Plasma Levels of β‐Endorphin and Substance P in the First Year of Life in Full‐Term and Preterm Infants

Abstract

2 7 . 2 2 6.2 pg/ml, r,=0.402, p<0.05). SPLI 38.327.7, r,=0.229) this correlation could not be found (Fig. 3).Thus prematurity must be considered as a decisive factor for the altered plasma levels of P-EDLI and SPLI also if the age is corrected for a gestational age of 40 weeks. This may indicate the immature state of development of preterms in comparison with full-terms of the same age.

Normative values of substance P and neurokinin A in neonates

“…Eleven per cent of the plasma SP results from the current study yielded a value of 0.0 pmol/L, but these were probably genuinely undetectable concentrations as NKA remained detectable in all the same samples, with concentrations ranging from 2.6 to 45.0 pmol/L (median 6.6 pmol/L). Moreover, other investigators have also reported undetectable concentrations of plasma SP not only in infants, 9 but also in adults. 10–12 In addition, we now know that unextracted plasma gives higher concentration measurements than extracted samples, and hence the accuracy of other published reports on high plasma SP concentrations (300–500 pmol/L) where sample extraction had not been performed 13–15 may be open to question.…”

“…Scholle et al 9 reported mean (standard error) plasma SP concentrations of 20.2 (4.6) pmol/L in 32 preterm infants, and 28.4 (5.7) pmol/ L in 19 term infants. 9 However, the results in Scholle's study were from unextracted plasma samples, which can yield higher concentrations of SP due to antibody cross-reactivity. There was also no description of sample handling and preservation procedures, which has been shown to be of importance (CMW, data published in PhD thesis).…”

“…The plasma SP concentrations found in neonates in this study were lower than those published elsewhere. Scholle et al 9 reported mean (standard error) plasma SP concentrations of 20.2 (4.6) pmol/L in 32 preterm infants, and 28.4 (5.7) pmol/ L in 19 term infants. 9 However, the results in Scholle's study were from unextracted plasma samples, which can yield higher concentrations of SP due to antibody cross-reactivity.…”

“…There was also no description of sample handling and preservation procedures, which has been shown to be of importance (CMW, data published in PhD thesis). Furthermore, despite claiming that their study was ‘designed to determine the plasma concentration pattern of SP during the first year of life in full- and preterm infants’, Scholle et al 9 studied only a small population of infants, and the investigations were performed any time after the third week of life, with results plotted according to the infants' corrected gestational age (which ranged from –4 to 63 weeks [0 being term]). This gave rise to a very heterogeneous group of infants, with a small number of infants having different numbers of plasma samples contributing to the final results.…”

“…Prior to this study, only one brief paper on plasma SP concentrations in healthy infants has been produced. 9 However, only ‘healthy’ infants older than three weeks were studied and the samples were random in time and age. SP and NKA have never before been studied in term and preterm infants receiving intensive care.…”