Comparative Medicine
Volume 58, Number 6, December 2008
ORIGINAL RESEARCH
Mouse Models
Chase et al. Murine Noroviruses: An Intercurrent Variable in a Mouse Model of BacteriaInduced Inflammatory Bowel Disease, pp. 522-533
Task 9 - Collaborate on the Selection and Development of Animal Models
Primary Species – Mouse
SUMMARY: Several mouse models of intestinal inflammation develop inflammatory bowel
disease (IBD) which may be driven by bacterial flora. Mdr1a-/- mice develop spontaneous IBD
that is accelerated by infection with Helicobacter bilis. Mdr1a -/- mice were singly infected with
Mouse Norovirus (MNV) and/or co-infected with H. bilis. Disease severity and immune
response were assessed. Mice were euthanized at set time points or when mice exhibited
severe diarrhea, 20% weight loss, or loss of body condition. Fecal and blood samples were
collected at time of euthanasia for H. bilis presence and biomarker analysis, respectively.
Degree of colon inflammation was assessed for severity.
MNV infection accelerates weight loss and exacerbates IBD progression in Mdr1a-/- mice.
Disease severity in MNV and H. bilis infected Mdr1a-/- mice also correlates with serum
biomarker levels.
QUESTIONS:
1. Norovirus belongs to the Family ________________________.
2. List 3 mouse models of intestinal inflammation that develop IBD that is driven by
Helicobacter spp.
3. Dendritic cells (DC) are important
a. In the regulation of tolerance in the intestine
b. In producing type 2 interferons
c. Are not altered by MNV4 infection
4. Dendritic cells play a mole in the initiation of IBD. Alterations in dendritic cells (DC)
response could
a. Slow down tissue damage
b. Lead to persistent bacterial infection
c. Aberrant activation of the acquired immune system
d. B and D
5. Mdr1a-/- mice coinfected with MNV4 and H. bilis lost significantly more/less weight than
controls and more mice had gross evidence of severe/mild colitis.
6. True or False. Lymphangitis was seen in the colonic mesentery less frequently in co-infected
animals than in singly infected animals.
7. Specific serum ___________ and _____________levels reflect immune responses in vivo
and correlate with disease progression in Mdr1a-/- mice.
ANSWERS:
1. Caliciviridae
2. SMAD3 – deficient, T-cell deficient, and IL10- deficient mice
3. A
4. D
5. More, severe
6. False
7. Cytokines, chemokine
Chichlowski et al. Helicobacter typhlonius and Helicobacter rodentium Differentially
Affect the Severity of Colon Inflammation and Inflammation-Associated Neoplasia in
IL10-Deficient Mice, pp. 534-541
SUMMARY: Infection with Helicobacter species is endemic in many animal facilities and may
alter the penetrance of inflammatory bowel disease (IBD) phenotypes. However, little is known
about the relative pathogenicity of H. typhlonius, H. rodentium, and combined infection in IBD
models. The authors infected adult and neonatal IL10 -/- mice with H. typhlonius , H. rodentium,
or both bacteria. Helicobacter infection of the adults was done via gavage. Infection was
confirmed at 1 wk after infection and at 4-wk intervals thereafter by analysis of feces by PCR.
Infected neonates were derived by breeding infected adults and then conducting PCR on fecal
pellets of the pups 1-2 wks postweaning.
Infection of IL10 -/- mice with H. rodentium, H. typhlonius, or both organisms can trigger
development of severe IBD that eventually leads to colonic neoplasia. Infected IL10 -/- mice
developed IBD with severity of noninfected (minimal to no inflammation) < H. rodendium <H.
typhlonius <mixed H. rodentium, H. typhlonius (severe inflammation). Combined treatment using
commercially available wafers containing amoxicillin, clarithromycin, metronidazole, and
omeprazole eradicated Helicobacter in infected mice and ameliorated established IBD in both
infected and noninfected mice. The similar anti-inflammatory effect of antibiotic therapy in
Helicobacter-infected and noninfected IL10 -/- mice with colitis indicates that unidentified
microbiota in addition to Helicobacter drive the inflammatory process in this model.
The study showed that the clinical severity of disease is affected by whether Helicobacter
infection is acquired before (as pups) or after establishing normal endogenous microbiota. Mice
infected as pups developed inflammation which resembled that of adults inoculated with the live
cultures, but the survival rate of mice infected as pups was much higher and the incidence of
inflammation-associated neoplasia was decreased relative to outcomes in the adult study. The
authors noted that the high incidence and multiplicity of neoplastic lesions in infected mice make
this model well-suited for future research related to the development and chemoprevention of
inflammation –associated colon cancer. Further, the rapid development of IBD makes this
model very suitable for the studies on the mechanisms of IBD pathogenesis and treatment.
IBD does not occur in germ-free IL10 -/- mice, indicating the importance of microorganisms as
environmental triggers of intestinal inflammation. However, conventionally colonized or SPF
IL10 -/- mice may develop colitis spontaneously or in response to specific triggers such as
NSAIDS or infections with certain bacteria. Nevertheless, despite a large number of studies, no
single bacterial type has fulfilled Koch postulates and been confirmed as a cause of IBD in
animals or humans.
QUESTIONS:
1. IBD does not occur in germ-free IL10 -/- mice T/F
2. As supported by the results in this study, no single bacterial type has fulfilled Koch
postulates and been confirmed as a cause of IBD in animals or humans. T/F
3. Combined treatment using commercially available wafers containing amoxicillin,
clarithromycin, metronidazole, and omeprazole was unsuccessful in eradicating Helicobacter
in infected mice. T/F
4. Infection of IL10 -/- mice with H. rodentium, H. typhlonius, or both organisms can trigger
development of severe IBD that eventually leads to colonic neoplasia. T/F
ANSWERS:
1. T
2. T
3. F was successful
4. T
Wall et al. Quantitative Tomography of Early-Onset Spontaneous AA Amyloidosis in
Interleukin 6 Transgenic Mice, pp. 542-550
Task 1:
K8
Species:
Prevent, Diagnose, Control, and Treat Disease
Clinical Medicine
Primary - Mice
SUMMARY: Amyloidosis results from overproduction of an acute phase reactant, serum
amyloid protein (AA); derived from its precursor Serum Amyloid A that is exclusively
synthesized from hepatocytes. Experimental models for amyloidosis using mice are created by
injecting pro-inflammatory stimulus such as silver nitrate, casein, Freund’s adjuvant or
lipopolysaccharide. The drawback with these models is to provide repeated injections,
associated toxicity and cessation of stimulus that may result in progressive resorption of amyloid
deposits.
In this article, the authors described a change in spontaneous disease in 2 transgenic mice
(H2/huIL-6) that were moribund at an early age of 5 months. Mice that constitutively express the
human interleukin-6 (IL-6) protein express high levels of serum amyloid protein A, precursor of
AA amyloid. These mice (H2/huIL-6) develop clinical signs at an early age of 5 months
developing splenic deposits of AA amyloid; and ultimately progresses to involve liver, kidneys
and vasculature; resulting in death of the animal at 8-9 months of age. Using image-based
analysis such as Single Photon Emission Computed Tomography (SPECT) with iodinated
serum amyloid P component (SAP) and by immunohistochemistry indicated heterogeneous
distribution of amyloid in spleen and liver. Thus, the authors conclude that these mice can be
then be used a robust model to study novel therapeutic and diagnostic imaging agents fro AA
amyloidosis.
QUESTIONS:
1. The precursor for serum amyloid protein AA, Serum amyloid protein A is produced
exclusively at
a. Splenocytes
b. Neutrophils
c. Hepatocytes
d. Enterocytes
2. Identify the interleukin associated with expressing high levels of serum amyloid protein A?
a. IL-1
b. IL-6
c. Il-2
d. TNF-alpha
3. The tissue amyloid deposits were identified using what stain
a. Luxol blue
b. Congo Red
c. Prussian Blue
d. India Ink
ANSWERS:
1. c
2. b
3. b
Rat Models
Chiba et al. The Petit Rat (pet/pet), a New Semilethal Mutant Dwarf Rat with Thymic and
Testicular Anomalies, pp. 551-559
Task: Animal model, Domain 3, T3, TT3
Primary species: Rat
ABSTRACT: The petit rat (pet/pet) is a recently discovered semi-lethal mutant dwarf. The
neonatal pet/pet rats had a low body weight and small thymus and testis. During the first 3 d
after birth, 50% of the male and 80% of the female pet/pet pups were lost or found dead.
Surviving pet/pet rats showed marked retardation of postnatal growth, and their body weights
were 41% (female rats) and 32% (male rats) of those of normal rats at the adult stage. The
pet/pet rats exhibited proportional dwarfism, and their longitudinal bones were shorter than
those of controls without skeletal malformations. Most organs of male pet/pet rats, especially the
thymus, testis, adipose tissue surrounding the kidney, and accessory sex organs, weighed
markedly less at 140 d of age than did those of their normal counterparts. The thymus of pet/pet
rats was small with abnormal thymic follicles. Testes from pet/pet rats exhibited 2 patterns of
abnormal histology. Spermatogenesis was present in testes that were only slightly anomalous,
but the seminiferous tubules were reduced in diameter. In severely affected testes, most of the
seminiferous tubules showed degeneration, and interstitial tissue was increased. Plasma growth
hormone concentrations did not differ between pet/pet and normal male rats. The dwarf
phenotype of pet/pet rats was inherited as an autosomal recessive trait. These results indicate
that the pet/pet rat has a semi-lethal growth-hormone-independent dwarf phenotype that is
accompanied by thymic and testicular anomalies and low birth weight.
SUMMARY: From a closed colony of Wistar-Imamichi rats, +/+ coisogenic strain of HDH
(hypogonadism strain, normal hgn-free) derived from HGN strain, the authors developed a new
strain of rat, the petit rat (pet/pet). Most anatomical and hormonal aspects linked to the severe
dwarfism seen in the strain petit rat are described in this report showing:




Lower body weights (more apparent in adults), growth retardation may begin in utero
and is apparent at birth #
Proportional dwarfism, all organ weights were lower
Testes with smaller seminiferous tubule diameters and in severe cases seminiferous
tubules were degenerated (Sertoli cells present with w/ many vacuoles in the cytoplasm)
and spermatogenesis present rarely
Thymus very small with increased connective tissue




No skeletal anomalies except for longitudinal bone shortening
Mortality is high especially in females (survival rate 3% in females, very low birth BW,
32% in males), however pet/pet are born alive.
Inheritance of the gene is single autosomal recessive, similar in males/females
Anterior pituitary gland similar size than normal rats as well as plasma growth hormone
concentrations
In mouse, deficiency in pleomorphic adenoma gene 1 shows similar postnatal dwarf phenotype
w/o postnatal mortality and thymic anomaly.
Two other mutant rat strains show growth retardation: LDE strain (lde/lde, severe dwarf
phenotype with premature lethality, growth retardation starting after 3d of age and high
incidence of epileptic seizures) and HGN strain (hgn/hgn body growth retardation starting in the
embryonic period, but less retardation after birth than pet/pet and lde/lde).
Pet/pet rat may be a unique model for severe dwarfism and with low birth body weight.
QUESTIONS:
1. What are the 2 main characteristics of the pet/pet rat strain?
a. Normal body weight at birth and male have lower survival rate
b. Growth retardation starting in utero and high incidence of epileptic seizures
c. Severe dwarfism and low birth body weight
2. When does the growth retardation likely starts in the pet/pet rat?
a. In utero
b. At 3 d of age
c. At 10 d of age
3. Are pet/pet rats born alive? Yes or No
4. Which sex is most affected by the pet/pet mutation?
5. What does pet stands for?
ANSWERS:
1. Severe dwarfism and with low birth body weight
2. In utero
3. Yes
4. Females (3% survival rate against 32% for males, may be due to a much smaller birth
weight)
5. Petit = Small
Tsuchida et al. Phenotypic Characterization of the Komeda Miniature Rat Ishikawa, an
Animal Model of Dwarfism Caused by a Mutation in Prkg2, pp. 560-567
Domain 1, Task 3
SUMMARY: Prkg2 encodes cGMP-dependent protein kinase type II (cGKII), which stops
proliferation and starts chondrocyte differentiation. An autosomal recessively inherited mutation
in Prk2 leads to dwarfism in rats, the Komeda Miniature Rat Ishikawa (KMI), with homozygous
mutant animals attaining only 70-80% of the size of their heterozygous littermates.
There was no significant difference in organ histopathology, blood biochemistry, hematology,
and urinalysis. Relative weights of most organs/tissues in homozygous mutants were
comparable to heterozygous animals, but retroperitoneal fat was reduced. The KMI model is
considered useful for the study of human dwarfism and longitudinal bone growth and for
functional studies of cGKII.
QUESTIONS:
1. cGKII is expressed in
a. Osseous tissues only
b. Non-osseous tissues only
c. Both osseous and non-osseous tissues
d. Neither osseous nor non-osseous tissues
2. The KMI dwarfism model is caused by
a. An endocrine defect
b. A nonendocrine defect
c. Both endocrine and nonendocrine defects
d. Neither endocrine nor nonendocrine defects
3. Prkg2 deficiency leads to
a. Infertility
b. Shortened femurs, tibias, and vertebrae
c. Resistance to E. coli STa toxin
d. B & c only
e. All of the above
ANSWERS:
1. c.
2. b.
3. d.
Pig Models
Schuleri et al. The Adult Gottingen Minipig as a Model for Chronic Heart Failure After
Myocardial Infarction: Focus on Cardiovascular Imaging and Regenerative Therapies, pp.
568-579
Species: Primary (Pig)
Domain: 3
Knowledge 3: Animal Model Development
SUMMARY: The objective of this research was to develop a porcine model for chronic heart
failure (CHF) after a myocardial infarction (MI) in the adult. There is an increasing demand for
large animal models to evaluate heart failure therapies, especially in an adult animal model.
Historically, cardiac therapeutics have been evaluated in the Yorkshire breed. However,
because they were bred to grow rapidly and gain weight as farm animals, they are difficult to
evaluate cardiac therapeutic effects long term. In addition, most cardiac research must be done
when the pigs are young to avoid the rapid growth and body changes that occur versus in
humans MIs and CHF occur in adults. The Gottingen minipig was chosen as a potential model
because they do not dramatically increase in bodyweight as they grow and they have good
fertility. They were created by cross-breeding the Minnesota minipig with Vietnamese potbelly
and German Landrace pigs.
The study evaluated MI and CHF in Gottingen minipigs and Yorkshire pigs. They induced
myocardial infarctions by placing a temporary balloon occlusion in the left coronary anterior
descending artery (LAD) for 120-150 minutes, followed by reperfusion. This was confirmed
using angiography, ECG, and MRI.
The study results demonstrated that Gottingen minipigs have smaller LADs versus other
species; however their coronary artery anatomy is similar to humans. Second, the Gottingen
coronary arteries were more prone to spasm versus the Yorkshire swine. Third, mortality from
the MI did not differ significantly between the Gottingen (18%) versus the Yorkshire (17%). The
Gottingens appeared to be more resistant to arrhythmias versus the Yorkshires; however the
Yorkshires were more likely to survive the arrhythmias with cardioversion versus Gottingen.
And last, the Gottingen minipigs showed a 10% increase in body weight during the 2 month
follow-up versus the Yorkshire gained 29% in body weight during the same period.
Overall, the study outcome demonstrated the Gottingen minipig represents an adult animal
model to study MI and CHF. Similar to humans, the Gottingen minipig had transmural anterior
MI that led to left ventricular remodeling and impairment. The left ventricular end-diastolic mass
in the minipigs also remained unchanged versus an increase in the Yorkshire. Second, the
Gottingen minipig is practical to house because of its small size and ease of handling. The
study recommends the Gottenpig to be used to evaluate new heart failure therapies and devices
based on their similarity to human patients’ cardiac pathophysiology, reproducibility, and ability
to utilize imaging.
QUESTIONS:
1. T/F In Yorkshire pigs, both body weight and heart weight continue to increase in juveniles
which can confound the evaluation of new cardiac, therapeutic approaches.
2. When do Gottingen minipig boars become sexually mature? Sows?
3. T/F: The standard farm pig increases in body weight and size rapidly, becoming a variable
to evaluating cardiac function and morphology over time.
ANSWERS:
1. TRUE
2. Boars become sexually mature at 3-4 months of age and sows at 4-5 months.
3. TRUE: This is why the Gottingen minipig is more suitable to evaluating cardiac therapeutics
and devices long term where their body weight and cardiac weight are not rapidly changing.
Liu et al. Bama Miniature Pigs (Sus scrofa domestica) as a Model for Drug Evaluation for
Humans: Comparison of In Vitro Metabolism and In Vivo Pharmacokinetics of Lovastatin,
pp. 580-587
Domain 3: Research
Task 2: Advise and consult with investigators on matters related to their research
K6. characterization of animal models
Primary Species – Pig
SUMMARY: The objective of this study was to demonstrate that Bama miniature pigs are a
suitable experimental animal model for the evaluation of drugs for man. Chinese Bama
miniature pigs are genetically stable, highly inbred, small, inexpensive and share anatomical
and physiological similarities to humans. Previous studies by these authors found similarities in
drug metabolism by liver microsomes between Chinese Bama miniature pigs and humans, in
particular, human cytochrome P450 (CYP) 3A4. In the current study, Lovastatin, a prescription
drug frequently used to treat cardiovascular disease which is specifically metabolized by
CYP3A4 in humans was chosen as the model drug.
For the in vitro study, samples of liver were collected from minipigs within 5 minutes of death.
Human liver samples were obtained from 3 Chinese autopsy samples. In vitro studies showed
no discernible differences between the metabolites of lovastatin produced by minipig and
human liver microsomes. Lovastatin metabolites were identified by their characteristic UV
absorption and HPLC-mass spectrometry spectra. Since the presence of enzymes in Bama
miniature pigs similar to CYP3A4 had been previously reported, TAO (triacetyloleandomycin), a
specific inhibitor for CYP3A4 in humans was also studied in vitro. TAO inhibited the conversion
of lovastatin in the pig microsomes, but to a lesser degree than the human microsomes.
For the in vivo study, thirty, 10-12 kg, male, healthy minipigs were divided into three groups:
Group I – 8 animals to study pharmacokinetic parameters and absolute bioavailability of
lovastatin after a single oral dose of 6 mg/kg or an iv dose of 1.2 mg/kg. Group II – 16 animals
for tissue distribution (4 negative control, 4 each received a single daily oral dose of 45 mg/kg at
1-, 4-, and 24-h intervals for 15 consecutive days). Group III – 6 animals used to determine the
excretion of lovastatin in urine and feces collected for 96 h after a single oral dose of 2.4 mg/kg.
Results of these studies indicated that the time to maximum plasma concentration(T peak), and
the constants of absorption (Ka) and elimination (Ke) were also similar in Bama minipigs and
humans (human data from referenced literature). Compared with mice, rats, and dogs, the
percentage of plasma protein binding and the lovastatin hydrolysis rate in Bama minipigs were
more representative of those in humans. Tissue distribution studies indicated that the majority
of lovastatin was metabolized or excreted by the gastrointestinal tract and exhibited high
selectivity for the liver, which is also the primary site of action in humans. Finally, a high
percentage of the total dose was recovered in the feces as compared to the urine, indicating
that as in humans, fecal excretion is the main route of elimination for lovastatin in Bama
minipigs.
The authors suggest that the liver microsomes of Bama minipigs exhibit a similar substrate
specificity and activity to CYP3A4 in humans and are thus a good model of drug metabolism
when human CYP3A4 is involved. However, the CYP3A enzymes from the Bama miniature
pigs need further characterization to study interspecies differences and variations with humans.
The similarities in pharmacokinetics of lovastatin also showed potential for the Bama minipig as
a preclinical model for other cardiovascular drug classes. The need for more data comparing
toxicological pathologies and characterization and comparison of the main metabolic enzymes
in Bama miniature pigs was noted.
QUESTIONS:
1. The results of this study suggest that the liver microsomes of Bama miniature pigs exhibit a
similar activity to what human enzyme?
2. What other drug has been shown to be a highly potent inhibitor of both Bama miniature pig
and human CYP3A4 in prior studies?
ANSWERS:
1. Cytochrome P450 3A4 (CYP3A4)
2. Ketoconazole
Primate Models
Murphy et al. Can Gender Differences Be Evaluated in a Rhesus Macaque (Macaca
mulatta) Model of Focal Cerebral Ischemia?, pp. 588-596
SUMMARY: The most common type of stroke is ischemic stroke, which accounts for 87% of
stroke cases. It occurs with a greater frequency in men than in women independent of age,
even beyond the menopausal years. This indicates that the presence of female sex steroids
may not fully explain the sexual dimorphism. Gender differences may also play a role in
response to therapeutics. For example, aspirin lowered ischemic stroke risk by 24% in women
and had no effect in men. The differences between men and women could influence the
outcome of clinical trials.
Focal ischemic stroke models in NHPs involve occlusion of a single artery (i.e. middle cerebral
artery). Methods to induce MCA occlusion include vascular clipping, use of an extrinsic balloon
device or snare ligature, electrocoagulation or photocoagulation and embolization by
interventional approach. This current study is a feasibility study in which they developed a
model of transient focal cerebral ischemia in male and female rhesus macaques. They
examined the histopathologic outcomes for gender differences that maybe helpful in evaluating
future clinical trials.
Six adult rhesus macaques (3 male, 3 female) underwent 90 min reversible MCA occlusion.
They found that they could consistently produce white matter injury in both sexes. They
observed variability in injury volume comparable to that of humans. The amount of injury did not
differ between male and females in the small sample. The variability in ischemic injury may be
due to small sample size, multiple factors including age, parity status and hormonal status. The
model closely mimics ischemic stroke as observed in men and women.
QUESTIONS:
1. List the three advantages to using NHPs for ischemic stroke model.
2. List the limitations of the rodent models of MCA occlusion.
3. What measures were taken to reduce perioperative variability in this study?
ANSWERS:
1. 1) Neuroanatomy and cerebrovasculature in NHPs is highly similar to humans; 2) White
matter and gray matter is interleaved in rodents unlike in NHPs and humans; 3) NHPs show
cerebral embolism without the effect of thrombus on the ischemic territory.
2. 1) Infarcts involve both cortex and striatum; 2) white matter injury is modest or inconsistent;
3) significant differences in response to ischemia and reperfusion compared to humans and
NHPs.
3. 1) Used the same surgeon; 2) time from anesthesia induction to MCA occlusion was not
significantly different between animals; 3) Time from initiation of reperfusion and cessation
of anesthesia was not significantly different; 4) blood loss was comparable; and 5)
anesthesia protocol was consistent.
Hopper et al. Effects of Maternal and Infant Characteristics on Birth Weight and
Gestation Length in a Colony of Rhesus Macaques (Macaca mulatta), pp. 597-603
Task 4: Animal Care
Primary Species: Macaque
SUMMARY: This was a retrospective study using maternal and birth statistics from an open,
captive rhesus macaque colony to determine the effects of parity, exposure to simians retrovirus
(SRV), housing, maternal parity, and maternal birth weight on infant birth weight, viability and
gestation length. The rhesus macaque is a useful model of human female reproduction
studies because the comparative physiology is nearly identical. SRV was endemic in the
colony and data was not available to determine viremia only serologic status. Viral infection,
particularly adenovirus and immunosuppressive retroviruses are associated with low birth
weight and infant mortality in humans and NHP.
Results inconsistent with published literature in humans/rhesus: No difference in mean birth
weights between infants from SRV positive and negative mothers, no correlation between
infants and maternal birth weight, No association between exposure (positive serologic status)
and decreased viability, no correlation between infant birth weight and gestation length, Infants
with longer gestation length were more likely to be non viable, non viable infants had a higher
mean birth weight than did viable infants.
Results consistent with published literature: Infants from multiparous macaque mothers were
significantly larger, and increasing parity associated with decreased viability, high odds of death
for infants from grand multiparous mothers (6 or more), over several generations, rhesus infant
birth weights increased in the open colony.
QUESTIONS:
1. T/F: A Shapiro-Wilkes constant of 1 indicates a completely normal distribution
2. For this study how as a grand multiparous mother defined?
3. Which of the following factors may after birth weight and neonatal viability in both humans
and macaques?
a. Maternal birth weight
b. Maternal age
c. Maternal parity
d. Underlying maternal disease
e. All of the above
ANSWERS:
1. T
2. 6 or more
3. e
CASE STUDY
Perry et al. Dietary supplementation with S-Adenysl Methionine was Associated with
Protracted Reduction of Seizures in a Line of Transgenic Mice, pp. 604-606
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and Conditions
Task 2. Control spontaneous or unintended disease or condition K6. Pharmacology with
emphasis on drugs used to treat spontaneous or induced disease Primary Species: Mouse
SUMMARY: The ApoE4 allele is associated with an increased risk of Alzheimer disease
(presence of 1 or more alleles) and increased psychotic symptoms in humans. Transgenic mice
lacking murine ApoE and expressing human ApoE4 (ApoE4 mice) are models for studying the
impact of ApoE on age-related cognitive decline and Alzheimer disease. ApoE4 mice display
increased aggression as compared to normal mice, mice lacking murine ApoE and mice lacking
murine ApoE and expressing other human ApoE alleles. S-adenosyl methionine (SAM) is a
nutriceutical shown to reduce aggressive behavior in ApoE4 mice, restore neurotransmitter
balance, increase working memory and modulate neuronal activity.
The objective of this study was to determine if SAM supplementation could provide functional
rescue of a shipment of ApoE4 mice that displayed uncharacteristically violent spontaneous and
handling-induced convulsions that persisted for at least 1 month thereby precluding intended
use (standard maze trials). Ten (n=10) ApoE mice on a C57Bl/6 background from Taconic
Farms were visually monitored for the occurrence (without quantitation) of seizure activity in 24
hour increments over the duration of 1 week. Mice (n=9) then received diet supplemented with1
of 2 commercially available SAM products (100mg/kg diet) for 1 week. SAM supplementation
was later withdrawn and all mice received a diet without SAM during weeks 3 and 4. During
weeks 5-8, mice were monitored for cognitive impairment by using a standard Y maze test over
5 minute intervals.
A ~50% reduction in seizure activity was observed during the first week of SAM
supplementation and seizures did not recur for 6 weeks after withdrawal of SAM. Further, mice
performed as well during maze testing as did mice of the same genetic background not
expressing the transgene and ApoE4 mice from prior studies that never exhibited seizures.
The single mouse (n=1) withheld from SAM supplementation in week 2 was observed to have
86%, 29% and 57% reductions in seizure activity during weeks 1, 2 and 3, respectively.
QUESTIONS:
1. True or False. S-adenosyl methionine (SAM) is a nutriceutical shown to reduce psychotic
symptoms in ApoE4 mice.
2. Assuming all other factors are the same, which mouse displays more aggression?
a. Mouse expressing murine ApoE and lacking human ApoE4
b. Mouse expressing human ApoE4 and lacking murine ApoE
c. Mouse lacking murine ApoE and lacking human ApoE4
d. Mouse lacking murine ApoE and expressing any human ApoE alleles
3. True or False. S-adenosyl methionine (SAM) alleviated seizure activity in an uncharacteristic
cohort of ApoE4 mice.
ANSWERS:
1. False. S-adenosyl methionine (SAM) is a nutriceutical shown to reduce aggressive behavior
in ApoE4 mice.
2. B. An ApoE4 mouse lacks murine ApoE and expresses human ApoE4
3. True