Maternal Diabetes Impairs Gastrulation and Insulin and IGF-I Receptor Expression in Rabbit Blastocysts

Abstract

Women with type 1 diabetes are subfertile. Diabetes negatively affects pregnancy by causing early miscarriage and poor prenatal outcomes. In this study we examine consequences of maternal type 1 diabetes on early embryo development, metabolic gene expression, and the pattern of insulin receptor (IR) and IGF-I receptor (IGF-IR) distribution in rabbit blastocysts. In female rabbits, type 1 diabetes was induced by alloxan treatment. Six-day-old blastocysts were recovered and assessed for receptor distribution and metabolic gene expression. In vitro culture of blastocysts was performed in medium containing 1 mM, 10 mM, or 25 mM glucose, simulating normo-and hyperglycemic developmental condition in vitro. The fertility rate of the diabetic rabbits clearly mirrored subfertility with a drop in blastocyst numbers by 40% (13.3 blastocysts in diabetic vs. 21.9 in control females). In blastocysts onset and progression of gastrulation was delayed and expression of IR and IGF-IR and their metabolic target genes (hexokinase, phosphoenolpyruvate carboxykinase), both in vivo and in vitro, was down-regulated. The amount of apoptotic cells in the embryonic disc was increased, correlating closely with the reduced transcription of the bcl-x(L) gene. Blastocyst development is clearly impaired by type 1 diabetes during early pregnancy. Insulin-stimulated metabolic genes and IR and IGF-IR are down-regulated, resulting in reduced insulin and IGF sensitivity and a delay in development. Dysregulation of the IGF system and embryonic glucose metabolism are potential reasons for diabetogenous subfertility and embryopathies and start as soon as during the first days of life. (Endocrinology 151: 4158 -4167, 2010)

Maternal diabetes promotes mTORC1 downstream signalling in rabbit preimplantation embryos

“…In our in vitro experiments, rabbit blastocysts revealed an increase in mTORC1 signalling just by amino acid supply and without insulin. This situation is comparable to the in vivo situation of a diabetic pregnancy as demonstrated before (Gü rke et al 2015), where blastocysts having no excess to insulin activate mTOR signalling and adapt to metabolic changes (Ramin et al 2010). We show that glucose and L-leucine are able to activate mTORC1 signalling each for itself in vitro.…”

“…In (B), the amount of phosphorylated protein was related to the non-phosphorylated protein and calculated relative to controls (set 100%) (NZ4; nZ30; *P!0.05). increase of glucose in uterine fluid during diabetes (Ramin et al 2010). Besides leucine and glucose, insulin signalling activates a series of phosphorylation events leading to the activation of mTORC1 pathway (reviewed by Hay (2005)).…”

“…Experimental insulin-dependent diabetes (IDD) was induced by alloxan (Sigma-Aldrich) treatment, as described before (Ramin et al 2010). Rabbits were held in single cage with chiaroscuro rhythm of 12:12 h and were fed ad libitum with customary food (REIKA, Reinsdorf, Germany).…”

“…To further analyse the effects of high glucose concentrations observed in uterine fluid from diabetic rabbits (Ramin et al 2010), blastocysts from healthy rabbits were cultured with high (10 mM) glucose concentration and without glucose (controls). The 10 mM glucose concentration induced mTORC1 and S6K1 phosphorylation.…”

Pregravid preparation for women with a history of miscarriage

“…Кроме того, в сочетании с другими факторами риска, характерными для больных СД (избыточная масса тела, артериальная гипертензия, сердечно-сосудистые заболевания, гипотиреоз) еще более ухудшается прогноз вынашивания беременности и рождения здорового ребенка. Для снижения риска акушерских и перинаталь-ных осложнений детальное обследование женщины и подбор адекватных методов стабилизации уровня глике-мии необходимо проводить в прегравидарном периоде совместно с врачами смежных специальностей [40][41][42].…”