The pups’ endometrium morphology is affected by maternal malnutrition during suckling

Protein restriction during puberty alters nutritional parameters and affects ovarian and uterine histomorphometry in adulthood in rats

In a large part of the population inefficient ingestion of proteins, whether for cultural, aesthetic or economic reasons, is a global concern. Low-protein diets can cause severe functional complications, mainly during the development and maturation of organs and systems, including the female reproductive system. The present study investigated the effect of nutritional protein restriction during puberty on the oestrous cycle and expression of sex steroid receptors (AR, ERα e ERβ) in ovarian and uterine tissues of adult rats. Protein restriction promoted lower body weight gain, feed efficiency and higher caloric intake. There was an increase in the oestrus phase arrest without changing the total length of the oestrous cycle. The consumption of low-protein diet also reduced the thickness of the uterine endometrium (uterine epithelium and endometrial stroma) in addition to increasing the number of primary and atretic follicles in the ovaries. Furthermore, the low-protein diet reduced the levels of androgen receptor (AR) and increased the oestrogen receptor β (ERβ) in the ovary, while no significant changes were observed in the uterus. Our study reinforces the importance of adequate protein intake during puberty, since physiological changes in this developmental period interfere with the histomorphometry of the ovaries and uteri, possibly resulting in impaired folliculogenesis and fertility in the reproductive period.

Preclinical Models of Altered Early Life Nutrition and Development of Reproductive Disorders in Female Offspring

Early epidemiology studies in humans have and continue to offer valuable insight into the Developmental Origins of Health and Disease (DOHaD) hypothesis, which emphasises the importance of early-life nutritional and environmental changes on the increased risk of metabolic and reproductive disease in later life. Human studies are limited and constrained by a range of factors which do not apply to preclinical research. Animal models therefore offer a unique opportunity to fully investigate the mechanisms associated with developmental programming, helping to elucidate the developmental processes which influence reproductive diseases, and highlight potential biomarkers which can be translated back to the human condition. This review covers the use and limitations of a number of animal models frequently utilised in developmental programming investigations, with an emphasis on dietary manipulations which can lead to reproductive dysfunction in offspring.

Maternal folic acid consumption during gestation and its long-term effects on offspring's liver: a systematic review

Abstract Objectives: describing the effects of maternal supplementation with folic acid (FA) exclusively during gestation on offspring's liver at later stages in life. Supplementation with FA during gestation has been recommended by the medical society worldwide. The liver has a central role on the substances of metabolism and homeostasis and some studies have shown that a high intake of FA at other periods in life may cause hepatic damage. Methods: a systematic review through which the following databases were consulted: Medline, through platforms of Pubmed, Lilacs and Scielo. The research was performed by keywords such as: "Folic acid", "Gestation", "Rat", "Offspring" and "Liver". Articles which evaluate the effect of FA consumption during both gestation and lactation were excluded. Results: FA consumption avoids disorders on expression of peroxisome proliferator-activated receptor alpha (PPARα) and glucocorticoid receptor (GccR), its lack did not change enzyme activity of the male offspring's liver in adulthood. Supplementation with FA during gestation did not change iron hepatic levels or lipid composition, but had an antioxidant effect on it. Conclusions: supplementation with FA at recommended doses did not cause toxic effects and is very likely to avoid deleterious effects in the liver of the offspring regarding the epigenetic level.

The effect of maternal malnutrition during lactation on the endometrial ERalpha expression, collagen type, and blood vessels in the rats offspring at puberty

The aim of this manuscript was to evaluate the effects of maternal protein-energy-restriction and energy restriction during lactation on endometrial collagen and blood vessels, uterus Eralpha expression, and estradiol serum levels in the rats offspring at puberty. At parturition, dams were grouped as: control group (C), with free access to standard rat chow containing 23% protein and 17,038.7 KJ/Kg; protein-energy restricted group (PER), with free access to formulated chow containing 8% protein but made isoenergetic to the C diet (17,038.7 KJ/Kg); and energy-restricted group (ER), which received standard rat chow containing 23% protein based on the mean ingestion of the PER group corresponding to 60% of that consumed by the control group. After weaning, all female pups had free access to standard laboratory chow until puberty, when they were killed at the diestrum stage. The uterine ERalpha expression was determined by Western-Blot and estradiol serum levels by radioimmunoassay. Endometrial collagen and blood vessels were quantified by stereology. The volumetric density of blood vessels (C = 70.7 +/- 2.2; PER = 29.2 +/- 2.4; ER = 32.3 +/- 3.6; P < 0.001) and endometrial collagen (C = 31.1 +/- 1; PER = 26.9 +/- 1.0; ER = 26.5 +/- 0.7; P < 0.05) were significantly reduced in both malnourished groups. The ER group presented higher estradiol serum levels (C = 69.2 +/- 6.4; PER = 73.4 +/- 5.5; ER = 101.0 +/- 5.4; P < 0.01) in relation to C and PER groups. ERalpha expression was greater in both malnourished groups (C = 0.11 +/- 0.02; PER = 0.41 +/- 0.12; ER = 0.35 +/- 0.03; P < 0.05). In conclusion, maternal malnutrition during lactation caused changes in endometrial angiogenesis, collagen deposition, and Eralpha expression in female offspring that will appear in puberty and could affect the reproductive biology of the female offspring.

Effects of maternal undernutrition during lactation on estrogen and androgen receptor expressions in rat ovary at puberty

OBJECTIVE

The aim of this study was to evaluate the effects of maternal protein and energy-restricted diets during lactation in folliculogenesis and its relations to androgen and estrogen receptors in the offspring at puberty.

METHODS

At parturition, dams were randomly assigned to a control (C) group, with free access to a standard laboratory diet containing 23% protein; a protein-energy-restricted (PER) group, with free access to an iso-energy and protein-restricted diet containing 8% protein; and an energy-restricted (ER) group, receiving standard laboratory diet in restricted quantities. After weaning, female pups had free access to standard laboratory diet.

RESULTS

The number of preantral (C 13.72 ± 2.87, PER 26.36 ± 3.03, ER 26.88 ± 2.31, P < 0.05) and small antral (C 9.32 ± 1.32, PER 17.64 ± 2.33, ER 17.04 ± 2.22, P < 0.05) follicles was significantly increased by maternal malnutrition. The number of primordial follicles (C 10.57 ± 1.61, PER 4.30 ± 0.62, ER 6.28 ± 1.30, P < 0.05), Graafian follicles (C 1.04 ± 0.09, PER 0.52 ± 0.10, ER 0.36 ± 0.11, P < 0.01), and corpus luteum (C 4.84 ± 0.62, PER 2.80 ± 0.50, ER 3.24 ± 0.27, P < 0.05) was significantly reduced. Maternal protein- and energy-restricted diets led to a significant decrease in the androgen (C 9815 ± 1015, PER 6071 ± 838.7, ER 5811 ± 699.3, P < 0.05) and estrogen (C 0.79 ± 0.244, PER 0.12 ± 0.035, ER 0.20 ± 0.036, P < 0.05) α-receptors. In growing follicles, androgen receptor was immuno-expressed in granulosa and theca cells. Estrogen receptor-α was mainly expressed in stroma cells.

CONCLUSION

Our results suggest that maternal protein- and energy-restricted diets during lactation can disturb the follicular development of the offspring, probably by reducing the number of androgen and estrogen receptors in the ovary.

Metabolic programming of ovarian angiogenesis and folliculogenesis by maternal malnutrition during lactation

OBJECTIVE

To evaluate whether maternal malnutrition during lactation programs ovarian folliculogenesis and the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and its receptors KDR, Flt-1, and FGFR.

DESIGN

Experimental study.

SETTING

University-based research laboratory.

ANIMAL(S)

Adult female rats from a urogenital research laboratory.

INTERVENTION(S)

Six rat dams randomly assigned to the following groups: control group (C), with free access to a standard laboratory diet containing 23% protein; and a protein-energy-restricted group (PER), with free access to an isoenergy and protein-restricted diet containing 8% protein. After weaning, the female pups had free access to the standard laboratory diet until 90 days of age, when they were sacrificed at the proestrum stage.

MAIN OUTCOME MEASURE(S)

Quantification of ovarian follicles, vessels, and expression of growth factors and their receptors.

RESULT(S)

Maternal malnutrition during lactation caused a significant reduction in the number of primordial (C = 6.60 +/- 0.24, PER = 5.20 +/- 0.20), primary (C = 5.80 +/- 0.66, PER = 4.00 +/- 0.31), and Graafian follicles/section (C = 2.18 +/- 0.29, PER = 1.08 +/- 0.37), in KDR (C = 0.22 +/- 0.04, PER = 0.09 +/- 0.01), Flt-1 (C = 0.28 +/- 0.05, PER = 0.12 +/- 0.02), and FGFR mRNA expression (C = 0.34 +/- 0.05, PER = 0.13 +/- 0.05) and in the vessel density of follicles (C = 17.26 +/- 2.30, PER = 9.96 +/- 0.97).

CONCLUSION(S)

Maternal malnutrition during lactation programs the follicular development by a reduction of VEGF and FGF mRNA receptors expression, probably from a direct action on the follicular development or a reduction in vasculature resulting in a decreased delivery of folliculotrophic substances in PER animals.

Maternal protein-energy and energy-restricted diets during lactation possibly could program folliculogenesis and the ovarian expression of leptin and its different isoform receptors in rats

Both protein-energy and energy-restricted diets during lactation program the ovarian function of the rat offspring, leading to a reduction of folliculogenesis, possibly as the consequence of the altered expression of leptin and its isoform receptor genes.