technical sheet

The Zucker Diabetic Fatty (ZDF) Rat
Diet Evaluation Study for the Induction of Type 2 Diabetes in Obese Female ZDF Rats
Guy B. Mulder, Director, Professional Services
Steve Luo, Sr. Manager, Research Model Quality
Peggy Gramlich, Operations Manager, Preconditioned Services

Strain Origin
A mutation occurred in a colony of outbred Zucker rats in the laboratory of Dr. Walter Shaw at Eli Lilly ResearchLaboratories in Indianapolis, IN, in 1974-75. In 1977, part of this colony containing the mutation was moved to thelaboratory of Dr. Julia Clark at Indiana University Medical School (IUMS). Several groups of animals with diabetic lineage
were identified and rederived in 1981. Inbreeding of selected pairs from this rederivation was performed in the laboratoryof Dr. Richard Peterson at IUMS. An inbred line of the Zucker Diabetic Fatty (ZDF) rat was established by Dr. Peterson in
1985. This colony was transferred to Genetic Models, Inc., in 1991 and then to Charles River in 2001.

Characteristics
Characteristics of the obese male ZDF rat maintained on Purina 5008 diet include hyperinsulinemia and hyperglycemia,
type 2 diabetes (T2D), insulin resistance and obesity beginning at six to seven weeks of age. By 10-12 weeks of age,glucose levels steadily increase, reaching an average of approximately 500 mg/dL. During this same period, insulin
production gradually decreases until the plasma insulin concentration reaches approximately 1 ng/mL or less.
Unlike the male, the female ZDF does not develop diabetes on the Purina 5008 diet as assessed by the oral glucose
tolerance test. However, it does develop metabolic syndrome as characterized by raised insulin and glucose levels.

Introduction
The obese male ZDF rat plays a pivotal role in studying the cascade of physiologic events associated with the onset andtreatment of T2D. The female ZDF can also be used as a model for T2D, but unlike the male, the female requires dietarymodification to induce the diabetic state.
Historically, females fed Research Diets (RD) C13004 diet starting at six weeks of age consistently developed diabetes by
12 weeks of age. The C13004 diet consists of a grain base supplemented with added fat. During the fall of 2007, several
research groups reported to Charles River that female ZDF rats fed C13004 did not reliably develop diabetes. CharlesRiver conducted a 14-week study feeding obese female ZDF rats the C13004 diet and confirmed that this specialized
diet no longer induced diabetes in this model. In conjunction with RD and Purina Lab Diets, Charles River learned that amodification in a specific fat component of the diet had occurred just prior to the initial customer reports. Subsequently,Charles River implemented a number of studies with the objective of identifying a diet that reliably induced diabetes infemale obese ZDF rats.

Figure 1

Next, a follow-up study was conducted to determine
whether diabetes could be induced and maintained if thestudy animals were kept on RD 12468 for a longer timeperiod. A group of ZDF females (N=20) were fed dietRD 12468 from five weeks of age through 20 weeks ofage. The RD 12468 with lactoalbumin was not evaluatedbecause we found no statistical difference between thetwo diets with regards to induced raised glucose levelsin the first test. Insulin and glucose values were collectedfrom 12 to 18 weeks of age and the results demonstrated
that a continuous diet of RD 12468 resulted in a sustained
hyperglycemia accompanied by a gradual decrease inserum insulin levels (see Figure 2), both of which indicatethat the study animals became diabetic.

450400350
300
250200150
100500RD12468
RD12468L

6810121416182022AGE (Weeks)This graph illustrates the mean blood glucose values infemale ZDF-Lepr fa /Crl rats fed RD12468 and RD12468L
until 12 weeks of age and then fed Purina 5008 diet for
the rest of the study (n=10, data presented as mean ±SEM ). Glucose was measured using an Ascensia ELITE®
handheld glucometer. Study date: 09/08

Glucose level of female obese ZDF rats fed RD 12468 and12468L, respectively, over a period of six weeks.

Figure 2: Fed Glucose and Insulin, Obese Female ZDF Rats
GlucoseInsulin
800

30700

25600
20500
400

15300

10200
5100
0
12INSULIN (ng/ml)

For further validation, two follow-up studies, eachconsisting of 20 female ZDF rats, were conductedfollowing a similar protocol to the one above. In Study 1,the females (N=20) received RD 12468 until 18 weeksof age, followed by a diet of Purina 5008. The femalesin Study 2 remained on diet RD 12468 throughout the26-week study period. Figures 3 and 4 illustrate that adiabetic phenotype was achieved and maintained in bothstudies regardless of whether the diet switched back toPurina 5008.

GLUCOSE (mg/dL)

An initial study using RD 12468 and 12468L (in which
lactoalbumin was added as an additional protein source)
was conducted. Both diets were reported to induce
hyperglycemia in ZDF females. However, upon removing
each of the test diets and placing the animals on Purina
5008 (at 12 weeks of age), the hyperglycemic state
resolved in the animals (see Figure 1).

Figure 1: Fed Glucose, Obese Female ZDF Rats

GLUCOSE (mg/dl)

Study01314151617181920

AGE (Weeks)This graph illustrates the mean blood glucose andinsulin values in female ZDF-Lepr fa /Crl rats fedRD12468 for the duration of the study (n=20, data
presented as mean ± SEM ). Glucose was measured
using Synchron CX4 Pro clinical analyzer. Insulin
was measured using M ercodia ELISA kits. Studydate: 12/09

Glucose and insulin values of female obese ZDF rats fed RD12468.

Figure 3: Fed Glucose and Insulin, Obese Female ZDF Rats

Figure 4: Fed Glucose and Insulin, Obese Female ZDF Rats
Glucose400

2520300

15200

10100

50068 10 12 14 16 18 20 22 24 26 28

GLUCOSE (mg/dl)

30500

30400

2520300

15200

10100

50068 10 12 14 16 18 20 22 24 26 28

AGE (Weeks)AGE (Weeks)This graph illustrates the mean blood glucose andinsulin values in female ZDF-Lepr fa /Crl rats fed RD12468
until 18 weeks of age and then fed Purina 5008 diet for
the rest of the study (n=20, data presented as mean ±SEM ). Glucose was measured using an Ascensia ELITE®
handheld glucometer. Insulin was measured using
M ercodia ELISA kits. Study date: 07/15/09 - 12/10/09

This graph illustrates the mean blood glucose andinsulin values in female ZDF-Lepr fa /Crl rats fed
RD12468 for the duration of the study (n=20, data
presented as mean ± SEM ). Glucose was measured
using an Ascensia ELITE® handheld glucometer.
Insulin was measured using M ercodia ELISA kits.
Study date: 10/14/09 - 03/03/10

Glucose and insulin levels of female obese ZDF rats fed
RD 12468 until 18 weeks of age, at which time the diet wasreplaced with Purina 5008 (Study 1).

Insulin
INSULIN (ng/ml)

500

Insulin
INSULIN (ng/ml)

GLUCOSE (mg/dl)

GlucoseGlucose and insulin values of female obese ZDF rats fed
RD 12468 over a period of 26 weeks (Study 2).

Summary
Although older studies documented that obese female ZDF rats became diabetic when fed RD C13004, beginning in
2007, Charles River received several reports from researchers that these rats no longer developed diabetes when placedon this diet. Subsequently, Charles River learned that certain nutritional components of RD C13004 had been modified.
After first ruling out environmental and genetic factors as possible causes of the loss of the diabetic phenotype, CharlesRiver experimentally evaluated the RD C13004 diet and confirmed that it no longer reliably produced diabetes in the obese
female. Subsequently, Charles River performed a series of studies that indicated that the semi-purified diet RD 12468reliably produced a diabetic phenotype, indicated by hyperglycemia and insulinopenia, in the female ZDF rat.
Charles River recommends that investigators consider utilizing RD 12468 to reliably induce a diabetic phenotype in thefemale ZDF rat. Alternatively, Charles River can provide preconditioned female ZDF rats fed RD 12468 upon request.

References
Shafrir, E. Animal Models of Diabetes: Frontiers in Research. 2nd ed. 1-357 (CRC Press, Boca Raton, 2007).

technical sheet

Charles River Disease Models
As the prevalence of certain diseases continues to increase worldwide, the need for new ways to explore
the mechanisms of disease has become paramount. Charles River’s portfolio of research animal models, which
includes cardiovascular, metabolic, renal and oncologic disease models, helps ensure that you will have the optimal
resources available in your chosen area of research.

Characteristic
Insulin ResistanceHyperinsulinemia
Type 2 Diabetes
Fasting Hyperglycemia
Hypertension
Obesity
Cardiovascular Disease
Hypertriglyceridemia
Hypercholesterolemia
Nephropathy
Leptin Receptor DefectSpecial Diet Requirements
Genetics

THE POUND
MOUSE™
++–+?
+––+–+–I

OP-CD++–+++–+–––+O

OR-CD++–++––+–––+O

Dahl/S S++––+––+++–+I

SS-13BN *++–––––+++–+C

SHR++––+––++–––I

Characteristic
Insulin ResistanceHyperinsulinemia
Type 2 Diabetes
Fasting Hyperglycemia
Hypertension
Obesity
Cardiovascular Disease
Hypertriglyceridemia
Hypercholesterolemia
Nephropathy
Leptin Receptor DefectSpecial Diet Requirements
Genetics

SHROB++––++–++++–I

SHROBLean++––+––++–––IGK++++–––––+––I

ZDF++++–+–+++, 1++I

ZSF1++++++–+++, 2++H

Zucker++–––+–+++, 1+–O

+ = Exhibits the characteristic_= Does not exhibit the characteristic? = Unknown at this time
1 = Hydronephrosis (Interference)
2 = Hydronephrosis (Interference) is found infrequently© 2010, Charles River Laboratories International, Inc.

StrokeProne++––+––+++–+I

I = Inbred
O = Outbred
H = Hybrid
C = Consomic*Dahl/SS control

The Zucker Diabetic Fatty (ZDF) Rat - Technical SheetCharles River Research Models and Services
T: +1 877 CRIVER 1 (+1 877 274 8371) • +800 3195 3430
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