Obesity

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Diet & Obesity

Genetic and environmental factors play a role in the development of obesity, and diet is one of the main environmental factors that contribute to obesity and its related metabolic diseases. Human studies have shown that increased fat intake is associated with body weight gain which can lead to obesity and other related metabolic diseases. As such, rodent animal models are useful tools to determine the mechanistic aspects of obesity and to develop therapeutic approaches as they will readily gain weight when fed high-fat diets.

Important factors to consider when designing a diet-induced obesity study using animal models are:

Matched Formulas Low-fat Purified Ingredient Diet*
Calories from Fat 32% to 60%
Types of Fat lard, beef tallow, coconut oil, milk fat, fish oils
Commonly Used Strains C57BL/6J, AKR/J mice, Sprague-
Dawley, Wistar, F344x Brown Norway rats

*For those requiring a matched control diet, be sure to use a purified ingredient matched diet rather than a grain-based diet.

Diabetes Insulin Resistance

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Diabetes Insulin Resistance

Refined carbohydrate sources such as high fructose corn syrup (HFCS) are used in many processed foods and surveys in the U.S. have suggested that the intake of this sweetener has increased dramatically since the 1970s. As we have learned over the past few decades, an excess intake of refined carbohydrates is associated with increased weight gain, hypertriglyceridemia (hyper-TG), and insulin resistance (IR) in humans and animal models. In order to understand more about the impact of refined carbohydrates on health and therapies to reduce these metabolic syndrome (MS) phenotypes, certain rodent models have been useful. Purified diets containing around 60% - 70% (by energy) fructose or sucrose (which is a 50:50 molar mixture of fructose and glucose) are capable of elevating TG and glucose production in the liver, ultimately leading to IR and hyper-TG relative to diets containing mainly glucose carbohydrate sources (i.e. dextrose, corn starch).

Types of Diets High fructose, High sucrose
Commonly Used Strains Sprague-Dawley, Wistar rats, Hamsters, C57BL/6, LDLr KO
Matched Control Diets Purified Ingredient match*

*For those requiring a matched control diet, be sure to use a purified ingredient matched diet rather than a grain-based diet.

Fatty Liver

Rdi fatty liver disease web2

Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of disorders characterized by excessive lipid accumulation in hepatocytes. Each stage of the disease spectrum has distinctive histopathological characteristics. The beginning stages include simple hepatic steatosis, which is characterized by fat droplet accumulation in hepatocytes and this is usually benign and asymptomatic. The disease may progress further to non-alcoholic steatohepatitis (NASH), which may include hepatocellular injury, ballooning (i.e. cellular swelling) and/or inflammation. If left unchecked, NASH can lead to fibrosis, cirrhosis, and ultimately HCC, thus affecting overall liver function.

In spite of the enormous amount of research in the field of NAFLD/NASH in the past decade, the precise mechanisms underlying the development of NAFLD and its progression to NASH have not been completely elucidated, including its link to metabolic syndrome, requiring additional studies and models to elucidate its pathophysiology. Because of its growing worldwide prevalence, various animal models that mirror both the pathophysiology and the histopathology of each stage of NAFLD/NASH are available. Certain dietary approaches can drive NAFLD/NASH in rodent models to mimic human disease and produce different severities of disease along the NAFLD spectrum, and depending on the dietary manipulations, likely work by unique mechanisms. This is essential in determining how the disease progresses, and also helps in evaluating different therapeutic approaches towards the treatment of specific stages of NAFLD.

Our Latest Publication

Targeted Nutrient Modifications in Purified Diets Differentially Affect Nonalcoholic Fatty Liver Disease and Metabolic Disease Development in Rodent Models
Sridhar Radhakrishnan, Jia-Yu Ke, Michael A Pellizzon
Current Developments in Nutrition, Volume 4, Issue 6, June 2020

Joint RDI/Taconic NAFLD Webinar

In case you missed it, here is the link to the presentation, "Nutrient Modifications in Purified Diets Differentially Affect Nonalcoholic Fatty Liver Disease (NAFLD) in Rodents." Presented by Dr. Sri Radhakrishnan.

Hypertension

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Hypertension

The pathogenesis of hypertension in humans is not fully understood. This disease of persistent elevation of blood pressure is a multifactorial combination of genetic and environmental factors. To better understand the specific mechanisms involved, as well as to research treatments for prevention of hypertension, various animal models have been developed to mimic the hypertensive responses seen in humans.

Historically, the preferred small animal model for hypertension research has been the rat. This may be due to the amount of published physiological data, relative small size, and robust responses seen in some genetic strains. Because of the polygenic nature of hypertension, numerous rat models have been developed including selective bred homozygous hypertensive rat strains (e.g. spontaneously hypertensive rat [SHR] and Dahl salt sensitive [Dahl SS]) and outbred strains (e.g. Sprague Dawley) to elucidate the desired hypertensive phenotype. As the form of hypertension can differ between strains, researchers need to not only be aware of the form of hypertension that the individual strain exhibits but also the impact that a particular type of diet may have on the phenotypic response.

Types of Diets High NaCl diets
Commonly Used Strains SHR, SS,SD and SHROB rats, 
Matched Control Diets Purified Ingredient match*

*For those requiring a matched control diet, be sure to use a purified ingredient matched diet rather than a grain-based diet.

Metabolic Syndrome

Diet induced metabolic syndrome web

Diet Induced Metabolic Syndrome

The Metabolic syndrome (MS) is a term used to describe the simultaneous occurrence of insulin resistance, abnormal blood lipid levels (hypertriglyceridemia and reduced high density lipoprotein cholesterol), and hypertension (high blood pressure). People with the MS are at increased risk for type 2 diabetes, cardiovascular disease, cancer, and nonalcoholic fatty liver disease. While certain people may be more susceptible to the MS than others, one key factor that may drive the MS in humans is diet. Like humans, certain rodent models are more sensitive than others to dietary changes.

Immunology

Rdi immunology web2

Immunology

It is well accepted that diet has far-reaching effects on the physiology of lab animals. Targeted phenotypes can be purposely induced by using specific diets, allowing the researcher to test their hypotheses. Like other areas of study, immunology is a field in which attention must be paid to the diet being fed, since changing the diet composition could result in a different immunological phenotype. This requires that researchers understand the differences between grain-based (GB) chows and purified ingredient diets, and unfortunately, many investigators (immunologists or not) are unaware of these differences.

Atherosclerosis

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Atherosclerosis

Atherosclerosis is a complex chronic disease characterized by the accumulation of lipids within arterial walls that eventually go on to form plaques, which can cause narrowing, hardening, and/or complete blockage of arteries. One well known risk factor in humans is hypercholesterolemia (i.e. elevated total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C)), and other important contributors to this disease include inflammation, oxidative stress, and insulin resistance. Foods high in dietary saturated fat (SF) and cholesterol (i.e. “Western-type diets”) have been linked to elevations in circulating cholesterol levels (in particular, LDL-C), prompting the recommendation that humans limit the intake of these dietary constituents. Like humans, Western-type diets can induce elevated LDL-C and atherosclerosis in certain rodent models (i.e. mice, hamsters, guinea pigs). Therefore, the use of such diets for promoting atherosclerosis in these models has been a valuable tool for both gaining more understanding of this disease and testing therapies that can potentially reverse it. Consult with one of our scientists on a custom formula for your study.

Types of Diets Western- type diets
Commonly Used Strains C57BL/6, (LDLr) null and apolipoprotein E
(apoE) null mice, Sprague-Dawley,
Wistar rats, Hamsters, Guinea pigs
Matched Control Diets Purified Ingredient match*

*For those requiring a matched control diet, be sure to use a purified ingredient matched diet rather than a grain-based diet.

Cancer

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Cancer & Diet

Laboratory animal models are important tools in oncology research, as they allow scientists to test their in vitro-generated hypotheses in a mammalian, whole-animal system. Since many types of cancer can be affected by environmental factors, having control over these factors is key to generating reproducible, meaningful data.
Research Diets products are routinely used for oncology research. OpenSource diets contain purified ingredients, which provide a clean background (i.e. phytoestrogen and chlorophyll-free) to reduce ‘noise’ during in vivo imaging and control over factors that may impact gene expression.

Ketosis

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Ketogenic Diets

The ketogenic diet (KD) was originally developed in the early 1920s as a treatment for pediatric epilepsy. It is characterized by very high levels of fat, minimal carbohydrate, and adequate protein. In the absence of glucose oxidation, ketone bodies (β-hydroxybutyrate, acetoacetate, and acetone) are formed as a byproduct of fatty acid oxidation in order to serve as an alternative source of fuel for the brain and peripheral tissues. KDs restrict carbohydrate consumption in order to limit circulating levels of glucose and, therefore, promote production and utilization of ketone bodies as a primary fuel source. This state of ketosis mimics starvation as ketone bodies are naturally produced in response to prolonged fasting or intense exercise.

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Steven Yeung, M.S.

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Sara Sturgess, M.S., R.D.N.

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Dima Paone, MB BCh.

Global Logistics Director and Scientist