20 April, 2017

Sprague Dawley®: The workhorse of reproductive endocrinology research - part 2

By Travis Rothrock

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Providing reliable learnings in reproductive endocrinology studies
An adverse fetal environment can lead to disorders and complications in an offspring’s health. From exposure to toxins to poor maternal nutrition, researchers have observed many connections that affect the reproductive potential of offspring. Sprague Dawley® SD® rats serve an important role in reproductive endocrinology studies by providing a reliable means to understand the underlying mechanisms of some of these relationships.

Evaluating the intrauterine environment
Preeclampsia, a condition unique to pregnancy that is characterized by high blood pressure, is often linked to obesity. Researchers continue to study the molecular mechanisms to better understand the factors driving this association.

Recent research by Palei et al. used Hsd:Sprague Dawley® SD® pregnant rats with injections of leptin on gestational day 14. The hormone leptin plays an important role in appetite and weight control, but its long-term effect on blood pressure during pregnancy is unknown. Along with increasing blood pressure, researchers observed that leptin increased placental tumor necrosis factor.

Another intrauterine study examined hypertensive protein-restricted females as compared to the controls. In this study, the authors observed that estradiol plays a role in limiting the severity of hypertension and contributing to sexual dimorphism.

Supporting reproductive toxicity studies
Many chemicals can adversely affect human reproductive systems but ongoing research is needed to fully understand the relationship between exposures and the risks of reproductive toxicity. Sprague Dawley® SD® rats present similar metabolic pathways to those of humans, making them an ideal, proven model for this significant research.

Nakamura et al. recently looked at a compound used in many cosmetic products: 2-Hydroxy-4-methoxybenzophenone (HMB), which may have harmful effects on fetal development. In their study, the researchers sought to determine the effects of maternal and lactation-related exposure to HMB on the development and reproductive organs of offspring. HSD:Sprague Dawley® SD® rats with exposure to high levels of HMB were associated with reduced body and organ weights in female and male offspring, among other changes, although these adverse events occurred are much higher than usual human exposure levels.

Manikkam et al. also utilized HSD:Sprague Dawley® SD® rats to investigate the effects of plastic-derived endocrine disruptor molecules. Gestating rats were exposed to Bisphenol A (BPA), bis(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP) during embryonic days 8 to 14, which is the period of gonadal sex determination. The authors concluded that a mixture of these compounds (i.e., BPA and phthalates) can promote epigenetic transgenerational inheritance of adult onset disease.

In another interesting study, Maranghi et al. sought to determine the short- and long-term effects of ethylenethiourea (ETU), a common metabolite of a widely-used fungicide, on thyroid function. HSD:Sprague Dawley® SD® rats were treated with ETU daily during pregnancy. The authors concluded that even low doses of ETU exposure during the critical stages of development can interfere with thyroid homeostasis and the reproductive hormone profile.

Sprague Dawley® rats: a key asset in reproductive studies
Reproductive endocrinology research with Sprague Dawley® rats is entering an exciting new phase that can offer new and better diagnostic tools and treatment of reproductive disorders. Research utilizing Sprague Dawley® rats have cast light on the causes of disorders related to reproduction and has extended our understanding of in utero effects on fetal and adult outcomes. Sprague Dawley® rats will no doubt continue to play a key role in unmasking the effects of environmental toxins and in furthering reproductive endocrinology research.

Many other reproductive encrinology challenges have been studied with the robust model of the Sprague Dawley® SD® rats. Read more in our whitepaper.

[White paper] Deciphering reproductive endocrinology challenges

Category // Research models and services, Sprague Dawley, Reproductive endocrinology