- Email: [email protected]
The effect of septal lesions on the drinking habits of the rats
Physiology and Behavior. Vol. 5, pp. 257-258. Pergamon Press, 1970. Printed in Great Britain
BRIEF COMMUNICATION The Effect of Septal Lesions on the Drinking Habits of the Rats EMMA
CHIARAVIGLIO 1
Instituto de 1nvestigacirn M~dica, Mercedes y Martin Ferreyra 2, C6rdoba, Argentina (Received 5 S e p t e m b e r 1969) CmARAVlGLIO,E. The effect of septal lesions on the drinking habits of the rats. PHYSIOL.BEHAV.5 (2) 257--258, 1970.Normal rats and rats with lesions in the olfactory bulbs, when given a choice of 1 per cent NaCl solution or tap water, drank the largest amount of liquid during the night. Rats with septal lesions, on the other hand, drank the same amount during the day as at night. Sodium deprivation did not affect the behavioral pattern of the two first mentioned groups, while it did affect the septal lesioned rats, which increased their diurnal intake of NaCl. This suggests that the septal area plays some important role in mediating biological rhythms. Circadian rhythm
Sodium chloride intake
Sodium deprivation
BIOLOGICAL rhythms have been found in several species of animals as well as in man [1]. These rhythms, which are called circadian rhythms, are maintained by a physiological mechanism that is as yet unknown, although it is responsible for the timing of many processes that are reflected in the metabolic or behavioral patterns of the organism [6, 11 ]. Lesioning or stimulating the septal area has been reported to alter the behavior patterns in rats, leading to a dramatic increase in appetite for sodium chloride solution [2, 8]. The present work is a study on the relationship between the effect of septal lesions and the circadian variations of the drinking habits in rats.
Olfactory bulb lesion
considered "high sodium drinkers" and suitable for the test [21. Test days were divided into two daily drinking periods: a diurnal one from 8 a.m. to 8 p.m. and a nocturnal one, from 8 p.m. to 8 a.m. RESULTS AND DISCUSSION
Table 1 (A) shows the amount of fluid ingested by the rats on ad libitum diet. Nine intact rats and nine with lesions in the olfactory bulbs showed higher intake of both liquids during the night. Conversely, nine rats with septal lesions were observed to drink an almost equal amount of saline solution in both daily periods, though a larger water intake was registered at night. Normal animals and those with olfactory bulb lesions, when deprived of sodium by fasting for 24 hr and given distilled water to drink, showed the same circadian drinking pattern as that observed when they were not sodium deprived. On the other hand, rats with septal lesions drank significantly higher amounts of sodium solution (p < 0.01) during the day Table 1 (B). The water intake of all the groups was higher at night. It was thought that the higher diurnal saline intake shown by animals with septal lesions could be due to a compensatory intake after the 24 hr period of sodium deprivation. To explore this possibility the septal animals were tested by starting with the nocturnal cycle. In 5 animals which began the test at 8 a.m., the diurnal 1 per cent NaCI intake
METHOD
A group of 15 adult male albino rats was chosen for bilateral septal lesions, performed under ether anesthesia, by means of a stereotaxic instrument. A nichrome electrode, 0.6 m m in diameter, was placed according to De Groot [3] atlas coordinates (AP: 7.4, H : + 2, L: 0,5), and a d.c. current of 2-3 m A was applied for 25 sec. Two control groups were run simultaneously with the septal lesioned rats. These were: a group of normal, intact rats, and another group with lesions in the olfactory bulbs. The animals were caged individually with food ad libitum and given a choice of 1 per cent NaCI solution or tap water. The liquid intake was recorded daily for 10 days, after the lesions were performed. Lesioned rats with a daily 1 per cent NaCI intake above the mean of the normal control group plus two standard deviations, were
XMember of Consejo Nacional de Investigaciones Cientifieas y Trcnicas, Argentina. 2Supported by grants from the Consejo Nacional de Investigaciones Cientificas y Trcnicas, Argentina. 257
258
CHIARAVIGLIO
was 104.0 ± 29.2 ml and the nocturnal intake was 59.0 + 11.8. When the test was started at 8 p.m., the nocturnal saline intake was 55.8 4 - 1 2 . 3 m l and the diurnal intake was 101.6 4- 26.7ml. This experiment showed that animals with septal lesions drank a larger amount of saline during the day, no mattel whether the test started with the diurnal or the nocturnal period. These experiments suggest that the septal area may play an important role in the regulation of the circadian rhythm. Since lesions in the olfactory bulb do not alter the drinking
habits, it can be inferred that the effect observed after the septal lesions is not due to the surgical procedure in itself. A n analysis of the function of the limbic system seems to stress its role in emotional behavior, drive and motivation [4, 5, 7]. The "septal syndrome" in rats, has been described [10] to produce emotional instability. On the other hand, there are evidences that the lesion of the septal area results in disinhibitory effects [7]. I n the present study the drinking habits were disrupted, suggesting that the septal structures play a role in mediating biological rhythms.
TABLE 1. CIRCADIAN VARIATIONS IN WATER AND 1 PER CENT NaC1 SOLUTIONINTAKEIN RATS
Conditions
Normal Olfactory bulb lesion Septal lesion
Normal Olfactory bulb lesion Septal lesion
Liquid Offered
Volume Intake (ml 4- SE) Diurnal Nocturnal (from 8 a.m. to 8 p.m.) (from 8 p.m. to 8 a.m.)
A. Following ad libitum access to food and water Water 9.6 + 2.0 (9) 1% NaC1 4.4 q- 1.7 (9)
p*
Value
16.7 ~ 1.0 (9) 8.3 4- 1.1 (9)
0.01 0.05
Water 1% NaCI
5.0 -4- 2.0 (9) 13.7 + 2.2 (9)
10.8 4- 1.6 (9) 21.6 4- 3.1 (9)
Water 1 ~o NaCI
7.6 4- 3.1 (9) 15.1 4- 4.0 (9)
13.1 i 2.7 (9) 15.9 4- 3.8 (9)
0.05 0.05 NS NS
6.0 4- 0.5 (6) 45.0 ± 6.7 (6)
NS 0.02
B. Following 24 hr food and sodium deprivation Water 3.5 q- 1.9 (6) 1% NaC1 19.8 ! 6.7 (6) Water 1% NaC1
3.6 4- 1.1 (6) 39.1 4- 14.1 (6)
3.3 ~: 0.8 (6) 55.0 4- 10.5 (6)
NS NS
Water 1% NaC1
0.8 4- 0.6 (6) 96.1 + 15.6 (6)
5.0 4- 1.3 (6) 45.0 4- 4.1 (6)
0.01 0.01
In brackets, number of animals. *"t" test diurnal vs. nocturnal.
REFERENCES
1. Aschoff, J. Comparative physiology: Diurnal rhythms. Ann. Rev. Physiol. 25: 581-600, 1963. 2. Chiaraviglio, E. Effects of lesions in the septal area and olfactory bulbs on sodium chloride intake. Physiol. Behav. 4: 693-967, 1969. 3. De Groot, J. The rat forebrain in stereotaxic coordinates. Trans. Roy. Neth. Acad. ScL 52: 1-40, 1959. 4. Ellen, P. and E. W. Powell. Temporal discrimination in rats with rhinencephalic lesions. Exp. Neurol. 6: 538-547, 1962. 5. Grossman, S. P. Effect of chemical stimulation of the septal area on motivation. J. comp. physiol. Psychol. 58: 194-200, 1964. 6. Halberg, F., R. E. Peterson and R. H. Silber. Phase relations of 24-hours periodicities in blood corticoesterona, mitoses in cortical adrenal parenchyma, and total body activity. Endocrinology 64: 222-230, 1959.
7. Hamilton, L. W., R. A. McCleary and S. P. Grossman. Behavioral effects of cholinergic septal blockade in the cat. J. comp. physiol. Psychol. 66: 563-568, 1968. 8. Nbgro Vilar, A., C. G. Gentil and M. R. Covian. Alterations in sodium chloride and water intake after septal lesions in the rat. Physiol. Behav. 2: 167-170, 1967. 9. Olds, J. Hypothalamic substrates of reward. Physiol. Rev. 42: 554-604, 1962. 10. Reymond, M. C. and K. Bfittig. A study of the "septal syndrome" in rats following electrolytic lesions. Jr. Physiol. (Paris) 56: 807-828, 1964. 11. Tarttelin, M. F. Cyclical variations in food and water intakes in ewes. J. Physiol. 195: 29-31, 1968.
BRIEF COMMUNICATION The Effect of Septal Lesions on the Drinking Habits of the Rats EMMA
CHIARAVIGLIO 1
Instituto de 1nvestigacirn M~dica, Mercedes y Martin Ferreyra 2, C6rdoba, Argentina (Received 5 S e p t e m b e r 1969) CmARAVlGLIO,E. The effect of septal lesions on the drinking habits of the rats. PHYSIOL.BEHAV.5 (2) 257--258, 1970.Normal rats and rats with lesions in the olfactory bulbs, when given a choice of 1 per cent NaCl solution or tap water, drank the largest amount of liquid during the night. Rats with septal lesions, on the other hand, drank the same amount during the day as at night. Sodium deprivation did not affect the behavioral pattern of the two first mentioned groups, while it did affect the septal lesioned rats, which increased their diurnal intake of NaCl. This suggests that the septal area plays some important role in mediating biological rhythms. Circadian rhythm
Sodium chloride intake
Sodium deprivation
BIOLOGICAL rhythms have been found in several species of animals as well as in man [1]. These rhythms, which are called circadian rhythms, are maintained by a physiological mechanism that is as yet unknown, although it is responsible for the timing of many processes that are reflected in the metabolic or behavioral patterns of the organism [6, 11 ]. Lesioning or stimulating the septal area has been reported to alter the behavior patterns in rats, leading to a dramatic increase in appetite for sodium chloride solution [2, 8]. The present work is a study on the relationship between the effect of septal lesions and the circadian variations of the drinking habits in rats.
Olfactory bulb lesion
considered "high sodium drinkers" and suitable for the test [21. Test days were divided into two daily drinking periods: a diurnal one from 8 a.m. to 8 p.m. and a nocturnal one, from 8 p.m. to 8 a.m. RESULTS AND DISCUSSION
Table 1 (A) shows the amount of fluid ingested by the rats on ad libitum diet. Nine intact rats and nine with lesions in the olfactory bulbs showed higher intake of both liquids during the night. Conversely, nine rats with septal lesions were observed to drink an almost equal amount of saline solution in both daily periods, though a larger water intake was registered at night. Normal animals and those with olfactory bulb lesions, when deprived of sodium by fasting for 24 hr and given distilled water to drink, showed the same circadian drinking pattern as that observed when they were not sodium deprived. On the other hand, rats with septal lesions drank significantly higher amounts of sodium solution (p < 0.01) during the day Table 1 (B). The water intake of all the groups was higher at night. It was thought that the higher diurnal saline intake shown by animals with septal lesions could be due to a compensatory intake after the 24 hr period of sodium deprivation. To explore this possibility the septal animals were tested by starting with the nocturnal cycle. In 5 animals which began the test at 8 a.m., the diurnal 1 per cent NaCI intake
METHOD
A group of 15 adult male albino rats was chosen for bilateral septal lesions, performed under ether anesthesia, by means of a stereotaxic instrument. A nichrome electrode, 0.6 m m in diameter, was placed according to De Groot [3] atlas coordinates (AP: 7.4, H : + 2, L: 0,5), and a d.c. current of 2-3 m A was applied for 25 sec. Two control groups were run simultaneously with the septal lesioned rats. These were: a group of normal, intact rats, and another group with lesions in the olfactory bulbs. The animals were caged individually with food ad libitum and given a choice of 1 per cent NaCI solution or tap water. The liquid intake was recorded daily for 10 days, after the lesions were performed. Lesioned rats with a daily 1 per cent NaCI intake above the mean of the normal control group plus two standard deviations, were
XMember of Consejo Nacional de Investigaciones Cientifieas y Trcnicas, Argentina. 2Supported by grants from the Consejo Nacional de Investigaciones Cientificas y Trcnicas, Argentina. 257
258
CHIARAVIGLIO
was 104.0 ± 29.2 ml and the nocturnal intake was 59.0 + 11.8. When the test was started at 8 p.m., the nocturnal saline intake was 55.8 4 - 1 2 . 3 m l and the diurnal intake was 101.6 4- 26.7ml. This experiment showed that animals with septal lesions drank a larger amount of saline during the day, no mattel whether the test started with the diurnal or the nocturnal period. These experiments suggest that the septal area may play an important role in the regulation of the circadian rhythm. Since lesions in the olfactory bulb do not alter the drinking
habits, it can be inferred that the effect observed after the septal lesions is not due to the surgical procedure in itself. A n analysis of the function of the limbic system seems to stress its role in emotional behavior, drive and motivation [4, 5, 7]. The "septal syndrome" in rats, has been described [10] to produce emotional instability. On the other hand, there are evidences that the lesion of the septal area results in disinhibitory effects [7]. I n the present study the drinking habits were disrupted, suggesting that the septal structures play a role in mediating biological rhythms.
TABLE 1. CIRCADIAN VARIATIONS IN WATER AND 1 PER CENT NaC1 SOLUTIONINTAKEIN RATS
Conditions
Normal Olfactory bulb lesion Septal lesion
Normal Olfactory bulb lesion Septal lesion
Liquid Offered
Volume Intake (ml 4- SE) Diurnal Nocturnal (from 8 a.m. to 8 p.m.) (from 8 p.m. to 8 a.m.)
A. Following ad libitum access to food and water Water 9.6 + 2.0 (9) 1% NaC1 4.4 q- 1.7 (9)
p*
Value
16.7 ~ 1.0 (9) 8.3 4- 1.1 (9)
0.01 0.05
Water 1% NaCI
5.0 -4- 2.0 (9) 13.7 + 2.2 (9)
10.8 4- 1.6 (9) 21.6 4- 3.1 (9)
Water 1 ~o NaCI
7.6 4- 3.1 (9) 15.1 4- 4.0 (9)
13.1 i 2.7 (9) 15.9 4- 3.8 (9)
0.05 0.05 NS NS
6.0 4- 0.5 (6) 45.0 ± 6.7 (6)
NS 0.02
B. Following 24 hr food and sodium deprivation Water 3.5 q- 1.9 (6) 1% NaC1 19.8 ! 6.7 (6) Water 1% NaC1
3.6 4- 1.1 (6) 39.1 4- 14.1 (6)
3.3 ~: 0.8 (6) 55.0 4- 10.5 (6)
NS NS
Water 1% NaC1
0.8 4- 0.6 (6) 96.1 + 15.6 (6)
5.0 4- 1.3 (6) 45.0 4- 4.1 (6)
0.01 0.01
In brackets, number of animals. *"t" test diurnal vs. nocturnal.
REFERENCES
1. Aschoff, J. Comparative physiology: Diurnal rhythms. Ann. Rev. Physiol. 25: 581-600, 1963. 2. Chiaraviglio, E. Effects of lesions in the septal area and olfactory bulbs on sodium chloride intake. Physiol. Behav. 4: 693-967, 1969. 3. De Groot, J. The rat forebrain in stereotaxic coordinates. Trans. Roy. Neth. Acad. ScL 52: 1-40, 1959. 4. Ellen, P. and E. W. Powell. Temporal discrimination in rats with rhinencephalic lesions. Exp. Neurol. 6: 538-547, 1962. 5. Grossman, S. P. Effect of chemical stimulation of the septal area on motivation. J. comp. physiol. Psychol. 58: 194-200, 1964. 6. Halberg, F., R. E. Peterson and R. H. Silber. Phase relations of 24-hours periodicities in blood corticoesterona, mitoses in cortical adrenal parenchyma, and total body activity. Endocrinology 64: 222-230, 1959.
7. Hamilton, L. W., R. A. McCleary and S. P. Grossman. Behavioral effects of cholinergic septal blockade in the cat. J. comp. physiol. Psychol. 66: 563-568, 1968. 8. Nbgro Vilar, A., C. G. Gentil and M. R. Covian. Alterations in sodium chloride and water intake after septal lesions in the rat. Physiol. Behav. 2: 167-170, 1967. 9. Olds, J. Hypothalamic substrates of reward. Physiol. Rev. 42: 554-604, 1962. 10. Reymond, M. C. and K. Bfittig. A study of the "septal syndrome" in rats following electrolytic lesions. Jr. Physiol. (Paris) 56: 807-828, 1964. 11. Tarttelin, M. F. Cyclical variations in food and water intakes in ewes. J. Physiol. 195: 29-31, 1968.