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Interaction of d-amphetamine with central nervous system depressants on food intake and spontaneous motor activity of mice
EUROPEAN JOURNALOF PHARMACOLOGY26 (1974) 119-121. NORTH-HOLLANDPUBLISHINGCOMPANY
Short c o m m u n i c a t i o n I N T E R A C T I O N OF d-AMPHETAMINE WITH C E N T R A L N E R V O U S SYSTEM D E P R E S S A N T S O N F O O D I N T A K E A N D S P O N T A N E O U S M O T O R A C T I V I T Y O F MICE Abdulmuniem H. ABDALLAH, Harold D. WHITE and Anant S. KULKARNI* Chemical Biology Research, The Dow Chemical Company, Midland, Michigan 48640, U.S.A.
Received 11 December 1973
Accepted 22 February 1974
A.H. ABDALLAH,H.D. WHITE and A.S. KULKARNI,Interaction old-amphetamine with central nervous system depressants on food intake and spontaneous motor activity of mice, European J. Pharmacol. 26 (1974) 119-121. Pentobarbitat, chlordiazepoxide, diazepam, meprobamate and piperacetazine antagonized the anorectic effect of d-amphetamine. However, theft antagonism of the motor stimulant effect of d-amphetamine was not uniform. Pentobarbital significantly increased but diazepam and piperacetazine significantly decreased the motor stimulant effect of d-amphetamine. Ch.lordiazepoxide and meprobamate did not alter the amphetamine effect on motor activity.
Motor activity Antipsychotic
Amphetamine Depressants
Anorexia Mice
1. Introduction
2. Materials and methods
d-Amphetamine is widely used as an anorectic. To attenuate its central stimulant effect, it is used in combination with various central nervous system depressants such as amobarb, meprobamate and prochlorperazine. However, in animals, the increase in spontaneous motor activity (SMA) induced by d-amphetamine is enhanced by pentobarbital, reserpine, meprobamate, chlordiazepoxide (Sethy et al., 1970) and chlorpromazine (Sulser and Dingell, 1968). The purpose of this study was to investigate the effect of combinations of d-amphetamine and some central nervous system depressants on food intake and spontaneous motor activity in mice.
2.1. Measurement of f o o d intake
* Present address: Head, Neuropsychiatry Section, Corporate Clinical Research, Abbott Laboratories, North Chicago, Illinois 60064, U.S.A.
Groups of 3 male albino mice obtained from Harlan Industries, Cumberland, Indiana, and weighing 2 5 - 3 0 g, were placed in suspended wire cages (10 X 25 × 13 cm) and trained for 5 days to eat their daily meal in spill-proof containers within 6 hr during the day and starved for the remaining 18 hr. The meal consisted of ground Wayne Lab Chow. Water was freely available. On the 6th day, compounds to be tested were administered orally 30 min before food was presented. One group of mice received an equivalent volume of Methocel ® and served as a control. Test compounds were dissolved in 0.5% Methocel 30 min before oral administration. Food consumption by each group was measured at 1 and 3 hr intervals and compared to the amount of food consumed by the control group. Food intake was recorded in g. The percentage reduction of food intake was calculated by comparing food intake of drug-treated group to that of the control group. Results were analyzed by
120
A.H. A bdallah et al., Amphetamine effects and CNS depressants
Student's t-test (one-tailed) and p < 0.05 was the critical level of significance. 2.2. Spontaneous motor activity (SMA ) 6 photo cell activity units mounted in a soundproof room were used to measure locomotor activity of adult male albino mice. Photo cell activity unit consisted of a solid-wall circular cage 21 cm in diameter and 20 cm in height and a 'runway width' of 9 cm, with 6 small equally spaced holes cut in the perimeter just above the floor. The electronic circuitry was arranged so that interruption of any of the 6 light beams within the cage causes a digital counter to record one count. The counters and recorder were located outside the soundproof room. Groups of 3 male albino mice ( 1 8 - 2 0 g) were placed in the activity cage for 30 min and the counts were recorded for 30 min. At the end of this period the mice were administered a drug dissolved in 0.05% Methocel ® orally and placed again in the activity cages and the counts were recorded for 2 more hr. The total counts during each 30 min interval after drug administration were divided by the total counts during the pretreatment 30 min interval, the ratios of drug-treated group were compared to those of the control group and changes were expressed as percentage change from vehicle-injected controls. Results were analyzed by one-tailed Mann Whitney Test (Siegel, 1956) and p < 0.05 was the critical level of significance. It should be noted that 3 0 - 9 0 min periods after drug administration would be equivalent to the one hour period of measurement of food as described earlier.
3. Results (table 1) Oral administration of 4.6 mg/kg of d-amphetamine caused a significant reduction of food intake and a significant increase in SMA of the mice. Generally speaking, the CNS depressants, as the doses employed, had no significant effect on food intake. On the other hand the SMA was decreased by chlordiazepoxide, diazepam and piperacetazine. Meprobamate showed a very small decrease and pentobarbital showed a marginal increase in SMA. Pentobarbital (36 mg/kg) and chlordiazepoxide (46 mg/kg)
Table 1 Changes in food consumption and motor activity. Drug
Dose (oral, mg/kg)
Average1 Change in food intake (% of control, 1 hr consumption)
Average2 Changein SMA (% of control) equivalent 1 hr period
d-Amphetamine Pentobarbital Chlordiazepoxide Diazepam Meprobamate Piperacetazine
4.6 (A) 36.0 (Pb) 46.0 (C) 21.0 (D) 46.0 (M) 1.0 (Pp)
-52* + 1 + 15 + 10 + 13 0
+230* + 25 - 80* - 90* - 40 - 90*
-34** - 7** -27** -25** -26**
+550** +150 +110"* +225 - 50**
Pb + A*** C +A D +A M +A Pp + A
lEach figure represents 5 measurements expressed as change from controls. 2Each figure represents 10 measurements expressed as change from controls. *Significant difference from controls p < 0.05, one-tailed. **p < 0.05, one-tailed, compared to "amphetamine alone" group (A). ***Simultaneous oral administration.
antagonized the anorectic effect of amphetamine. On SMA, however, pentobarbital (36 mg/kg) demonstrated a very large increase in the amphetamine-induced stimulation of SMA. Chlordiazepoxide did not alter the amphetamine-induced increase in SMA. Diazepam (21 mg/kg) antagonized both the anorectic and the SMA stimulant effect of amphetamine. Meprobamate (46 mg/kg) reduced the anorectic effect of amphetamine. It appeared to increase the stimulant effect of amphetamine on SMA, but the change was not significant. Piperacetazine (1 mg/kg) reduced both the anoretic and SMA stimulant effect of amphetamine.
4. Discussion Our results support those of Sethy et al. (1970) and Kumar (1971), who showed that pentobarbital and amylobarbitone in combination with d-amphetamine caused a greater increase in SMA of mice and
A.H. Abdallah et al., Amphetamine effects and CArS depressants
rats respectively as compared to amphetamine alone. The antagonism of the anorectic effect of d-amphetamine by barbiturates may be explained due to the fact that barbiturates increase the metabolism o f amphetamine (Goldstein et al., 1968). However, this explanation is not likely because the acute administration of the same dose of pentobarbital potentiates the stimulant effect of d-amphetamine on one hand and antagonizes its anoretic effect on the other. Chlordiazepoxide (46 mg/kg) and diazepam (21 mg/kg) antagonize both the anorectic and SMA stimulant effect of amphetamine. These results partly disagree with those of Randall et al. (1960) who showed that chlordiazepoxide (10 and 21 mg/kg) increased the anorectic effect of d-amphetamine in dogs. These differences could be due to differences in dose ratios or species used in the two studies. Our results show that all central nervous system depressants studied show an antagonism to the anorectic effect of d-amphetamine. However, their effects on amphetamine-induced increase in SMA are not uniform. The finding that CNS depressants antagonize the anorectic activity of d-amphetamine but do not uniformly antagonize its stimulant activity, probably indicates that amphetamine's anorectic activity is not a result of its stimulation of motor activity.
121
Acknowledgements The authors are grateful to those who supplied the following compounds: chlordiazepoxide and diazepam (HoffmanLa Roche, Inc., Nutley, N.J.); meprobamate (Wyeth Labs, Inc., Philadelphia, Pa.).
References Goldstein, A., I. Aronow and S.M. Kalman, 1968, Drug metabolism, in: Principles of Drug Action (The Basis of Pharmacology) (Harper and Row, New York) p. 206. Kumar, R., 1971, Extinction of fear. I. Effects of amylobarbitone and dexamphetamine given separately or in combination on fear and exploratory behavior in rats, Psychopharmacology 19,163. Randall, L.O., W. SchaUek, G.A. Heise, E.F. Keith and R.E. Bagdon, 1960, The psychoactive properties of methamine diazepoxide, J. Pharmacol. Exptl. Therap. 129, 163. Sethy, V.H., P.Y. Naik and U.K, Sheth, 1970, Effect of d-amphetamine sulfate in combination with CNS depressants on spontaneous motor activity of mice, Psychopharmacologia (Berlin) 18, 19. Siegel, S., 1956, Non-parametric Statistics (McGraw Hill, New York, N.Y.). Sulser, F. and J.V. DingeU, 1968, Potentiation and blockade of the central action of amphetamine by chlorpromazine, Biochem. Pharmacol. 17,634.
Short c o m m u n i c a t i o n I N T E R A C T I O N OF d-AMPHETAMINE WITH C E N T R A L N E R V O U S SYSTEM D E P R E S S A N T S O N F O O D I N T A K E A N D S P O N T A N E O U S M O T O R A C T I V I T Y O F MICE Abdulmuniem H. ABDALLAH, Harold D. WHITE and Anant S. KULKARNI* Chemical Biology Research, The Dow Chemical Company, Midland, Michigan 48640, U.S.A.
Received 11 December 1973
Accepted 22 February 1974
A.H. ABDALLAH,H.D. WHITE and A.S. KULKARNI,Interaction old-amphetamine with central nervous system depressants on food intake and spontaneous motor activity of mice, European J. Pharmacol. 26 (1974) 119-121. Pentobarbitat, chlordiazepoxide, diazepam, meprobamate and piperacetazine antagonized the anorectic effect of d-amphetamine. However, theft antagonism of the motor stimulant effect of d-amphetamine was not uniform. Pentobarbital significantly increased but diazepam and piperacetazine significantly decreased the motor stimulant effect of d-amphetamine. Ch.lordiazepoxide and meprobamate did not alter the amphetamine effect on motor activity.
Motor activity Antipsychotic
Amphetamine Depressants
Anorexia Mice
1. Introduction
2. Materials and methods
d-Amphetamine is widely used as an anorectic. To attenuate its central stimulant effect, it is used in combination with various central nervous system depressants such as amobarb, meprobamate and prochlorperazine. However, in animals, the increase in spontaneous motor activity (SMA) induced by d-amphetamine is enhanced by pentobarbital, reserpine, meprobamate, chlordiazepoxide (Sethy et al., 1970) and chlorpromazine (Sulser and Dingell, 1968). The purpose of this study was to investigate the effect of combinations of d-amphetamine and some central nervous system depressants on food intake and spontaneous motor activity in mice.
2.1. Measurement of f o o d intake
* Present address: Head, Neuropsychiatry Section, Corporate Clinical Research, Abbott Laboratories, North Chicago, Illinois 60064, U.S.A.
Groups of 3 male albino mice obtained from Harlan Industries, Cumberland, Indiana, and weighing 2 5 - 3 0 g, were placed in suspended wire cages (10 X 25 × 13 cm) and trained for 5 days to eat their daily meal in spill-proof containers within 6 hr during the day and starved for the remaining 18 hr. The meal consisted of ground Wayne Lab Chow. Water was freely available. On the 6th day, compounds to be tested were administered orally 30 min before food was presented. One group of mice received an equivalent volume of Methocel ® and served as a control. Test compounds were dissolved in 0.5% Methocel 30 min before oral administration. Food consumption by each group was measured at 1 and 3 hr intervals and compared to the amount of food consumed by the control group. Food intake was recorded in g. The percentage reduction of food intake was calculated by comparing food intake of drug-treated group to that of the control group. Results were analyzed by
120
A.H. A bdallah et al., Amphetamine effects and CNS depressants
Student's t-test (one-tailed) and p < 0.05 was the critical level of significance. 2.2. Spontaneous motor activity (SMA ) 6 photo cell activity units mounted in a soundproof room were used to measure locomotor activity of adult male albino mice. Photo cell activity unit consisted of a solid-wall circular cage 21 cm in diameter and 20 cm in height and a 'runway width' of 9 cm, with 6 small equally spaced holes cut in the perimeter just above the floor. The electronic circuitry was arranged so that interruption of any of the 6 light beams within the cage causes a digital counter to record one count. The counters and recorder were located outside the soundproof room. Groups of 3 male albino mice ( 1 8 - 2 0 g) were placed in the activity cage for 30 min and the counts were recorded for 30 min. At the end of this period the mice were administered a drug dissolved in 0.05% Methocel ® orally and placed again in the activity cages and the counts were recorded for 2 more hr. The total counts during each 30 min interval after drug administration were divided by the total counts during the pretreatment 30 min interval, the ratios of drug-treated group were compared to those of the control group and changes were expressed as percentage change from vehicle-injected controls. Results were analyzed by one-tailed Mann Whitney Test (Siegel, 1956) and p < 0.05 was the critical level of significance. It should be noted that 3 0 - 9 0 min periods after drug administration would be equivalent to the one hour period of measurement of food as described earlier.
3. Results (table 1) Oral administration of 4.6 mg/kg of d-amphetamine caused a significant reduction of food intake and a significant increase in SMA of the mice. Generally speaking, the CNS depressants, as the doses employed, had no significant effect on food intake. On the other hand the SMA was decreased by chlordiazepoxide, diazepam and piperacetazine. Meprobamate showed a very small decrease and pentobarbital showed a marginal increase in SMA. Pentobarbital (36 mg/kg) and chlordiazepoxide (46 mg/kg)
Table 1 Changes in food consumption and motor activity. Drug
Dose (oral, mg/kg)
Average1 Change in food intake (% of control, 1 hr consumption)
Average2 Changein SMA (% of control) equivalent 1 hr period
d-Amphetamine Pentobarbital Chlordiazepoxide Diazepam Meprobamate Piperacetazine
4.6 (A) 36.0 (Pb) 46.0 (C) 21.0 (D) 46.0 (M) 1.0 (Pp)
-52* + 1 + 15 + 10 + 13 0
+230* + 25 - 80* - 90* - 40 - 90*
-34** - 7** -27** -25** -26**
+550** +150 +110"* +225 - 50**
Pb + A*** C +A D +A M +A Pp + A
lEach figure represents 5 measurements expressed as change from controls. 2Each figure represents 10 measurements expressed as change from controls. *Significant difference from controls p < 0.05, one-tailed. **p < 0.05, one-tailed, compared to "amphetamine alone" group (A). ***Simultaneous oral administration.
antagonized the anorectic effect of amphetamine. On SMA, however, pentobarbital (36 mg/kg) demonstrated a very large increase in the amphetamine-induced stimulation of SMA. Chlordiazepoxide did not alter the amphetamine-induced increase in SMA. Diazepam (21 mg/kg) antagonized both the anorectic and the SMA stimulant effect of amphetamine. Meprobamate (46 mg/kg) reduced the anorectic effect of amphetamine. It appeared to increase the stimulant effect of amphetamine on SMA, but the change was not significant. Piperacetazine (1 mg/kg) reduced both the anoretic and SMA stimulant effect of amphetamine.
4. Discussion Our results support those of Sethy et al. (1970) and Kumar (1971), who showed that pentobarbital and amylobarbitone in combination with d-amphetamine caused a greater increase in SMA of mice and
A.H. Abdallah et al., Amphetamine effects and CArS depressants
rats respectively as compared to amphetamine alone. The antagonism of the anorectic effect of d-amphetamine by barbiturates may be explained due to the fact that barbiturates increase the metabolism o f amphetamine (Goldstein et al., 1968). However, this explanation is not likely because the acute administration of the same dose of pentobarbital potentiates the stimulant effect of d-amphetamine on one hand and antagonizes its anoretic effect on the other. Chlordiazepoxide (46 mg/kg) and diazepam (21 mg/kg) antagonize both the anorectic and SMA stimulant effect of amphetamine. These results partly disagree with those of Randall et al. (1960) who showed that chlordiazepoxide (10 and 21 mg/kg) increased the anorectic effect of d-amphetamine in dogs. These differences could be due to differences in dose ratios or species used in the two studies. Our results show that all central nervous system depressants studied show an antagonism to the anorectic effect of d-amphetamine. However, their effects on amphetamine-induced increase in SMA are not uniform. The finding that CNS depressants antagonize the anorectic activity of d-amphetamine but do not uniformly antagonize its stimulant activity, probably indicates that amphetamine's anorectic activity is not a result of its stimulation of motor activity.
121
Acknowledgements The authors are grateful to those who supplied the following compounds: chlordiazepoxide and diazepam (HoffmanLa Roche, Inc., Nutley, N.J.); meprobamate (Wyeth Labs, Inc., Philadelphia, Pa.).
References Goldstein, A., I. Aronow and S.M. Kalman, 1968, Drug metabolism, in: Principles of Drug Action (The Basis of Pharmacology) (Harper and Row, New York) p. 206. Kumar, R., 1971, Extinction of fear. I. Effects of amylobarbitone and dexamphetamine given separately or in combination on fear and exploratory behavior in rats, Psychopharmacology 19,163. Randall, L.O., W. SchaUek, G.A. Heise, E.F. Keith and R.E. Bagdon, 1960, The psychoactive properties of methamine diazepoxide, J. Pharmacol. Exptl. Therap. 129, 163. Sethy, V.H., P.Y. Naik and U.K, Sheth, 1970, Effect of d-amphetamine sulfate in combination with CNS depressants on spontaneous motor activity of mice, Psychopharmacologia (Berlin) 18, 19. Siegel, S., 1956, Non-parametric Statistics (McGraw Hill, New York, N.Y.). Sulser, F. and J.V. DingeU, 1968, Potentiation and blockade of the central action of amphetamine by chlorpromazine, Biochem. Pharmacol. 17,634.