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The influence of X-radiography and anaesthesia on weight gain and skull growth in the rat
Arch
oral Bid.
Vol. 18, pp. 141-143, 1973.Pergamon Press. Printed in Great Britain.
THE INFLUENCE OF X-RADIOGRAPHY AND ANAESTHESIA ON WEIGHT GAIN AND SKULL GROWTH IN THE RAT H.
VILMANN
Department of Anatomy, Royal Dental College, Copenhagen, Denmark, and Department of Orthodontics, University of Nymegen, the Netherlands Summary-Normal weight gain of rats subjected to frequent anaesthesia and X-radiography was slightly depressed. However, no influence of these mild stresses was found on the growth of the skull.
IT IS well-known that gain in body weight of rats is influenced by the introduction of several sorts of mild stress (for instance WIDDOWSONand KENNEDY, 1962; ROUBICEK,PAHNISHand TAYLOR,1964). It seems likely that such conditions also influence the growth of the skull (DIAMOND,ROSENZWEIG and KRECH, 1965 ; STEEGMANNand PLATNER,1968; JEFFERYS,1969). Longitudinal roentgenocephalometric studies of rats make use of frequent anaesthesia and X-ray exposures (VILMANN,1968, 1972). These manipulations might introduce mild stress. As these studies compared the quantitative data with qualitative data from studies using a vital staining technique, evaluation of the magnitude of the error introduced by the stresses referred to is appropriate. The period studied ran from 7 to 150 days of age. The study was based on comparisons of weight and skull measurements of two groups of rats. The experimental group consisted of 24 male and 25 female rats. These rats originated from 9 mothers. At 9 age-levels between 7 and 150 days, the rats from this group were weighed, anaesthetized and X-radiographed. The control group consisted of the same number of rats. They originated from 7 mothers. These rats were weighed at the same 9 age-levels as the other group. At 150 days, they were radiographed. All rats were kept under identical conditions to minimize the influence of environmental differences. The equipment and the measuring method used are described in VILMANN(1968, 1972). For a representative evaluation of size and shape of the skull, measurements were made of length of 4 bones, i.e. nasal bone, parietal bone, basisphenoid bone and cribriform plate of ethmoid bone, of length of 2 distances representing cranial units, i.e. neurocranial length and height, and of 2 angles, i.e. nasal angle and cribriform angle. Figure 1 shows the mean weights for the groups. The mean weights of the control groups are systematically higher than those of the experimental groups. 141
142
H.
\‘IL.MANN
253
100
50
71421304b
60
90
120
150
Days
FIG. 1. Mean weight curves from 7 to 150 days of age of the two groups of rats. - - - - - - - - - experimental group ($). . . experimental group ($2). control
group (8 and 0).
As regards the measurements of size and shape of the skull, no significant differences were found between the groups. The results seem to confirm the general view that small changes in environmental conditions may influence the weight gain in the rat. It is, however, obvious that the changes inducedin the present study are insignificant compared to changes introduced by other sorts of changes in environmental conditions. DIAMOND et al. (1965), for instance, describe in 2 studies differences in weight of about 10 per cent between male rats raised in enriched conditions and rats raised under non-enriched conditions. The percentage difference between the groups in the present study at a comparable age level is only about 5 per cent. The relative insignificance of the differences in weight between the two groups is also reflected in the lack of evidence of differences in skull parameters. Other studies have, indeed, been able to demonstrate such differences between control rats and rats subjected to changes in environment such as isolation (DIAMOND et al.) and cold stress (STEEGMANN and PLATNER, 1968). Thus, it may be concluded that the stress condition introduced by the use of frequent ether anaesthesia and X-ray exposures is small and that the error introduced in longitudinal roentgenocephalometric studies by this means is probably negligible. ROum&-Le gain normal du poids des rats sujets a des anesthesies et radiographies freqrentes Btait legitrement abaisst. Cependant on n’a pas trouve d’influence de ces stress mod&es sur la croissance du crane. Zusammeofasaung-Normaler Gewichtsgewinn von Ratten, die h&dig einer Anlsthesie oder Riintgenbestrahlung ausgesetzt waren, war etwas niedriger. Es wurde aber kein Einfluss dieser milden Beanspruchung auf das Wachstum des Schldels festgestellt.
INFLUENCE
OF X-RADIOGRAPHY AND ANAESTHESIA ON RATS
143
REFERENCES DIAMOND,M. C., ROSENZWEIG,M. R. and KRECH, D. 1965. Relationships between body weight and skull development in rats raised in enriched and impoverished conditions. J. exp. Zool. 160, 29-36. JEFFERYS,J. F. 1969. Growth pattern and environment. Ph.D. Thesis, University of Nymegen, the Netherlands. ROUBICEK,C. B., PAHNISH,0. F. and TAYLQR,R. L. 1964. The growth curve of the rat in relation to adult size and temperature. Growth 28, 233-41. STEEGMANN. A. T. and PLATNPR.W, S. 1968. Exoerimental cold modification of crania-facial morphology. Am. J.phys. Anthrhp. 28, 17-30. VILMANN,H. 1968. The growth of the parietal bone in the albino rat studied by roentgenocephalometry and vital staining. Archs oral Biol. 13, 887-901. VILMANN,H. 1972. The growth of the cranial vault in the albino rat. Archs oral Biol. 17, 399-414. WIDDOWSON,E. M. and KENNEDY,G. L. 1962. Rate of growth, mature weight, and life-span. Proc. R. Sot. B. 156,96-108.
oral Bid.
Vol. 18, pp. 141-143, 1973.Pergamon Press. Printed in Great Britain.
THE INFLUENCE OF X-RADIOGRAPHY AND ANAESTHESIA ON WEIGHT GAIN AND SKULL GROWTH IN THE RAT H.
VILMANN
Department of Anatomy, Royal Dental College, Copenhagen, Denmark, and Department of Orthodontics, University of Nymegen, the Netherlands Summary-Normal weight gain of rats subjected to frequent anaesthesia and X-radiography was slightly depressed. However, no influence of these mild stresses was found on the growth of the skull.
IT IS well-known that gain in body weight of rats is influenced by the introduction of several sorts of mild stress (for instance WIDDOWSONand KENNEDY, 1962; ROUBICEK,PAHNISHand TAYLOR,1964). It seems likely that such conditions also influence the growth of the skull (DIAMOND,ROSENZWEIG and KRECH, 1965 ; STEEGMANNand PLATNER,1968; JEFFERYS,1969). Longitudinal roentgenocephalometric studies of rats make use of frequent anaesthesia and X-ray exposures (VILMANN,1968, 1972). These manipulations might introduce mild stress. As these studies compared the quantitative data with qualitative data from studies using a vital staining technique, evaluation of the magnitude of the error introduced by the stresses referred to is appropriate. The period studied ran from 7 to 150 days of age. The study was based on comparisons of weight and skull measurements of two groups of rats. The experimental group consisted of 24 male and 25 female rats. These rats originated from 9 mothers. At 9 age-levels between 7 and 150 days, the rats from this group were weighed, anaesthetized and X-radiographed. The control group consisted of the same number of rats. They originated from 7 mothers. These rats were weighed at the same 9 age-levels as the other group. At 150 days, they were radiographed. All rats were kept under identical conditions to minimize the influence of environmental differences. The equipment and the measuring method used are described in VILMANN(1968, 1972). For a representative evaluation of size and shape of the skull, measurements were made of length of 4 bones, i.e. nasal bone, parietal bone, basisphenoid bone and cribriform plate of ethmoid bone, of length of 2 distances representing cranial units, i.e. neurocranial length and height, and of 2 angles, i.e. nasal angle and cribriform angle. Figure 1 shows the mean weights for the groups. The mean weights of the control groups are systematically higher than those of the experimental groups. 141
142
H.
\‘IL.MANN
253
100
50
71421304b
60
90
120
150
Days
FIG. 1. Mean weight curves from 7 to 150 days of age of the two groups of rats. - - - - - - - - - experimental group ($). . . experimental group ($2). control
group (8 and 0).
As regards the measurements of size and shape of the skull, no significant differences were found between the groups. The results seem to confirm the general view that small changes in environmental conditions may influence the weight gain in the rat. It is, however, obvious that the changes inducedin the present study are insignificant compared to changes introduced by other sorts of changes in environmental conditions. DIAMOND et al. (1965), for instance, describe in 2 studies differences in weight of about 10 per cent between male rats raised in enriched conditions and rats raised under non-enriched conditions. The percentage difference between the groups in the present study at a comparable age level is only about 5 per cent. The relative insignificance of the differences in weight between the two groups is also reflected in the lack of evidence of differences in skull parameters. Other studies have, indeed, been able to demonstrate such differences between control rats and rats subjected to changes in environment such as isolation (DIAMOND et al.) and cold stress (STEEGMANN and PLATNER, 1968). Thus, it may be concluded that the stress condition introduced by the use of frequent ether anaesthesia and X-ray exposures is small and that the error introduced in longitudinal roentgenocephalometric studies by this means is probably negligible. ROum&-Le gain normal du poids des rats sujets a des anesthesies et radiographies freqrentes Btait legitrement abaisst. Cependant on n’a pas trouve d’influence de ces stress mod&es sur la croissance du crane. Zusammeofasaung-Normaler Gewichtsgewinn von Ratten, die h&dig einer Anlsthesie oder Riintgenbestrahlung ausgesetzt waren, war etwas niedriger. Es wurde aber kein Einfluss dieser milden Beanspruchung auf das Wachstum des Schldels festgestellt.
INFLUENCE
OF X-RADIOGRAPHY AND ANAESTHESIA ON RATS
143
REFERENCES DIAMOND,M. C., ROSENZWEIG,M. R. and KRECH, D. 1965. Relationships between body weight and skull development in rats raised in enriched and impoverished conditions. J. exp. Zool. 160, 29-36. JEFFERYS,J. F. 1969. Growth pattern and environment. Ph.D. Thesis, University of Nymegen, the Netherlands. ROUBICEK,C. B., PAHNISH,0. F. and TAYLQR,R. L. 1964. The growth curve of the rat in relation to adult size and temperature. Growth 28, 233-41. STEEGMANN. A. T. and PLATNPR.W, S. 1968. Exoerimental cold modification of crania-facial morphology. Am. J.phys. Anthrhp. 28, 17-30. VILMANN,H. 1968. The growth of the parietal bone in the albino rat studied by roentgenocephalometry and vital staining. Archs oral Biol. 13, 887-901. VILMANN,H. 1972. The growth of the cranial vault in the albino rat. Archs oral Biol. 17, 399-414. WIDDOWSON,E. M. and KENNEDY,G. L. 1962. Rate of growth, mature weight, and life-span. Proc. R. Sot. B. 156,96-108.