Research reportFischer (F-344) rats have different morphology, sensorimotor and locomotor abilities compared to Lewis, Long–Evans, Sprague–Dawley and Wistar rats
Introduction
Rats have been used for experimental purposes since at least the mid 1800’s [16]. Since these early experiments, and the domestication of the wild Norway rat (Rattus norvegicus), many strains of rats have been developed through intensive breeding programs throughout the world. Breeding and husbandry programs for the laboratory rat in North America were primarily brought about by the Wistar Institute of Philadelphia, USA [16]. Breeding programs have been developed based on the needs of various researchers and institutes.
Many strains of rats have been propagated using inbreeding or out-breeding strategies. A particular strain of animal is considered inbred if it was created following more than 20 generations of sibling or parent–offspring matings (inbred animals are considered homozygous but homozygosity may not be truly present until after 40 sibling matings; [8], [9]). Outbred strains, however, are strains that are maintained to have a considerable amount of genetic heterozygosity [12]. Confirmation of genetic heterozygosity within outbred strains can be verified using a variety of genetic screening tests [12]. Regardless, some of the more popular strains of rats originally developed in the early 1900’s are still in use today (for historical highlights of breeding practices see [16]).
Animal husbandry practices generally select and enhance particular traits of a given species of animal. There is no better example of this than the result of breeding practices of domesticated dogs. Purebred dogs have been bred for selected characteristics for hundreds of years [37]. Consequently, highly breed-specific morphological and sensorimotor characteristics have been developed. For example, dogs can range in size from 1 to 100 kg [34], and particular breeds appear to be more sensitive to painful stimuli than others [10]. Although the laboratory rat has been bred for a shorter period of time [16], these animals can propagate quickly and are intensely bred by many established institutes and animal suppliers. Like many domesticated species of animals, laboratory rats have developed many strain specific characteristics, although they may not be as obvious as in domestic dogs. Because the laboratory rat is a popular animal used for studying sensory and motor behaviours, and particular anatomical characteristics may contribute to these behaviours, we have set out to determine whether differences in morphology and sensory and/or motor behaviours exist between various strains of rats. We hypothesized that differences exist with regard to specific morphological, sensory, and motor abilities of different strains of rats. Specifically, based on grossly observing morphological differences between different strains of rats, we hypothesized that the Fischer strain is least similar amongst the strains of rats examined. By using morphologic, endpoint, kinematic and kinetic measurements, we have described the morphologic, sensory, and motor differences that exist between five strains of rats. We found that Fischer rats tend to be most dissimilar from the other strains we examined. These differences have implications for investigations involving sensorimotor behavioural manifestations of neurologic disease such as spinal cord injury. We discuss our findings in light of their significance for those studying sensory and motor behaviour in the neurosciences.
Section snippets
Subjects
Eleven female rats of each of five different age-matched strains were obtained from Charles River Laboratories, Canada (Quebec, Canada). Animals were approximately 4 months of age and considered to be mature. The strains used included: Fischer (CDF(F-344)/CrlBR); Lewis (LEW/CrlBR); Long–Evans (Crl:(LE)BR); Sprague–Dawley (Crl:CD (SD)IGS BR) and Wistar (Crl:(WI)BR). Fischer and Lewis are inbred albino strains; Long–Evans (pigmented), Sprague–Dawley (albino) and Wistar (albino) rats are outbred
Morphometric analysis
There were several differences noted between long-bone lengths of different strains of rats (Fig. 4). Wistar and Sprague–Dawley rats had longer femurs than Fischer (P<0.01), Lewis (P<0.01) and Long–Evans (P<0.01) rats. Wistar rats also had longer tibiae when compared to Fischer (P<0.001), Lewis (P<0.01) and Long–Evans (P<0.01); there were no statistical differences between the tibiae of Sprague–Dawley, Long–Evans, and Lewis rats. Fischer rats had significantly shorter tibiae than Sprague–Dawley
Discussion
Several recent papers have examined strain differences in rats specifically pertaining to visual acuity, reaching, and spatial performance [11], [24], [35]. This, however, is one of the first studies which describes simultaneously the morphologic, sensorimotor and locomotor differences between different age-matched strains of rats. We found that Fischer rats are much different in their morphology, sensory and locomotor abilities compared to the other four strains examined. Fischer rats are
Acknowledgements
The authors thank Dr. Valerie Verge and Tracy Wilson for providing the von Frey filaments and pedal withdrawal apparatus for this study. Funding was provided by a grant from Rick Hansen (Saskatchewan) Neurotrauma Fund to GDM and a WCVM Interprovincial Fellowship to AAW.
References (37)
- et al.
A grasp-related deficit in tactile discrimination following dorsal column lesion in the rat
Brain Res. Bull.
(2001) - et al.
Fischer 344 and wistar rats differ in anxiety and habituation but not in water maze performance
Neurobiol. Learn. Mem.
(2002) - et al.
Different effects of diazepam in Fischer rats and two stocks of Wistar rats in tests of anxiety
Pharmacol. Biochem. Behav.
(2001) - et al.
Chronic pain after clip-compression injury of the rat spinal cord
Exp. Neurol.
(2002) - et al.
Cortical and subcortical lesions impair skilled walking in the ladder rung walking test: a new task to evaluate fore- and hindlimb stepping, placing, and co-ordination
J. Neurosci. Methods
(2002) - et al.
The “staircase test”: a measure of independent forelimb reaching and grasping abilities in rats
J. Neurosci. Methods
(1991) - et al.
Differences in acquisition and full performance in skilled forelimb use as measured by the ‘staircase test’ in five rat strains
Behav. Brain Res.
(1998) - et al.
Paw withdrawal threshold in the von Frey hair test is influenced by the surface on which the rat stands
J. Neurosci. Methods
(1999) - et al.
Variation in visual acuity within pigmented and albino rat strains
Behav. Brain Res.
(2002) - et al.
Functional recovery of paraplegic rats and motor axon regeneration in their spinal cords by olfactory ensheathing glia
Neuron
(2000)
Strain differences in fear-motivated behavior of rats
Pharmacol. Biochem. Behav.
CNS plasticity and assessment of forelimb sensorimotor outcome in unilateral rat models of stroke, cortical ablation, parkinsonism and spinal cord injury
Neuropharmacology
Ladder beam and camera video recording system for evaluating forelimb and hindlimb deficits after sensorimotor cortex injury in rats
J. Neurosci. Methods
Graded unilateral cervical spinal cord injury in the rat: evaluation of forelimb recovery and histological effects
Behav. Brain Res.
Long–Evans rats have a larger cortical topographic representation of movement than Fischer 344 rats: a microstimulation study of motor cortex in naive and skilled reaching-trained rats
Brain Res. Bull.
The evolution of domestic pets and companion animals
Vet. Clin. North Am. Small Anim. Pract.
A sensitive and reliable locomotor rating scale for open field testing in rats
J. Neurotrauma.
Systemically administered interleukin-10 reduces tumor necrosis factor-alpha production and significantly improves functional recovery following traumatic spinal cord injury in rats
J. Neurotrauma
Cited by (51)
Transient strain differences in an operant delayed non-match to position task
2023, Behavioural ProcessesRefining rodent models of spinal cord injury
2020, Experimental NeurologySystemic epothilone D improves hindlimb function after spinal cord contusion injury in rats
2018, Experimental NeurologyCitation Excerpt :Species and strain differences may also account for different outcomes between the current and previous studies. Rat strains and even sub-strains differ in terms of functional recovery and tissue sparing after SCI (Kjell and Olson, 2016; Mills et al., 2001; Webb et al., 2003). Given our data that Epo D treatment results in different outcomes depending upon the lesion severity it can be hypothesized that with the same contusion force in rats ranging in a 10–30% difference in animal weight (in the present study inbred Fischer 344 rats weighing around 160–180 g were used, whereas in the previous study outbred Sprague Dawley rats weighing around 200–250 g were used) may affect injury severity and thus may result in a differential response to treatment.
Aversive properties of negative incentive shifts in Fischer 344 and Lewis rats
2017, Behavioural Brain ResearchRecovery of sensorimotor function following sciatic nerve injury across multiple rat strains
2017, Journal of Neuroscience MethodsComparative outcome measures in peripheral regeneration studies
2017, Experimental Neurology