Adipocyte morphology and leptin signaling in rat offspring from mothers supplemented with flaxseed during lactation

January 1, 2011 Human Health and Nutrition Data 0 Comments

Adipocyte morphology and leptin signaling in rat offspring from mothers supplemented with flaxseed during lactation

Year: 2011
Authors: Sarto Figueiredo, M. Cottini da Fonseca Passos, M. Hara Trevenzoli, I. Andrade Troina, A. Santana Carlos, A. Alves Nascimento-Saba, C.C. Carneiro Fraga, M. et. al.
Publication Name: Nutrition & Metabolism
Publication Details: doi:10.1016/j.nut.2011.07.002

Abstract:

We have recently shown that maternal flaxseed supplementation during lactation induces insulin resistance in adult offspring. Here, we studied the effects of maternal dietary flaxseed during lactation on adipocyte morphology and leptin signaling in the hypothalamicpituitary thyroid axis as well as on behavioral traits in the adult progeny. Lactating rats were fed a control (C) diet or a diet with 25% flaxseed (F). After weaning, pups received a standard diet until postnatal day (PN) 180. Male offspring were killed at PN21 and 180. Data were considered significant at P < 0.05. Weaned F rats presented a lower total and subcutaneous fat mass and higher subcutaneous adipocyte area (+ 48%), but at adulthood they presented higher subcutaneous and visceral adipocyte areas (+ 40% and 1.9 fold increase, respectively), with no change in body fat mass. At PN21, F pups had hyperleptinemia (+ 69%), lower T3 (- 33%), higher TSH (2.1 fold increase), higher pituitary leptin receptor (Ob-R,  +11%), signal transducer and activator of transcription 3 (STAT3, + 21%), and phosphorylated-STAT3 (p-STAT3, + 77%) protein content. Adult F offspring only showed lower T4 (- 28%) and higher thyroid Ob-R (+ 52%) expression. Maternal flaxseed intake during lactation did not result in behavioral changes in the adult offspring. Maternal flaxseed supplementation decreases offspring adiposity and increases pituitary leptin signaling at weaning, but it induces hypertrophic adipocytes and higher thyroid leptin receptor in adulthood. The present data suggest that extensive use of flaxseed during lactation is undesirable. (Authors abstract)
In this study, maternal flaxseed in the diet during lactation programmed changes in the leptin signaling pathway and in adipocyte morphology. The maternal flaxseed diet used during lactation had flaxseed as the exclusive source of oil and fiber and represented a dose of 25% flaxseed in the diet. A higher adipocyte area in the subcutaneous tissue was noted but a normal visceral adipocyte area.  Estrogen receptors have been found in adipocytes, and the administration of estrogen stimulates the secretion of leptin by adipose tissue in vitro. Flaxseed has high concentrations of phytoestrogens, whose consumption in periods such as pregnancy and/or lactation may result in estrogen changes in the offspring.  At adulthood, F offspring had normal total and visceral fat mass and leptinemia but higher adipocyte areas in subcutaneous and visceral adipose tissues. A greater increase in visceral than in subcutaneous adipocyte area in adult F offspring was found which suggests a higher cardiovascular risk in these animals. At 21 d of age, F pups showed no changes in the leptin signaling pathway in the hypothalamus compared with the C group. However hyperleptinemia was noted at this age, suggesting relative brain insensitivity to leptin as confirmed by a relatively unchanged food intake. Adult offspring of dams that were fed flax oil during pregnancy and lactation did not present alterations in memory/learning in a water maze task. In the present study, anxiety-like behavior and novelty-seeking behavior were not affected by the flaxseed diet, suggesting the diet does not present significant adverse behavioral effects. A flaxseed diet during lactation was associated with lower adiposity but, paradoxically, higher subcutaneous adipocyte area at weaning, suggesting an impairment of adipogenesis. It is possible that this change alters leptin production and signaling in the pituitary gland, resulting in higher Ob-R, STAT3, and p-STAT3 protein content. At adulthood, F offspring normalized their adiposity but still presented a higher subcutaneous adipocyte area and also visceral adipocyte area, which could be related to insulin resistance. The experimental data suggest that during this period, women should limit their intake of flaxseed or other phytoestrogen containing substances to prevent altered adipogenesis and leptin action in their progeny. (Editors comments)



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