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Quantification of dopaminergic supersensitization using apomorphine-induced behavior in the mouse
Life Sciences, Vol. 37, pp. 1419-1423 Printed in the U.S.A.
Pergamon Press
QUANTIFICATION OF DOPAMINERGIC SUPERSENSITIZATION APOMORPHINE-INDUCED BEHAVIOR IN THE MOUSE.
USING
P a t r i c k K. Randall Department of Physiology and Biophysics, USC S c h o o l o f M e d i c i n e and Andrus Gerontology Center, University P a r k , Los A n g e l e s , California 90089-0191
(Received in final form August 5, 1985) Summar~
Dose-response curves f o r apomorphine-induced behavior were determined in C57BL/6J mice with and without a 30 day treatment with 2.5 mg/kg/day h a l o p e r i d o l . The e f f e c t of the chronic n e u r o l e p t i c , whether a s s e s s e d by the dose-response curve for t o t a l r a t i n g s or by a m u l t i p l e l o g i s t i c method determlning EDs0'S for t r a n s i t i o n s between i n d i v i d u a l s t e r e o t y p e r a t i n g s , was [o s h i f t the curve to the l e f t by a f a c t o r of s l i g h t l y l e s s than 2. This e s t i m a t e i s considerably d i f f e r e n t from those using the r o t a t i o n a l model and denervatJon as the s u p e r s e n s i t i z i n gs t i m u l u s . There was no i n d i c a t i o n of s e l e c t i v e e f f e c t s of the n e u r o l e p t i c treatment on i n d i v i d u a l components of the behavioral response. Chronic treatment with dopaminergic (DA) a n t a g o n i s t s and denervation by d e s t r u c t i o n of the n i g r o - s t r i a t a l pathway r e s u l t in an apparent DA s u p e r s e n s i t i z a t i o nas a s s e s s e d by e i t h e r receptor binding, or behavioral response Loa DA a g o n i s t (1-3). A number of i n v e s t i g a t o r s have r e c e n t l y made q u a n t i t a t i v e e s t i m a t e s of the degree of s u p e r s e n s i t i z a t i o n in the denervation model by measuring a g o n i s t {apomorphine)-induced r o t a t i o n a l behavior in rodents with u n i l a t e r a l l e s i o n s i n t e r r u p t i n g s t r i a t a l e f f e r e n t s before and a f t e r 6-hydroxy-dopamine (60HDA) l e s i o n s of the c o n t r a l a t e r a l n i g r o - s t r i a t a ] pathway. Rotation a f t e r the e f f e r e n t l e s i o n a l o n e - - e l e c t r o l y t i c s t r i a t o - n i g r a l l e s i o n (4-6) or kainate-induced l e s i o n of the s t r i a t u m ( 7 ) - - p r o v i d e s a b a s e l i n e measure of s e n s i t i v i t y of the "normosensitive" s t r i a t u m . The r e s u l t i n g i n c r e a s e in s e n s i t i v i t y i s a p p r o p r i a t e l y expressed as the " s h i f t " to the l e f t in the dose-response curve r a t h e r than as d i f f e r e n c e s in magnitude of response a t ay p a r t i c u l a r dose (8). Analyzed in t h i s manner the f u n c t i o n r e l a t i n g receptor occupancy i s indeterminant, i . e . i t does not require a l i n e a r r e l a t i o n s h i p between occupancy and response (9). I t ] s n e c e s s a r y , however, to obtain r e l a t i v e l y complete dose--response curves in both c o n t r o l and s u p e r s e n s i t i z e d p r e p a r a t i o n s . Estimates of the degree of s u p e r s e n s i t i v i t ymade in t h i s manner range from 10 to 30 f o l d . This e s t i m a t e i s q u i t e high to be accounted for by the t y p i c a l 30% d i f f e r e n c e in receptor number ( ] , I 0 , 1 ] ) . Supersensitization of apomorphine-induced stereotypic behavior has not been as extensively quantified. The n e c e s s i t y of evaluating full dose-response curves is even more evident in this case than in the rotational behavior model because of the questionable measurement status of stereotypic "ratings", i.e. ratings are, at best, ordinal measures of the response. C l e a r l y an i n c r e a s e i n mean r a t i n g f r o m "3" t o " 4 " d o e s n o t r e p r e s e n t a 33% i n c r e a s e in the magnitude of the
0024-3205/85 $3.00 + .00 Copyright (c) 1985 Pergamon Press Ltd.
1420
Quantification
of DA Supersensitization
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apomorphine response. However, if the position of the dose-response curve along t h e X - a x i s c a n be a c c u r a t e l y determined, alterations in this parameter have obvious quantitative meaning, particularly if different components of the behavioral response are taken into account. We r e p o r t h e r e a q u a n t i t a t i v e study of behavioral DA s u p e r s e n s i t i z a t i o n i n d u c e d by c h r o n i c h a l o p e r i d o l administration, assessing dose-response curves apomorphine with and without a 30-day haloperido] treatment.
to
Methods Animals and d e s i g n C57BI,/6J m i c e o b t a i n e d f r o m J a c k s o n I , a b o r a l o r i e s ( B a r H~J~.'bor', NI';) seJ'w~d a s subjects for this experiment. They w e r e 5 - 6 mo o f a g e a t t h e t i m e o f t i m experiment. Mice w e r e a s s i g n e d t o a f a c t o r i a l c o m b i n a t i o n ( 8 - 1 0 mice~group} o f Chronic Treatment (2.5 mg/kg/day haloperidol vs. lactic acid vehicle) and Apomorphine Dose (0.5, 1.0, 2.(I, 4.0, or 8.0 mg/kg). Haloperidol was administered in the drinking water starting a t 20ug/ml and a d j u s t e d in accot'daucr with monitored daily water intake to represent approximately 2 . 5 mg/kg/day. A p o m o r p h i n e was d i s s o l v e d i n 0.9% s a l i n e , p l a c e d on i c e , and i n j e c t e d intraperitonea]ly w i t h i n 10 min o f b e i n g p r e p a r e d . Behavioral
testing
ApomorphJne induced
took place
after
a 7 day drug-free
period.
behavior
The b e h a v i o r a l r e s p o n s e t o a p o m o r p h i n e was a s s e s s e d i n 15 x 15 X 15 cm enclosures of 1/4 in w i r e mesh w i t h s o l i d p l e x i g l a s s t o p s and f l o o r s . Apomorphine was a d m i n i s t e r e d a f t e r a 10 min h a b i t u a t i o n period. Thirty second observations w e r e made e v e r y 6 min f o l l o w i n g i n j e c t i o n for a period of 1 hr. At each observation a r a t i n g o f t h e d r u g - i n d u c e d b e h v i o r was made a c c o r d i n g t o a 7 p o i n t r a t i n g s c a l e d e v e l o p e d on t h e C 5 7 B L / 6 J m o u s e ( 1 2 , 1 3 ) . This scale gives a log--linear dose-response c u r v e over' a w i d e r a n g e e f d o s e s . Twelve mice were tested simultaneously in one of four sessions pet" d a y : two b e t w e e n 0900 and 1300 a n d two b e t w e e n 1400 a n d 1 7 0 0 . All groups were equally represented in e a c h r u n so t h a t time of day and run v a r i a b l e s were balanced across groups. Data Analysis Data were analyzed first by s t a n d a r d ANOVA t e c h n i q u e s . El)50's for 1oral stereotypic ratings were then estimated u s i n g t h e ALLFIT ( 1 5 ) p r o g r a m for" t h e logistic function. Finally, a non-linear regression r o u t i n e was u s e d to esi. imat~ t h e ED values for lransiticns between ratings. For this analysis t i l e [,:D50 and 50 " " slopes of quantai dose response curves (12) representing ratings of greake}: than o r e q u a l t o 3, 4, o r 5 w e r e d e t e r m i n e d . I n tile l a t t e r aua]ysJs th~ geometric mean o f t h e E D s o ' S f o r i r l d i v i d u t J l c o m p o n e n t s was u s e d a s a g e n c r t ; ] p o s i t i o n parameter. R e s u ] t.s The 3{1 d a y h a l o p e r ~ d o ~ t r e a t m e n t p r o d u c e d a s i ? , n i f i c a n t eleval;on in t h e intensity of apomorphine induced behavior as reflected in s t e r e o t y p e :'atings (F=]8.25;df=l.63;p<.05). Mean t o t a l riltirlgs f o r lh(,' two g r o u p s ~ll e a c h a p o m o r p h i n e d o s e i s s h o w n i n F i g . 1. The i n c r e a s e d r e s p o n s e was n o t d e p e n d e n t . upon alteration o f t i m e c n u r s e s ~ n c e I;he Time a f t e r a p o m o r p h : i n e J n j e c [ i u [ l X Baloperidol treatment interaction failed to approach significance (p>.05). Dose of apomorphine (F-lO1.4;df:4,63;p<.OOl) a n d Time a f t e r a p o m o r p h i n e i n j e c t i o n
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Quantification of DA Supersensitization
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(F=59.66;df=9,587;p<.001) were both highly significant as expected. In addition, the Dose X Time after apomorphine interaction was significant (F=4.04; df-36,587;p<.001), indicating a more prolonged behavioral response in those mice receiving the higher apomorphine doses. Calculation o f ED__ v a l u e s f o r t h e two g r o u p s w a s d o n e b y f i t t i n g the ou generalized logistic function. No s i g n i f i c a n t difference between fits of models sharing either slopes or maximum responses was obtained, so final values are best fitting parameters w i t h maximum r e s p o n s e a n d s l o p e s s h a r e d . In all fits the minimum response was constrained to zero. S h a r i n g E D 5 _ ' s o f t h e two c u r v e s d i d result in a degredation of the fit (F=25 22;df=7,6;p<.~25) relative to the fit allowing maxima, slopes, a n d ED ' s t o d i v e r g e The resultant ED 5_ v a l u e s w e r e 0 1.022 and 1.77 mg/kg for the ha~operidol and control groups respectively, representing a 1.73 fold increase in sensitivity.
50 o
40
Z
N 30 _1 0 I--
tx
20 I0 I
0.5
1.0 2.0 4.0 8 . 0 r l ~ / ~
DOSE APOMORPHINE Fig. i Mean t o t a l ratings for C57BL/6J mice as a function of apomorphine dose and chronic drug treatment. Closed circles represent mice receiving 2.5 mg/kg/day haloperido] in the drinking water. Open circles represent control mice receiving only dilute lactic a c i d f o r 30 d a y s . Lines represent best--fitting logistic dose-response curve (see text). A final analysis was done to determine the extent to which the shift in rating magnitude might be related to increases in a particular, perhaps highly rated, category of behavior vs an actual shift to the left in the curve. Analysis of logistic dose-response curves of individual rating transitions for ratings greater than or equal to 3, 4, or 5 were highly consistent with the simple shift hypothesis. The best fitting curves along with their ED__'s is oU s h o w n i n F i g . 2. It can be seen that each component shifted in a consistent manner by factors of 1.67, 1.57, and 1.53. Thus, there was no alteration in the sequence of behavioral c h a n g e s w i t h d o s e i n t h e two c o n d i t i o n s . The chronic haloperidol treated mice simply went through the sequence at slightly lower doses. The overall shift {alteration in geometric m e a n o f t h e two f a m i l i e s of curves) is 1.28/.81=1.52.
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Quantification of DA Supersensitization
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These data convincingly demonstrate that chronic haloperidol treatment in the mouse results in a shift i n t h e d o s e r e s p o n s e c u r v e by a f a c t o r of approximately 1 . 5 t o 2. There is no indication of differential effects of the chronic treatment on p a r t i c u l a r ratings indicating different constellations of drug induced behavior. The slightly greater shift in the total ratings is probably the result of integration over the time-course of the response. The m a g n i t u d e o f Lhe s h i f t is consistent w i t h t h e 30% ( 1 2 , 1 3 ) e l e v a t i o n in DA r e c e p t o r b i n d i n g t h a t we o b s e r v e w i t h t h i s t r e a t m e n t and wikh apomorphine acting as a full agonist over the range of behaviors observed (10). IL i s strikingly different, however, from estimates of the magnitude of denervation supersensitization observed in mice (6) and rats (4) using the rotational model. The increases i n D-2 b i n d i n g , h o w e v e r , a r e b o t h on t h e o r d e r o f 30% ( 1 6 ) . The degree to which this discrepancy is the result of differences in the response topographies, DA r e c e p t o r subtypes not detected w i t h °H n e u r o l e p t i c binding, or the contributions of denervation P~E ~ , is an important question for the interpretation of supersensitization experiments and the relationship of these models to human disorders t h o u g h t t o be r e l a t e d to similar processes.
- 3 0 days Vehicle 30 days Haldol
......////
~---
I ~ / ~ / / / / /
50%
-
!
I\ IX,\
h3 v3 h4h5 v4 v5 DOSE APOMORPHINE Fig. 2 *Best-fitting quantal logistic curves for surpassing r a t i n F . . s 3, 4, a n d 5 in control and chronic haloperidol treated mice. Cut-yes were all fit simultaneously by solving for parameters w h i c h m i n i m i z e t h e Xz a c r o s s l.h~ ratings distributions at all doses in both groups. E D s o ' S f o r khe haloperidol-treated group were h3=0.49 *.04; h4=0.91 )-.07; h5=1.19 4.1. The values for the control mice ~ere v3=0.82 +.07 v 4 = 1 . 4 3 ~'.14; v 5 = 1 . 8 2 +.15.
This research was supported by a g r a n t f r o m t h e N1A A G 0 3 2 7 2 1 . t h a n k s J . S. R a n d a l l f o i ~ t e c h n i c a l assistance and preparation of the illustrations.
Tim m l t h o r
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Quantification of DA Supersensitization
1423
References I. 2. 3. 4. 5 6 7 8 9 10. 11.
12. 13. 14. 15. 16.
P. SEEMAN, P h a r m a c o l . R e v . , 3__2 2 2 9 - 3 1 3 ( 1 9 8 0 ) . I . CREESE, D.R. BURT a n d S . H . SNYDER, S c i e n c e , 19~7 5 9 6 - 5 9 8 ( 1 9 7 7 ) . D.R. BURT, I . CREESE a n d S.H. SNYDER, S c i e n c e , 196 3 2 6 - 3 2 8 ( 1 9 7 6 ) . J . F . MARSHALL a n d U. UNGERSTEDT, E u r . J . P h a r m a c o l . , 4_11 3 6 1 - 3 6 7 ( 1 9 7 7 ) . K.A. NEVE, M.R. KOZLOWSKI a n d J . F . MARSHALL, B r a i n R e s . , 24_~4 3 3 - 4 4 ( 1 9 8 2 ) . R . J . MANDEL a n d P . K . RANDALL, B r a i n R e s . , i n P r e s s ( 1 9 8 5 ) . R. SCHWARCZ, K. FUXE, L . F . A(;NATI, T. HOKFELT, a n d J . T . COYLE, B r a i n R e s . , 170 4 8 5 - 4 9 5 ( 1 9 7 9 ) . U. T r e n d e l e n b e r g , P h a r m a c o l . R e v . , 15 2 2 5 - 2 7 6 ( 1 9 6 3 ) R.J. Tallarida a n d L . S . J a c o b , Thee D o s e R e § p o n s e R e l a t i o n i n P h a r m a c o l q ~ , Springer-Verlag, N.Y. ( 1 9 7 9 ) . R . B . P a r k e r a n d D.R. Waud, J . P h a r m a c o l . E x p t . T h e r a p . ! ~ 1-12 (1971). S. LIST a n d P. SEEMAN, i n Lon~ Term E f f e c t s o f Neuroleptic__a. (CATTABENI, F . , SPANO, P . F . , RACAGNI, G. a n d COSTA, E . , e d s . ) Raven P r e s s , N.Y. Adv. B i o c h e m . P s y c h o p h a r m a c o ] . , 23 9 5 - 1 0 1 ( 1 9 8 0 ) . P . K . RANDALL, J . A . SEVERSON a n d C . E . FINCH, J . P h a r m a c o l . E x p t . T h e r a p . , 2_~19 695-700 (1981). J . A . SEVERSON, P . K . RANDALL a n d C . E . FINCH, B r a i n R e s . , 21__0 2 0 1 - 2 1 5 ( 1 9 8 1 ) . A. DELEAN, P . J . MUNSON a n d D. RODBARD, Am. J . P h y s i o l . , 235 97-102 ( 1 9 7 8 ) . D.R. WAUD, J . P h a r m a c o l . E x p t . T h e r a p . , 183 5 7 7 - 6 0 7 ( 1 9 7 2 ) . J . A . SEVERSON a n d P . K . RANDALL, B r a i n R e s . , 2_79 2 9 5 - 2 9 8 ( 1 9 8 3 ) .
Pergamon Press
QUANTIFICATION OF DOPAMINERGIC SUPERSENSITIZATION APOMORPHINE-INDUCED BEHAVIOR IN THE MOUSE.
USING
P a t r i c k K. Randall Department of Physiology and Biophysics, USC S c h o o l o f M e d i c i n e and Andrus Gerontology Center, University P a r k , Los A n g e l e s , California 90089-0191
(Received in final form August 5, 1985) Summar~
Dose-response curves f o r apomorphine-induced behavior were determined in C57BL/6J mice with and without a 30 day treatment with 2.5 mg/kg/day h a l o p e r i d o l . The e f f e c t of the chronic n e u r o l e p t i c , whether a s s e s s e d by the dose-response curve for t o t a l r a t i n g s or by a m u l t i p l e l o g i s t i c method determlning EDs0'S for t r a n s i t i o n s between i n d i v i d u a l s t e r e o t y p e r a t i n g s , was [o s h i f t the curve to the l e f t by a f a c t o r of s l i g h t l y l e s s than 2. This e s t i m a t e i s considerably d i f f e r e n t from those using the r o t a t i o n a l model and denervatJon as the s u p e r s e n s i t i z i n gs t i m u l u s . There was no i n d i c a t i o n of s e l e c t i v e e f f e c t s of the n e u r o l e p t i c treatment on i n d i v i d u a l components of the behavioral response. Chronic treatment with dopaminergic (DA) a n t a g o n i s t s and denervation by d e s t r u c t i o n of the n i g r o - s t r i a t a l pathway r e s u l t in an apparent DA s u p e r s e n s i t i z a t i o nas a s s e s s e d by e i t h e r receptor binding, or behavioral response Loa DA a g o n i s t (1-3). A number of i n v e s t i g a t o r s have r e c e n t l y made q u a n t i t a t i v e e s t i m a t e s of the degree of s u p e r s e n s i t i z a t i o n in the denervation model by measuring a g o n i s t {apomorphine)-induced r o t a t i o n a l behavior in rodents with u n i l a t e r a l l e s i o n s i n t e r r u p t i n g s t r i a t a l e f f e r e n t s before and a f t e r 6-hydroxy-dopamine (60HDA) l e s i o n s of the c o n t r a l a t e r a l n i g r o - s t r i a t a ] pathway. Rotation a f t e r the e f f e r e n t l e s i o n a l o n e - - e l e c t r o l y t i c s t r i a t o - n i g r a l l e s i o n (4-6) or kainate-induced l e s i o n of the s t r i a t u m ( 7 ) - - p r o v i d e s a b a s e l i n e measure of s e n s i t i v i t y of the "normosensitive" s t r i a t u m . The r e s u l t i n g i n c r e a s e in s e n s i t i v i t y i s a p p r o p r i a t e l y expressed as the " s h i f t " to the l e f t in the dose-response curve r a t h e r than as d i f f e r e n c e s in magnitude of response a t ay p a r t i c u l a r dose (8). Analyzed in t h i s manner the f u n c t i o n r e l a t i n g receptor occupancy i s indeterminant, i . e . i t does not require a l i n e a r r e l a t i o n s h i p between occupancy and response (9). I t ] s n e c e s s a r y , however, to obtain r e l a t i v e l y complete dose--response curves in both c o n t r o l and s u p e r s e n s i t i z e d p r e p a r a t i o n s . Estimates of the degree of s u p e r s e n s i t i v i t ymade in t h i s manner range from 10 to 30 f o l d . This e s t i m a t e i s q u i t e high to be accounted for by the t y p i c a l 30% d i f f e r e n c e in receptor number ( ] , I 0 , 1 ] ) . Supersensitization of apomorphine-induced stereotypic behavior has not been as extensively quantified. The n e c e s s i t y of evaluating full dose-response curves is even more evident in this case than in the rotational behavior model because of the questionable measurement status of stereotypic "ratings", i.e. ratings are, at best, ordinal measures of the response. C l e a r l y an i n c r e a s e i n mean r a t i n g f r o m "3" t o " 4 " d o e s n o t r e p r e s e n t a 33% i n c r e a s e in the magnitude of the
0024-3205/85 $3.00 + .00 Copyright (c) 1985 Pergamon Press Ltd.
1420
Quantification
of DA Supersensitization
Vol. 37, No. 15, 1985
apomorphine response. However, if the position of the dose-response curve along t h e X - a x i s c a n be a c c u r a t e l y determined, alterations in this parameter have obvious quantitative meaning, particularly if different components of the behavioral response are taken into account. We r e p o r t h e r e a q u a n t i t a t i v e study of behavioral DA s u p e r s e n s i t i z a t i o n i n d u c e d by c h r o n i c h a l o p e r i d o l administration, assessing dose-response curves apomorphine with and without a 30-day haloperido] treatment.
to
Methods Animals and d e s i g n C57BI,/6J m i c e o b t a i n e d f r o m J a c k s o n I , a b o r a l o r i e s ( B a r H~J~.'bor', NI';) seJ'w~d a s subjects for this experiment. They w e r e 5 - 6 mo o f a g e a t t h e t i m e o f t i m experiment. Mice w e r e a s s i g n e d t o a f a c t o r i a l c o m b i n a t i o n ( 8 - 1 0 mice~group} o f Chronic Treatment (2.5 mg/kg/day haloperidol vs. lactic acid vehicle) and Apomorphine Dose (0.5, 1.0, 2.(I, 4.0, or 8.0 mg/kg). Haloperidol was administered in the drinking water starting a t 20ug/ml and a d j u s t e d in accot'daucr with monitored daily water intake to represent approximately 2 . 5 mg/kg/day. A p o m o r p h i n e was d i s s o l v e d i n 0.9% s a l i n e , p l a c e d on i c e , and i n j e c t e d intraperitonea]ly w i t h i n 10 min o f b e i n g p r e p a r e d . Behavioral
testing
ApomorphJne induced
took place
after
a 7 day drug-free
period.
behavior
The b e h a v i o r a l r e s p o n s e t o a p o m o r p h i n e was a s s e s s e d i n 15 x 15 X 15 cm enclosures of 1/4 in w i r e mesh w i t h s o l i d p l e x i g l a s s t o p s and f l o o r s . Apomorphine was a d m i n i s t e r e d a f t e r a 10 min h a b i t u a t i o n period. Thirty second observations w e r e made e v e r y 6 min f o l l o w i n g i n j e c t i o n for a period of 1 hr. At each observation a r a t i n g o f t h e d r u g - i n d u c e d b e h v i o r was made a c c o r d i n g t o a 7 p o i n t r a t i n g s c a l e d e v e l o p e d on t h e C 5 7 B L / 6 J m o u s e ( 1 2 , 1 3 ) . This scale gives a log--linear dose-response c u r v e over' a w i d e r a n g e e f d o s e s . Twelve mice were tested simultaneously in one of four sessions pet" d a y : two b e t w e e n 0900 and 1300 a n d two b e t w e e n 1400 a n d 1 7 0 0 . All groups were equally represented in e a c h r u n so t h a t time of day and run v a r i a b l e s were balanced across groups. Data Analysis Data were analyzed first by s t a n d a r d ANOVA t e c h n i q u e s . El)50's for 1oral stereotypic ratings were then estimated u s i n g t h e ALLFIT ( 1 5 ) p r o g r a m for" t h e logistic function. Finally, a non-linear regression r o u t i n e was u s e d to esi. imat~ t h e ED values for lransiticns between ratings. For this analysis t i l e [,:D50 and 50 " " slopes of quantai dose response curves (12) representing ratings of greake}: than o r e q u a l t o 3, 4, o r 5 w e r e d e t e r m i n e d . I n tile l a t t e r aua]ysJs th~ geometric mean o f t h e E D s o ' S f o r i r l d i v i d u t J l c o m p o n e n t s was u s e d a s a g e n c r t ; ] p o s i t i o n parameter. R e s u ] t.s The 3{1 d a y h a l o p e r ~ d o ~ t r e a t m e n t p r o d u c e d a s i ? , n i f i c a n t eleval;on in t h e intensity of apomorphine induced behavior as reflected in s t e r e o t y p e :'atings (F=]8.25;df=l.63;p<.05). Mean t o t a l riltirlgs f o r lh(,' two g r o u p s ~ll e a c h a p o m o r p h i n e d o s e i s s h o w n i n F i g . 1. The i n c r e a s e d r e s p o n s e was n o t d e p e n d e n t . upon alteration o f t i m e c n u r s e s ~ n c e I;he Time a f t e r a p o m o r p h : i n e J n j e c [ i u [ l X Baloperidol treatment interaction failed to approach significance (p>.05). Dose of apomorphine (F-lO1.4;df:4,63;p<.OOl) a n d Time a f t e r a p o m o r p h i n e i n j e c t i o n
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Quantification of DA Supersensitization
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(F=59.66;df=9,587;p<.001) were both highly significant as expected. In addition, the Dose X Time after apomorphine interaction was significant (F=4.04; df-36,587;p<.001), indicating a more prolonged behavioral response in those mice receiving the higher apomorphine doses. Calculation o f ED__ v a l u e s f o r t h e two g r o u p s w a s d o n e b y f i t t i n g the ou generalized logistic function. No s i g n i f i c a n t difference between fits of models sharing either slopes or maximum responses was obtained, so final values are best fitting parameters w i t h maximum r e s p o n s e a n d s l o p e s s h a r e d . In all fits the minimum response was constrained to zero. S h a r i n g E D 5 _ ' s o f t h e two c u r v e s d i d result in a degredation of the fit (F=25 22;df=7,6;p<.~25) relative to the fit allowing maxima, slopes, a n d ED ' s t o d i v e r g e The resultant ED 5_ v a l u e s w e r e 0 1.022 and 1.77 mg/kg for the ha~operidol and control groups respectively, representing a 1.73 fold increase in sensitivity.
50 o
40
Z
N 30 _1 0 I--
tx
20 I0 I
0.5
1.0 2.0 4.0 8 . 0 r l ~ / ~
DOSE APOMORPHINE Fig. i Mean t o t a l ratings for C57BL/6J mice as a function of apomorphine dose and chronic drug treatment. Closed circles represent mice receiving 2.5 mg/kg/day haloperido] in the drinking water. Open circles represent control mice receiving only dilute lactic a c i d f o r 30 d a y s . Lines represent best--fitting logistic dose-response curve (see text). A final analysis was done to determine the extent to which the shift in rating magnitude might be related to increases in a particular, perhaps highly rated, category of behavior vs an actual shift to the left in the curve. Analysis of logistic dose-response curves of individual rating transitions for ratings greater than or equal to 3, 4, or 5 were highly consistent with the simple shift hypothesis. The best fitting curves along with their ED__'s is oU s h o w n i n F i g . 2. It can be seen that each component shifted in a consistent manner by factors of 1.67, 1.57, and 1.53. Thus, there was no alteration in the sequence of behavioral c h a n g e s w i t h d o s e i n t h e two c o n d i t i o n s . The chronic haloperidol treated mice simply went through the sequence at slightly lower doses. The overall shift {alteration in geometric m e a n o f t h e two f a m i l i e s of curves) is 1.28/.81=1.52.
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Quantification of DA Supersensitization
Vol. 37, No. 15, 1985
These data convincingly demonstrate that chronic haloperidol treatment in the mouse results in a shift i n t h e d o s e r e s p o n s e c u r v e by a f a c t o r of approximately 1 . 5 t o 2. There is no indication of differential effects of the chronic treatment on p a r t i c u l a r ratings indicating different constellations of drug induced behavior. The slightly greater shift in the total ratings is probably the result of integration over the time-course of the response. The m a g n i t u d e o f Lhe s h i f t is consistent w i t h t h e 30% ( 1 2 , 1 3 ) e l e v a t i o n in DA r e c e p t o r b i n d i n g t h a t we o b s e r v e w i t h t h i s t r e a t m e n t and wikh apomorphine acting as a full agonist over the range of behaviors observed (10). IL i s strikingly different, however, from estimates of the magnitude of denervation supersensitization observed in mice (6) and rats (4) using the rotational model. The increases i n D-2 b i n d i n g , h o w e v e r , a r e b o t h on t h e o r d e r o f 30% ( 1 6 ) . The degree to which this discrepancy is the result of differences in the response topographies, DA r e c e p t o r subtypes not detected w i t h °H n e u r o l e p t i c binding, or the contributions of denervation P~E ~ , is an important question for the interpretation of supersensitization experiments and the relationship of these models to human disorders t h o u g h t t o be r e l a t e d to similar processes.
- 3 0 days Vehicle 30 days Haldol
......////
~---
I ~ / ~ / / / / /
50%
-
!
I\ IX,\
h3 v3 h4h5 v4 v5 DOSE APOMORPHINE Fig. 2 *Best-fitting quantal logistic curves for surpassing r a t i n F . . s 3, 4, a n d 5 in control and chronic haloperidol treated mice. Cut-yes were all fit simultaneously by solving for parameters w h i c h m i n i m i z e t h e Xz a c r o s s l.h~ ratings distributions at all doses in both groups. E D s o ' S f o r khe haloperidol-treated group were h3=0.49 *.04; h4=0.91 )-.07; h5=1.19 4.1. The values for the control mice ~ere v3=0.82 +.07 v 4 = 1 . 4 3 ~'.14; v 5 = 1 . 8 2 +.15.
This research was supported by a g r a n t f r o m t h e N1A A G 0 3 2 7 2 1 . t h a n k s J . S. R a n d a l l f o i ~ t e c h n i c a l assistance and preparation of the illustrations.
Tim m l t h o r
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References I. 2. 3. 4. 5 6 7 8 9 10. 11.
12. 13. 14. 15. 16.
P. SEEMAN, P h a r m a c o l . R e v . , 3__2 2 2 9 - 3 1 3 ( 1 9 8 0 ) . I . CREESE, D.R. BURT a n d S . H . SNYDER, S c i e n c e , 19~7 5 9 6 - 5 9 8 ( 1 9 7 7 ) . D.R. BURT, I . CREESE a n d S.H. SNYDER, S c i e n c e , 196 3 2 6 - 3 2 8 ( 1 9 7 6 ) . J . F . MARSHALL a n d U. UNGERSTEDT, E u r . J . P h a r m a c o l . , 4_11 3 6 1 - 3 6 7 ( 1 9 7 7 ) . K.A. NEVE, M.R. KOZLOWSKI a n d J . F . MARSHALL, B r a i n R e s . , 24_~4 3 3 - 4 4 ( 1 9 8 2 ) . R . J . MANDEL a n d P . K . RANDALL, B r a i n R e s . , i n P r e s s ( 1 9 8 5 ) . R. SCHWARCZ, K. FUXE, L . F . A(;NATI, T. HOKFELT, a n d J . T . COYLE, B r a i n R e s . , 170 4 8 5 - 4 9 5 ( 1 9 7 9 ) . U. T r e n d e l e n b e r g , P h a r m a c o l . R e v . , 15 2 2 5 - 2 7 6 ( 1 9 6 3 ) R.J. Tallarida a n d L . S . J a c o b , Thee D o s e R e § p o n s e R e l a t i o n i n P h a r m a c o l q ~ , Springer-Verlag, N.Y. ( 1 9 7 9 ) . R . B . P a r k e r a n d D.R. Waud, J . P h a r m a c o l . E x p t . T h e r a p . ! ~ 1-12 (1971). S. LIST a n d P. SEEMAN, i n Lon~ Term E f f e c t s o f Neuroleptic__a. (CATTABENI, F . , SPANO, P . F . , RACAGNI, G. a n d COSTA, E . , e d s . ) Raven P r e s s , N.Y. Adv. B i o c h e m . P s y c h o p h a r m a c o ] . , 23 9 5 - 1 0 1 ( 1 9 8 0 ) . P . K . RANDALL, J . A . SEVERSON a n d C . E . FINCH, J . P h a r m a c o l . E x p t . T h e r a p . , 2_~19 695-700 (1981). J . A . SEVERSON, P . K . RANDALL a n d C . E . FINCH, B r a i n R e s . , 21__0 2 0 1 - 2 1 5 ( 1 9 8 1 ) . A. DELEAN, P . J . MUNSON a n d D. RODBARD, Am. J . P h y s i o l . , 235 97-102 ( 1 9 7 8 ) . D.R. WAUD, J . P h a r m a c o l . E x p t . T h e r a p . , 183 5 7 7 - 6 0 7 ( 1 9 7 2 ) . J . A . SEVERSON a n d P . K . RANDALL, B r a i n R e s . , 2_79 2 9 5 - 2 9 8 ( 1 9 8 3 ) .