Composition of Rat Milk from Day 5 to 20 of Lactation and Milk Intake of Lean and Preobese Zucker Pups

Godbole, V.; Grundleger, Melvin L.; Pasquine, Teresa A.; Thenen, Shirley W.

doi:10.1093/jn/111.3.480

Cited by 84 publications

(21 citation statements)

References 20 publications

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“…AR rats infused with rat milk weighed substantially less at 16 days than M F rats (Table I) even though the caloric intake of AR rats was calculated to approximate that of M F rats (24). Slow body weight gain also was observed in AR rats fed RCFL, RCFG, and CMF.…”

Section: Resultsmentioning

confidence: 97%

Rat Milk Maintains Intestinal Lactase Activity in Rat Pups whereas Artificial Formulas Do Not

Yeh

Holt

1985

Pediatr Res

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ABSTRACT. Intestinal lactase activity is maintained a t high levels in suckling rats during the first 2 wk after birth. When 12-day-old rat pups were either mother fed (MF) or artificially reared (AR) with natural rat milk or several artificial formulas, the small intestines had gained similar weight in all animal groups by 16 days except in AR rats fed a chemically defined formula. In the ileum, villus length was similar in M F and AH rats, but crypt depth was significantly higher in all groups of AR rats. Ileal absorptive cells in both MF and AR rats showed immature characteristics, including supranuclear vacuoles, apical tubular systems, and pinocytotic vesicles. Jejunal lactase specific activity and total intestinal lactase activity were significantly higher in AR rats fed rat milk than M F rats at 16 days. Ileal lactase specific activity was similar in these two animal groups. In contrast, AR rats fed artificial formulas supplemented with either glucose or lactose a s the sole carbohydrate source exhibited significantly lower ileal lactase specific activity and total intestinal lactase activity than M F rats. Intestinal sucrase activity was prematurely elevated in all AH rats, even when fed natural rat milk. Addition of prolactin (3.3 pg/ml) to an artificial formula did not prevent the premature decrease in intestinal lactase specific and total activities in AR rats. We conclude that (I) natural rat milk plays a cardinal role in maintaining lactase activity during the suckling period; (2) the lactose and prolactin content of rat milk are not essential components in maintaining lactase activity in AR rat pups; and (3) the artificial feeding procedure, rather than dietary composition, induces premature elevation of sucrase activity. (Pediatr Res 19: 963-967, 1985) Abbreviations MF, mother fed AR, artificially reared CMF, cow milk formula RCF, Rose carbohydrate-free formula CDF, chemically defined formula G, glucose I,, lactoseIntestinal lactase. which is essential for the hydrolysis and absorption of lactose, is abundant in mammals at birth, remains at high activity before weaning and then generally falls to a low level (I). In thc rat, lactase activity is high for about 2 wk after Rece~ved I-ehrusry 19. 1985: accepted April 30. 1985 birth and declines gradually thereafter to reach adult levels during the 4th wk (2-4). In parallel, intestinal maltase activity, which is low, and sucrase activity, which is absent during the first :?postnatal wk, increase rapidly in the end of the 3rd wk (4). Accumulated evidence indicates that the ontogenetic increase of maltase and sucrase in the rat is modulated by hormones produced by the pituitary-adrenal and pituitary-thyroid systems (5.-7), and the ontogenetic decrease of intestinal lactase activity is regulated in part by the pituitary-thyroid system (8).Previous studies from our laboratory have shown that lactase activity at 24 days postpartum is higher in rats hypophysectomized at 6 days than at 10 days of age (8), suggesting that pituitary hormones have exerted the...

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Section: Resultsmentioning

confidence: 97%

Rat Milk Maintains Intestinal Lactase Activity in Rat Pups whereas Artificial Formulas Do Not

Yeh

Holt

1985

Pediatr Res

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“…Separate the dam from her offspring for a minimum of 5 min prior to milking 12 . NOTE: The dam can be milked up to 5-6 hr after separation 1,6,13 , however periods of separation longer than 4 hr may alter milk composition 14 . While separation time does not appear to impact milk collection volume 12 , it is advised that a consistent separation time be maintained throughout the study.…”

Section: Separate Dam From Offspringmentioning

confidence: 99%

Milk Collection in the Rat Using Capillary Tubes and Estimation of Milk Fat Content by Creamatocrit

Paul

Hallam

Reimer

2015

JoVE

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Milk, as the sole source of nutrition for the newborn mammal, provides the necessary nutrients and energy for offspring growth and development. It also contains a vast number of bioactive compounds that greatly affect the development of the neonate. The analysis of milk components will help elucidate key factors that link maternal metabolism and health with offspring growth and development. The laboratory rat represents a popular model organism for maternal studies, and rat milk can be used to examine the effect of various maternal physiological, nutritional, and pharmacological interventions on milk components, which may then impact offspring health. Here a simple method of manually collecting milk from the lactating rat that can be performed by a single investigator, does not require specialized vacuum or suction equipment, and provides sufficient milk for subsequent downstream analysis is described. A method for estimating the fat content of milk by measuring the percentage of cream within the milk sample, known as the creamatocrit, is also presented. These methods can ultimately be used to increase insight into maternal-child health and to elucidate maternal factors that are involved in proper growth and development of offspring. Video LinkThe video component of this article can be found at

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“…Milk fat was estimated by the difference in weight of a sample after extraction of the lipid-soluble compounds with petroleum-ether (Godbole et al, 1981). Carbohydrate content was measured by a colorimetric assay using orcinol-sulfuric acid (Jevons, 1964).…”

Section: Milk Macronutrient Compositionmentioning

confidence: 99%

Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins, with no Effect on Milk Composition or Yield

et al. 2005

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IGF-I regulates lactation by stimulating mammary mitogenesis, inhibiting apoptosis, and partially mediating the effects of growth hormone on lactogenesis. Herein, lactation performance during first and second parity was assessed in transgenic swine (TG) that over-expressed human IGF-I in milk under the control of the bovine alpha-lactalbumin promoter, regulatory regions and signal peptide coding sequence. Milk samples were collected throughout lactation (farrowing to d24) from TG sows and non-transgenic littermates (CON) and IGF-I, IGF-II, and IGFBP determined. Colostral (<24 h postpartum) IGF-I content was 26-fold greater (p<0.001) in TG sows (949+/- 107 microg/L; range 228-1,600 microg/L) than CON (36+/-17.8 microg/L) and was 50- to 90-fold greater (p< 0.001) in mature milk (d2-24 postpartum). There was no effect of parity on milk IGF-I content. Milk IGF-II concentration was unaffected by IGF-I over-expression. Low molecular weight IGFBP (IGFBP-2 and -5) in the milk of TG sows were higher (p=0.02) than CON in the early postpartum period, but did not differ in mature milk. Milk yield, determined by weigh-suckle-weigh, was similar in TG and CON as was litter weight gain. Milk nutrient composition was not significantly affected by IGF over-expression. Thus, mammary specific transgenic over-expression of IGF-I significantly increased milk IGF-I and IGFBP content, but did not impact lactation performance in swine.

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Composition of Rat Milk from Day 5 to 20 of Lactation and Milk Intake of Lean and Preobese Zucker Pups

Cited by 84 publications

References 20 publications

Rat Milk Maintains Intestinal Lactase Activity in Rat Pups whereas Artificial Formulas Do Not

Rat Milk Maintains Intestinal Lactase Activity in Rat Pups whereas Artificial Formulas Do Not

Milk Collection in the Rat Using Capillary Tubes and Estimation of Milk Fat Content by Creamatocrit

Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins, with no Effect on Milk Composition or Yield

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