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Food deprivation effects on the running-wheel activity of wild and domestic Norway rats
Behauioural Processes, 1 (1976) o Elsevier Scientific Publishing
191-196 Company,
191 Amsterdam
-
Printed
in The Netherlands
Short Communication FOOD DEPRIVATION EFFECTS ON THE RUNNING-WHEEL OF WILD AND DOMESTIC NORWAY RATS
EDWARD
0. PRICE*
Zoology Department, State University of New and Forestry, Syracuse, NY 13210 (U.S.A.) (Received
ACTIVITY
20 March
York,
College
of Environmental
Science
1976)
ABSTRACT Price, E.O., domestic
1976. Food deprivation effects Norway rats. Behau. Processes,
on the running-wheel 1: 191-196.
activity
of wild and
Increases in activity typically accompany the food deprivation of Norway rats housed in activity wheels. The hypothesis that domestication has reduced the intensity of this response to food deprivation was tested by comparing the wheel-running scores of adult male wild (laboratory-reared) and domestic Norway rats when food-deprived and satiated. Wild rats were more active in the wheels than domestic subjects, irrespective of the presence or absence of food. However, the proportional increase in wheel-running when food-deprived was the same for both stocks. It is hypothesized that the process of domestication has had little influence on the wheel-running response of rats to food deprivation.
INTRODUCTION
Increases in activity during food deprivation have been frequently reported for the common laboratory rat, Rattus noruegicus (e.g. Finger, 1951; Hall, 1956; Bolles, 1963; Draper, 1967). However, attempts to explain this phenomenon have been generally unsatisfactory, due to the multi-dimensional nature of activity and the large number of variables (e.g., the schedule of deprivation, the type of measuring device, the immediate environment, prior experiences of the organism, its sex, age and species and the interaction of these variables) that may influence the data obtained (see reviews by Bindra, 1961; Baumeister et al., 1964; Gross, 1968). Cornish and Mrosovsky (1965) and Campbell et al. (1966) have compared the changes in activity of several species of mammals in response to food deprivation when housed in activity wheels and activity cages. Species differences * Present address: 95616 (U.S.A.)
Department
of Animal
Science,
University
of California,
Davis,
Calif.,
192
were interpreted in terms of ancestral requirements for survival in their native habitats. One could apply this same line of reasoning to hypothesize differences between animal populations that have typically had to search for food and those that have evolved under conditions where food was always readily available. If increased activity in response to food shortage has been selected for in nature one might predict some loss in the intensity of this response after many generations of breeding in captivity where food is generally supplied ad libitum. Thus, one could hypothesize that wild animals would exhibit more dramatic changes in activity when fasted than their domestic counterparts. Richter and Rice (1954) sought to examine this hypothesis using wild and domestic stocks of the Norway rat. A greater increase in wheel-running was found for wild rats than their domestic counterparts in response to total food deprivation (142 and 32 percent, respectively). The authors postulated that genetic changes accompanying the domestication process could explain the relatively lower increase in wheel-running of fasted domestic rats. However, an unspecified number of their wild subjects had been trapped in the field. The finding of Draper (1967) that early fasting experience can have a cumulative effect on the activity of the rat in response to food deprivation suggests that early experience (prior to being brought into the laboratory) could have contributed to the enhanced wheel-running scores of the fasted wild rats in Richter and Rice’s study. A second study (Kurcz, 1961) likewise compared the changes in activity of wild and domestic Norway rats to total food deprivation. Whereas the length of the daily activity period did not change for the wild rats, a marked increase in time active was noted for the domestic subjects in response to 48 h of food deprivation. However, the intensity of activity was not measured in this study and, again, the wild rat subjects had been trapped in the field. The following study examines the hypothesis that domestication has reduced the response of the Norway rat to total food deprivation. Both wild and domestic subjects were born and reared in the laboratory under identical conditions. Activity wheels were used to assess the response to fasting because running-wheel activity has been found most sensitive to the effects of food deprivation (Weasner et al., 1960; Treichler and Hall, 1962). METHODS
Ten male wild Norway rats were born and reared in the laboratory to 9 mated pairs of field-trapped wild rats obtained from a landfill near Syracuse, New York. Ten male domestic Norway rats were reared by 5 mated pairs of SpragueDawley stock originally obtained from Huntington Farms, West Conshohocken, Pa. Ages of wild and domestic subjects at the start of testing averaged 236 (range: 203-276) and 175 (range: 157-193) days, respectively. Body weights at the start of testing averaged 326 g (range: 267-404) and 423 g (range: 315-532) respectively, for wild and domestic males. All subjects were maintained in homosexual groups of two or three rats in
193
35.6 X 35.6 X 17.8 cm metal cages from weaning (25*1 days) until testing. “Charles River Rodent Diet” and water were provided ad libitum during this period. Subjects were transferred to 35.6 cm diameter “Wahmann” activity wheels to which 15.2 X 25.4 X 12.7 cm wire living cages were attached. Water was provided ad libitum during the 32-day test period. Food was provided ad libitum for all subjects on days l-15, 18-25, and 28-32. All subjects were food-deprived on days 16 and 17 but only 4 wild and 4 domestic rats were fasted on days 26 and 27, the remaining subjects serving as controls. The total number of wheel revolutions was recorded daily between 15.00 and 17.00 h from cyclometers attached to the wheels. Activity wheels were housed in a 3.1 X 7.3 X 2.5 m room on a 14:lO 1ight:dark cycle with light commencing at 07.00 h. Temperature was controlled between 20 and 22°C. Changes in wheel-running activity due to food deprivation were measured relative to the mean daily wheel-running scores of individuals for the five days preceding and following deprivation (days combined). RESULTS
A comparison
TABLE
of mean pre- and post-deprivation
wheel-running
scores (days
I
Mean daily wheel-running scores when satiated and food deprived Deprivation
period
1 (days
(wheel revolutions)
16 and 17)
Pre- and post-depreviation (days 11-15 and 18-22) fF24 h food deprivation (day 16) Mean percent increase in wheel-running* 24-48 h food deprivation (day 17) Mean percent increase in wheel-running* ______.~ Deprivation period 2-(days 26 and 27) Experimental subjects: pre- and postdeprivation (days 21-25 and 28-32) Experimental subjects: food deprivation (days 26 and 27) Mean percent increase in wheel-running* Non-deprived controls (days 21-25 and 28-32) Non-deprived controls (days 26 and 27) Mean percent change in wheel-running* * Relative
--
of wild and domestic
Wild
Domestic
1620 2080 75% 3707 227%
381 521 60% 814 232%
263
419
518 127%
530 194%
2430 2714 +7%
to mean daily pre- and post-deprivation
408 398 -12%
score.
Norway
rats
194
11-15 and 18-22 combined) revealed that wild rats are significantly more active than their domestic counterparts (t = 2.07, df = 9, P < 0.05; see Table I). Relative to these base-line values a significant increase in wheel-running scores was obtained during the first 24 h of food deprivation (day 16) for wild rats (t = 3.00, df = 9, P < 0.01) and a similar tendency was noted for domestic subjects (t = 1.72, df = 9, P < 0.10). The increase in activity during the second day of continuous food deprivation (day 17) was more than twice as great as base-line levels for both stocks (wild: t = 3.56, df = 9, P < 0.005; domestic: t = 4.25, df = 9, P < 0.005). Wheel-running scores were significantly greater during 24-48 h of food deprivation (day 17) than during the first 24 h of food deprivation (day 16) for both wild (t = 3.30; df = 9, P < 0.005) and domestic (t = 3.95, df = 9, P < 0.005) subjects. The absolute increase in wheel-running scores (relative to base-line levels) during the first 24 h of food deprivation was greater for wild than domestic rats (t = 1.84, df = 9, P < 0.05). However, the relative (proportional) change did not differ between the two strains (t = 0.30, df = 9). The absolute increase in wheel-running during the second 24 h of food deprivation (day 17) was also greater for wild than domestic rats (t = 2.78, df = 9,P < 0.025). Again, however, stocks did not differ in regard to relative changes in activity (t = 0.05, df = 9). During the second period of deprivation (days 26 and 27) the changes in wheel-running of the eight fasted animals were similar to the changes observed during the first deprivation period (days 16 and 17). Both wild and domestic control groups exhibited non-significant changes in activity on days 26 and 27 (mean score of twoday period) relative to the mean base-line scores obtained on days 21-25 and 28-32 (wild: t = 1.24, df = 5; domestic: t = 0.34, df = 5). DISCUSSION
The results of the present study reveal that although adult male wild Norway rats are normally more active in running wheels than their domestic counterparts both stocks show the same proportional increase in wheel-running in response to total food deprivation. This result would suggest that the intensity of selection for this response has not been significantly altered during the domestication process. This hypothesis is intuitively acceptable considering that the direct or indirect behavioral responses to physiological deficits may be just as important for survival in the laboratory environment as in the animal’s natural habitat. For example, artificial selection for rapid growth and large body size in the laboratory rat (Donaldson, 1924) may have strengthened the association between physiological deficits and increased activity, the only difference being the distance wild and domestic rats must normally travel and possibly the energy expended to satisfy these physiological requirements. The results of the present study do not rule out the possibility that early experience in terms of differential fasting experience may have an important effect on the magnitude of the response to food deprivation (Draper, 1967).
195
Huck and Price (1975) have demonstrated that early experience has a greater impact on the open-field behavior of wild rats than their domestic counterparts. Could early fasting experience have a greater effect on the subsequent wheel-running responses of food-deprived wild rats than similarly-treated domestic rats? The mean percent increase in wheel-running during the second day of total food deprivation was more than three times greater than that during the first day of deprivation for both wild and domestic subjects. Finger (1951) working with laboratory rats likewise found a sharp increase in activity on the second and third days of deprivation. Richter and Rice (1954) found that food-deprived wild and domestic rats reached peaks in wheel-running some 2.2-2.4 days after food was withheld. The subjects used in the present study showed less wheel-running than the wild and domestic rats used by Richter and Rice regardless of food availability. In addition the latter investigators found no difference between base-line activity levels of the two stocks. One or both of these differences could be accounted for by the very young age of the subjects used by Richter and Rice (< 100 days as opposed to about 200 days of age in the present study), acknowledging the fact that Finger (1951) and others have demonstrated that wheel-running decreases with age in domestic rats. Of course, the differences could be due, in part, to the different gene pools from which the subjects were derived. Domestic subjects used in the present study were both younger and heavier than the wild rats. This relationship constitutes a compromise in that groups of wild and domestic rats matched by age will differ in body weight and vice versa (Donaldson, 1924). Since it is believed that domestic Norway rats mature at a faster rate than wild rats (Donaldson, 1924) the younger domestic rats used in the present study may more closely approximate the maturational state of the wild rats at the time of testing than if the two groups had been matched by chronological age. The relatively low base-line wheel-running scores of the wild rats fooddeprived during the second deprivation period (Table I) is believed to be coincidental to selecting the two subjects exhibiting the greatest relative increase and the two subjects showing the least relative change in wheel-running in response to deprivation on test days 16 and 17. One of the two high scoring wild rats exhibited an unexplained sudden drop in wheel-running on the second day of deprivation (day 27) thus, accounting for the relatively low “mean percent increase in wheel-running” score for the experimental wild rats in the second deprivation period. The small number of rats deprived on days 26 and 27 and the individual variability obtained, precluded statistical analysis of these data. The present investigation has shown that domestication has not appreciably changed the effect of fasting on the activity of the naive male Norway rat. Further study is needed to determine whether a genotype-environment interaction exists in regard to early fasting experience.
196
ACKNOWLEDGEMENT
This investigation was supported by Grant MH21467-01 from the National Institutes of Mental Health.
REFERENCES
*
Baumeister, A., Hawkins, W.F. and Cromwell, R.T., 1964. Need states and activity level. Psychol. Bull., 61: 438-453. Bindra, D., 1961. Components of general activity and the analysis of behavior. Psychol. Rev., 68: 205-215. Bolles, R.C., 1963. Effect of food deprivation upon the rat’s behavior in its home cage. J. Comp. Physiol. Psychol., 56: 456-460. Campbell, B.A., Smith, N.F., Misanin, J.R. and Jaynes, J., 1966. Species differences in activity during hunger and thirst. J. Comp. Physiol. Psychol., 61: 123-127. Cornish, E.R. and Mrosovsky, N., 1965. Activity during food deprivation and satiation of six species of rodent. Anim. Behav., 13: 242-248. Donaldson, H.H., 1924. The rat. Data and reference tables for the albino rat and the Norway rat. Mem. Wistar Inst. Anat. Biol., Philadelphia, No. 6, pp. l-458. Draper, W.A., 1967. A behavioural study of the home-cage activity of the white rat. Behaviour, 28: 280-306. Finger, F.W., 1951. The effect of food deprivation and subsequent satiation upon general activity in the rat. J. Comp. Physiol. Psychol., 44: 557-564. Gross, C.G., 1968. General activity. In: L. Weiskrantz (Editor), Analysis of Behavioral Change. Harper & Row, New York, pp. 91-106. Hall, J.F., 1956. The relationship between external stimulation, food deprivation and activity. J. Comp. Physiol. Psychol., 49: 339-341. Huck, U.W. and Price, E.O., 1975. Differential effects of environmental enrichment on the open field behavior of wild and domestic Norway rats. J. Comp. Physiol. Psychol., 89: 892-898. Kurcz, M., 1961. A comparative study of the spontaneous activity of the white rat and the brown or wharf rat. Acta Biol., 11: 271-283. Richter, C.P. and Rice, K.K., 1954. Comparison of the effects produced by fasting on gross bodily activity of wild and domesticated Norway rats. Am. J. Physiol., 179: 305-308. Treichler, F.R. and Hall, J.F., 1962. The relationship between deprivation weight loss and several measures of activity. J. Comp. Physiol. Psychol., 55: 346-349. Weasner, M.H., Finger, F.W. and Reid, L.S., 1960. Activity changes under food deprivation as a function of recording device. J. Comp. Physiol. Psychol., 53: 470-474.
191-196 Company,
191 Amsterdam
-
Printed
in The Netherlands
Short Communication FOOD DEPRIVATION EFFECTS ON THE RUNNING-WHEEL OF WILD AND DOMESTIC NORWAY RATS
EDWARD
0. PRICE*
Zoology Department, State University of New and Forestry, Syracuse, NY 13210 (U.S.A.) (Received
ACTIVITY
20 March
York,
College
of Environmental
Science
1976)
ABSTRACT Price, E.O., domestic
1976. Food deprivation effects Norway rats. Behau. Processes,
on the running-wheel 1: 191-196.
activity
of wild and
Increases in activity typically accompany the food deprivation of Norway rats housed in activity wheels. The hypothesis that domestication has reduced the intensity of this response to food deprivation was tested by comparing the wheel-running scores of adult male wild (laboratory-reared) and domestic Norway rats when food-deprived and satiated. Wild rats were more active in the wheels than domestic subjects, irrespective of the presence or absence of food. However, the proportional increase in wheel-running when food-deprived was the same for both stocks. It is hypothesized that the process of domestication has had little influence on the wheel-running response of rats to food deprivation.
INTRODUCTION
Increases in activity during food deprivation have been frequently reported for the common laboratory rat, Rattus noruegicus (e.g. Finger, 1951; Hall, 1956; Bolles, 1963; Draper, 1967). However, attempts to explain this phenomenon have been generally unsatisfactory, due to the multi-dimensional nature of activity and the large number of variables (e.g., the schedule of deprivation, the type of measuring device, the immediate environment, prior experiences of the organism, its sex, age and species and the interaction of these variables) that may influence the data obtained (see reviews by Bindra, 1961; Baumeister et al., 1964; Gross, 1968). Cornish and Mrosovsky (1965) and Campbell et al. (1966) have compared the changes in activity of several species of mammals in response to food deprivation when housed in activity wheels and activity cages. Species differences * Present address: 95616 (U.S.A.)
Department
of Animal
Science,
University
of California,
Davis,
Calif.,
192
were interpreted in terms of ancestral requirements for survival in their native habitats. One could apply this same line of reasoning to hypothesize differences between animal populations that have typically had to search for food and those that have evolved under conditions where food was always readily available. If increased activity in response to food shortage has been selected for in nature one might predict some loss in the intensity of this response after many generations of breeding in captivity where food is generally supplied ad libitum. Thus, one could hypothesize that wild animals would exhibit more dramatic changes in activity when fasted than their domestic counterparts. Richter and Rice (1954) sought to examine this hypothesis using wild and domestic stocks of the Norway rat. A greater increase in wheel-running was found for wild rats than their domestic counterparts in response to total food deprivation (142 and 32 percent, respectively). The authors postulated that genetic changes accompanying the domestication process could explain the relatively lower increase in wheel-running of fasted domestic rats. However, an unspecified number of their wild subjects had been trapped in the field. The finding of Draper (1967) that early fasting experience can have a cumulative effect on the activity of the rat in response to food deprivation suggests that early experience (prior to being brought into the laboratory) could have contributed to the enhanced wheel-running scores of the fasted wild rats in Richter and Rice’s study. A second study (Kurcz, 1961) likewise compared the changes in activity of wild and domestic Norway rats to total food deprivation. Whereas the length of the daily activity period did not change for the wild rats, a marked increase in time active was noted for the domestic subjects in response to 48 h of food deprivation. However, the intensity of activity was not measured in this study and, again, the wild rat subjects had been trapped in the field. The following study examines the hypothesis that domestication has reduced the response of the Norway rat to total food deprivation. Both wild and domestic subjects were born and reared in the laboratory under identical conditions. Activity wheels were used to assess the response to fasting because running-wheel activity has been found most sensitive to the effects of food deprivation (Weasner et al., 1960; Treichler and Hall, 1962). METHODS
Ten male wild Norway rats were born and reared in the laboratory to 9 mated pairs of field-trapped wild rats obtained from a landfill near Syracuse, New York. Ten male domestic Norway rats were reared by 5 mated pairs of SpragueDawley stock originally obtained from Huntington Farms, West Conshohocken, Pa. Ages of wild and domestic subjects at the start of testing averaged 236 (range: 203-276) and 175 (range: 157-193) days, respectively. Body weights at the start of testing averaged 326 g (range: 267-404) and 423 g (range: 315-532) respectively, for wild and domestic males. All subjects were maintained in homosexual groups of two or three rats in
193
35.6 X 35.6 X 17.8 cm metal cages from weaning (25*1 days) until testing. “Charles River Rodent Diet” and water were provided ad libitum during this period. Subjects were transferred to 35.6 cm diameter “Wahmann” activity wheels to which 15.2 X 25.4 X 12.7 cm wire living cages were attached. Water was provided ad libitum during the 32-day test period. Food was provided ad libitum for all subjects on days l-15, 18-25, and 28-32. All subjects were food-deprived on days 16 and 17 but only 4 wild and 4 domestic rats were fasted on days 26 and 27, the remaining subjects serving as controls. The total number of wheel revolutions was recorded daily between 15.00 and 17.00 h from cyclometers attached to the wheels. Activity wheels were housed in a 3.1 X 7.3 X 2.5 m room on a 14:lO 1ight:dark cycle with light commencing at 07.00 h. Temperature was controlled between 20 and 22°C. Changes in wheel-running activity due to food deprivation were measured relative to the mean daily wheel-running scores of individuals for the five days preceding and following deprivation (days combined). RESULTS
A comparison
TABLE
of mean pre- and post-deprivation
wheel-running
scores (days
I
Mean daily wheel-running scores when satiated and food deprived Deprivation
period
1 (days
(wheel revolutions)
16 and 17)
Pre- and post-depreviation (days 11-15 and 18-22) fF24 h food deprivation (day 16) Mean percent increase in wheel-running* 24-48 h food deprivation (day 17) Mean percent increase in wheel-running* ______.~ Deprivation period 2-(days 26 and 27) Experimental subjects: pre- and postdeprivation (days 21-25 and 28-32) Experimental subjects: food deprivation (days 26 and 27) Mean percent increase in wheel-running* Non-deprived controls (days 21-25 and 28-32) Non-deprived controls (days 26 and 27) Mean percent change in wheel-running* * Relative
--
of wild and domestic
Wild
Domestic
1620 2080 75% 3707 227%
381 521 60% 814 232%
263
419
518 127%
530 194%
2430 2714 +7%
to mean daily pre- and post-deprivation
408 398 -12%
score.
Norway
rats
194
11-15 and 18-22 combined) revealed that wild rats are significantly more active than their domestic counterparts (t = 2.07, df = 9, P < 0.05; see Table I). Relative to these base-line values a significant increase in wheel-running scores was obtained during the first 24 h of food deprivation (day 16) for wild rats (t = 3.00, df = 9, P < 0.01) and a similar tendency was noted for domestic subjects (t = 1.72, df = 9, P < 0.10). The increase in activity during the second day of continuous food deprivation (day 17) was more than twice as great as base-line levels for both stocks (wild: t = 3.56, df = 9, P < 0.005; domestic: t = 4.25, df = 9, P < 0.005). Wheel-running scores were significantly greater during 24-48 h of food deprivation (day 17) than during the first 24 h of food deprivation (day 16) for both wild (t = 3.30; df = 9, P < 0.005) and domestic (t = 3.95, df = 9, P < 0.005) subjects. The absolute increase in wheel-running scores (relative to base-line levels) during the first 24 h of food deprivation was greater for wild than domestic rats (t = 1.84, df = 9, P < 0.05). However, the relative (proportional) change did not differ between the two strains (t = 0.30, df = 9). The absolute increase in wheel-running during the second 24 h of food deprivation (day 17) was also greater for wild than domestic rats (t = 2.78, df = 9,P < 0.025). Again, however, stocks did not differ in regard to relative changes in activity (t = 0.05, df = 9). During the second period of deprivation (days 26 and 27) the changes in wheel-running of the eight fasted animals were similar to the changes observed during the first deprivation period (days 16 and 17). Both wild and domestic control groups exhibited non-significant changes in activity on days 26 and 27 (mean score of twoday period) relative to the mean base-line scores obtained on days 21-25 and 28-32 (wild: t = 1.24, df = 5; domestic: t = 0.34, df = 5). DISCUSSION
The results of the present study reveal that although adult male wild Norway rats are normally more active in running wheels than their domestic counterparts both stocks show the same proportional increase in wheel-running in response to total food deprivation. This result would suggest that the intensity of selection for this response has not been significantly altered during the domestication process. This hypothesis is intuitively acceptable considering that the direct or indirect behavioral responses to physiological deficits may be just as important for survival in the laboratory environment as in the animal’s natural habitat. For example, artificial selection for rapid growth and large body size in the laboratory rat (Donaldson, 1924) may have strengthened the association between physiological deficits and increased activity, the only difference being the distance wild and domestic rats must normally travel and possibly the energy expended to satisfy these physiological requirements. The results of the present study do not rule out the possibility that early experience in terms of differential fasting experience may have an important effect on the magnitude of the response to food deprivation (Draper, 1967).
195
Huck and Price (1975) have demonstrated that early experience has a greater impact on the open-field behavior of wild rats than their domestic counterparts. Could early fasting experience have a greater effect on the subsequent wheel-running responses of food-deprived wild rats than similarly-treated domestic rats? The mean percent increase in wheel-running during the second day of total food deprivation was more than three times greater than that during the first day of deprivation for both wild and domestic subjects. Finger (1951) working with laboratory rats likewise found a sharp increase in activity on the second and third days of deprivation. Richter and Rice (1954) found that food-deprived wild and domestic rats reached peaks in wheel-running some 2.2-2.4 days after food was withheld. The subjects used in the present study showed less wheel-running than the wild and domestic rats used by Richter and Rice regardless of food availability. In addition the latter investigators found no difference between base-line activity levels of the two stocks. One or both of these differences could be accounted for by the very young age of the subjects used by Richter and Rice (< 100 days as opposed to about 200 days of age in the present study), acknowledging the fact that Finger (1951) and others have demonstrated that wheel-running decreases with age in domestic rats. Of course, the differences could be due, in part, to the different gene pools from which the subjects were derived. Domestic subjects used in the present study were both younger and heavier than the wild rats. This relationship constitutes a compromise in that groups of wild and domestic rats matched by age will differ in body weight and vice versa (Donaldson, 1924). Since it is believed that domestic Norway rats mature at a faster rate than wild rats (Donaldson, 1924) the younger domestic rats used in the present study may more closely approximate the maturational state of the wild rats at the time of testing than if the two groups had been matched by chronological age. The relatively low base-line wheel-running scores of the wild rats fooddeprived during the second deprivation period (Table I) is believed to be coincidental to selecting the two subjects exhibiting the greatest relative increase and the two subjects showing the least relative change in wheel-running in response to deprivation on test days 16 and 17. One of the two high scoring wild rats exhibited an unexplained sudden drop in wheel-running on the second day of deprivation (day 27) thus, accounting for the relatively low “mean percent increase in wheel-running” score for the experimental wild rats in the second deprivation period. The small number of rats deprived on days 26 and 27 and the individual variability obtained, precluded statistical analysis of these data. The present investigation has shown that domestication has not appreciably changed the effect of fasting on the activity of the naive male Norway rat. Further study is needed to determine whether a genotype-environment interaction exists in regard to early fasting experience.
196
ACKNOWLEDGEMENT
This investigation was supported by Grant MH21467-01 from the National Institutes of Mental Health.
REFERENCES
*
Baumeister, A., Hawkins, W.F. and Cromwell, R.T., 1964. Need states and activity level. Psychol. Bull., 61: 438-453. Bindra, D., 1961. Components of general activity and the analysis of behavior. Psychol. Rev., 68: 205-215. Bolles, R.C., 1963. Effect of food deprivation upon the rat’s behavior in its home cage. J. Comp. Physiol. Psychol., 56: 456-460. Campbell, B.A., Smith, N.F., Misanin, J.R. and Jaynes, J., 1966. Species differences in activity during hunger and thirst. J. Comp. Physiol. Psychol., 61: 123-127. Cornish, E.R. and Mrosovsky, N., 1965. Activity during food deprivation and satiation of six species of rodent. Anim. Behav., 13: 242-248. Donaldson, H.H., 1924. The rat. Data and reference tables for the albino rat and the Norway rat. Mem. Wistar Inst. Anat. Biol., Philadelphia, No. 6, pp. l-458. Draper, W.A., 1967. A behavioural study of the home-cage activity of the white rat. Behaviour, 28: 280-306. Finger, F.W., 1951. The effect of food deprivation and subsequent satiation upon general activity in the rat. J. Comp. Physiol. Psychol., 44: 557-564. Gross, C.G., 1968. General activity. In: L. Weiskrantz (Editor), Analysis of Behavioral Change. Harper & Row, New York, pp. 91-106. Hall, J.F., 1956. The relationship between external stimulation, food deprivation and activity. J. Comp. Physiol. Psychol., 49: 339-341. Huck, U.W. and Price, E.O., 1975. Differential effects of environmental enrichment on the open field behavior of wild and domestic Norway rats. J. Comp. Physiol. Psychol., 89: 892-898. Kurcz, M., 1961. A comparative study of the spontaneous activity of the white rat and the brown or wharf rat. Acta Biol., 11: 271-283. Richter, C.P. and Rice, K.K., 1954. Comparison of the effects produced by fasting on gross bodily activity of wild and domesticated Norway rats. Am. J. Physiol., 179: 305-308. Treichler, F.R. and Hall, J.F., 1962. The relationship between deprivation weight loss and several measures of activity. J. Comp. Physiol. Psychol., 55: 346-349. Weasner, M.H., Finger, F.W. and Reid, L.S., 1960. Activity changes under food deprivation as a function of recording device. J. Comp. Physiol. Psychol., 53: 470-474.