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Elevated cerebrospinal fluid level of substance P and decreased undecapeptidase activity at term pregnancy
Z Liu1, S Lyrenäs, M Thörnwall
1Department of Pharmaceutical Biosciences, University of Uppsala, Sweden.
This paper reports a study of substance P and its converting enzyme substance P endopeptidase (SPE) in cerebrospinal fluid (CSF) collected from 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 with that detected in CSF from control, non-pregnant, non-puerperal women. The result indicates a significant increase in substance P-like immunoreactivity at term pregnancy (19.9 +/- 3.9 fmol/ml, n = 10) compared with that of control subjects (12.3 +/- 2.8 fmol/ml, n = 9; P < 0.001). 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 radioimmunoassay specific for this fragment. It was found that the enzyme activity was significantly decreased in CSF from pregnant women (11.2 +/- 0.71 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 exist between the level of substance P and the activity of SPE (P < 0.05, r2 = 0.65), suggesting that the enzyme may be involved in a mechanism regulating the level of substance P concentration.
This paper reports a study of substance P and its converting enzyme substance P endopeptidase (SPE) in cerebrospinal fluid (CSF) collected from 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 with that detected in CSF from control, non-pregnant, non-puerperal women. The result indicates a significant increase in substance P-like immunoreactivity at term pregnancy (19.9 +/- 3.9 fmol/ml, n = 10) compared with that of control subjects (12.3 +/- 2.8 fmol/ml, n = 9; P < 0.001). 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 radioimmunoassay specific for this fragment. It was found that the enzyme activity was significantly decreased in CSF from pregnant women (11.2 +/- 0.71 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 exist between the level of substance P and the activity of SPE (P < 0.05, r2 = 0.65), suggesting that the enzyme may be involved in a mechanism regulating the level of substance P concentration.