid (CSF) collected f rom women at term pregnancy, A method was developed to assess the CSF levels of substance P itself with minimum contribution from prestages or fragments of the undecapetide. The measured activity was compared w ith that detected in CSF from control, non-pregnant, non-puerperal wom en. The result indicates a significant increase in substance P-like im munoreactivity at term pregnancy (19.9 +/- 3.9 fmol/ml, n = 10) compar ed with that of control subjects (12.3 +/- 2.8 fmol/ml, n = 9; P < 0.0 01). This elevation was suggested to reflect an increased activity in spinal sensory neurons at this stage of pregnancy, The activity of SPE was assessed by measuring the product substance P1-7 by a radioimmuno assay specific for this fragment, It was found that the enzyme activit y was significantly decreased in CSF from pregnant women (11.2 +/- 0.7 1 pmol/h.ml), compared with control samples (18.4 +/- 0.73 pmol/h.ml; P < 0.05). Moreover, a significant negative correlation was found to e xist between the level of substance P and the activity of SPE (P < 0.0 5, r(2) = 0.65), suggesting that the enzyme may be involved in a mecha nism regulating the level of substance P concentration.