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Acquisition of schedule-induced polydipsia in the mongolian gerbil
Physiology & Behavior, Vol. 21, pp. 825-827. Pergamon Press and Brain Research Publ., 1978. Printed in the U.S.A.
BRIEF COMMUNICATION Acquisition of Schedule-Induced Polydipsia in the Mongolian Gerbil 1 J O S E P H H. P O R T E R A N D W I L S O N E. B R Y A N T , JR.
Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284 (Received 22 May 1978) PORTER, J. H. AND W. E. BRYANT, JR. Acquisition of schedule-induced polydipsia in the Mongolian gerbil. PHYSIOL. BEHAV. 21(5) 825-827, 1978.--Three food-deprived Mongolian gerbils reliably displayed schedule-induced polydipsia when fixed-time food schedules were increased to 3-min interpellet intervals. No polydipsia was evident with shorter interpellet intervals. These data further extend the species generality of schedule-induced polydipsia, and indicate the importance o f systematic variation of relevant variables before concluding that a given species does not display schedule-induced polydipsia.
Schedule-induced polydipsia
Mongoliangerbils
Speciesgenerality
SINCE Falk's [4] original demonstration of scheduleinduced polydipsia with rats, numerous other species also have been shown to exhibit schedule-induced polydipsia. It has been shown in mice [10, 1I, 18], guinea pigs [14], pigeons [9,17], rhesus monkeys [1, 13, 15, 16], Java monkeys [2], and humans [7]. However, not all species which have been tested readily show schedule-induced polydipsia. Wilson and Spencer [19], S. H. Hobbs (personal communication), and testing in our laboratory (unpublished observations) have all failed to find polydipsia in golden hamsters. Symons and Sprott [18] have shown that not all strains of mice develop schedule-induced polydipsia, and J. D. Allen (personal communication) has failed to find polydipsia in wild rats. Recently, we [12] reported that it is possible to show schedule-induced polydipsia in Mongolian gerbils, but our observation was limited to only 1 gerbil out of 5 which were tested on fixed-time 30-sec and 60-sec schedules. The purpose of the present study was to determine if scheduleinduced polydipsia could be reliably shown in Mongofian gerbils under the proper testing conditions. We decided to vary the interpellet interval of the food schedule, since Magyar et al. [9] found that pigeons did not develop schedule-induced polydipsia until the interpellet interval was at least two minutes in length. METHOD
Animals Three naive male (64, 72 and 75 gin) Mongolian gerbils
(Meriones unguiculatus) were used. They were housed individually with an 8 a.m. to 7 p.m. light/dark cycle. Water
was always available in the home cage. They were maintained at 85% of their free-feeding body weights throughout the study by restricting their daily ration of Purina rat chow.
Apparatus The test chamber was a modified Scientific Prototype operant conditioning chamber (Model A-100) mounted on a standard 14 in. (35.7 era) dia. activity wheel (Wahmann, Model LC-34). Access to the activity wheel was blocked by a Plexiglas door throughout the entire study. The food tray was centered on the intelligence panel 1 cm above the grid floor. Water was made available from a water bottle mounted behind the intelligence panel. The drinking tube protruded 2.5 cm into the test chamber through a 2.5 cm dia. hole located 2 cm to the right of the food tray and 1 cm above the grid floor. A Scientific Prototype (Model 101K) drinkometer was used to record drinking tube contacts. The test chamber was housed in a sound attenuated cubicle with a 28 V dc house light and masking noise. Standard formula 45 mg Noyes pellets served as reinforcers. Standard electromechanical and solid state programming and recording equipment were located in an adjacent room.
Procedure Test sessions were conducted daily and were terminated after the delivery of 30 food pellets. Thus, the length of the test session depended on the length of the fixed-time (FT) food schedules. Water intake was determined by weighing the water bottle before and after each test session (1 gin= 1 ml), and water intake values were corrected for spillage from
tThe authors would like to thank Gerald C. Llewellyn for supplying the gerbils. Reprint requests should be sent to Joseph H. Porter, Department of Psychology, Virginia Commonwealth University, Richmond, Virginia 23284.
Copyright © 1978 Brain Research Publications Inc.--0031-9384/78/110825-03502.00/0
826
PORTER AND BRYANT TABLE 1 MEAN WATER INTAKE (ML) FOR THE LAST 2 SESSIONS OF EACH SCHEDULE CONDITION. DURING BASELINE SESSIONS ALL 30 PELLETS WERE PLACED IN THE FOOD MAGAZINE AT THE BEGINNING OF THE TEST SESSION. THE LENGTH OF THE TEST SESSIONS IS INDICATED IN PARENTHESES.
Animal
Baseline (30-min)
FT 1-min (30-min)
Baseline (30-min)
FT 2-min (60-min)
FT 3-min (90-min)
Baseline (90-min)
FT 3-min (90-min)
G-8 G-9 G-10
0.9 0.1 2.0
0.0 0.4 0.2
0.3 0.0 0.1
0.0 0.1 0.3
10.1 10.9 7.4
0.5 4.9 2.7
11.6 9.4 13.0
handling. Initially, the gerbils w e r e p l a c e d in the t e s t c h a m b e r for six 30-min Baseline s e s s i o n s . During e a c h session 30 food pellets w e r e p l a c e d in the f o o d tray. The pellet d i s p e n s e r w a s o p e r a t e d o n c e e v e r y m i n u t e , but no pellets w e r e d e l i v e r e d to the test c h a m b e r . O v e r the n e x t 15 ses-
sions food pellets w e r e d e l i v e r e d i n d e p e n d e n t l y o f the anim a l ' s b e h a v i o r a c c o r d i n g to a F T 1-min s c h e d u l e . T h e n , 5 m o r e Baseline s e s s i o n s (30-min) w e r e c o n d u c t e d . T h e fixed time s c h e d u l e w a s s u b s e q u e n t l y i n c r e a s e d to 2-min for 5 s e s s i o n s , and to 3-min for 10 s e s s i o n s . S e v e n m o r e Baseline
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FIG. 1. Sample cumulative records for gerbil G- 10 from the two FT 3-min and the 90-min Baseline testing conditions. During the first FT 3-min condition, cumulative records are shown for Sessions 1, 3, 5 and 10. Each tube contact advanced the response pen, and pellet deliveries are indicated by the hatch marks on the event pen. No pellets were delivered during the Baseline condition. The response pen was reset to baseline with each pellet delivery.
S C H E D U L E - I N D U C E D POLYDIPSIA IN T H E GERBIL sessions (90-min) were conducted, and finally, 5 more sessions on the F T 3-min schedule were run. RESULTS Table 1 shows the mean water intake (ml) for the last 2 sessions of each schedule condition. The length of the test sessions is indicated in parentheses. There was no reliable increase in water intake during the FT schedules, as compared to Baseline water intakes, until the interpellet interval was increased to 3-min. When all 30 pellets were given at the beginning of the 90-rain Baseline sessions, water intake was greatly reduced for all 3 gerbils. When returned to the FT 3-min schedule, session water intakes values were recaptured with G-10 showing an increase of 5.6 ml per session. Sample cumulative records from the two FT 3-min and the 90-min Baseline testing conditions are shown in Fig. 1 for gerbil G-10. During the first FT 3-min condition, cumulative records are shown for Sessions l, 3, 5 and 10. As the schedule-induced polydipsia was developing, G-10 drank after an increasingly greater number of pellets, drinking in 29 of the 30 intervals by Session 10. The pattern of drinking was very similar to that seen with rats, with each pellet being followed immediately by a drinking bout and little or no drinking occurring in the rest of the interval. When all 30 pellets were given at the beginning of the 90-min session during the Basline condition, both the amount of drinking (see Table 1) and the post-pellet pattern (of course, no pellets were being delivered) were greatly diminished. Upon return to the FT 3-min food schedule, the post-pellet pattern of drinking reappeared and session water intake increased (see Table 1).
827 DISCUSSION The present study demonstrated that schedule-induced polydipsia does occur reliably in Mongolian gerbils under the proper testing conditions. All three gerbils developed schedule-induced polydipsia when the interpellet interval was increased to 3 min. These results somewhat parallel findings with pigeons in which the polydipsia did not develop until the interpellet interval was at least 2 rain in length [9]. While it is not certain as to why these two species require longer interpellets intervals than rats to develop polydipsia, it may be related to differences in kidney function for both pigeons [6], and gerbils [8]. Regardless of the exact reason, these findings point out the necessity of further testing with species which have failed to display schedule-induced polydipsia. Bitterman [3] has suggested that meaningful comparisons between species may be made if "control by systematic variation" is used. Essentially, Bitterman is aruging for extensive testing of a given species by varying the parameters of a number of different variables which may affect the behavior in question. In the case of schedule-induced polydipsia, it has been shown that the interpellet interval, body weight, reinforcer magnitude, and reinforcer composition are all important variables in the control and development of polydipsia [5]. The present study has shown that manipulation of one of these variables (i.e., interpellet interval) resulted in a reliable demonstration of schedule-induced polydipsia in the Mongolian gerbil, and further extended the species generality of this phenomenon. Perhaps, the generality of scheduleinduced polydipsia can be extended to other species (e.g., hamsters) if the appropriate variable(s) is manipulated.
REFERENCES
1. Allen, J. D. and D. R. Kenshalo, Jr. Schedule-induced drinking as a function of interreinforcement interval in the rhesus monkey. J. exp. Analysis Behav. 26: 257-267, 1976. 2. Allen, J. D. and D. R. Kenshaio, Jr. Schedule-induced drinking as functions of interpellet interval and draught size in the Java macaque. J. exp. Analysis Behav. 30: 139-151, 1978. 3. Bitterman, M. E. Phyletic differences in learning. Am. Psych. 20: 396--410, 1965. 4. Falk, J. L. Production of polydipsia in normal rats by an intermittent food schedule. Science 33: 195-196, 1961. 5. Falk, J. L. Conditions producing psychogenetic polydipsia in animals. Ann. N.Y. Acad. Sci. 157: 569-589, 1969. 6. Hawkins, R. C. and J. D. Corbit. Drinking in response to cellular dehydration in the pigeon. J. comp. physiol. Psychol. 84: 265-267, 1973. 7. Kachanoff, R., R. Leveille, J. P. McLelland and M. J. Wayner. Schedule-induced behavior in humans. Physiol. Behav. 11: 395-398, 1973. 8. Kutscher, C. L. Species differences in the interaction of feeding and drinking. Ann. N. Y. Acad. Sci. 157: 539-552, 1969. 9. Magyar, R. L., R. Allen, A. Sicignano and E. F. Malagodi. Schedule-induced polydipsia in the pigeon. Paper presented at the meeting of the Southeastern Psychological Association, Hollywood, Florida, 1977.
10. Ogata, H., F. Ogata, J. H. Mendelson and N. K. Mello. A comparison of techniques to induce alcohol dependence and tolerance in the mouse. J. Pharmac. exp. Ther. 180: 216-230, 1972. II. Palfai, T., C. L. Kutscher and J. P. Symons. Schedule-induced polydipsia in the mouse. Physiol. Behav. 6: 461-462, 1971. 12. Porter, J. H. and W. E. Bryant, Jr. Adjunctive behavior in the Mongolian gerbil. Physiol. Behav. 21: 151-155, 1978. 13. Porter, J. H. and D. R. Kenshalo, Jr. Schedule-induced drinking following omission of reinforcement in the rhesus monkey. Physiol. Behav. 12: 1075-1077, 1974. 14. Porter, J. H., N. N. Sozer and T. P. Moeschl. Schedule-induced polydipsia in the guinea pig. Physiol. Behav. 19: 573-575, 1977. 15. Salzberg, C. L., W. W. Henton and J. J. Jordan. Concurrent water drinking on FT and CRF food-reinforcement schedules in the rhesus monkey. Psychol. Rep. 22: 1065-1070, 1968. 16. Schuster, C. R. and J. H. Woods. Schedule-induced polydipsia in the rhesus monkey. Psychol. Rep. 19: 823-828, 1966. 17. Schanab, M. E. and J. L. Peterson. Polydipsia in the pigeon. Psychon. Sci. 15: 51-52, 1969. 18. Symons, J. P. and R. S. Sprott. Genetic analysis of scheduleinduced polydipsia. Physiol. Behav. 17: 837-839, 1976. 19. Wilson, S. and W. B. Spencer. Schedule-induced polydipsia: Species limitations. Psychol. Rep. 36: 863-866, 1975.
BRIEF COMMUNICATION Acquisition of Schedule-Induced Polydipsia in the Mongolian Gerbil 1 J O S E P H H. P O R T E R A N D W I L S O N E. B R Y A N T , JR.
Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284 (Received 22 May 1978) PORTER, J. H. AND W. E. BRYANT, JR. Acquisition of schedule-induced polydipsia in the Mongolian gerbil. PHYSIOL. BEHAV. 21(5) 825-827, 1978.--Three food-deprived Mongolian gerbils reliably displayed schedule-induced polydipsia when fixed-time food schedules were increased to 3-min interpellet intervals. No polydipsia was evident with shorter interpellet intervals. These data further extend the species generality of schedule-induced polydipsia, and indicate the importance o f systematic variation of relevant variables before concluding that a given species does not display schedule-induced polydipsia.
Schedule-induced polydipsia
Mongoliangerbils
Speciesgenerality
SINCE Falk's [4] original demonstration of scheduleinduced polydipsia with rats, numerous other species also have been shown to exhibit schedule-induced polydipsia. It has been shown in mice [10, 1I, 18], guinea pigs [14], pigeons [9,17], rhesus monkeys [1, 13, 15, 16], Java monkeys [2], and humans [7]. However, not all species which have been tested readily show schedule-induced polydipsia. Wilson and Spencer [19], S. H. Hobbs (personal communication), and testing in our laboratory (unpublished observations) have all failed to find polydipsia in golden hamsters. Symons and Sprott [18] have shown that not all strains of mice develop schedule-induced polydipsia, and J. D. Allen (personal communication) has failed to find polydipsia in wild rats. Recently, we [12] reported that it is possible to show schedule-induced polydipsia in Mongolian gerbils, but our observation was limited to only 1 gerbil out of 5 which were tested on fixed-time 30-sec and 60-sec schedules. The purpose of the present study was to determine if scheduleinduced polydipsia could be reliably shown in Mongofian gerbils under the proper testing conditions. We decided to vary the interpellet interval of the food schedule, since Magyar et al. [9] found that pigeons did not develop schedule-induced polydipsia until the interpellet interval was at least two minutes in length. METHOD
Animals Three naive male (64, 72 and 75 gin) Mongolian gerbils
(Meriones unguiculatus) were used. They were housed individually with an 8 a.m. to 7 p.m. light/dark cycle. Water
was always available in the home cage. They were maintained at 85% of their free-feeding body weights throughout the study by restricting their daily ration of Purina rat chow.
Apparatus The test chamber was a modified Scientific Prototype operant conditioning chamber (Model A-100) mounted on a standard 14 in. (35.7 era) dia. activity wheel (Wahmann, Model LC-34). Access to the activity wheel was blocked by a Plexiglas door throughout the entire study. The food tray was centered on the intelligence panel 1 cm above the grid floor. Water was made available from a water bottle mounted behind the intelligence panel. The drinking tube protruded 2.5 cm into the test chamber through a 2.5 cm dia. hole located 2 cm to the right of the food tray and 1 cm above the grid floor. A Scientific Prototype (Model 101K) drinkometer was used to record drinking tube contacts. The test chamber was housed in a sound attenuated cubicle with a 28 V dc house light and masking noise. Standard formula 45 mg Noyes pellets served as reinforcers. Standard electromechanical and solid state programming and recording equipment were located in an adjacent room.
Procedure Test sessions were conducted daily and were terminated after the delivery of 30 food pellets. Thus, the length of the test session depended on the length of the fixed-time (FT) food schedules. Water intake was determined by weighing the water bottle before and after each test session (1 gin= 1 ml), and water intake values were corrected for spillage from
tThe authors would like to thank Gerald C. Llewellyn for supplying the gerbils. Reprint requests should be sent to Joseph H. Porter, Department of Psychology, Virginia Commonwealth University, Richmond, Virginia 23284.
Copyright © 1978 Brain Research Publications Inc.--0031-9384/78/110825-03502.00/0
826
PORTER AND BRYANT TABLE 1 MEAN WATER INTAKE (ML) FOR THE LAST 2 SESSIONS OF EACH SCHEDULE CONDITION. DURING BASELINE SESSIONS ALL 30 PELLETS WERE PLACED IN THE FOOD MAGAZINE AT THE BEGINNING OF THE TEST SESSION. THE LENGTH OF THE TEST SESSIONS IS INDICATED IN PARENTHESES.
Animal
Baseline (30-min)
FT 1-min (30-min)
Baseline (30-min)
FT 2-min (60-min)
FT 3-min (90-min)
Baseline (90-min)
FT 3-min (90-min)
G-8 G-9 G-10
0.9 0.1 2.0
0.0 0.4 0.2
0.3 0.0 0.1
0.0 0.1 0.3
10.1 10.9 7.4
0.5 4.9 2.7
11.6 9.4 13.0
handling. Initially, the gerbils w e r e p l a c e d in the t e s t c h a m b e r for six 30-min Baseline s e s s i o n s . During e a c h session 30 food pellets w e r e p l a c e d in the f o o d tray. The pellet d i s p e n s e r w a s o p e r a t e d o n c e e v e r y m i n u t e , but no pellets w e r e d e l i v e r e d to the test c h a m b e r . O v e r the n e x t 15 ses-
sions food pellets w e r e d e l i v e r e d i n d e p e n d e n t l y o f the anim a l ' s b e h a v i o r a c c o r d i n g to a F T 1-min s c h e d u l e . T h e n , 5 m o r e Baseline s e s s i o n s (30-min) w e r e c o n d u c t e d . T h e fixed time s c h e d u l e w a s s u b s e q u e n t l y i n c r e a s e d to 2-min for 5 s e s s i o n s , and to 3-min for 10 s e s s i o n s . S e v e n m o r e Baseline
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FIG. 1. Sample cumulative records for gerbil G- 10 from the two FT 3-min and the 90-min Baseline testing conditions. During the first FT 3-min condition, cumulative records are shown for Sessions 1, 3, 5 and 10. Each tube contact advanced the response pen, and pellet deliveries are indicated by the hatch marks on the event pen. No pellets were delivered during the Baseline condition. The response pen was reset to baseline with each pellet delivery.
S C H E D U L E - I N D U C E D POLYDIPSIA IN T H E GERBIL sessions (90-min) were conducted, and finally, 5 more sessions on the F T 3-min schedule were run. RESULTS Table 1 shows the mean water intake (ml) for the last 2 sessions of each schedule condition. The length of the test sessions is indicated in parentheses. There was no reliable increase in water intake during the FT schedules, as compared to Baseline water intakes, until the interpellet interval was increased to 3-min. When all 30 pellets were given at the beginning of the 90-rain Baseline sessions, water intake was greatly reduced for all 3 gerbils. When returned to the FT 3-min schedule, session water intakes values were recaptured with G-10 showing an increase of 5.6 ml per session. Sample cumulative records from the two FT 3-min and the 90-min Baseline testing conditions are shown in Fig. 1 for gerbil G-10. During the first FT 3-min condition, cumulative records are shown for Sessions l, 3, 5 and 10. As the schedule-induced polydipsia was developing, G-10 drank after an increasingly greater number of pellets, drinking in 29 of the 30 intervals by Session 10. The pattern of drinking was very similar to that seen with rats, with each pellet being followed immediately by a drinking bout and little or no drinking occurring in the rest of the interval. When all 30 pellets were given at the beginning of the 90-min session during the Basline condition, both the amount of drinking (see Table 1) and the post-pellet pattern (of course, no pellets were being delivered) were greatly diminished. Upon return to the FT 3-min food schedule, the post-pellet pattern of drinking reappeared and session water intake increased (see Table 1).
827 DISCUSSION The present study demonstrated that schedule-induced polydipsia does occur reliably in Mongolian gerbils under the proper testing conditions. All three gerbils developed schedule-induced polydipsia when the interpellet interval was increased to 3 min. These results somewhat parallel findings with pigeons in which the polydipsia did not develop until the interpellet interval was at least 2 rain in length [9]. While it is not certain as to why these two species require longer interpellets intervals than rats to develop polydipsia, it may be related to differences in kidney function for both pigeons [6], and gerbils [8]. Regardless of the exact reason, these findings point out the necessity of further testing with species which have failed to display schedule-induced polydipsia. Bitterman [3] has suggested that meaningful comparisons between species may be made if "control by systematic variation" is used. Essentially, Bitterman is aruging for extensive testing of a given species by varying the parameters of a number of different variables which may affect the behavior in question. In the case of schedule-induced polydipsia, it has been shown that the interpellet interval, body weight, reinforcer magnitude, and reinforcer composition are all important variables in the control and development of polydipsia [5]. The present study has shown that manipulation of one of these variables (i.e., interpellet interval) resulted in a reliable demonstration of schedule-induced polydipsia in the Mongolian gerbil, and further extended the species generality of this phenomenon. Perhaps, the generality of scheduleinduced polydipsia can be extended to other species (e.g., hamsters) if the appropriate variable(s) is manipulated.
REFERENCES
1. Allen, J. D. and D. R. Kenshalo, Jr. Schedule-induced drinking as a function of interreinforcement interval in the rhesus monkey. J. exp. Analysis Behav. 26: 257-267, 1976. 2. Allen, J. D. and D. R. Kenshaio, Jr. Schedule-induced drinking as functions of interpellet interval and draught size in the Java macaque. J. exp. Analysis Behav. 30: 139-151, 1978. 3. Bitterman, M. E. Phyletic differences in learning. Am. Psych. 20: 396--410, 1965. 4. Falk, J. L. Production of polydipsia in normal rats by an intermittent food schedule. Science 33: 195-196, 1961. 5. Falk, J. L. Conditions producing psychogenetic polydipsia in animals. Ann. N.Y. Acad. Sci. 157: 569-589, 1969. 6. Hawkins, R. C. and J. D. Corbit. Drinking in response to cellular dehydration in the pigeon. J. comp. physiol. Psychol. 84: 265-267, 1973. 7. Kachanoff, R., R. Leveille, J. P. McLelland and M. J. Wayner. Schedule-induced behavior in humans. Physiol. Behav. 11: 395-398, 1973. 8. Kutscher, C. L. Species differences in the interaction of feeding and drinking. Ann. N. Y. Acad. Sci. 157: 539-552, 1969. 9. Magyar, R. L., R. Allen, A. Sicignano and E. F. Malagodi. Schedule-induced polydipsia in the pigeon. Paper presented at the meeting of the Southeastern Psychological Association, Hollywood, Florida, 1977.
10. Ogata, H., F. Ogata, J. H. Mendelson and N. K. Mello. A comparison of techniques to induce alcohol dependence and tolerance in the mouse. J. Pharmac. exp. Ther. 180: 216-230, 1972. II. Palfai, T., C. L. Kutscher and J. P. Symons. Schedule-induced polydipsia in the mouse. Physiol. Behav. 6: 461-462, 1971. 12. Porter, J. H. and W. E. Bryant, Jr. Adjunctive behavior in the Mongolian gerbil. Physiol. Behav. 21: 151-155, 1978. 13. Porter, J. H. and D. R. Kenshalo, Jr. Schedule-induced drinking following omission of reinforcement in the rhesus monkey. Physiol. Behav. 12: 1075-1077, 1974. 14. Porter, J. H., N. N. Sozer and T. P. Moeschl. Schedule-induced polydipsia in the guinea pig. Physiol. Behav. 19: 573-575, 1977. 15. Salzberg, C. L., W. W. Henton and J. J. Jordan. Concurrent water drinking on FT and CRF food-reinforcement schedules in the rhesus monkey. Psychol. Rep. 22: 1065-1070, 1968. 16. Schuster, C. R. and J. H. Woods. Schedule-induced polydipsia in the rhesus monkey. Psychol. Rep. 19: 823-828, 1966. 17. Schanab, M. E. and J. L. Peterson. Polydipsia in the pigeon. Psychon. Sci. 15: 51-52, 1969. 18. Symons, J. P. and R. S. Sprott. Genetic analysis of scheduleinduced polydipsia. Physiol. Behav. 17: 837-839, 1976. 19. Wilson, S. and W. B. Spencer. Schedule-induced polydipsia: Species limitations. Psychol. Rep. 36: 863-866, 1975.