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Stimulation of brain metabolism by perinatal cocaine exposure
DevelopmentalBrain Research, 42 (1988) 137-141 Elsevier
137
BRD 60267
Short Communications
Stimulation of brain metabolism by perinatal cocaine exposure Diana L. Dow-Edwards, Laurel A. Freed and Thomas H. Milhorat Laboratory of CerebralMetabolism, Departmentof Neurosurgery, State University of New York, Health Science Centerat Brooklyn, Brooklyn, NY 11203 (U.S.A.)
(Accepted 16 February 1988) Key words: Deoxyglucose; Brain development; Drug abuse; Pregnancy; Dopamine
Cocaine was administered to neonatal rats between day 1 and day 10, which in the rat falls within a developmental stage roughly equivalent to the third trimester of gestation in human fetuses. At 60 days of age, when the animals had reached adulthood, cerebral glucose metabolic patterns were examined by quantitative autoradiography. Adult females, but not adult males, exhibited significant increases in metabolic activity in a number of cerebral structures, including those of the limbic, motor, and sensory systems. Many of these structures are the same as those which are ~xcited in adult rats by the acute administration of cocaine and other stimulants. These data suggest that cocaine consumption during pregnancy may constitute a risk factor leading to long-term alterations in brain function in the adult. Illicit cocaine use has reached epidemic proportions throughout the world among most age groups and social strata. A study by the California Teratology Registry states that questions regarding cocaine use during pregnancy were more frequent than questions regarding any other substance 4. Clinical studies of cocaine abuse during pregnancy demonstrate early behavioral changes in the newborn, including jitteriness, increased startle responses and deficient interactive behavior 1,3. A few animal studies have now appeared describing the teratologic effects of cocaine 7,14, and preliminary neurobehavioral and functional studies have also been presented (Spear et al., personal communication). For this reason, we examined the effects of cocaine administration during the neonatal period in rats, the period during which many brain regions are undergoing synaptogenesis. This was done by measuring local cerebral glucose utilization in adult rats that had been treated with cocaine neonatally. Sprague-Dawley rat pups (8/litter) were given either 50 mg/kg body weight cocaine-HCl s.c. or the vehicle (water) daily between the first and the tenth days of life. On days I and 2 the dose was divided into two 25-mg/kg doses per day. These doses were se-
lected because they produced viable individuals, whereas higher doses of up to 100 mg/kg produced severe growth stunting and an increase in mortality. The cocaine injections were discontinued on day 10, the rats were weaned at 21 days, and were then housed under standard laboratory conditions until the postpubescent period. At 50 days of age, the females underwent daily vaginal smears to determine the phase of the estrus cycle. At 60-65 days of age, when the females were in diestrus, the quantitative deoxyglucose method of Sokoloff22 was carried out. At least 2 h after the insertion of arterial and venous femoral catheters under halothane anesthesia, 125/~Ci/kg body weight [14C]deoxyglucose (American Radiolabelled Chemicals, Inc. St. Louis, MO) was administered. The arterial blood was sampled for the next 45 min for [14C] and glucose determination. The experiment was terminated with a lethal dose of pentobarbital, the brains were removed, frozen, and processed for autoradiography. Brain areas of interest were evaluated using a Sargent-Welch microdensitometer, and rates of glucose consumption were calculated by the operational equation used in the method 22, Of the 42 structures evaluated in the female rats,
Correspondence: D.L. Dow-Edwards, Box 1189, State University of New York, 450 Clarkson Avenue, Brooklyn, NY 11203, U.S.A.
0165-3806/88/$03.50 © 1988 Elsevier Science Publishers B.V. (Biomedical Division)
138 -['ABLE I Brain metabolism in cocaine-treated Jemales Data are in/zmol/100 g tissue/rain; mean ± S.E.M. for the numbers of animals in parentheses. Control (6)
Cocainetreated (6)
% Change
79 + 3 89 + 2* 47 4- 1 80 + 2* 48 + 1 68 ± 2* 51 ± i* 54 + 3 108 ± 5 41 ± 1 38 ± 2
+14 + 14 +4 + 19 +9 + 15 +11 + 13 + 13 +8 +6
74 ± 1 34 + 1
84 ± 5 36 ± 1
+ 14 +6
77 4- 3
89 ± 3*
+16
64 ± 2 47 ± 1
70 ± 4 48 + l
+9 +2
86 + 2 84 ± 5 112 4- 6
102 ± 4* 91 + 4 125 4- 6
+19 +8 +12
35 + 2 95 ± 4
36 ± 2 108 + 5
+3 + 14
Motor structures Motor cortex Caudate nucleus Globus pallidus Thalamus ventral nucleus Substantia nigra Red nucleus Pontine nuclei Pontine reticular formation Vestibular nucleus Cerebellar cortex Corpus callosu~
69 78 45 67 44 59 46 48 96 38 36
Mesolimbicforebrain Accumbens Bed nucleus stria terminalis Horizontal limb of diagonal band Septum Medial Lateral Limbic cortex Cingulate Pit±form Insular Hypothalamus Medial preoptic nucleus Mammillary body
± 4 + 4 + 2 + 3 ± 2 ± 3 ± 2 + 3 ± 4 4- 4 ± 2
Hippocampus CA1 Dentate gyrus Amygdala Lateral nucleus Cortical nucleus Habenula Medial nucleus Lateral nucleus Thalamus Mediodorsal nucleus Ventral tegmental area Interpeduncular nucleus Medial raphe nucleus Central gray
Control (6)
Cocainetreated (6)
61 ± 3 43 ± 3
70 ± 2* 47 + l
+15 +9
64 ___2 44 ± 1
70 ± 1" 48 ± 2
+9 +9
58 ± 3 97 ± 2
67 4- 3 109 + 5*
+ 16 + 12
88 51 83 82 51
106 ± 6* 59 ± 1" 100 ± 5* 99 ± 7* 57 4- 1
+20 + 16 +20 +21 + 12
4- 4 4- 2 ± 5 4- 3 ± 3
% Change
Sensory structures Sensory cortex Head Vibrissa Association (parietal) cortex
74 ± 4 76 ± 4 69 ± 3
83 4- 2 83 4- 4 76 ± 3
+ t2 +9 + 10
Primary olfactory cortex
94 ± 4
106 4- 3*
+ 13
Occipital cortex Lateral geniculate nucleus Superior colliculus
77 ± 4 69 ± 3 63 ± 3
86 + 4 78 ± 2* 73 4- 5
+ 12 + 13 +16
113 + 11 130 + 6 103 + 8 123 + 4* 129 __+11 143 + 5
+15 + 19 +11
Auditory cortex Medial geniculate nucleus Inferiorcolliculus
* Significant difference from control value, P < 0.05 by t-test. 16 s h o w e d
statistically significant increases (P <
0.05, t-test) in g l u c o s e u t i l i z a t i o n in t h e t r e a t e d ani-
area (A10), interpeduncular nucleus, hippocampus, and cingulate cortex.
m a l s ( T a b l e I). E i g h t o f t h e 21 l i m b i c a n d a s s o c i a t e d
I n t h e m a l e s , o n l y o n e s t r u c t u r e s h o w e d a statisti-
a r e a s m e a s u r e d w e r e s i g n i f i c a n t l y m o r e a c t i v e in t h e
cally s i g n i f i c a n t d i f f e r e n c e in g l u c o s e u t i l i z a t i o n at
treated rats compared to the controls. The increases
t h e P = 0.05 l e v e l ( T a b l e II). T h i s w a s t h e a u d i t o r y
in 3 s t r u c t u r e s w e r e s t a t i s t i c a l l y s i g n i f i c a n t at t h e P =
c o r t e x , a n d it s h o w e d a d e c r e a s e r a t h e r t h a n a n in-
0 . 0 0 2 level. T h e s e s t r u c t u r e s w e r e t h e v e n t r a l t h a -
c r e a s e in m e t a b o l i s m .
lamic nucleus and two regions within the dopamin-
s t a n d a r d t-test, u n c o r r e c t e d f o r t h e 42 c o m p a r i s o n s
ergic mesocortical pathway,
i n v o l v e d , o n e w o u l d e x p e c t at l e a s t o n e s t r u c t u r e to
the ventral tegmental
area (VTA) and the cingulate cortex. Neonatal
cocaine administration
However,
since w e u s e d a
a p p e a r t o b e statistically s i g n i f i c a n t a t t h i s l e v e l d u e a p p e a r s t o in-
to c h a n c e a l o n e . I n a n y e v e n t , it is v e r y c l e a r t h a t t h e
c r e a s e t h e m e t a b o l i c r a t e s in m o s t b r a i n s t r u c t u r e s , as
b r a i n m e t a b o l i c a c t i v i t y in t h e m a l e s d i d n o t s h o w
s h o w n in Fig. 1. I n this f i g u r e , c o m p u t e r i z e d i m a g i n g
l o n g - t e r m i n c r e a s e s f o l l o w i n g p e r ± n a t a l c o c a i n e ex-
techniques depict the rates of glucose metabolism,
p o s u r e , a f i n d i n g t h a t is in s h a r p c o n t r a s t t o t h e ef-
demonstrating that they are generally increased by
fects o f c o c a i n e a d m i n i s t r a t i o n in t h e f e m a l e s .
neonatal cocaine treatment. Several structures show
Sex d i f f e r e n c e s in r e s p o n s e to c o c a i n e h a v e b e e n
obvious increases, including the ventral tegmental
r e p o r t e d p r e v i o u s l y 9'1°. A d u l t f e m a l e r a t s r o t a t e al-
Fig. 1. Pseudocolor transforms of glucose utilization in coronal sections of control(A,B,C) and treated (D,E,F) rat brains. Sections A and D are taken at the level of the caudate nucleus; sections B and E at the level of the cingulate cortex, hippocampus, habenula nuclei and thalamus; and sections C and F at the level of the medial geniculate body, ventral tegmental area, and the substantia nigra, x3.
140 TABLE II Brain metabolism in cocaine treated males Data in/~mol/100 g tissue/rain; mean _+ S.E.M. for the numbers of animals in parentheses. Control (.5) Motor structures Motor cortex Caudate nucleus Globus pallidus Thalamus ventral nucleus Substantia nigra Red nucleus Pontine nuclei Pontine reticular formation Vestibular nucleus Cerebellar cortex Corpus callosum Mesolimbicforebrain Accumbens Bed nucleus stria terminalis Horizontal limb of diagonal band Septum Medial Lateral Limbic cortex Cingulate Piriform Insular cortex Hypothalamus Medial preoptic Mammillary body
Cocainetreated (6)
83 ± 3 82 __+3 89 _+ 2 93 ± 4 52 ± 1 52 ± 2 86 + 2 85 _+ 2 49 ± 1 50 _+ 2 70 ± 3 67 ± 2 55 + 3 54 ± 4 59 ± 5 54 ± 2 1I1 ± 10 106 ± 4 42 _ 4 41 ± 2 33 _+_+3 37 ± 2
% Change
- 1 +4 0 -1 +2 -4 -2 -8 -5 -2 + 12
85 ± 4 41 ± 1
85 _+ 4 41 ± 1
0 0
96 ± 6
93 ± 4
-3
82 ± 2 51 ± 3
77 + 3 49 ___2
-6 -4
114 ± 6 103 _+.6 137 ± 7
109 _ 6 98 ± 4 130 ± 5
-4 -5 -5
39 + 2 113 ± 5
39 + 2 116 _+ 5
0 +3
%
Control (5)
Cocainetreated (6)
73 _+ 4 49 _+ 3
70 _+ 3 47 _+ I
-4 -4
78 + 1 56 ± 3
75 _+ 2 57 _+ 2
-4 +2
Change
Hippocampus CA1 Dentate gyrus Amygdala Lateral nucleus Cortical nucleus Habenula Medial nucleus Lateral nucleus Thalamus Mediodorsal nucleus Ventral tegmental area Interpeduncular nucleus Medial raphe nucleus Central gray
66 + 4 113 _+ 4
66 _+ 2 108 + 3
0 -5
1t 1 ± 7 58 ± 2 101 ± 4 108 + 6 67 _+ 5
116 + 5 57 + 2 95 + 4 97 __+2t 60 + 2
+4 -2 -6 - 10 - l0
Sensory structures Sensory cortex Head Vibrissa Association (parietal) cortex Primary olfactory cortex Occipital cortex Lateral geniculate nucleus Superior colliculus Auditory cortex Medial geniculate nucleus Inferior colliculus
85 + 4 86 + 3 80 ± 3 117 __+7 97 ± 9 81 ± 2 79 + 5 148 + 7 124 + 3 153 ± 8
86 _+ 2 87 _+ 3 83 ± 3 116 + 5 91 ± 5 83 ± 3 76 _+ 3 126 + 5* 125 + 3 152 ± 1
+1 +I +4 - 1 -6 +3 -4 -15 + t0 -10
* Significant difference from control value, P < 0.05 by t-test.
m o s t t w i c e as r a p i d l y as m a l e s f o l l o w i n g a single d o s e
ergic p a t h w a y s a p p e a r t o b e a c t i v a t e d b y b o t h t r e a t -
of cocaine, and females remain sensitized to subse-
m e n t s . In c o n t r a s t , f o l l o w i n g n e o n a t a l a d m i n i s t r a -
q u e n t c o c a i n e d o s e s f o r at l e a s t o n e w e e k a f t e r ad-
tion, only the medial portion of the ventral tegmen-
m i n i s t r a t i o n . S e n s i t i z a t i o n was n o t s e e n , h o w e v e r , in
tum (including the VTA and the interpeduncular nu-
m a l e s 9"t°. T h i s r a i s e d t h e q u e s t i o n o f w h e t h e r t h e fe-
cleus) was s t i m u l a t e d . T h e l a t e r a l p o r t i o n o f t h e v e n -
m a l e r a t will also s h o w a n i n c r e a s e in s e n s i t i v i t y a n d
tral t e g m e n t u m , t h e s u b s t a n t i a n i g r a , was not. T h i s
persistence of sensitization to cocaine administered
suggests t h a t n e o n a t a l c o c a i n e e x p o s u r e i n d u c e s a
d u r i n g t h e n e o n a t a l p e r i o d . T h e r e is c e r t a i n l y a m p l e
functional imbalance within the central dopamin-
e v i d e n c e t h a t t h e m e c h a n i s m s r e g u l a t i n g t h e s e sys-
ergic p a t h w a y s .
t e m s a r e s i m i l a r in n e o n a t a l a n d a d u l t b r a i n s s,6.
A n o t h e r n o t a b l e d i f f e r e n c e b e t w e e n t h e r e s u l t s of
T o a l a r g e e x t e n t , t h e e x t r a p y r a m i d a l m o t o r sys-
n e o n a t a l a d m i n i s t r a t i o n a n d a c u t e a d m i n i s t r a t i o n in
tem and the limbic regions which we found to be stim-
t h e a d u l t is t h a t a c u t e a d m i n i s t r a t i o n o f d o p a m i n e r g i c
u l a t e d b y n e o n a t a l c o c a i n e a d m i n i s t r a t i o n a r e also
a g o n i s t s ( c o c a i n e a n d a m p h e t a m i n e ) in t h e a d u l t p r o -
stimulated by acute cocaine or amphetamine admini s t r a t i o n in t h e a d u l t 13~t9'2°23. T h e c a u d a t e , h i p p o -
d u c e s a d e c r e a s e in t h e a c t i v i t y in t h e l a t e r a l h a b e n u la 18-2°23. H o w e v e r , n e o n a t a l a d m i n i s t r a t i o n c a u s e s
campus, and ventral thalamic nuclei demonstrate significant metabolic increases regardless of whether
ity. S i n c e t h e h a b e n u l a is a m a j o r r e l a y n u c l e u s be-
c o c a i n e is g i v e n n e o n a t a i l y , as in o u r s t u d y , o r is ad-
tween
m i n i s t e r e d a c u t e l y to t h e a d u l t . C e n t r a l d o p a m i n -
structures, our results suggest that perinatal cocaine
a n i n c r e a s e r a t h e r t h a n a d e c r e a s e in h a b e n u l a r activthe limbic forebrain
and limbic brainstem
administration increases c o m m u n i c a t i o n within this catecholaminergic p a t h w a y , instead of decreasing the activity, as occurs after acute administration in the adult. The functional significance of the increase in metabolic activity in these m a j o r c e r e b r a l systems following neonatal cocaine administration is speculative at present. Of the several n e u r o t r a n s m i t t e r systems in the adult known to be responsive to cocaine, the d o p a m i n e system has received the most interest, and has been e x a m i n e d in the greatest detail developmentally. Cocaine is known to be a p o t e n t inhibitor of d o p a m i n e and n o r e p i n e p h r i n e r e u p t a k e in the adult 2-8A1, which has also b e e n shown to occur in neonatal brain 17. T h e r e is ample evidence that the various c o m p o n e n t s of the mesencephalic d o p a m i n e r g i c system are undergoing differentiation and synaptogenesis during the p e r i o d of our n e o n a t a l drug administration 15,16. D o p a m i n e r g i c terminals a p p e a r in the caudate nucleus of the rat prior to birth, and then
gradually attain their adult distribution by approximately the second postnatal w e e k 15. Prenatal administration of the d o p a m i n e blocking agent, haloperidol, results in a decrease in the density of d o p a m i n e receptors in the striatum of the adult 21. Likewise, neonatal administration of the precursor, L - D O P A (administration of which in the adult increases the a m o u n t of d o p a m i n e in the synapse, as does administration of cocaine) results in a long-term increase in the density of the d o p a m i n e r e c e p t o r 12. Perhaps the increase in metabolic activity that we found in the dopaminergic regions was due to an increase in the n u m b e r of d o p a m i n e receptors in those regions. O u r findings are consistent with previous studies, and provide evidence that pharmacologic m a n i p u l a t i o n of the dopaminergic system during this critical phase of d e v e l o p m e n t results in alterations in the function
1 Bingol, H., Fuchs, M., Diaz, V., Stone, R.K. and Gromiseh, D.S., Teratogenicity of cocaine in humans, J. Pediatr., 110 (1987) 93-96. 2 Carmichael, F.J. and Israel, Y., In vitro inhibitory effects of narcotic analgesics and other psychotrophic drugs on the active uptake of norepinephrine mouse brain tissue, J. Pharm. Exp. Ther., 186 (1973) 253-260. 3 Chasnoff, I.J., Burns, W.J., Scholl, S.H. and Burns, K.A., Cocaine use in pregnancy, N. Engl. J. Med., 313 (1985) 666-669. 4 Chernoff, G.F., Jones, K.L. and Kelly, C.D., The California teratogen registry: 5 1/2 years of operations experience, J. Perinatol., 6 (1986) 44-47. 5 Cheronis, J.C., Erinoff, L., Heiler, A. and Hoffman, P.C., Pharmacological analysis of the functional ontogeny of the nigrostriatal dopaminergic neurons, Brain Research, 169 (1979) 545-560. 6 Coyle, J.T. and Henry, D., Catecholamines in fetal and newborn rat brain, J. Neurochem., 21 (1973) 61-67. 7 Fantel, A.G. and Macphail, T., The teratogenicity of cocaine, Teratology, 26 (1982) 17-19. 8 Fuxe, K., Hamberger, B. and Malmfors, T., The effect of drugs on accumulation of monoamines in tubero-infundibular dopamine neurons, Eur. J. Pharmacol., 1 (1967) 334-341. 9 Glick, S.D. and Hinds, P.A., Sex differences in sensitization to cocaine-induced rotation, Eur. J. Pharmacol., 99 (1984) 119-123. 10 Glick, S.D., Hinds, P.A. and Shapiro, R.M., Cocaine-induced rotation: sex-dependent differences between leftand right-sided rats, Science, 221 (1983) 775-777. 11 Komiskey, H.L., Miller, D.D., LaPidus, J.B. and Patil, P.N., The isomers of cocaine and tropacocaine: effect on [3H]catecholamine uptake by rat brain synaptosomes, Life Sci., 21 (1977) 1117-1122. 12 Loizou, A.L., The postnatal ontogeny of monoamine-conraining neurons in the CNS of albino rats, Brain Research, 40 (1972) 395-418. 13 London, E.D., Wilkerson, G., Goldberg, S.R. and Risner, M.E., Effects of L-cocaine on local cerebral glucose utilization in the rat, Neurosci. Lett., 68 (1986) 73-78. 14 Mahalik, M.P., Gautieri, R.F. and Mann, D.E., Terato-
genic potential of cocaine hydrochloride in CF-1 mice, J. Pharmacol. Sci., 69 (1980) 703-709. 15 Moon-Edley, S. and Herkenham, M., Comparative development of striatal opiate receptors and dopamine revealed by autoradiography and histofluorescence, Brain Research, 305 (1984) 27-42. 16 Murrin, L.C., Gibbens, D.L. and Ferrer, J.R., Ontogeny of dopamine serotonin and spirodecanone receptors in rat forebrain - - an autoradiographic study, Dev. Brain Res., 23 (1985) 91-109. 17 Nomura, Y., Naitoh, F. and Segawa, T., Regional changes in monoamine content and uptake of the rat brain during postnatal development, Brain Research, 101 (1976) 305-315. 18 Orzi, F., Dow-Edwards, D.L., Jehle, J., Kennedy, C. and Sokoloff, L., Comparative effects of acute and chronic administration of amphetamine on local cerebral glucose utilization in the conscious rat, J. Cereb. Blood Flow Metabol., 3 (1983) 154-160. 19 Porrino, L.P., Lucignani, G., Dow-Edwards, D.L. and Sokoloff, L., Correlation of dose-dependent effects of acute amphetamine administration on behavior and local cerebral metabolism in rats, Brain Research, 307 (1984) 311-320. 20 Porrino, L.P., Domer, F.R., Crane, A.M. and Sokoloff, L., Selective alterations in cerebral metabolism within the mesocortical dopaminergic system produced by acute cocaine administration in rats, Brain Research, in press. 21 Rosengarten, H. and Friedhoff, A.J., Enduring changes in dopamine receptor cells of pups from drug administration to pregnant and nursing rats, Science, 203 (1979) 1133-1135. 22 Sokoloff, L., Reivich, M., Kennedy, C., Des Rosiers, M.H., Patlak, C.S., Pettigrew, K.D., Sakurada, O. and Shinohara, M., The [14C]deoxyglucose measurement of local cerebral glucose utilization: theory, procedure and normal values in the conscious and anesthetized albino rat, J. Neurochem., 28 (1977) 897-916. 23 Wechsler, L.R., Savaki, H.E. and Sokoloff, L., Effects of D- and L-amphetamine on local cerebral glucose utilization in the conscious rat, J. Neurochem., 32 (1979) 15-22.
of the m a j o r c o m p o n e n t s of this system in the adult. S u p p o r t e d by G r a n t DA04118.
137
BRD 60267
Short Communications
Stimulation of brain metabolism by perinatal cocaine exposure Diana L. Dow-Edwards, Laurel A. Freed and Thomas H. Milhorat Laboratory of CerebralMetabolism, Departmentof Neurosurgery, State University of New York, Health Science Centerat Brooklyn, Brooklyn, NY 11203 (U.S.A.)
(Accepted 16 February 1988) Key words: Deoxyglucose; Brain development; Drug abuse; Pregnancy; Dopamine
Cocaine was administered to neonatal rats between day 1 and day 10, which in the rat falls within a developmental stage roughly equivalent to the third trimester of gestation in human fetuses. At 60 days of age, when the animals had reached adulthood, cerebral glucose metabolic patterns were examined by quantitative autoradiography. Adult females, but not adult males, exhibited significant increases in metabolic activity in a number of cerebral structures, including those of the limbic, motor, and sensory systems. Many of these structures are the same as those which are ~xcited in adult rats by the acute administration of cocaine and other stimulants. These data suggest that cocaine consumption during pregnancy may constitute a risk factor leading to long-term alterations in brain function in the adult. Illicit cocaine use has reached epidemic proportions throughout the world among most age groups and social strata. A study by the California Teratology Registry states that questions regarding cocaine use during pregnancy were more frequent than questions regarding any other substance 4. Clinical studies of cocaine abuse during pregnancy demonstrate early behavioral changes in the newborn, including jitteriness, increased startle responses and deficient interactive behavior 1,3. A few animal studies have now appeared describing the teratologic effects of cocaine 7,14, and preliminary neurobehavioral and functional studies have also been presented (Spear et al., personal communication). For this reason, we examined the effects of cocaine administration during the neonatal period in rats, the period during which many brain regions are undergoing synaptogenesis. This was done by measuring local cerebral glucose utilization in adult rats that had been treated with cocaine neonatally. Sprague-Dawley rat pups (8/litter) were given either 50 mg/kg body weight cocaine-HCl s.c. or the vehicle (water) daily between the first and the tenth days of life. On days I and 2 the dose was divided into two 25-mg/kg doses per day. These doses were se-
lected because they produced viable individuals, whereas higher doses of up to 100 mg/kg produced severe growth stunting and an increase in mortality. The cocaine injections were discontinued on day 10, the rats were weaned at 21 days, and were then housed under standard laboratory conditions until the postpubescent period. At 50 days of age, the females underwent daily vaginal smears to determine the phase of the estrus cycle. At 60-65 days of age, when the females were in diestrus, the quantitative deoxyglucose method of Sokoloff22 was carried out. At least 2 h after the insertion of arterial and venous femoral catheters under halothane anesthesia, 125/~Ci/kg body weight [14C]deoxyglucose (American Radiolabelled Chemicals, Inc. St. Louis, MO) was administered. The arterial blood was sampled for the next 45 min for [14C] and glucose determination. The experiment was terminated with a lethal dose of pentobarbital, the brains were removed, frozen, and processed for autoradiography. Brain areas of interest were evaluated using a Sargent-Welch microdensitometer, and rates of glucose consumption were calculated by the operational equation used in the method 22, Of the 42 structures evaluated in the female rats,
Correspondence: D.L. Dow-Edwards, Box 1189, State University of New York, 450 Clarkson Avenue, Brooklyn, NY 11203, U.S.A.
0165-3806/88/$03.50 © 1988 Elsevier Science Publishers B.V. (Biomedical Division)
138 -['ABLE I Brain metabolism in cocaine-treated Jemales Data are in/zmol/100 g tissue/rain; mean ± S.E.M. for the numbers of animals in parentheses. Control (6)
Cocainetreated (6)
% Change
79 + 3 89 + 2* 47 4- 1 80 + 2* 48 + 1 68 ± 2* 51 ± i* 54 + 3 108 ± 5 41 ± 1 38 ± 2
+14 + 14 +4 + 19 +9 + 15 +11 + 13 + 13 +8 +6
74 ± 1 34 + 1
84 ± 5 36 ± 1
+ 14 +6
77 4- 3
89 ± 3*
+16
64 ± 2 47 ± 1
70 ± 4 48 + l
+9 +2
86 + 2 84 ± 5 112 4- 6
102 ± 4* 91 + 4 125 4- 6
+19 +8 +12
35 + 2 95 ± 4
36 ± 2 108 + 5
+3 + 14
Motor structures Motor cortex Caudate nucleus Globus pallidus Thalamus ventral nucleus Substantia nigra Red nucleus Pontine nuclei Pontine reticular formation Vestibular nucleus Cerebellar cortex Corpus callosu~
69 78 45 67 44 59 46 48 96 38 36
Mesolimbicforebrain Accumbens Bed nucleus stria terminalis Horizontal limb of diagonal band Septum Medial Lateral Limbic cortex Cingulate Pit±form Insular Hypothalamus Medial preoptic nucleus Mammillary body
± 4 + 4 + 2 + 3 ± 2 ± 3 ± 2 + 3 ± 4 4- 4 ± 2
Hippocampus CA1 Dentate gyrus Amygdala Lateral nucleus Cortical nucleus Habenula Medial nucleus Lateral nucleus Thalamus Mediodorsal nucleus Ventral tegmental area Interpeduncular nucleus Medial raphe nucleus Central gray
Control (6)
Cocainetreated (6)
61 ± 3 43 ± 3
70 ± 2* 47 + l
+15 +9
64 ___2 44 ± 1
70 ± 1" 48 ± 2
+9 +9
58 ± 3 97 ± 2
67 4- 3 109 + 5*
+ 16 + 12
88 51 83 82 51
106 ± 6* 59 ± 1" 100 ± 5* 99 ± 7* 57 4- 1
+20 + 16 +20 +21 + 12
4- 4 4- 2 ± 5 4- 3 ± 3
% Change
Sensory structures Sensory cortex Head Vibrissa Association (parietal) cortex
74 ± 4 76 ± 4 69 ± 3
83 4- 2 83 4- 4 76 ± 3
+ t2 +9 + 10
Primary olfactory cortex
94 ± 4
106 4- 3*
+ 13
Occipital cortex Lateral geniculate nucleus Superior colliculus
77 ± 4 69 ± 3 63 ± 3
86 + 4 78 ± 2* 73 4- 5
+ 12 + 13 +16
113 + 11 130 + 6 103 + 8 123 + 4* 129 __+11 143 + 5
+15 + 19 +11
Auditory cortex Medial geniculate nucleus Inferiorcolliculus
* Significant difference from control value, P < 0.05 by t-test. 16 s h o w e d
statistically significant increases (P <
0.05, t-test) in g l u c o s e u t i l i z a t i o n in t h e t r e a t e d ani-
area (A10), interpeduncular nucleus, hippocampus, and cingulate cortex.
m a l s ( T a b l e I). E i g h t o f t h e 21 l i m b i c a n d a s s o c i a t e d
I n t h e m a l e s , o n l y o n e s t r u c t u r e s h o w e d a statisti-
a r e a s m e a s u r e d w e r e s i g n i f i c a n t l y m o r e a c t i v e in t h e
cally s i g n i f i c a n t d i f f e r e n c e in g l u c o s e u t i l i z a t i o n at
treated rats compared to the controls. The increases
t h e P = 0.05 l e v e l ( T a b l e II). T h i s w a s t h e a u d i t o r y
in 3 s t r u c t u r e s w e r e s t a t i s t i c a l l y s i g n i f i c a n t at t h e P =
c o r t e x , a n d it s h o w e d a d e c r e a s e r a t h e r t h a n a n in-
0 . 0 0 2 level. T h e s e s t r u c t u r e s w e r e t h e v e n t r a l t h a -
c r e a s e in m e t a b o l i s m .
lamic nucleus and two regions within the dopamin-
s t a n d a r d t-test, u n c o r r e c t e d f o r t h e 42 c o m p a r i s o n s
ergic mesocortical pathway,
i n v o l v e d , o n e w o u l d e x p e c t at l e a s t o n e s t r u c t u r e to
the ventral tegmental
area (VTA) and the cingulate cortex. Neonatal
cocaine administration
However,
since w e u s e d a
a p p e a r t o b e statistically s i g n i f i c a n t a t t h i s l e v e l d u e a p p e a r s t o in-
to c h a n c e a l o n e . I n a n y e v e n t , it is v e r y c l e a r t h a t t h e
c r e a s e t h e m e t a b o l i c r a t e s in m o s t b r a i n s t r u c t u r e s , as
b r a i n m e t a b o l i c a c t i v i t y in t h e m a l e s d i d n o t s h o w
s h o w n in Fig. 1. I n this f i g u r e , c o m p u t e r i z e d i m a g i n g
l o n g - t e r m i n c r e a s e s f o l l o w i n g p e r ± n a t a l c o c a i n e ex-
techniques depict the rates of glucose metabolism,
p o s u r e , a f i n d i n g t h a t is in s h a r p c o n t r a s t t o t h e ef-
demonstrating that they are generally increased by
fects o f c o c a i n e a d m i n i s t r a t i o n in t h e f e m a l e s .
neonatal cocaine treatment. Several structures show
Sex d i f f e r e n c e s in r e s p o n s e to c o c a i n e h a v e b e e n
obvious increases, including the ventral tegmental
r e p o r t e d p r e v i o u s l y 9'1°. A d u l t f e m a l e r a t s r o t a t e al-
Fig. 1. Pseudocolor transforms of glucose utilization in coronal sections of control(A,B,C) and treated (D,E,F) rat brains. Sections A and D are taken at the level of the caudate nucleus; sections B and E at the level of the cingulate cortex, hippocampus, habenula nuclei and thalamus; and sections C and F at the level of the medial geniculate body, ventral tegmental area, and the substantia nigra, x3.
140 TABLE II Brain metabolism in cocaine treated males Data in/~mol/100 g tissue/rain; mean _+ S.E.M. for the numbers of animals in parentheses. Control (.5) Motor structures Motor cortex Caudate nucleus Globus pallidus Thalamus ventral nucleus Substantia nigra Red nucleus Pontine nuclei Pontine reticular formation Vestibular nucleus Cerebellar cortex Corpus callosum Mesolimbicforebrain Accumbens Bed nucleus stria terminalis Horizontal limb of diagonal band Septum Medial Lateral Limbic cortex Cingulate Piriform Insular cortex Hypothalamus Medial preoptic Mammillary body
Cocainetreated (6)
83 ± 3 82 __+3 89 _+ 2 93 ± 4 52 ± 1 52 ± 2 86 + 2 85 _+ 2 49 ± 1 50 _+ 2 70 ± 3 67 ± 2 55 + 3 54 ± 4 59 ± 5 54 ± 2 1I1 ± 10 106 ± 4 42 _ 4 41 ± 2 33 _+_+3 37 ± 2
% Change
- 1 +4 0 -1 +2 -4 -2 -8 -5 -2 + 12
85 ± 4 41 ± 1
85 _+ 4 41 ± 1
0 0
96 ± 6
93 ± 4
-3
82 ± 2 51 ± 3
77 + 3 49 ___2
-6 -4
114 ± 6 103 _+.6 137 ± 7
109 _ 6 98 ± 4 130 ± 5
-4 -5 -5
39 + 2 113 ± 5
39 + 2 116 _+ 5
0 +3
%
Control (5)
Cocainetreated (6)
73 _+ 4 49 _+ 3
70 _+ 3 47 _+ I
-4 -4
78 + 1 56 ± 3
75 _+ 2 57 _+ 2
-4 +2
Change
Hippocampus CA1 Dentate gyrus Amygdala Lateral nucleus Cortical nucleus Habenula Medial nucleus Lateral nucleus Thalamus Mediodorsal nucleus Ventral tegmental area Interpeduncular nucleus Medial raphe nucleus Central gray
66 + 4 113 _+ 4
66 _+ 2 108 + 3
0 -5
1t 1 ± 7 58 ± 2 101 ± 4 108 + 6 67 _+ 5
116 + 5 57 + 2 95 + 4 97 __+2t 60 + 2
+4 -2 -6 - 10 - l0
Sensory structures Sensory cortex Head Vibrissa Association (parietal) cortex Primary olfactory cortex Occipital cortex Lateral geniculate nucleus Superior colliculus Auditory cortex Medial geniculate nucleus Inferior colliculus
85 + 4 86 + 3 80 ± 3 117 __+7 97 ± 9 81 ± 2 79 + 5 148 + 7 124 + 3 153 ± 8
86 _+ 2 87 _+ 3 83 ± 3 116 + 5 91 ± 5 83 ± 3 76 _+ 3 126 + 5* 125 + 3 152 ± 1
+1 +I +4 - 1 -6 +3 -4 -15 + t0 -10
* Significant difference from control value, P < 0.05 by t-test.
m o s t t w i c e as r a p i d l y as m a l e s f o l l o w i n g a single d o s e
ergic p a t h w a y s a p p e a r t o b e a c t i v a t e d b y b o t h t r e a t -
of cocaine, and females remain sensitized to subse-
m e n t s . In c o n t r a s t , f o l l o w i n g n e o n a t a l a d m i n i s t r a -
q u e n t c o c a i n e d o s e s f o r at l e a s t o n e w e e k a f t e r ad-
tion, only the medial portion of the ventral tegmen-
m i n i s t r a t i o n . S e n s i t i z a t i o n was n o t s e e n , h o w e v e r , in
tum (including the VTA and the interpeduncular nu-
m a l e s 9"t°. T h i s r a i s e d t h e q u e s t i o n o f w h e t h e r t h e fe-
cleus) was s t i m u l a t e d . T h e l a t e r a l p o r t i o n o f t h e v e n -
m a l e r a t will also s h o w a n i n c r e a s e in s e n s i t i v i t y a n d
tral t e g m e n t u m , t h e s u b s t a n t i a n i g r a , was not. T h i s
persistence of sensitization to cocaine administered
suggests t h a t n e o n a t a l c o c a i n e e x p o s u r e i n d u c e s a
d u r i n g t h e n e o n a t a l p e r i o d . T h e r e is c e r t a i n l y a m p l e
functional imbalance within the central dopamin-
e v i d e n c e t h a t t h e m e c h a n i s m s r e g u l a t i n g t h e s e sys-
ergic p a t h w a y s .
t e m s a r e s i m i l a r in n e o n a t a l a n d a d u l t b r a i n s s,6.
A n o t h e r n o t a b l e d i f f e r e n c e b e t w e e n t h e r e s u l t s of
T o a l a r g e e x t e n t , t h e e x t r a p y r a m i d a l m o t o r sys-
n e o n a t a l a d m i n i s t r a t i o n a n d a c u t e a d m i n i s t r a t i o n in
tem and the limbic regions which we found to be stim-
t h e a d u l t is t h a t a c u t e a d m i n i s t r a t i o n o f d o p a m i n e r g i c
u l a t e d b y n e o n a t a l c o c a i n e a d m i n i s t r a t i o n a r e also
a g o n i s t s ( c o c a i n e a n d a m p h e t a m i n e ) in t h e a d u l t p r o -
stimulated by acute cocaine or amphetamine admini s t r a t i o n in t h e a d u l t 13~t9'2°23. T h e c a u d a t e , h i p p o -
d u c e s a d e c r e a s e in t h e a c t i v i t y in t h e l a t e r a l h a b e n u la 18-2°23. H o w e v e r , n e o n a t a l a d m i n i s t r a t i o n c a u s e s
campus, and ventral thalamic nuclei demonstrate significant metabolic increases regardless of whether
ity. S i n c e t h e h a b e n u l a is a m a j o r r e l a y n u c l e u s be-
c o c a i n e is g i v e n n e o n a t a i l y , as in o u r s t u d y , o r is ad-
tween
m i n i s t e r e d a c u t e l y to t h e a d u l t . C e n t r a l d o p a m i n -
structures, our results suggest that perinatal cocaine
a n i n c r e a s e r a t h e r t h a n a d e c r e a s e in h a b e n u l a r activthe limbic forebrain
and limbic brainstem
administration increases c o m m u n i c a t i o n within this catecholaminergic p a t h w a y , instead of decreasing the activity, as occurs after acute administration in the adult. The functional significance of the increase in metabolic activity in these m a j o r c e r e b r a l systems following neonatal cocaine administration is speculative at present. Of the several n e u r o t r a n s m i t t e r systems in the adult known to be responsive to cocaine, the d o p a m i n e system has received the most interest, and has been e x a m i n e d in the greatest detail developmentally. Cocaine is known to be a p o t e n t inhibitor of d o p a m i n e and n o r e p i n e p h r i n e r e u p t a k e in the adult 2-8A1, which has also b e e n shown to occur in neonatal brain 17. T h e r e is ample evidence that the various c o m p o n e n t s of the mesencephalic d o p a m i n e r g i c system are undergoing differentiation and synaptogenesis during the p e r i o d of our n e o n a t a l drug administration 15,16. D o p a m i n e r g i c terminals a p p e a r in the caudate nucleus of the rat prior to birth, and then
gradually attain their adult distribution by approximately the second postnatal w e e k 15. Prenatal administration of the d o p a m i n e blocking agent, haloperidol, results in a decrease in the density of d o p a m i n e receptors in the striatum of the adult 21. Likewise, neonatal administration of the precursor, L - D O P A (administration of which in the adult increases the a m o u n t of d o p a m i n e in the synapse, as does administration of cocaine) results in a long-term increase in the density of the d o p a m i n e r e c e p t o r 12. Perhaps the increase in metabolic activity that we found in the dopaminergic regions was due to an increase in the n u m b e r of d o p a m i n e receptors in those regions. O u r findings are consistent with previous studies, and provide evidence that pharmacologic m a n i p u l a t i o n of the dopaminergic system during this critical phase of d e v e l o p m e n t results in alterations in the function
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of the m a j o r c o m p o n e n t s of this system in the adult. S u p p o r t e d by G r a n t DA04118.