2009 - Volume 36 - Issue 3

229-240
A Critical Appraisal of Carbon Monoxide Uptake Measurements for the Follow-up of Experimental Respiratory Diseases in the Laboratory Mouse
by Jean-Belt Habyarimana, Thierry Flandre, Pedro Faisca, Nicolas Antoine-Moussiaux & Daniel Desmecht

Adaptation of double-chamber plethysmography to the laboratory mouse was recently proven to yield stable and reliable pulmonary function values. This approach to investigation of the respiratory function in mice owes its success to its decisive advantages in terms of non-invasiveness, practical implementation and generation of quantitative flow/volume measurements and undisputed airway resistance calculation. When implemented to screen the resistance/susceptibility patterns to pathogens displayed by a panel of mouse inbred strains, the resistance value obtained was indeed able to detect tracheobronchic inflammation and to quantify its severity. However, extension of the pathological process to the most distal parts of the respiratory system did not result in further alteration of resistance, suggesting that its value reflects constraints acting on airflow in the airways rather than pathologic processes located in the more distal parts of the lungs. In this context, we hypothesized that a more exhaustive functional picture could be obtained, still non-invasively, by combining double-chamber plethysmography with carbon monoxide (CO) uptake measurements. The feasibility of CO-uptake measurements in mice was demonstrated and the conditions under which reproducibility can be maximized were defined. Differences linked to strain, somatic growth, and sex were examined and discussed, and reference values in growing male and female conscious and healthy BALB/cBy, SJL/J, C57BL/6, C3H/HeN, DBA/2 and 129/Sv mice were given. Finally, double-chamber plethysmography and CO-uptake values were proven to be exquisitely complementary in assessing and dissecting the functional impact of Sendai virus pneumonia in the laboratory mouse.

243-249
Significant Improvement in Survival of Tabby Jimpy Mutant Mice by Providing Folded-paper Nest Boxes
by Tohru Kimura, Mitsuko Kubota & Hiroyuki Watanabe

There is little scientific evidence that environmental enrichment meets the physiological needs for laboratory animals. The purpose of this study was to evaluate whether the provision of nest boxes improved the lifespan of Tabby jimpy (Ta-jp) mutant mice carrying a lethal gene. Nest boxes tested in this study were small folded-paper trapezoid-shaped houses. The Nest box group was reared in cages with the nest boxes and the Control group was raised in only standard cages. Weaning results and survival rates in Ta-jp mice were compared between both groups. By the weaning stage, all of the Ta-jp mice survived in the Nest box group. There was a significant difference in weaning rates between both groups. The body weight of weanlings demonstrated a significant difference between both groups. The survival analysis indicated that the Nest box group (29.9 days) significantly had a longer lifespan than the Control group (25.7 days). The Nest box group developed few abnormal jumping behaviours. The nest boxes served as shelters from environmental stimuli. In conclusion, we confirmed that folded-paper nest boxes had a beneficial effect on weaning rates of Ta-jp mice. Our results revealed that there was significant improvement in survival of Ta-jp mice using the nest boxes.

253-261
Assessment of Body Composition of Rats by Bioimpedance Spectroscopy: Validation Against Dual-Energy X-Ray Absorptiometry
by LC Ward & KJ Battersby

Fat-free mass (FFM) and fat mass (FM) were determined in male and female out-bred Wistar strain rats by both dual-energy X-ray absorptiometry (DXA) and by bioimpedance spectroscopy (BIS). Data obtained by both methods were highly correlated and exhibited a small (4%) bias for FFM, with relatively small limits of agreement (approximately ± 10%), but differed to a much larger degree for FM (14 to 27% bias), with wide limits of agreement (± 50%). Inter-method correction equations are provided to allow conversion of data from one method to another, eliminating bias, but not altering the limits of agreement. Since both methods exhibited a high degree of precision of measurement, it is suggested that the poor agreement for measurement of fat mass is a reflection that fat mass is an indirectly-derived value, which includes unavoidable propagation of prediction errors associated with the primary measures. Both BIS and DXA provide rapid, minimally invasive and, in the case of BIS, portable techniques for body composition analysis. Their use for estimation of FFM may be recommended, but, for prediction of fat mass, exercise of caution would be prudent.

265-269
Morphometry of the Glomerular Tuft During Normal Postnatal Growth in Female Rats. Effects of Age, Location of Glomeruli and Methods of Obtaining and Processing the Renal Tissue
by Georgina P. Ossani, Nora I. Castiglia, María F. Martino, Silvia L. Fariña, Ana M. Uceda & Alberto J. Monserrat

Total glomerular filtration rate depends upon the structural integrity, number and area of glomeruli. Counting the number of glomeruli as well as measuring glomerular area or volume is nowadays widely employed in human and experimental biology. Although functional and morphological differences between superficial and juxtamedullary glomeruli have been described, this is not always taken into account in morphometric studies. The aim of this paper was to study in female rats the area of juxtamedullary glomeruli and the area of superficial glomeruli as well as the influence of the age of rats and the methods of obtaining and processing the renal tissue. The glomerular area was larger in kidneys collected in liquid nitrogen and smaller in those fixed in Bouin (See Materials and Methods); 4% formaldehyde. These results were obtained in superficial and in juxtamedullary glomeruli (F=29.60, p<0.0001). Glomerular area increased with time in superficial as well as in juxtamedullary glomeruli (F=9.21, p<0.0001). The area of the juxtamedullary glomeruli was significantly higher (F=329.29, p<0.0001) than that of superficial glomeruli, independently of the different methods of obtaining and processing renal tissue, or the age of the animals. The results indicate that glomerular area is greater in juxtamedullary glomeruli, increases with age, and that different methods of obtaining and processing the renal tissue do have influence on glomerular size.

271-281
Alternatives for Analgesiometric Tests in Animals: The Feasibility to Reduce Discomfort by Anaesthesia
by Mathieu G. Sommers, Jan van Egmond, Jan G. Veening, Kris C. Vissers & Merel Ritskes-Hoitinga

Animal pain and nociception studies have greatly contributed to our understanding of acute and chronic pain processing and thereby contributed to the reduction of suffering of patients in pain. In classic analgesiometric tests in conscious animals, animal suffering is inevitable as pain behaviour is the primary outcome. Therefore, the feasibility of refining analgesiometric tests by anaesthesia is reviewed. The influence on analgesiometric tests of different anaesthetics is described. Other objective primary outcome measures than pain behaviour, including quantification of neural activation with c-fos and functional MRI (fMRI), are suggested to reduce animal discomfort for pain testing. In conclusion, reflex analgesiometric tests may be refined by choosing the right anaesthetics and alternative outcome measures such as c-fos or fMRI. Complex, higher order pain behaviour testing still requires conscious animals and can currently not be refined by the use of anaesthetics.

283-293
Induction of Strategies and Habits in Rats Through two Behavioural T-maze Paradigms
by Anette Moustgaard, Jann Hau & Nanna Marie Lind

Two different behavioural paradigms in T-maze were developed with the aim to induce patterns of behavioural persistence in rats. These new procedures were based not on traditional asymmetric reinforcement methodology, but on a modified Krechevsky paradigm using olfactory stimuli, where we found rats spontaneously developed patterns of behavioural persistence – or behavioural “strategies” - with less than 1% probability of these occurring by chance. Rats predominantly developed spatial position (win-stay) strategies, but also spatial alternation (win-shift) strategies, olfactory strategies, and, to a minor degree, olfactory alternation strategies. Spatial alternation behaviour was significantly more frequent during early (first 40 trials) than during late testing. Position bias (spatial win-stay behaviour) increased gradually with the number of trials and was significantly increased in late (over 120 trials) compared to early testing. In the second paradigm, habits were induced in rats using a forced-choice procedure. After 100 forced-choice trials of running to the same side in a T- or Y-maze, the rats showed a significant propensity for this side when allowed to choose freely, compared to the situation in which only one forced-choice trial had been performed. Ten forced trials were not sufficient to induce this habit. Both paradigms may be useful for modelling aspects of human habit formation and for behavioural neuroscience experiments.