Functional Changes of the Mammary Glands of the Guinea Pig in vitro During Late Pregnancy and Lactation

SUMMARY Whole-ribosome and polysome-enriched fractions were prepared from the mammary glands of rabbits during late pregnancy and lactation. The composition of the fractions was determined by sucrose density gradient analysis and electron microscopy. The range of size of polysomal aggregates was similar in the late-pregnant and lactating gland, with aggregates containing five to nine ribosomal units predominating. However, the amount of polysomes relative to monosomes was invariably found to increase after parturition. The greater portion of this increase was accounted for by the increased abundance of aggregates containing five to nine units.

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The miR-200 family in normal mammary gland development

BMC Developmental Biology ◽

10.1186/s12861-021-00243-7 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Majesta J. Roth ◽

Roger A. Moorehead

Keyword(s):

Mammary Tumor ◽

Mammalian Species ◽

Late Pregnancy ◽

Mammary Glands ◽

Mammary Development ◽

Normal Mammary Gland ◽

Ductal Morphogenesis ◽

Mammary Tumor Growth ◽

Pregnancy And Lactation ◽

The Impact

AbstractThe miR-200 family of microRNAs plays a significant role in inhibiting mammary tumor growth and progression, and its members are being investigated as therapeutic targets. Additionally, if future studies can prove that miR-200s prevent mammary tumor initiation, the microRNA family could also offer a preventative strategy. Before utilizing miR-200s in a therapeutic setting, understanding how they regulate normal mammary development is necessary. No studies investigating the role of miR-200s in embryonic ductal development could be found, and only two studies examined the impact of miR-200s on pubertal ductal morphogenesis. These studies showed that miR-200s are expressed at low levels in virgin mammary glands, and elevated expression of miR-200s have the potential to impair ductal morphogenesis. In contrast to virgin mammary glands, miR-200s are expressed at high levels in mammary glands during late pregnancy and lactation. miR-200s are also found in the milk of several mammalian species, including humans. However, the relevance of miR-200s in milk remains unclear. The increase in miR-200 expression in late pregnancy and lactation suggests a role for miR-200s in the development of alveoli and/or regulating milk production. Therefore, studies investigating the consequence of miR-200 overexpression or knockdown are needed to identify the function of miR-200s in alveolar development and lactation.

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EFFECT OF PERINATAL HYPOTHYROIDISM ON PITUITARY SECRETION OF GROWTH HORMONE AND PROLACTIN IN RATS

Journal of Endocrinology ◽

10.1677/joe.0.0620213 ◽

1974 ◽

Vol 62 (2) ◽

pp. 213-223 ◽

Cited By ~ 21

Author(s):

SAKAE KIKUYAMA ◽

HIROSHI NAGASAWA ◽

REIKO YANAI ◽

KOREHITO YAMANOUCHI

Keyword(s):

Growth Hormone ◽

Late Pregnancy ◽

Gonadal Development ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Pregnancy And Lactation ◽

Pituitary Glands ◽

Pituitary Secretion ◽

Prolactin Content

SUMMARY Female Sprague—Dawley rats were fed 6-propyl-2-thiouracil (PTU) in their diet during late pregnancy and lactation. The growth and gonadal development of their pups were inhibited and in females the day of vaginal opening and onset of oestrous cycles were delayed; thyroid glands were hypertrophied. Treatment of the pups with thyroxine largely reversed these changes. The effect on body weight persisted even after treatment with PTU had stopped. At 20 days of age, the anterior pituitary glands of the pups of PTU-treated mothers contained significantly less growth hormone (GH) and prolactin than those of normal pups of both sexes. These changes persisted at 60 days of age. If the pups of PTU-treated mothers were given thyroxine from day 1 to day 20 of age, pituitary GH and prolactin content on day 20 had returned towards normal values. Thyroid deficiency was found to suppress the synthesis and release of prolactin and the synthesis of GH by the pituitary in vitro. These findings suggest that thyroxine influenced the maturation of the pituitary directly and/or through the hypothalamus and that thyroxine deficiency in early life brought about persistent alteration of the pituitary secretion of GH and prolactin.

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CORTICOSTEROID-BINDING ACTIVITY IN SERUM OF MOUSE, RABBIT AND GUINEA PIG DURING PREGNANCY AND LACTATION: POSSIBLE INVOLVEMENT IN THE INITIATION OF LACTATION

Acta Endocrinologica ◽

10.1530/acta.0.0550047 ◽

1967 ◽

Vol 55 (1) ◽

pp. 47-61 ◽

Cited By ~ 32

Author(s):

Richard R. Gala ◽

Ulrich Westphal

Keyword(s):

Guinea Pig ◽

Sex Difference ◽

Equilibrium Dialysis ◽

Late Pregnancy ◽

Binding Activity ◽

Multiple Equilibrium ◽

Endocrine Control ◽

Corticosteroid Binding Globulin ◽

Pregnancy And Lactation ◽

Approximate Amount

ABSTRACT Corticosteroid-binding activity was determined during pregnancy and lactation in the sera of mouse, rabbit and guinea pig. The measurements were made by multiple equilibrium dialysis using 14C labeled corticosteroids at 37° C. There was a marked increase of binding activity in all three species during pregnancy followed by a decline to the levels of nonpregnant animals during lactation. Serum corticosteroid concentrations paralleled but appeared subsequent to changes in corticosteroid-binding activity during pregnancy and lactation. In the mouse, no sex difference in »resting« corticosterone levels was noted, but the corticosteroid-binding activity was almost 3 times higher in the female animal than in the male. This difference was reflected in a greater amount of unbound corticosterone in the male as evidenced by lower thymus weights. Calculation of the approximate amount of unbound corticosteroid in the mouse and rat during pregnancy revealed a decline at mid pregnancy, followed by an increase from late pregnancy through lactation. In the rabbit and guinea pig, unbound corticosteroid values did not follow similar trends. A mechanism is suggested for the initiation of lactation in the rat, involving the corticosteroid-binding globulin and its endocrine control.

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ENZYMES OF LACTOSE BIOSYNTHESIS IN NORMAL AND HORMONALLY STIMULATED RABBIT MAMMARY GLANDS

Journal of Endocrinology ◽

10.1677/joe.0.0400081 ◽

1968 ◽

Vol 40 (1) ◽

pp. 81-84 ◽

Cited By ~ 6

Author(s):

R. J. HEITZMAN

Keyword(s):

Enzyme Activities ◽

Deoxyribonucleic Acid ◽

Late Pregnancy ◽

Mammary Glands ◽

Uridine Diphosphate ◽

Early Lactation ◽

Uridine Diphosphate Glucose ◽

Pregnancy And Lactation ◽

Diphosphate Glucose ◽

The Difference

SUMMARY The activities of uridine diphosphate glucose (UDPG) pyrophosphorylase and UDPG-4′-epimerase in mammary glands of rabbits were determined in late pregnancy and lactation. The activities in animals during the last 4 days of pregnancy and during days 0–4, 5–9 and 11–21 of lactation increased but the difference in the activities was significant between the days 5–9 and 11–21 only and for the pyrophosphorylase activity between days for 0–4 and 5–9. Prolactin and cortisol acetate given daily for 3 or 5 days to rabbits pseudopregnant for 15 days caused increases in enzyme activities that were several times greater than those found in controls. The enzyme activities in the stimulated glands were similar to those observed in early lactation. The levels of deoxyribonucleic acid/g. wet tissue were the same in the stimulated and lactating glands.

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Structural and functional changes by ethanol on in vitro guinea pig gastric mucosa

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.251.4.g518 ◽

1986 ◽

Vol 251 (4) ◽

pp. G518-G528 ◽

Cited By ~ 1

Author(s):

M. J. Rutten ◽

S. Ito

Keyword(s):

Gastric Mucosa ◽

Guinea Pig ◽

Basal Lamina ◽

Basal Cell ◽

Morphological Changes ◽

Short Circuit ◽

Secretory Activity ◽

Functional Changes ◽

Ussing Chambers

Relationships between morphological and electrophysiological changes with low concentrations of ethanol on in vitro guinea pig gastric mucosa were investigated. Tissues mounted in Ussing chambers allowed recording of transepithelial potential difference (PD), resistance (R), short-circuit current (Isc), and acid secretion (H+). At selected times the mucosae were processed for morphological analysis. With luminal 10% ethanol there was a decrease in PD, R, Isc, and H+ within 1 min, and they eventually went to low steady-state values between 10 and 40 min. At 1 min many surface epithelial cells lifted off from the basal lamina but were still anchored by thin basal cell processes. After 10 min in ethanol many surface cells had completely detached from the basal lamina but remained connected to adjacent cells by their junctions. Numerous cytoplasmic blebs formed on both apical and basal cell surfaces. Concurrently, there was a significant increase in microvillus length. After 40 min most of the surface cells were detached from the basal lamina as sheets forming epithelial blisters. Upon ethanol washout there was epithelial cell reattachment to the basal lamina and a return of the PD, R, and Isc to control values within 40 min. Incubation of the luminal surface with 10% ethanol for 5 h resulted in a gradual rise of the PD, R, Isc, and H+ to control values by 4 h with a coincident return of the normal mucosal morphology. These studies indicate that ethanol has reversible and possibly adaptable effects on the in vitro guinea pig gastric mucosa and that the morphological changes are closely correlated with the decline and recovery of the electrical and secretory activity of the tissue.

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The nutrition of grazing ewes during pregnancy and lactation: a comparison of alkane-based and chromium/in vitro-based estimates of herbage intake

Australian Journal of Agricultural Research ◽

10.1071/ar99174 ◽

2000 ◽

Vol 51 (6) ◽

pp. 765 ◽

Cited By ~ 21

Author(s):

H. Dove ◽

M. Freer ◽

J. Z. Foot

Keyword(s):

Late Pregnancy ◽

In Vitro Digestibility ◽

Faecal Output ◽

Stage Of Lactation ◽

Herbage Intake ◽

Faecal Samples ◽

Pregnancy And Lactation ◽

The Difference

The n-alkane and chromium/in vitro procedures for estimating herbage intake were compared in grazing ewes during late pregnancy, early lactation, and mid-lactation. To ensure differences in herbage intake, the ewes were grazed in 4 plots of phalaris-dominant pasture at 2 levels of stocking: 17.1 ewes/ha and 30.8 ewes/ha. To investigate whether either procedure for estimating herbage intake was influenced by supplement consumption, half of the ewes at each stocking level received 500 g/day air-dry of a pelletted supplement (1 : 1 milled oat grain : sunflower meal). Supplement intakes were estimated using tritiated gypsum as a marker. During intake measurement periods, ewes were dosed twice daily with both alkane capsules and capsules containing chromium sesquioxide. For the last 6 days of the 12-day dosing period, rectal faecal samples were taken twice daily, immediately before the dosing. Over these same periods, wether sheep fitted with faecal collection harnesses were similarly dosed and sampled, and their total faecal output collected to establish the faecal recovery of chromium and the alkanes. Herbage intakes were estimated using the C27/C28, C29/C28, C31/C32, and C33/C32 alkane pairs. Estimates of intake based on the shorter alkane pairs were lower than those estimated with the C33/C32 alkane pair, by amounts which differed between the periods. Evidence is presented that estimates based on the last pair of alkanes (C33/C32) are the most accurate and are also more accurate than those based on the chromium/in vitro procedure. The relationship between these 2 methods for estimating intake was different in mid-pregnancy compared with either stage of lactation. The consumption of supplement did not interfere with any of the methods for estimating herbage intake. Estimates of faecal output based on the use of chromium, C28 alkane, or C32 as an external marker were statistically identical, indicating that the difference between the 2 methods for estimating herbage intake was not related to a failure to accommodate the incomplete recovery of any of the markers used or to the failure of rectal grab samples to be representative of total faeces. Our results indicate that herbage collected by oesophageally fistulated (OF) sheep was representative of that grazed by the ewes and could thus be used to provide the herbage alkane data needed to estimate herbage intake by the alkane method. However, the in vitro digestibility values obtained from the OF samples did not represent the digestibilities actually occurring in vivo. This was the main cause of the observed difference between the 2 methods for estimating intake. Possible reasons for the differences between the in vitro and in vivo estimates of digestibility are discussed.

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Ultrasonographic assessment of the feline mammary gland

Journal of Feline Medicine and Surgery ◽

10.1016/j.jfms.2008.03.006 ◽

2008 ◽

Vol 10 (5) ◽

pp. 466-471 ◽

Cited By ~ 4

Author(s):

Rita Payan-Carreira ◽

Ana C. Martins-Bessa

Keyword(s):

Mammary Gland ◽

Diagnostic Tool ◽

Late Pregnancy ◽

Mammary Glands ◽

Mammary Tissue ◽

Physiological Changes ◽

Linear Transducer ◽

Pregnancy And Lactation ◽

Ultrasonographic Assessment ◽

Ultrasonographic Appearance

The aim of this study is to characterise the feline mammary echotexture using B-mode ultrasonography, which is not routinely used to examine the feline mammary gland. Using a 5–9 MHz linear transducer the ultrasonographic appearance of non-stimulated and stimulated mammary glands was determined in 35 mature intact non-pregnant, pregnant and lactating queens aged from 16 months to 8 years. In intact non-pregnant queens, mammary glands are fairly underdeveloped and on the ultrasonograms they appear with a regular hypoechoic texture and generally show a thickness of less than 2.0 mm. The stimulated mammary tissue typically presents a more hyperechoic appearance compared to the non-stimulated gland and a fine granular echotexture. Maximum echogenicity of the mammary gland is reached during lactation. In late pregnancy, the mammary glands reach 6–9 mm in thickness. During lactation, the size of the glands depends on the existence of a suckling stimulus, with the suckled glands reaching about 11 mm in thickness. Ductal structures can only be imaged during late pregnancy and lactation. Ultrasonographic evaluation of the feline mammary gland can become a valuable diagnostic tool to characterise physiological changes and may further contribute to a better characterisation of diseased mammary tissue.

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Phenotypic variations in osmotic lysis of Sahel goat erythrocytes in non-ionic glucose media

Journal of Basic and Clinical Physiology and Pharmacology ◽

10.1515/jbcpp-2015-0036 ◽

2016 ◽

Vol 27 (2) ◽

Author(s):

Nanacha Afifi Igbokwe ◽

Ikechukwu Onyebuchi Igbokwe

Keyword(s):

Glucose Transporter ◽

Osmotic Fragility ◽

Late Pregnancy ◽

Transporter Protein ◽

Extracellular Glucose ◽

Pregnancy And Lactation ◽

Osmotic Lysis ◽

Sahel Goat ◽

In Vitro Interaction

AbstractErythrocyte osmotic lysis in deionised glucose media is regulated by glucose influx, cation efflux, and changes in cell volume after water diffusion. Transmembrane fluxes may be affected by varied expression of glucose transporter protein and susceptibility of membrane proteins to glucose-induced glycosylation and oxidation in various physiologic states.Variations in haemolysis of Sahel goat erythrocytes after incubation in hyposmotic non-ionic glucose media, associated with sex, age, late pregnancy, and lactation, were investigated.The osmotic fragility curve in glucose media was sigmoidal with erythrocytes from goats in late pregnancy (PRE) or lactation (LAC) or from kid (KGT) or middle-aged (MGT) goats. Non-sigmoidal phenotype occurred in yearlings (YGT) and old (OGT) goats. The composite fragility phenotype for males and non-pregnant dry (NPD) females was non-sigmoidal. Erythrocytes with non-sigmoidal curves were more stable than those with sigmoidal curves because of inflectional shift of the curve to the left. Erythrocytes tended to be more fragile with male than female sex, KGT and MGT than YGT and OGT, and LAC and PRE than NPD. Thus, sex, age, pregnancy, and lactation affected the haemolytic pattern of goat erythrocytes in glucose media.The physiologic state of the goat affected the in vitro interaction of glucose with erythrocytes, causing variations in osmotic stability with variants of fragility phenotype. Variations in the effect of high extracellular glucose concentrations on the functions of membrane-associated glucose transporter, aquaporins, and the cation cotransporter were presumed to be relevant in regulating the physical properties of goat erythrocytes under osmotic stress.

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Progesterone Control of the Initiation of Lactose Synthesis in the Rat

Australian Journal of Biological Sciences ◽

10.1071/bi9810435 ◽

1981 ◽

Vol 34 (4) ◽

pp. 435 ◽

Cited By ~ 13

Author(s):

KR Nicholas ◽

PE Hartmann

Keyword(s):

Late Pregnancy ◽

Mammary Tissue ◽

Pregnancy And Lactation ◽

Lactose Synthesis

The in vitro incorporation of ['4C]glucose into lactose in mammary tissue, the concentration of lactose in the mammary tissue and the concentration of lactose in the mammary secretion were determined during late pregnancy and lactation in the rat. These changes were related to the decline in blood progesterone during late pregnancy.

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