Contemporary Topics in Laboratory Animal Medicine
Volume
42 (3)
Does
cage size affect heart rate and blood pressure of male rats at rest or after
procedures that induce stress-like responses? Contemporary Topics 42 (3): 08.
The objective of the study was to compare, under various conditions, the
cardiovascular function and home-cage behavior of male Sprague-Dawley rats
housed with 3 other rats in cages that provided either 920 or 1250 cm2 of total
floor space. The Guide recommends that 200-500g rats be given between 190-450
cm2 of floor space per animal. Previous studies had shown that 1) individually
housed animals had either comparable or higher serum corticosterone levels than
group housed animals and 2) group-housed rats given about 175cm2 of floor
space/rat had significantly elevated corticosterone levels over less crowded
animals. These previous studies were not consistent in the strain of rat used
or many other variables. Therefore, it is difficult to compare results. This
study examined food and water intakes, body weight, and the cardiovascular and
behavioral responses of male rats housed in groups of 4 in cages with 1250cm2
or 920 cm2 total floor space. 920 cm2 represents approximately 60% of the space
recommended by The Guide. Heart rate and blood pressures measurements were
collected by use of surgically implanted radiotelemetry transmitters. Animal
behavior within its cage was also observed. Animals were subjected to
potentially stressful procedures including routine cage change, restraint and
SQ injection, restraint and tail-vein injection, witnessing a simulated
decapitation, witnessing decapitations, witnessing decapitation and necropsies,
witnessing tail-vein injection, exposure to odors of urine and feces from stressed
rats, exposure to odors of urine and feces from stressed rats, exposure to the
odor of dried rat blood, a simulated cage change, transport to another room and
SQ injection, and being handled and weighed. Significant differences noted
between groups included the following: - At the completion of the study, rats
housed in the smaller cage had gained more weight - Undisturbed nocturnal HR,
MAP, and activity were reduced in smaller cages - Cage change induced a
prolonged increase in heart rate in large cages - Witnessing simulated or
actual decapitation or decapitation and necropsy increased the sleeping
behavior of animals in larger cages and decreased the behavior in smaller cages
The authors concluded that housing rats with approximately 60% of the space
recommended by The Guide did not induce crowding stress which they defined as
conditions that significantly elevate heart rate and blood pressure. Therefore,
they suggest that housing rats in smaller cages may be less stressful than
housing them in larger cages. However, the authors do state that it is
difficult to accurately evaluate the stress level in an animal by examining a
small number of physiologic measurements.
1. In this study, rats housed in smaller cages gained (more/less) weight than
those housed in larger cages?
2. Undisturbed nocturnal HR, MAP, and activity were (reduced/increased) in
large cages?
3. Witnessing simulated or actual decapitation or decapitation and necropsy
(increased/decreased) the sleeping behavior of animals in larger cages and
(increased/decreased) the behavior in smaller cages?
1. more
2. reduced
3. increased in larger cages; decreased in smaller cages
Use of
cyanoacrylate gel as a substitute for dental cement in intracerebroventricular
cannulations in rats. Contemporary Topics
42 (3): 13.
Summary
The purpose of the study was to determine whether cyanoacrylate gel (CAG) was
suitable for use as a substitute for dental cement during brain implant surgery
of rats. In brief, the implant device is anchored to the skull with several
screws and a headcap is built up to cover the screws to further secure the
implant in place. The devices serve as microdialysis probes, cannulae for drug
infusions, or electrodes. Prior to this study, the headcap was made by
combining 2 types of dental cement - zinc polycarboxylate (white cement) and
methyl methacrylate (pink cement). The white cement contains a solvent that has
been associated with increased incidence of surgical of surgical problems. Due
to this noted problem, the authors evaluated CAG for adverse effects as well as
investigation of the degree of reduction in surgical time when compared with
current dental cement technique.
The results indicate that the use of CAG significantly reduced surgical time
for the preparation of ICV implants in rats and had no adverse effects on the
postoperative period when compared to the dental cement technique. Also, the
advantages of the CAG technique was reduction of the number of screws used for
the implant, resulting in less trauma to the skull, and reduction of the size
of the headcap. In addition, the transparent nature of the gel may allow early
visual detection of inflammation and infection under the headcap. In this
study, clinical signs suggestive of the presence of infection were not observed
in the CAG technique or the dental cement method.
T/F When compared to the traditional dental cement technique, the use of
cyanoacrylate gel in ICV cannulations in rats is associated with a
significantly reduced surgical time and an absence of adverse effects.
True
A
novel approach for documentation and evaluation of activity patterns in owl
monkeys during development of environmental enrichment program. Contemporary
Topics 42 (3): 17.
In developing an enrichment plan for primates, it is challenging to determine
to evaluate and document the effectiveness of a program. This becomes even more
challenging in nocturnal primates. This paper discusses the assessment of an
enrichment program with owl monkeys (Aotus lemurinus griseimembra). Cages were
supplied with cardboard core rolls, crumpled white newsprint paper, a 10 cm
diameter plastic spool and a yellow plastic rope chain. PVC tubes were also
present which allowed movement between upper and lower perches. The cage also
contained a box used to mimic tree hollows, which are used for sleeping sites.
Videotaping was accomplished with the use of infrarred lights and an infrared
-sensitive camera.Videotaping began at sundown (17:30) and continued
uninterrupted for 6 hours. This period was divided into 7 intervals. Tapes were
analyzed using the software product Hindsight. Passive activities (perch
sitting, perch sleeping, box usage and floor sitting) were compared to active
behaviors (perch pacing, perch circling, somersaulting, bar climbing and floor
walking), eating/drinking and manipulation of objects.
Duration and frequency for combined passive activities exceeded all other
categories of behaviors. Active behaviors increased to a maximum at interval
four (20:30) and was inversely related to the trend for passive activity. The
overall trend for combined eating and drinking activities showed a pattern of
peaks and troughs over the 7 time intervals. Most of the enrichment objects
were ignored by the monkeys.
The data supports that dusk is the environmental stimulus that synchronizes the
circadian cycle of the owl monkey to begin its daily activities. It also
documents that the enrichment objects used in the current program were
minimally used by the monkeys.
1. Name the order, suborder, superfamily, family, genus and species of the
common owl monkey.
2. Give two other common names of owl monkeys.
3. What is the best known role for owl monkeys in biomedical research?
1. Order Primates, Suborder Anthropoidea, Superfamily Ceboidea, Family Cebidae,
Genus Aotus, Species trivirgatus. Note: A. lemurinus griseimembra are a
separate natural group distinguished by karyotype, color and pelage patterns.
A. lemurinum is a primitive gray-neck species.
2. Two other common names of owl monkeys are night monkeys and douroucouli.
3. Best known role of owl monkeys in research is their role in developing
antimalarial drugs. They are also known for immunology and vision research.
(All info from ACLAM book: Nonhuman primates in Biomedical Research - Biology
and Management)
Development
of renal function tests for measurement of urine concentrating ability, urine
acidification, and glomerular filtration rate in female cynomolgus monkeys.
Contemporary Topics 42 (3): 22.
This article discusses development of more sensitive in vivo tests of renal
function in 2-3 year old female cynos (Macaca fasicularis). This species is
often used in pharmacology and toxicology testing in which renal toxicity may
be a potential effect of study compounds therefore it would be ideal to have
more sensitive measures of renal function. Current methods (i.e.. renal
enzymes, blood urea nitrogen (BUN) and creatinine) are less sensitive as they
do not detect subtle renal changes therefore making early detection of renal
dysfunction difficult. Proposed tests are that of urine concentrating ability,
urine acidification ability and glomerular filtration rate (GFR) which are
currently used in humans to assess early stage renal dysfunction. Urine
concentrating ability was determined by changes in specific gravity and osmolality
after SC administration of desmopressin acetate (0.3-0.4 ug/kg). Baseline
specific gravity: 1.005 - 1.031 and baseline urine osmolality: 182 - 1081
mOsm/kg. Administration of desmopressin resulted in increased specific gravity
(range 1.019 - 1.043) and osmolality (range 432 - 1298 mOsm/kg) indicating
urine concentration within 4 hours. Urine acidification ability was determined
by comparing change in urine pH and osmolality in response to nasogastric
administration of 0.1 g/kg of ammonium chloride. Baseline pH: 7.64 with a range
of 6.4 - 8.2. Administration of ammonium chloride resulted in decreased urine
pH (4.76 with a range of 4.1 - 7.1) indicating urine acidification within 6-7
hours. GFR was determined by measuring urine and blood creatinine, osmolality,
Na, K and Cl in response to nasogastric administration of 0.45% NaCl (20
ml/kg). Results demonstrated osmolality clearance from 0.03-0.07 ml/kg/min,
creatinine clearance from 1.84-2.53 ml/kg/min, fractional excretion of Na from
0.17-0.77%, fractional excretion of K from 4.46-19.87%, fractional excretion of
Cl from 0.25-1.08%. Formulas were used to determine creatinine clearance rate
(CCR), osmolality clearance rate (OCR) and fractional excretion of electrolytes
(FEE). The formulas are as follows: CCR(ml/kg/min) = [urine volume(ml)] x
[urine creatinine (mg/dl)] / [collection time (min)] x [serum creatinine
(mg/dl) / urine creatinine (mg/dl)] x [body weight (kg)] OCR(ml/kg/min) =
[urine volume(ml)] x [urine osmolality (mOsm/dl)] / [collection time (min)] x
[serum osmolality (mOsm/dl) / urine osmolality (mOsm/dl)] x [body weight (kg)]
FEE(%) = [urine electrolyte (mmol/L) / serum electrolyte (mmol/L)] / [serum
creatinine (mg/dl) / urine creatinine (mg/dl)] x 100% Overall, these tests have
proven to be specific and sensitive diagnostic tools in detecting subtle renal
dysfunction and can also be used successfully for collection of experimental
data.
1. What is another method to test urine concentrating ability?
2. T or F: The renal structure of macaques is characterized by a poorly
developed inner medullary zone and have a single renal medulla and papilla.
3. Which of the following statements is false:
A. Creatinine is eliminated almost entirely by glomerular filtration and its
clearance provides an approximation of GFR.
B. The desert rat (Psammomys obesus) which has mostly short-looped nephrons is
able to produce highly concentrated urine which is related to its outer
medullary organization.
C. Serum creatinine and BUN concentrations are sensitive measures of glomerular
filtration rate.
1. Water Deprivation Test. However, subcutaneous desmopressin acetate has
proven to be a more specific and sensitive test than the water deprivation test
when determining urinary concentrating ability. It also has the advantage of
being less labor intensive, specifically evaluates renal tubular function,
quickly concentrates urine with 4 hours (vs. up to 48 hours) and prevents
welfare issues of depriving animals water.
2. True. Note that this is true for most nonhuman primates except the spider
monkey (Ateles geoffroyi). Also note that humans have a multipapillate kidney.
3. C is false. Creatinine may be a sensitive measure of GFR but BUN is not.
There are many non-renal variables that can alter BUN such as diet, glucocorticoid
therapy, or tetracycline therapy which may increase BUN while anabolic steroids
and liver disease may decrease BUN. Generally there has to be marked renal
dysfunction to see a renal change in BUN.
Monitoring lab animal feeding by using subcutaneous
microchip transponders: validation of use with group-housed rats. Contemporary
Topics 42 (3): 26.
This article discusses whether accurate and reliable animal identification and feeding behavior can be established in group housed rats with a commercially available microchip transponder and scanner system for the purpose of designing lab animal housing in orbiting international space stations.
Male rat triads were used in each of the 4 experiments; one albino, onesolid dark and one black-hooded or black and white. The frequency modulation(FM) microchip transponder from BioMedic Data Systems was implanted subcutaneously (SC) on the dorsal midline directly behind the ears of the rats with the coil end either in line with the shoulders or in line with the ears. The rats were housed on wire bottom cages and did not have bedding so that video confirmation of animal activity could be used to compare with the data collected with the BioMedic instrumentation system. There were 3 food tunnels in each cage where the food was distributed at the end of the tunnel using a triggered feed-pellet feeding system. Only one tunnel was instrumented with a ring scanner.
The results indicated that the BioMedic system did not misidentify any of the rats at any time. However there were system errors noted when
determining feeding. That is, pellets were known to be delivered but no
scanner activity was noted when a rat had taken the pellet. Reasons for these errors were not determined but it was believed that the rats may have moved faster than what could be recorded as the system requires the transponder to be in range for approximately 1 sec to be accurately recorded. There may have also been some radio frequency interference which in the future could be avoided using Faraday cage-type radio-frequency shielding. It was believed that this system can be optimized by placing the transponders SC with the coil end in line with ears (more anterior) and taking the precautions of using radio frequency shielded cages and delaying food release after triggered. Overall, this system appears to be very accurate and precise with a 96%-99% detection.
QUESTIONS:
1. Very basic question here: What is the genus and species of the rat?
2. From the following list choose the only non-albino outbred rat:
A. Wistar
B. Sprague-Dawley
C. Long-Evans
D. Holtzman
3. Which of the following is true:
A. Rats cannot vomit
B. Lack a foramen of Magendie
C. Pulmonary vein wall contains cardiac striated muscle fibers
D. A and B
E. All of the above
ANSWERS:
1. Rattus norvegicus2. C. Long-Evans is a "hooded" rat
3. E
Mortality
rates of interventional and surgical procedures performed in domestic juvenile
farm pigs and Yucatan mini-pigs. Contemporary Topics 42 (3): 29.
Authors collected a retrospective analysis of mortality data in cardiovascular
catheter and surgical studies performed in domestic Juvenile swine (DJS) and
Yucatan mini-swine (YMS). A total of 529 animals in 35 studies were included in
the analysis, which included six study categories: coronary stenting (Stent)
and percutaneous transluminal coronary angioplasty (PTCA) alone; Stent and PTCA
in combination with ionizing radiation (Stent/Rad, PTCA/Rad); myocardial
ischemia (ISCH); and three non-ISCH surgical procedures grouped under
"other surgeries" (Other Surg). The highest mortality rate occurred
in the ISCH group (29.7% ± 2.2%). Mortality of the Stent/Rad animals (26.1% ±
6.3%) was significantly higher than those in the Stent and PTCA groups (12.1% ±
3.1% and 7.9% ± 3.2%; P < 0.05 for both). Similarly, mortality in the
ISCH group was significantly higher than that in the Stent, PTCA, or Other Surg
animals (29.7% ± 2.2% versus 12.1% ± 3.1%, 7.9% ± 3.2%, and 3.0% ± 3.0%,
respectively; P < 0.05 for all comparisons). Authors did not observe
differences between YMS and DJS. Authors concluded that radiation therapy used
in combination with stenting increases the mortality rate of this
catheter-based procedure. Animals subjected to ISCH or a transcatheter
procedure in combination with ionizing radiation should be monitored closely
during the perioperative period to prevent unacceptably high mortality rates.
Take home message:
1)Swine models become common in cardiovascular research such as postangioplasty
restenosis, in-stent restenosis, atherosclerosis and myocardial ischemia.
2) Drug coated stents constitute the latest technological advance in the
prevention of in-stent restenosis.
3) Creatinine kinase and troponin are markers that can be used to assess the
myocardial injury.
4) Ticlopidine and acetylsalicylic acids can be used as an antithrombotic
agents in cardiovascular studies.
None provided
Cardiac
catheterization technique in a closed-chest murine model. Contemporary Topics
42 (3): 34.
Murine studies have been a mainstay of analyzing the effects of genetic
manipulation to evaluate cardiac phenotype. Reliable and efficient methods to
evaluate cardiac phenotype are necessary and need to be established. However,
cardiac catheterization techniques for obtaining such data have not been
standardized. The goal of this study was to establish a simple and less
invasive technique for cardiac catheterization in a closed-chest mice model.
C57BL/6J mice 17 to 35 gram body weight were anesthetized with ketamine and
xylazine.
A mid-line incision was made to expose the common, internal and external
arteries. These three vessels were isolated in a triangle bordered by the
cervical muscles medially, submandibular muscles cranially and the
sterno-cleido-mastoid-like muscle caudally. The right thyroid was removed to
have a clear field. Careful blunt dissection through the muscle covering the
floor of this triangle exposed the common carotid, vagus nerve and jugular
vein. The digastric muscle was divided bluntly to expose the external and
internal carotid. The external carotid artery and a branch of the tracheal
artery as well as the cranial end of the internal carotid artery were ligated.
The distal end of the common carotid artery was occluded with a microvessel
clip. Then a 26-gauge needle was used to start the incision, which was enlarged
with microscissors. A 1.4-French conductance catheter was advanced to the
microvessel clip where double ties of 8-0 monofilament were placed around the
common carotid artery and then the microvessel microclip was removed, advancing
the catheter into the left ventricle. The entire procedure was performed using
an operating microscope and echocardiaphic means to guide the catheter into
position and away from the ventricular wall. The conductance catheter was
calibrated with a mercury manometer. This entire procedure after some practice
takes approximately 20 minutes. The major problem with this technique was
ventricle perforation, which produced cardiac tamponade.
One great advantage of this procedure is that it avoids thoracotomy and
mechanical ventilation which are required in an open chest model and often
cause unphysiologic hemodynamics (immeasurable fluid loss). This technique also
enables assessments of cardiac physiology by combining echocardiography for
various hemodynamic assessments which is not available in open-chest model.
M-mode echocardiogram
combined with simultaneous LVP can give better understanding of cardiac
physiology such as measurement of diastolic stiffness constant to assess myocardial
compliance and assessment of fractional shortening against end-systolic stress
relationship to detail the LV ejection performance. This catheterization was
also combined with atrial cardiac pacing or intravenous administration via the
right external jugular vein of agents such as dobutamine and esmolol to assess
cardiac function response.
1. The two primary technical aids used to perfect this procedure were
___________ and ____________?
2. The primary problem with the catheterization procedure is______________?
3.Closed -chest surgery avoids ___________ and _____________?
1. Operating microscope and echocardiography
2. Left ventricular perforation
3 Thoracotomy and mechanical ventilation
A new
surgical technique for perfusion of the epididymal fat pad in situ in rats.
Contemporary Topics 42 (3): 39.
This article describes a novel procedure for isolating and perfusing in situ
the epididymal fat pad in male rats. This cancer research laboratory wanted to
evaluate the relationship between the neoplastic processes and fatty acid
metabolism that occurs in adipose tissue. These processes include membrane
synthesis, protein metabolism, signal transduction, and transcriptional
regulation. Recent studies from this laboratory have shown that melatonin,
omega-3 fatty acids, and conjugated linoleic acid suppress total fatty acid
(TFA) in tumor tissue and inguinal fat depots by means of an inhibitory
G-protein-coupled melatonin receptor-mediated mechanism. The investigators
state that increased lipolysis and hyperlipidemia, which are known
characteristics of cancer, cachexia, and obesity-related diseases, are involved
directly with several types of white adipose tissue (WAT). Epididymal WAT
functions as a protective insulator for the epididymis and testis however, it
major functi! on is lipid transport and energy production. Therefore, the
investigations thought that this unique tissue site was ideal for their
research looking at the physiological actions of melatonin and omega-3 fatty
acid metabolism. Experimental Procedure: Please familiarize yourself with the
excellent figures that describe the surgical technique for perfusion of the rat
epididymal fat pad on pages 40 and 41. Figure 1: This diagram illustrates the
anatomy of the epidydymal fat pad, its arterial and venous circulation, and its
relationship to the male rat reproductive structures. Figure 2: This figure
highlights the presentation of the epididymal fat pad artery and vein that will
be cannulated for perfusion. Figures 3 and 4 demonstrate how the epididymal fat
pad artery and vein is cannulated and describes the perfusion sequence. Donor
arterial blood perfusate is pumped through the system at a rat of 35 ”l/min
(normal flow rate) through the fat pad artery while venous blood effluent is
collected for analysis. The laboratory use an artificial lung and perfusion
pump system previously described in references 9 and 11. This model allows for
the successful evaluation of total fatty acid metabolism and ! transport in
this tissue in vivo over time.
1. T or F: Increased lipolysis and
hyperlipidemia are a characteristic for cancer, cachexia, and obesity-related
disease.
2. T or F: The primary function of
white adipose tissue surrounding the epididymis is lipid transport and energy
production.
T, T
Failed air supply to individually ventilated caging system
causes acute hypoxia and mortality of rats. Contemporary Topics 42 (3): 44.
BACKGROUND: In a colony of Lewis rats, more than 30% unexpected mortality was observed in pups of weaning age kept with their dams. The rats were housed in a cubicle in individually ventilated cages. Rats in adjacent cubicles that were not individually ventilated showed no morbidity or mortality. Necropsies failed to show evidence of infectious disease and serology of blood from 2 dams showed them to be free of antibodies to clinically significant rat pathogens. Because there were ongoing renovation projects in other parts of the building, the unexpected mortality was suspected to be the results of a transient, undocumented power outage causing failure of the IVC system.
METHODS: 8 cages of long evans rat dams and pups housed in IVC cages
were subjected to a controlled power failure.
RESULTS:
* Within 60 minutes all pups were immobile and prone, and 2 of 8 adult females were prostrate and hyperventilating.
* Oxygen concentrations in the air within the IVC were <10%.
* The temperature rose 3.1 +/- 0.6 degrees.
* CO2 levels exceeded the 5% threshold measurable by the multi-gas monitor.
* When power was restored at 90 minutes, oxygen levels returned to >20% and temp dropped within 4 minutes.
CONCLUSIONS: Loss of power to IVC housing rats is potentially a life-threatening condition requiring an immediate response and affirms the consideration of emergency (backup) electrical power where these systems are used.
QUESTIONS:
1. What are the advantages of individually ventilated caging systems?
2. Which of the following did not occur within 60 minutes after the power was lost to IVC caging housing rat dams and pups
a. Oxygen concentrations fell below 10%
b. Temperature was significantly elevated
c. CO2 levels were significantly elevated
d. Rats had no clinically apparent signs of distress
3. T/F Loss of power to IVC caging housing rats is not potentially life threatening.
ANSWERS:
1. The advantages of using IVC are that they offer greater control of the microenvironment, they save labor, and they minimize allergens in environment.
2. d. All pups and 2 dams were recumbent.
3. False
Serum
clinical chemistry and hematology reference values in outbred stocks of albino
mice from three commonly used vendors and two inbred strains of albino mice.
Contemporary Topics 42 (3): 46.
-Authors collected serum clinical chemistries and CBS from outbred albinos
(males and females) from commonly used, large, commercial vendors to provide
current data on a variety of strains as reference material.
-Health status was based on exhaustive serological panels, respiratory and
gastrointestinal bacterial cultures and diagnostics for ecto and endo
parasites. One strain outbred HSD:NSA (CF-1) animals were positive for
Helicobacter hepaticus as the only finding.
-Blood was collect from mice 14-18 weeks old after 4h fasts by asphyxiation
with CO2 followed by cardiocentesis.
-Authors felt this update of data was warranted because a. reference data for
specific strains is difficult to locate b. references are from aged sources c.
genetic drift d. modern clinical pathology techniques and instrumentation have
evolved over time
-Trends observed: a. Creatinine levels for inbred and outbred strains were in a
tight range (0.1-0.4 mg/dl) b. Creatine phosphokinase had the highest
variability c. Red cell dependent values were less variable than white blood
cell parameters d. Platelet values exhibited the broadest ranges and largest
values for standard deviation
-Trends should be enhance interpretation. For example; clinical values outside
of the given range for a parameter with high variability may not be as
indicative of a clinically important change. (opposite holds true as well)
None provided
T,
radial arms, and Barnes maze. Contemporary Topics 42 (3): 53.
BLUF (Bottom Line Up Front) - This article summarizes the use of three types of
behavioral paradigms designed to test learning and memory in rodents, particularly
rats and mice. These include the T maze, radial arm maze and the Barnes Maze,
three tests that have reduced animal welfare concerns in relation to those
raised by use of another test, the Morris Water Maze. Types of memory to be
tested, and the paradigms used for such testing include a) working memory
(memory useful to the animal while performing the current task T maze, radial
arm maze), b) test reference memory (memory useful to the animal during any
exposure to the task T maze and radial-arm maze), and c) spatial memory (Barnes
maze). Habituation: All of these behavioral learning/memory paradigms require
various types of environmental habituation prior to actual data collection.
Among the elements requiring habituation are: handling, the food-based
reinforcer/reward, food or water restriction (if part of the training methods),
and the equipment itself. T maze: this is a Tshaped maze with a stem and two
arms extending in opposite directions, perpendicular to the stem. Trials
consist of placement in the stem and receipt of a food reward when the correct
arm is entered. Often the arm with the food reward is altered (Win/Shift
strategy). Alternative uses include keeping the reward in the same arm
(Win/Stay strategy), or use of negative reinforcers (e.g., mild foot shock)
such that the reward is avoidance of the negative reinforcer. Radial arm maze:
This is a maze with a central platform and 8, 12 or 16 arms. Guillotine doors
control access to each maze arm. The most basic use involves provision of a food
reward at the end of each arm, with the time recorded for the animal to obtain
all the rewards. This version tests working memory. This is a variation of the
win/shift search strategy. Variations include only baiting certain arms, making
this a test of reference memory. Barnes maze: The Barnes maze is a
dry-landmodification of the Morris water maze, designed to be compatible with
natural behavioral tendencies of rats and mice, i.e., the tendency to find
shelter in dark, enclosed areas. The apparatus is placed in a room with
prominent environmental cues placed on the walls, similar to the Morris water
maze. The subject animal is placed on a central disc, around the perimeter of
which are 18 (for rats) or 40 (for mice) holes. Underneath one of the holes is a
tube leading to a dark box or drawer. Often a mild noxious stimulus (bright
light, fan, loud tone) is trained on the disk to encourage the rodent to search
for escape. Use of this paradigm does not require food or water deprivation.
Animal welfare concerns: Among the concerns are the use of food or water
restriction. Often arguments are made that dietary restriction (to ~85% of
free-feeding body weight) has been shown to be associated with longer life and
less spontaneous pathology in rodents. Some rodent species, e.g., guinea pigs,
exhibit aberrant behavioral changes associated with the required habituation
and training procedures, making use of these paradigms unsuitable for these
species. Finally, use of common apparatus, which often are difficult to properly
disinfect, may lead to exposure to and spread of infectious agents from one
group of animals to another.
1) List important factors to which to habituate experimental animals prior to
actual data acquisition in behavioral paradigms.
2) The T, Radial Arm and Barnes mazes are experimental behavioral paradigms to
test what?
3) A behavioral paradigm in which the subject is required to remember where the
reinforcer was the last time and choose an alternate place uses what kind of
strategy?
a. Win/stay b. Win/win
c. Win/shift d. Win/lose
4) Contrast the Barnes maze with the Morris water maze
5) List possible animal welfare concerns with regard to behavioral testing
1) Handling, food-based reinforcers, food restriction, equipment
2) Memory and learning
3) c. win/shift
4) Both test spatial memory, and take place in an apparatus placed within a
large room in which special cues are placed on the walls. In the water maze,
the animal is placed in opaque water in a tank, and must swim to find a hidden
platform on which to stop and rest. The Barnes maze is a dry landtechnique, in
which the animal is encouraged to find refuge from a mild negative reinforcer
by finding among multiple holes the one hole through which it can enter a
tunnel and escape to an enclosed chamber.
5) Food or water restriction, use of negative reinforcers, unnecessarily
stressful conditions that can be modified with behavior more naturally suited
to a species, possible exposure to pathogens through use of a common apparatus
by different animal groups.