- Email: [email protected]
Chronic treatment with haloperidol affect the response of the brain to pentobarbital
0028-3908/86 S3.00+0.00 Pergamon Journals Ltd
Neuropharmacology Vol. 25, No. 8, pp.943.945, 1986 Printed in Great Britain
CHRONIC TREATKENT WITB HALOPERIDOL AFFECT TRE RESPONSE OF THE BRAIN TO PENTOEARBITAL
J. Yanai, C.G. Pick and Carmela Iser-Strenger
The
Melvin
A.
and
Eleanor Ross Laboratory for Studies in Brain Defects Department of
Anatomy
and Smbryology
Hebrew University-BadassahAledicafSchool
91010 Jerusalem, Israel.
Summary. Treatment of mice with haloperidol increased the number of dopsmine D receptors (Enax ). The animals were given 40 or SO mg of pentobarbi .2 al. Animals treated with haloperidol had a shorter duration of narcosis induced by pentobarbital than the controls, suggesting a decreased sensitivity to pentobarbital which was functional (CNS), since the animals treated with haloperidol had higher levels of pentobarbital in the brain upon awakening than the controls. The results suggest that increased Bmnx reduces the sensitivity of the brain to pentobarbital. Key words: dopaminc receptor number, haloperidol, mice narcosis, pentobarbital sensitivity.
The present study demonstrates that the number of postsynaptic dopamine (DA) ) in mice is a significant determinant of the sensitivity of the brain to receptors (B barbiturates.max This suggestion is important for understanding the mechanisms of drug addicition since, at least with alcohol, the initial sensitivity to the addictive substance is correlated with being at risk of addicition to it (Schuckit, 1982; Pollock, 1986). Thus, it was relevant to estabiish an animal model for the neural mechanism of sensitivity to pentobarbitsl. The dopaminergic system may be involved in the response of the brain to barbiturates since changes in DA have been demonstrated after administration of barbiturates (Chang and Ho, 1979). Consequently, the number of postsynaptic DA receptors has been increased in mice and the effect of this alteration in the brain on the sensitivity to narcosis induced by barbiturates studied. It has been established that prolonged exposure to haloperidol induced several neurochemical changes (Seeman, 1980). Of particular significance is the increased number ) of DA receptors. Bannet, Belmaker and Ebstein (1980) described a procedure to (R ac?%plish this alteration in receptors by administering haloperidol in the food. Thus, in the present experiment, heterogeneous RS/Ibg male mice were housed in groups of eight and were given milled mouse food containing 26 mg/kg of haloperidol as their only food Supply and water, both available ad libitum; control mice received unadulterated milled food. The nice were maintained on this x for four weeks. .At day four after withdrawal, the treated mice and the control mice were used for biochemical or pharmacological eValUatiOn. For the evaluation of binding to dopamine receptors, the striata from 24 mice were used to produce each Scatchard plot, which was u&ed to derive the B,, and KD values (Table 1). The specific binding of [SK]spiroperidolwas determined according to Crease, Stewart and Snyder (1979). Thus, the binding was assessed at various concentrations of [3R]spiroperidol (0.2 0.6 ntd),using approximately 200 ug of protein in each incubation tube. The specific binding was measured as the difference in the binding obtained after iBCub@tiOn in the presence or absence of 10 uBdhaloperidol. The B,, (imole boundlmg protein) and KQ (n&i) were determined by linear regression analysis. Climbing behaviour, induced by apomorphine, was tested according to Protais, Conatentin and Schwartz (1976). The animals were injected subcutaneously with 2 or II mg/kg of apomorphine and their climbing was rated between 5 and 25 min after injection in a climbing cage (Protair et al., 1976). The number of postsynaptic DA receptors ) in the animals treated with (B,, haloperidol was 24% above the control level (p
944
Preliminary Notes
increase in Bmax of the dopamine D2 receptors in the haloperidol-treatedmice. The mice treated with haloperidol and the control mice were tested for th sensitivity to pentobarbital after intraperifoneal injection of 40 or 50 mg/kg of [nir Clpentobarbitone. The resulting narcosis (sleeping time,)was monitored as previously described (Yanai, Rosselli-Austin and Tabokoff, 1979). The levels of pentobarbitone in the brain were determined upon awakening by extraction and liquid scintillation counting (Yanai -.t et al 1979). The sleeping time of the animals treated with haloperidol was 4oLkshorter than the controls after an injection of 40 mg/kg of pentobarbitone and 23% shorter after SO mg/kg (p
Table 1.
The effect of chronic exposure to haloperidol on the sleeping time induced by intraperitoaeal injection of 40 or 50 mg/kg of pentobarbitsl, on the level of penrobarbital ia the brain upon awakening (in the group given 40 mg/kg), on the climbing induced by apomorphine (1 mg/kg), and on the binding of DA receptors.
Sleeping time (min) Treatment
Control
40 mg/kg
50 mg/kg
43.823.6
56.423.7
(21) Haloperidol
(34)
Pentobarbitone Climbing levels in brain scores (up/g)
22.121.7 !17)
25.8f3.4***43.41t2.9** 29.9*2.3*** (20)
(34)
(17)
7t2 (20) 15+,1*** (20)
DA receptor binding B (fnole)a KD(nb4) max
lS20~80 (24)
0.281f0.067 (24)
1882t102**0.246+0.088 (24)
(24)
Values are mean f SKM; ( ) = sample size; l * P
The number of postsynaptic DA receptors may be a major determinant of the sensitivity mice to narcosis induced by pentobarbitone, since in the present experiment, increasing the B,, of dopamine D2 receptors reduced the sensitivity to pentobarbitone-inducednarcosis. The present results are in line with findings with a related sedative hypaotic, ethanol. In the study with ethanol, inorearing the B,, for DA receptors, either by chronic treatment with haloperidol or by destruction of presynaptic terminals with 8-hydroxydopamine. caused a decrease in the narcosis induced by ethanol (Yanai, Feigenbaum and Banret, 1983). Similarly, when the S,,, was reduced in ratsby expeoure to haloperidol prenatally, narcosis induced by pentobarbitone was increased (Yanai and Fishman, 1984). Further support for this hypothesis comes from acute studies in which the administration of DA agonists attenuated (Osuide and Wambebe, 1980), and DA antagonists accentuated (Bhargava, 1982; Yanai, Fishman and Mittleman, 1984) narcosis induced by barbiturates. It ia well know that halopetidol affects other neurotraneaitter systems, in addition to dopuine (Seeman, 1980). However, taken together with previous findings, it is clear that altering DA receptors affects drug-induced narcosis, regardless of the method used. Therefore, it is most likely that haloperidol exerts it influence on narcosis induced by barbiturates, through its effect oa dOpamiBe receptors. of
The mechanism by which the number of DA receptors affects the sensitivity to barbiturates has not yet been determined. However, it appears that barbiturates depress presynaptic DA activity (Chang and So, 1979). Therefore, it is possible that an increased number or increased activity of poetsynaptic receptors is an adaptive phenomenon which offsets the preeyaaptic depression induced by the barbiturate.
Reliminary
Notes
945
There are suggestions that a reduced sensitivity to a drug is related to the liability to become addicted to it (Schuckit, 1982). Whether persons at risk who become addicted to barbiturates also posses a large number of postsynaptic DA receptors must remain an open question which warrants further investigation.
Acknowledgement. Supported by the Melvin A. and Eleanor Ross Fund.
REFERENCES
Bannet, J., Belmaker, R.H. and Ebstein, R.B. (1980). The effect of drug holidays in an animal model of tardive dyskinesia. P~y~hophnnac~l~gy, -69:223-224. Bhargava, K.N. (1982). Enhanced sensitivity to pentobarbital in haloperidol or pimoside treated mice and rats. Res. Convn.Chem.Patkol.Pha_nnmcol., %:267-283. of acute and chronic administration of pentoChang, Y-Y.H. and Ro, I.K. (1979). Effects barbital on catecholamine uptake in mouse brain synaptosomes. Res.Comn.Chem.Pathol. Phwnacol., -23:465-474. Creese, I.K., Stewart, II.and Snyder, S.H. (1979). Species variation in the dopamine receptor binding. Eur.J.Phannacol., 60:55-66. Osuide, G. and Wambebe, C. (1980). Antagonism of pentobarbitone sleep by dopamine, levodopa and apomorphine in chicks. clin.exp.Phaxwucot.Physiol., 1:237-248. Pollock, V.E. (1986). High risk research on alcoholism: a review of physiological findings. In: Alcohoi Dependence,the Family and the Community,J. Yanai, Ii.Bauml, P. Eldar and J.M. Rosenfeld teds). Freund, London (in press). Protais, P., Constentin, J. and Schwartz, J.C. (1976). Climbing behaviour Induced by apomorphfne in mice: a simple test for the study of dopamine receptors in striatum. Psychophaancco~., Jo:l-6. Schuckit, M.A. (1982). Biochemical markers of a predisposition to alcoholism. In: CZinicaI Biochemistryof Alcoholism,S.B. Rosalki (ed), Churchill Livingstone, Edinburgh. Seeman, P. (1980). Brain dopamine
receptors. Pharrriacol.iiet' , =:229-313.
Yanai, J., Rosselli-Austin, L. and Tftbokoff, B. (1979). Neuronal deficits in mice following prenatal exposure to phenobarbital. ,&,"p.iVeuro~., =:237-244. Yanai, J.. Feigenbaum, J.J. and Bannet, J. (1983). Supersensitivity of dopaminergic receptors diminishes sensitivity to ethanol narcosis. Res.Sonan.Substance Abuse, 4:263266. Yanai, J. and Fishman, R.H.B. (1984). Resistance to barbiturate is changed by developmental alteration of dopamine receptor sensitivity. Int.J.Dev.Neurosci., 1:61-64. Yanai, J., Fishman, R.A.B. and Mittleman, L. (1984). Ascorbic acid effect on ethanol and AlcoholActions/Misuse, 2: sensitivity via possible dopaminergic mediation. 2~
169-174.
Neuropharmacology Vol. 25, No. 8, pp.943.945, 1986 Printed in Great Britain
CHRONIC TREATKENT WITB HALOPERIDOL AFFECT TRE RESPONSE OF THE BRAIN TO PENTOEARBITAL
J. Yanai, C.G. Pick and Carmela Iser-Strenger
The
Melvin
A.
and
Eleanor Ross Laboratory for Studies in Brain Defects Department of
Anatomy
and Smbryology
Hebrew University-BadassahAledicafSchool
91010 Jerusalem, Israel.
Summary. Treatment of mice with haloperidol increased the number of dopsmine D receptors (Enax ). The animals were given 40 or SO mg of pentobarbi .2 al. Animals treated with haloperidol had a shorter duration of narcosis induced by pentobarbital than the controls, suggesting a decreased sensitivity to pentobarbital which was functional (CNS), since the animals treated with haloperidol had higher levels of pentobarbital in the brain upon awakening than the controls. The results suggest that increased Bmnx reduces the sensitivity of the brain to pentobarbital. Key words: dopaminc receptor number, haloperidol, mice narcosis, pentobarbital sensitivity.
The present study demonstrates that the number of postsynaptic dopamine (DA) ) in mice is a significant determinant of the sensitivity of the brain to receptors (B barbiturates.max This suggestion is important for understanding the mechanisms of drug addicition since, at least with alcohol, the initial sensitivity to the addictive substance is correlated with being at risk of addicition to it (Schuckit, 1982; Pollock, 1986). Thus, it was relevant to estabiish an animal model for the neural mechanism of sensitivity to pentobarbitsl. The dopaminergic system may be involved in the response of the brain to barbiturates since changes in DA have been demonstrated after administration of barbiturates (Chang and Ho, 1979). Consequently, the number of postsynaptic DA receptors has been increased in mice and the effect of this alteration in the brain on the sensitivity to narcosis induced by barbiturates studied. It has been established that prolonged exposure to haloperidol induced several neurochemical changes (Seeman, 1980). Of particular significance is the increased number ) of DA receptors. Bannet, Belmaker and Ebstein (1980) described a procedure to (R ac?%plish this alteration in receptors by administering haloperidol in the food. Thus, in the present experiment, heterogeneous RS/Ibg male mice were housed in groups of eight and were given milled mouse food containing 26 mg/kg of haloperidol as their only food Supply and water, both available ad libitum; control mice received unadulterated milled food. The nice were maintained on this x for four weeks. .At day four after withdrawal, the treated mice and the control mice were used for biochemical or pharmacological eValUatiOn. For the evaluation of binding to dopamine receptors, the striata from 24 mice were used to produce each Scatchard plot, which was u&ed to derive the B,, and KD values (Table 1). The specific binding of [SK]spiroperidolwas determined according to Crease, Stewart and Snyder (1979). Thus, the binding was assessed at various concentrations of [3R]spiroperidol (0.2 0.6 ntd),using approximately 200 ug of protein in each incubation tube. The specific binding was measured as the difference in the binding obtained after iBCub@tiOn in the presence or absence of 10 uBdhaloperidol. The B,, (imole boundlmg protein) and KQ (n&i) were determined by linear regression analysis. Climbing behaviour, induced by apomorphine, was tested according to Protais, Conatentin and Schwartz (1976). The animals were injected subcutaneously with 2 or II mg/kg of apomorphine and their climbing was rated between 5 and 25 min after injection in a climbing cage (Protair et al., 1976). The number of postsynaptic DA receptors ) in the animals treated with (B,, haloperidol was 24% above the control level (p
944
Preliminary Notes
increase in Bmax of the dopamine D2 receptors in the haloperidol-treatedmice. The mice treated with haloperidol and the control mice were tested for th sensitivity to pentobarbital after intraperifoneal injection of 40 or 50 mg/kg of [nir Clpentobarbitone. The resulting narcosis (sleeping time,)was monitored as previously described (Yanai, Rosselli-Austin and Tabokoff, 1979). The levels of pentobarbitone in the brain were determined upon awakening by extraction and liquid scintillation counting (Yanai -.t et al 1979). The sleeping time of the animals treated with haloperidol was 4oLkshorter than the controls after an injection of 40 mg/kg of pentobarbitone and 23% shorter after SO mg/kg (p
Table 1.
The effect of chronic exposure to haloperidol on the sleeping time induced by intraperitoaeal injection of 40 or 50 mg/kg of pentobarbitsl, on the level of penrobarbital ia the brain upon awakening (in the group given 40 mg/kg), on the climbing induced by apomorphine (1 mg/kg), and on the binding of DA receptors.
Sleeping time (min) Treatment
Control
40 mg/kg
50 mg/kg
43.823.6
56.423.7
(21) Haloperidol
(34)
Pentobarbitone Climbing levels in brain scores (up/g)
22.121.7 !17)
25.8f3.4***43.41t2.9** 29.9*2.3*** (20)
(34)
(17)
7t2 (20) 15+,1*** (20)
DA receptor binding B (fnole)a KD(nb4) max
lS20~80 (24)
0.281f0.067 (24)
1882t102**0.246+0.088 (24)
(24)
Values are mean f SKM; ( ) = sample size; l * P
The number of postsynaptic DA receptors may be a major determinant of the sensitivity mice to narcosis induced by pentobarbitone, since in the present experiment, increasing the B,, of dopamine D2 receptors reduced the sensitivity to pentobarbitone-inducednarcosis. The present results are in line with findings with a related sedative hypaotic, ethanol. In the study with ethanol, inorearing the B,, for DA receptors, either by chronic treatment with haloperidol or by destruction of presynaptic terminals with 8-hydroxydopamine. caused a decrease in the narcosis induced by ethanol (Yanai, Feigenbaum and Banret, 1983). Similarly, when the S,,, was reduced in ratsby expeoure to haloperidol prenatally, narcosis induced by pentobarbitone was increased (Yanai and Fishman, 1984). Further support for this hypothesis comes from acute studies in which the administration of DA agonists attenuated (Osuide and Wambebe, 1980), and DA antagonists accentuated (Bhargava, 1982; Yanai, Fishman and Mittleman, 1984) narcosis induced by barbiturates. It ia well know that halopetidol affects other neurotraneaitter systems, in addition to dopuine (Seeman, 1980). However, taken together with previous findings, it is clear that altering DA receptors affects drug-induced narcosis, regardless of the method used. Therefore, it is most likely that haloperidol exerts it influence on narcosis induced by barbiturates, through its effect oa dOpamiBe receptors. of
The mechanism by which the number of DA receptors affects the sensitivity to barbiturates has not yet been determined. However, it appears that barbiturates depress presynaptic DA activity (Chang and So, 1979). Therefore, it is possible that an increased number or increased activity of poetsynaptic receptors is an adaptive phenomenon which offsets the preeyaaptic depression induced by the barbiturate.
Reliminary
Notes
945
There are suggestions that a reduced sensitivity to a drug is related to the liability to become addicted to it (Schuckit, 1982). Whether persons at risk who become addicted to barbiturates also posses a large number of postsynaptic DA receptors must remain an open question which warrants further investigation.
Acknowledgement. Supported by the Melvin A. and Eleanor Ross Fund.
REFERENCES
Bannet, J., Belmaker, R.H. and Ebstein, R.B. (1980). The effect of drug holidays in an animal model of tardive dyskinesia. P~y~hophnnac~l~gy, -69:223-224. Bhargava, K.N. (1982). Enhanced sensitivity to pentobarbital in haloperidol or pimoside treated mice and rats. Res. Convn.Chem.Patkol.Pha_nnmcol., %:267-283. of acute and chronic administration of pentoChang, Y-Y.H. and Ro, I.K. (1979). Effects barbital on catecholamine uptake in mouse brain synaptosomes. Res.Comn.Chem.Pathol. Phwnacol., -23:465-474. Creese, I.K., Stewart, II.and Snyder, S.H. (1979). Species variation in the dopamine receptor binding. Eur.J.Phannacol., 60:55-66. Osuide, G. and Wambebe, C. (1980). Antagonism of pentobarbitone sleep by dopamine, levodopa and apomorphine in chicks. clin.exp.Phaxwucot.Physiol., 1:237-248. Pollock, V.E. (1986). High risk research on alcoholism: a review of physiological findings. In: Alcohoi Dependence,the Family and the Community,J. Yanai, Ii.Bauml, P. Eldar and J.M. Rosenfeld teds). Freund, London (in press). Protais, P., Constentin, J. and Schwartz, J.C. (1976). Climbing behaviour Induced by apomorphfne in mice: a simple test for the study of dopamine receptors in striatum. Psychophaancco~., Jo:l-6. Schuckit, M.A. (1982). Biochemical markers of a predisposition to alcoholism. In: CZinicaI Biochemistryof Alcoholism,S.B. Rosalki (ed), Churchill Livingstone, Edinburgh. Seeman, P. (1980). Brain dopamine
receptors. Pharrriacol.iiet' , =:229-313.
Yanai, J., Rosselli-Austin, L. and Tftbokoff, B. (1979). Neuronal deficits in mice following prenatal exposure to phenobarbital. ,&,"p.iVeuro~., =:237-244. Yanai, J.. Feigenbaum, J.J. and Bannet, J. (1983). Supersensitivity of dopaminergic receptors diminishes sensitivity to ethanol narcosis. Res.Sonan.Substance Abuse, 4:263266. Yanai, J. and Fishman, R.H.B. (1984). Resistance to barbiturate is changed by developmental alteration of dopamine receptor sensitivity. Int.J.Dev.Neurosci., 1:61-64. Yanai, J., Fishman, R.A.B. and Mittleman, L. (1984). Ascorbic acid effect on ethanol and AlcoholActions/Misuse, 2: sensitivity via possible dopaminergic mediation. 2~
169-174.