[Dynamic changes of enzymes activities and growth factors contents in human colostrum]

To study the dynamic changes of the activities of superoxide dismutase (SOD), amylase (AM) and alkaline phosphatase (ALP) and of the contents of epithelium growth factors (EGF) and insulin growth factors (IGF-1) in human colostrum (lactation 1 - 7 days postpartum).

A total of 118 samples of human colostrum were taken from 20 healthy women postpartum. The activities of SOD, AM and ALP in human colostrum were determined by methods of pyrogallol autoxidation, colorimetry of iodine-starch and pyrocatechol phosphate respectively. EGF and IGF-1 contents in human colostrum were measured by radioimmunoassay.

The SOD activity of human colostrum increased slightly during lactation 1 - 4 days postpartum, from (18.7 +/- 2.2) kU/L to (22.5 +/- 2.9) kU/L, then it tended to decrease, being (11.2 +/- 2.1) kU/L on the 7th day. The SOD activities in lactation 1 - 5 days postpartum were significantly higher than that on day 7 (P < 0.05 or P < 0.01). AM and ALP activities of human colostrum gradually decreased within a week postpartum. AM activity declined from (155 +/- 12) kU/L to (17 +/- 4) kU/L. ALP activity declined from (105 +/- 17) kU/L to (54 +/- 9) kU/L. AM activities in lactation 1 - 5 days postpartum were significantly higher than that on day 7 (P < 0.05 or P < 0.01); and ALP activity on the first lactation day was significantly higher than that on day 7 (P < 0.05). EGF and IGF-1 concentrations in human colostrum quickly declined during lactation 1 - 4 days postpartum. EGF concentration decreased from (105 +/- 11) micro g/L to (40 +/- 5) micro g/L, and IGF-1 concentration decreased from (25.9 +/- 2.7) micro g/L to (5.6 +/- 1.3) micro g/L. Both concentrations altered slightly during lactation 4 - 7 days postpartum. EGF concentrations in lactation 1 - 3 days postpartum were remarkably higher than that on day 7 (P < 0.05 or P < 0.01); IGF-1 concentration on the first lactation day was significantly higher than that on day 7 (P < 0.01).

Human colostrum contains SOD, AM and ALP with high activities, and is also rich in EGF and IGF-1. All of these are indispensable to normal growth and development of infants. Breast-feeding should be emphasized and encouraged for infants.