Summary.Daily changes in the composition of the milk of two lactaling women were recorded from Ihe time of the last menstrua! period prior to conception throughout the first two months of gestation. The changes in the composilion of the milk from these women were compared to [he diiily changes in the milk composilion of [wo women during the peiiod of gradual weaning.In lhc weaning subjects the conccn[ralion of sodium and [o[al pro[cin had increased 14-and 1 6-fold, respectively, by the end of the study. The concentrations of potassium, glucose and lactose decreased 13-, 149-and 3 6-fold. respectively, from before weaning commenced lo the end of the study. These changes were closely correlated to the decrease in the suckling frequency of the infant. The concentration of sodium and total proiein in the milk from the unsuckled breast of two women was 11-and 2-8-fold higher than in [he milk from [he normally suckled breast of the same woman. The concentrations of potassium, glucose and lactose were 11-, 70-and 1-9-fold lower, emphasizing the necessity of a regular suckling pattern on the maintenance of lactation.The concentrations of sodium and total protein similarly increased during pregnancy, being 8-and 3-8-fold higher by the second month of gestation. The concentrations of potassium, glucose and lactose decreased 1-4-, 73-and 4 4-fold, respectively, over the same period of time. The changes in the milk composition showed no significant correlation to the infant's suckling frequency.The results indicate a progressive loss of secretory activity hy the mammary gland during weaning and early gestation. During weaning this loss appears [o be directly related to the decrease in the infant's suckling frequency, whereas during early gestation Ihere would appear to be an inhibition of milk secretion which over-rides [he positive stimulus provided by the infant's suckling. The mechanisms regulating the secre[ion of milk during weaning and pregnancy are discussed in the light of the compositional changes observed.
Lactating goats exhibiting widely divergent responses to short-term (4 days) treatment with bovine GH (bGH) were retrospectively divided into two groups based on the magnitude of this response. There was no difference between groups in terms of the pretreatment milk yield, but by day 4 of treatment milk secretion had increased by 4.99 +/- 2.5 (S.E.M.) ml/h (P greater than 0.05 compared with pretreatment) for group 1 and 22.9 +/- 2.4 ml/h (P less than 0.001) for group 2. Plasma GH increased in both groups, but concentrations were significantly higher both before and during treatment in group 1 compared with group 2. Plasma concentrations of insulin-like growth factor-I (IGF-I) increased significantly during bGH treatment for both groups and there was no significant difference between the two until day 4 of treatment when levels of IGF-I in group 1 began to decline, whereas those from group 2 were maintained. Concentrations of IGF-I in milk from goats in group 1 were not significantly altered by GH administration, whereas those in goats in group 2 were increased by 40% (P less than 0.01 compared with pretreatment). Levels of IGF-I in mammary secretory tissue from four animals from group 1 were not altered by bGH (2.8 +/- 0.2 and 2.77 +/- 0.08 nmol/kg tissue before and after treatment respectively), but were significantly (P less than 0.05) increased in four animals from group 2 (2.80 +/- 0.2 and 9.9 +/- 1.1 nmol/kg tissue).(ABSTRACT TRUNCATED AT 250 WORDS)
SUMMARY1. Breast milk composition was followed for a period of 28 days in five women during lactational amenorrhea and in another two who were taking oral contraceptives. The milk composition was also studied in two women during an anovulatory menstrual cycle and in six women during an ovulatory menstrual cycle. Samples of milk were collected from each breast at each feed for each day of the study.2. Two acute changes, the first 5-6 days before and the second 6-7 days after ovulation, occurred in the milk composition during the ovulatory menstrual cycle. At both times there was an increase in Na and Cl concentrations from (mean +S.E. ofmean) 4-6 + 02 mm and 11 1 + 0-2 mm to 10.1 + 0 9 mm and 22-0 + 0 9 mm respectively and a decrease in lactose and K concentrations from 7-8±0-2 g/100 ml. and 13-6 + 0-4 mmto 6-0 + 0-2 g/100 ml. and 10-2 + 0 5 mm respectively. The mean duration of the first change was 28 hr and the second was 32 hr. The concentrations of lactose, Cl, K and Na remained relatively constant during lactational amenorrhea, anovulatory menstrual cycles and for those women taking oral contraceptives.3. These observations indicate that an increase in the permeability of the mammary epithelium was elicited by changes related to ovulation. It is suggested that the first acute change in the breast milk composition may be associated with the final stages of follicle maturation and the second with the regression of the corpus luteum during the ovulatory menstrual cycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.