Autoradiographic studies of post-mortem human narcoleptic brain

35

Neurophysiol Clin (I 993) 23, 35-45 © Elsevier, Paris

Memoir

A u t o r a d i o g r a p h i c studies of p o s t - m o r t e m h u m a n narcoleptic brain * MS Aldrich, Z Hollingsworth**/JB Penney** Department of Neurology, Taubman Center 1920/0316, University of Michigan Medical Center, 1500 East Medical Center Drive, Ann Arbor, Michigan, 48109-0316, USA (Received 24 June 1992; accepted 25 October 1992)

Summary - Although the pathological basis for narcolepsy is unkamwn, studies of human and canine narcolepsy have suggested that monoamine and cholinergic metabolism may be altered. We used quantitative autoradiography to assess binding of dopaminergic, noradrenergic, and cholinergic ligands to basal ganglia and anLygdala of five narcoleptic and 17 control human brains. Dopanfine receptor studies revealed significant increases in D-1 and D-2 receptor binding in tile caudate nucleus, as well as large but not significant increases of D-1 binding in the medial globus pallidus, and D-2 binding in ihe lateral globus pallidus and the lateral nucleus of the amygdala, Alpha-adrenergic receptor studies revealed a significant increase in alpha-2 receptor binding in the putamen and large but not significant increases of alpha-2 binding in the caudate nucleus, and basal and lateral nuclei of the amygdala. Alpha-1 receptor binding was decreased in several areas but tile changes were not statistically significant. Studies of two narcoleptic brains revealed small but not statistically significant increases in muscarinic receptor binding in tile caudate nucleus, putamen, and amygdala. Although we cannot exclude the possibility that stimulant medications used before death may be partly responsible for these findings, tile results suggest that human narcolepsy is associated with upregulation of dopamine and alpha-2 adrenergic receptors in specific brain regions.

narcolepsy / dopamine / receptors / sleep disorders

RSs~m$ - l~tude autoradiographique post-mortem du cerveau humain narcoleptique~ Les dtudes humaines et canitws sugg~rent que le mdtabolisme des monoamines et de l'ac~tylcholine peut ~-tre alttrd dans la narcolepsie. Nous avons dtudig les liaisons de haute affinitd ties ligands dopaminergiques, noradr#nergiques et cholinergiques au niveau des noyaux gris de la base, et de l' amygdale chez cinq narcoleptiques et 17 contrOles. I1 existe une augmentation significative ties liaisons D1 et D2 au niveau du

* Supported by tile American Narcolepsy Association and USPIIS Grant AG08671. ** Present address: Neurology Research, Welhnan 405, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

36

MS Aldrich et al

noyau caudd, ainsi qu'une augmentation importante, mais non significative des liaisons D1 du pallidum m~dial et D2 du pallidum latdral et du noyau latdral de l' amygdale. II existe une augmentation significarive des liaisons or2 du putamen ainsi qu'une augmentation non significative des liaisons or2 du noyau caudd et des noyaux basaux et latdraux de l'amygdale. Les liaisons at1 dtaient dimb~udes de f a f o n non significative dans plusieurs rdgions. Chez deux narcoleptiques les liaisons muscariniques dtaient augmentdes de f a f o n non significative au niveau du noyau caudd, du putamen et de l' amygdale. On ne peut exclure que les nufdicaments excitants aient joud un r~le dans ces nwdifications. Nos rdsultats sont compatibles avec un accroissement de la synthkse des rdcepteurs dopaminergiques et t~2 adrdnergiques dans certaines rdgions spdcifiques du cerveau.

narcolepsie / dopanfine / r6cepteur / d6sordres du sommeil

Introduction

The characteristic features of narcolepsy include excessive sleepiness, cataplexy and abnormalities of REM sleep. Although there is clear evidence of a genetic substrate for most cases of human narcolepsy, the brain pathology of narcolepsy remains obscure. Few histopathological studies have been reported (Erlich and Itabashi, 1986; Leverenz et al, 1988), and the findings in these studies are probably incidental. Clinical practice suggests that metabolism of norepinephrine may be abnormal, since stimulants, the mainstay of treatment of narcolepsy, increase synaptic availability of norepinephrine. There is also evidence from neurochemical studies that metabolism of dopamine is altered in human narcolepsy. Studies of cerebrospinal fluid have revealed low concentrations of free dopamine and its metabolite homovanillic acid suggesting that metabolism of dopamine may be decreased (Parkes et al, 1974; Montplaisir et al, 1982). In postmortem studies of human striatal tissue, Kish et al (1992) found that dopamine D-2 receptor density was increased, dopamine and homovanillic acid levels were normal, and 3, 4-dihydroxyphenylacetic acid (DOPAC) levels were reduced. Canine narcolepsy is associated with excessive sleepiness, cataplexy, and REM sleep abnormalities, and although it is genetically distinct from human narcolepsy, it is a useful model of the human disease. There is evidence from pharmacological and anatomic studies of canine narcolepsy that dopanainergic, noradrenergic, and cholinergic metabolism is altered. Canine cataplexy is suppressed by dopamine D-1 and D-2 receptor antagonists and exacerbated by D-2 agonists, but D-1 agonists have little effect (Nishino et al, 1991). In addition, dopamine D-2 receptor density is increased and relative concentrations of dopamine, DOPAC, and homovanillic acid are altered in the amygdala of canine narcoleptic brain, and cerebrospinal fluid levels of DOPAC are reduced (Barchas et al, 1979; Bowersox et al, 1987). These findings suggest that dopamine metabolism may be altered in specific areas of the brain (Mefford et al, 1983; Faull et al, 1986; Miller et al, 1990). Canine studies also indicate that noradrenergic and cholinergic functions are disturbed. Canine cataplexy is exacerbated by prazosin, an alpha-1 receptor antagonist, and inhibited by alpha-2 antagonists and alpha-1 agonists, and there are increases of

Autoradiographic studies

37

alpha-1 r e c e p t o r s in the a m y g d a l a and a l p h a - 2 r e c e p t o r s in the locus c o e r u l e u s o f canine n a r c o l e p t i c b r a i n ( M i g n o t et al, 1988a; M i g n o t et al, 1988b; F r u h s t o r f e r et al, 1989; N i s h i n o et al, 1990). There is also e v i d e n c e o f an i n c r e a s e in the n u m b e r o f m u s c a r i n i c M - 2 r e c e p t o r s in the b r a i n s t e m o f n a r c o l e p t i c d o g s ( K i l d u f f et al, 1986). T h e n e u r o c h e m i c a l studies o f h u m a n and canine n a r c o l e p s y , t o g e t h e r with the evidence of a genetic substrate, suggest that narcolepsy may be associated with d e m o n s t r a b l e n e u r o c h e m i c a l changes. T o e v a l u a t e this p o s s i b i l i t y , w e p e r f o r m e d r e c e p t o r a u t o r a d i o g r a p h y u s i n g l i g a n d s for d o p a m i n e r g i c , a l p h a a d r e n e r g i c , a n d m u s c a r i n i c r e c e p t o r s o n p o s t m o r t e m h u m a n n a r c o l e p t i c and control brains. T h e stud i e s d e s c r i b e d h e r e h a v e b e e n p r e v i o u s l y r e p o r t e d in p a r t ( A l d r i c h et al, 1990; A l d r i c h et al, 1991; A l d r i c h et al, 1992).

Methods

P o s t - m o r t e m tissue Between 1987 and 1990, we obtained five narcoleptic brains at autopsy. Informed consent was obtained postmortem fi'om next of kin and some of the patients gave premortem consent. Detailed medical history and the results of sleep recordings were obtained (table I). Brain tissue was removed shortly after death. After median sagittal transection, one half was fixed in formalin and preserved for conventional histopathologic examination. Approximately 1 cm thick coronal sections were cut from the other half at the level of the preoptic area, amygdala and basal ganglia, posterior hypothalamus and thalamus, pontine tegmentum and locus coeruleus, and nucleus reticulm'is gigantocellularis and medullary reticular formation. Slices were then frozen with crushed dry ice, transported by air express to our labora-

Table I. Narcoleptic subjects.

ApproxinuTte duration of narcoleptic Age~sex Symptoms (years) Cataplexy

Sleep-Onset REM

85/Male

35

Possible

48/Male

23

82/Male 54/Male 23/Male

69 30 5

Medication

Cause of death

Unknown

Ephedrine Prednisone

Pulmonary fibrosis

Possible

Yes

Dextroamphetanline Sodium valproate Clonazepam Nortript yline

Myocardial infarction

Yes Yes Yes

Yes Unknown Yes

None Dextroamphetamine Imipramine

Gastric lymphoma Gunshot wound Klfife wound

38

MS Aldrich et al

tory, and stored at -70°C until sectioned. In some cases, hemispheres were frozen whole, transported on crushed dry ice, thawed to 4°C, and then cut and stored as described above. Control tissue was obtained in a similar fashion from 17 neurologically normal persons. Autoradiography For dopamine receptor studies, we used methods similar to those of Richfield et al (1986, 1987a, 1987b). Appropriate coronal sections of the narcoleptic brains were warmed to - 1 0 to -20°C and 2 × 8 cm blocks containing basal ganglia and amygdala were removed. Technical factors prevented analysis of amygdala tissue from narcoleptic subject 4. From 17 control brains, blocks containing amygdala were cut from 10 and blocks containing basal ganglia were cut from 12. We used a Lipshaw cryostat microtome to cut 20 micron sections from the coronal tissue blocks, which were then thaw-mounted onto gelatin-coated slides, dehydrated on a warming plate, and stored at -20°C. For dopamine D-1 receptor autoradiography, the buffer contained 25 nlM Tris-HCI, 100 mM NaCI, 1 mM MgC12, 1/aM pargyline, and 0.001% ascorbate at pH of 7.50. Slides were allowed to warm to room temperature for 1 hour and were then incubated in buffer containing 1.65 nM [3H]-SCH23390 (Amersham, Aylesbury, UK; specific activity 72.5-83 Ci/mM). For the dopamine D-2 assay, the same buffer was used with the addition of 100 nM mianserin and slides were incubated with 0.75 nM [3H]-spiperone (New England Nuclear, Boston, MA; specific activity 72.9-93 Ci/mM). Nonspecific binding was determined in the presence of 1 /aM cisflupentixol for the D-1 assay and 5 0 / J M dopamine for the D-2 assay. Following incubation, slides were washed for ten minutes in buffer at 4°C, dipped quickly in distilled HzO, and dried in a stream of warm air. For the alpha-I assay, slides were warmed to room temperature for 1 hour and incubated at 22°C for 30 rain in 170 mM Tris-HCI buffer containing 2nM [31:t]- prazosin. For the alpha-2 assay, we used a buffer containing 50 mM Tris-HCI, 0.1 mM MnC12 at pH of 7.40, and slides were incubated at 22°C for 90 min with 5 nM [3H]-UK14304. For each assay, nonspecific binding was determined in the presence of 10 pM phentolamine. Muscarinic receptor assays were carried out on two narcoleptic and 10 control brains with the use of [3H]-scopolamine in phosphate-buffered saline at room temperature. Slides were preincubated in buffer for 30 minutes and then incubated for 30 minutes in buffer containing 1.0nM [3H]-scopolamine. The muscarinic M-1 receptor subtype was partially resolved in adjacent sections with inclusion of pirenzepine in the incubation. Slides were then rinsed twice for 5 minutes in ice-cold buffer, dipped briefly in distilled water, and air dried. Dried slides were placed in a photographic film cassette with calibrated 14C standards and exposed to Hyperfilm 3H (Amersham) at 4°C. Duration of exposure was 21 days for D- 1 and D2 assays, 42 days for adrenergic alpha- 1, 63 days for adrenergic atpha-2, and 28 to 56 days for the muscarinic assays. Hyperfilm 3H was developed for 4 minutes at room temperature in Kodak D19 and fixed for 4 minutes in Kodak rapid fix. We determined binding data in caudate, putamen, lateral globus pallidus, medial globus pallidus, and amygdala with direct analysis of film density using a computer-based imaging system (Imaging Research Inc, St Catharines, ON, Canada). We identifed nuclear subdivisions of the amygdala using adjacent sections stained for cholinesterase and for adrenergic receptor binding with [3H]-prazosin. Amygdaloid nuclei were named according to the terminology of Sims and Williams (1990).

39

Autoradiographic studies 0.3 0.250.20.15 O

8e~

"~,

0.1 0.05

CAUD CAUD

PUT

LGP

MGP ACC BA$ LAT AMYODALA

PUT

LGP

M G P ACC

BAS

LAT

AMYGDALA

Fig 1. Dopamine D-1 receptor binding (Mean :t:

Fig 2. Dopamine D-2 receptor binding (Mean +

SEM) following incubation with 1.65 nM [3H]SCH23390 and subtraction o f non-specific binding. In the narcoleptic group, there was a lfigldy significant 57% increase in caudate binding (P = 0.00006) and a 54% increase in medial globus pallidus binding that was not statistically significant (P = 0.21). Abbreviations: CAUD = caudate nucleus; PUT = putamen; LGP = lateral globus pallidus; MGP = medial globus pallidus; ACC = accessory basal nucleus o f the amygdala; BAS = basal nucleus o f the amygdal'a; L A T = lateral n u c l e u s o f t h e a m y g d a l a . 'l~] n a r c o l e p s y ; [ ] control.

SEM) following incubation with 0.75 nM [3H]Spiperone and subtraction o f non-specific binding. In the'narcoleptic group, there was a significant 63% increase in caudate binding (P = 0.04), a 95% increase in lateral globus paUidus binding (P = 0.07), and a 93% increase in binding to the lateral n u c l e u s o f the a m y g d a l a (P = 0.11). A b r e v i a t i o n s as in figure 1. [ ] narcolepsy; [ ] control.

For each assay, two or tba'ee sections from each brain were used to determine total binding and two or three adjacent sections were used to determine nonspecific binding. Mean film densities of the duplicate or triplicate sections were determined for each anatomical region of interest and were converted to picomoles per milligram of protein. Mean non-specific binding was subtracted from mean total binding to obtain ~ecific binding for each region. For each region of interest, we compared mean specific binding in narcoleptic and control brains using analysis of variance.

Results Control brains were f r o m 11 men and 6 w o m e n with a m e a n age o f 69 years (range 49-81) and a mean p o s t m o r t e m delay before freezing of 16 h (range 3.5-24). Narcoleptic subjects were all male and had a mean age o f 58 years (range 23-85). The difference in age was not statistically significant but the mean postmortem delay o f 3 0 h (range 8-60) for narcoleptic subjects was significantly increased ( F = 6.71, P -0.02). Except for the 23-year old narcoleptic, who was diagnosed with the disease at 18 years, all had narcolepsy for more than 20 years. Three had definite cataplexy and sleep-onset R E M periods had been recorded in three. One had a family history o f narcolepsy and one had the H L A - D R 2 antigen; the other four were not tested. D o p a m i n e D-1 assay results are shown in figure 1. The most striking finding was a highly significant 57% increase in specific D-1 receptor binding in the caudate. A

40

MS Aldrich et al

0"10 0.09I 0.08 0.07 o.06 0.05 00 0.04 '~ 0.03 0.02 0.01

0.10 -6 0.08 3 0.06 "~, 0.04 0.00

0

CAUD PUT LGP MGP ACC BAS LAT AMYGDALA

Fig 3. Adrenergic alpha-1 receptor binding (Mean + SEM) following incubation with 2 nM [3H]Prazosin and subtraction of non-specific binding. In the narcoleptic group, there was a trend toward decreased binding in the lateral globus pallidus, the medial globus pallidus, the accessory basal nucleus of the amygdala, and the basal nucleus of the amygdala, but these changes were not statistically significant. Abbreviations as in figure 1. [ ] narcolepsy; • control.

.

0

0

CAUD

,

~

PUT

LGP

MGP

,

,

ACC BAS LAT AMYGDALA

Fig 4. Adrenergic alpha-2 receptor binding (Mean + SEM) following incubation with 5 nM [3H]UK14304 and subtraction of non-specific binding. In the narcoleptic group, there was a significant 77% increase in putamen binding compared to control (P = 0.02). There was a trend toward increased binding in the caudate nucleus (67%; P = 0.06), tile basal nucleus of the amygdala (65%; P = 0.09), and the lateral nucleus of tile amygdala (105%; P = 0.08). Abbreviations as in figure 1. [ ] narcolepsy; • control.

54% increase in binding in the medial globus pallidus approached statistical significance. In other regions, narcoleptic and control tissue had similar levels of binding. There was no significant correlation of age to D1 receptor binding in the narcoleptic subjects. Dopamine D-2 assay results are shown in figure 2. The D-2 receptor binding was increased significantly in the candate nucleus of the narcoleptic tissue, and increases in the lateral globus pallidus and the lateral nucleus of the amygdala were almost statistically significant. Other regions of narcoleptic and control tissue had similar levels of binding. Noradrenergic alpha-1 assay results are shown in figure 3. Compared to control tissue, alpha 1 receptor binding was decreased in narcoleptic tissue in the medial and lateral globus pallidus and in the basal and basal accessory nuclei of the amygdala, but the differences were not significant. Binding was similar in the caudate nucleus, putamen, and lateral nucleus of the amygdala. Noradrenergic alpha-2 assay results are shown in figure 4. Compared to controls, there was a statistically significant 77% increase in alpha-2 receptor binding in the narcoleptic putamen (P < 0.02). There was a trend toward increases of alpha-2 receptor binding compared to control in the caudate nucleus of 67% and in the lateral amygdala of 105%. In the medial globus pallidus, lateral globus pallidus, and basal accessory nucleus of the amygdala, binding was similar in narcoleptic and control tissue.

41

Autoradiographic studies

©

"6

"6 'E,

C A U D PUT LGP

MGP ACC BAS LAT AMYGDALA

CAUD P U T

LGP

MGP ACC BAS LAT AMYGDALA

Fig 5. Muscarinic receptor binding (Mean +

Fig 6. Muscarinic M-1 receptor binding (Mean +

SEM) following incubation with 10 nM [3H]-Scopolamine. In the narcoleptic group (n = 2), there was a suggestion of increased binding in the caudate, putamen, and the accessory basal, basal, and lateral nuclei of the amygdala. Abbreviations as in figure 1. [ ] narcolepsy; • control.

SEM) following subtraction of binding of 10 nM [31I]-Scopolamine in the presence of pirenzipine from binding in the presence of [3H]-Scopolamine alone. There was a suggestion of increased binding in the caudate, putamen, and the accessory basal, basal, and lateral nuclei of the amygdala in the narcoleptic group (n = 2). Abbreviations as in figure l. [ ] narcolepsy; • control.

Muscarinic receptor assay results are shown in figures 5 and 6. There was a trend toward increased binding of tritiated scopolamine in the putamen (34%) and in lateral amygdala (63%). Lesser increases were present in the caudate nucleus and in'the basal and accessory basal nuclei of the amygdala. Assay results in the presence of pirenzipine (fig 6) suggested that alterations in M-1 muscarinic receptor binding were responsible for the observed changes. Because of the small number of brains studied with muscarinic receptor ligands, we did not perform statistical analysis for these assays.

Discussion

Our findings indicate that monoaminergic, and possibly cholinergic receptor function is altered in human narcolepsy. We found significant increases of D-1 and D-2 receptor binding in the caudate nucleus and adrenergic alpha-2 receptor binding in the putamen. In addition, increases of D-1 receptors in the medial globus pallidus, D-2 receptors in the lateral globus pallidus and lateral nucleus of the amygdala, and adrenergic alpha-2 receptors in the caudate nucleus and basal and lateral nuclei of the amygdala approached statistical significance. Unlike Kish et al (1989), we did not observe an increase in D-2 receptor binding in the putamen. Although the D-2 receptor findings in the caudate are similar to those in canine narcolepsy, we did not find alterations in dopamine D-2 receptors or adrenergic alpha-1 receptors in the amygdala, as have been reported in canine narcolepsy (Mignot et aL 1988a; Mignot et aL 1988b, Fruhstorfer et al, 1989).

42

MS Aldrichet al

Although we cannot exclude the possibility that stimulant use contributed to the findings we observed, we believe that medication was not responsible for the principal findings. Stimulants enhance presynaptic release of catecholamine and block their reuptake. Long term use of these medications can result in altered sensitivity or function of some catecholamine receptors including dopamine receptors (Kosten, 1990), and some authorities have suggested that the development of tolerance to the effects of amphetamines may be due at least in part to altered sensitivity of dopamine D-2 receptors (Levy et al, 1988). For example, chronic high dose treatment of rats with amphetamines leads to a reduction of caudate dopamine content and of dopamine uptake sites. Amphetamine treatment in animals does not appear to alter dopamine D-1 receptor binding, although it can lead to a decrease in stimulation of adenylate cyclase activity by D-1 agonists (Roseboom and Gnegy, 1989). Animal studies of the effects of high doses of dextroampbetamine on dopamine receptors have usually shown decreased numbers of dopamine D-2 receptors and reduced striatal D2 binding site density (Howlett and Nahorski, 1978; Daiguji and Meltzer, 1982; Robertson, 1982; Robertson, 1986), although in one study striatal dopamine D-2 receptor binding was increased, perhaps because dopamine depletion was particularly severe (Trulson and Crisp, 1985). The relevance to human narcolepsy of these studies on the effects of amphetamines in animals is uncertain because the doses used were 10--100 fold greater than those customarily used in the treatment of narcolepsy. Two of the narcoleptic subjects were taking tricyclic antidepressants at the time of death, and it is also possible that this medication may have influenced our findings. Dopamine D-2 receptor binding is not affected by most tricyclic antidepressants, although desipramine can produce a decrease in D-1 and D-2 receptor affinity for specific ligands (Hall and Ogren, 1981; Suhara et al, 1990; Willner, 1983). It is possible that differences in age and postmortem delay between the narcoleptic and control groups made a small contribution to the findings presented here. The narcoleptic group was slightly younger than the control group, and some investigators have found a decline with age in the number of D-1 and D-2 receptors in the caudate nucleus, the frontal cortex, and possibly in the putamen (Rinne et al, 1990; DeKeyser et al, 1990a; DeKeyser et al, 1990b). However, we found no significant correlation of age with dopamine receptor density in narcoleptic or control groups for any of the regions assessed. We also found no significant correlation of postmortem delay with dopamine receptor density in narcoleptic or control groups. We doubt therefore that differences in age or postmortem delay could account for all of the findings we observed. These findings suggest that alterations in monoaminergic function and cholinergic function may contribute to the pathogenesis of human narcolepsy. There is ample evidence that noradrenergic systems are involved in the control of sleep and wakefulness (Jouvet, 1972) and that cholinergic neurons are intimately involved with the control and expression of REM sleep. Dopamine also plays a role in sleep/wake regulation. Dopamine D-1 agonists lead to arousal (Ongini et al, 1985). Low doses of dopamine D-2 agonists, such as apo-

Autoradiographic studies

43

morphine, produce sedation and sleep while higher doses suppress REM sleep and lead to arousal (Corsini et al, 1977; Mereu et al, 1979; Svensson et al, 1987; Bagetta et al, 1988). Although dopamine containing neurons of the mesostriatal system are primarily involved with the control of movement, a reduction in activity in this system might be responsible for the periodic limb movements of sleep, which are frequent in persons with narcolepsy and often respond to treatment with levodopa (Boivin et al, 1989). Mesoneocortical and mesoallocortical dopamine neurons, which have their cell bodies in the ventral tegmentum, m a y be more closely associated with sleep and wakefulness than mesostriatal neurons. Studies by Nishino et al (1991) have provided evidence that dopamine D-2 receptors, possibly heteroreceptors located on noradrenergic projection neurons, may be significant in' the expression of canine cataplexy. I f so, altered function of dopaminergic and adrenergic receptors, as we observed in these studies, may contribute to the pathogenesis of narcolepsy. On the other hand, it may be that the changes we observed are compensatory responses to a primary, as yet unidentified, neurochemical abnormality.

References Aldrich MS, Frey K, Albin RL, Penney JB (1990) Muscarinic receptor autoradiographic studies of postmortem human narcoleptic brain. Sleep Res 19, 179 Aldrich MS, Hollingsworth ZR, Penney JB (1992) Dopamine-receptor autoradiography of human narcoleptic brain. Neurology 42, 410-415 Aldrich MS, Hollingsworth Z, Penney JB (1991) Adrenergic receptor autoradiography of human narcoleptic brain. Sleep Res 20A, 280 Bagetta G, DeSarro G, Priolo E, Nistico G (1988) Ventral tegmental area: site through which dopamine D-2-receptor agonists evoke behavioural and electrocortical sleep in rats. Br J Pharmacol 95, 860-866 Barchas JD, Dement WC, Faull K, Foutz AS, Holman RB (1979) The concentrations of amine metabolites in cerebrospihal fluid from normal and narcoleptic dogs. J Physiol 296, 94-95P

Boivin DB, Montplaisir J, Poirier G (1989) The effects of L-dopa on per!odic leg movements and sleep organization in narcolepsy. Clin Neuropharmacol 12, 339-345 Bowersox SS, Kilduff TS, Faull KF, ZellerDeAmicis L, Dement WC, Ciaranello RD (1987) Brain dopamine receptor levels elevated in canine narcolepsy. Brain Res 402, 44-48 Corsini GU, DelZompo M, Manconi S, Piccardi MP, Onali PL, Mangoni A (1977) Evidence for dopamine receptors in the human brain mediating sedation and sleep. Life Sci 20, 1613-1618 Daiguji M, Meltzer ItY (1982) Effect of chronic phencyclidine or d-amphetamine treatment on [3H] spiroperidol binding in rat caudate-putamen and nucleus accumbens. Eur J Pharmacol 85, 339-342 DeKeyser J, Ebinger G, Vauquelin G (1990a) Age-related changes in the human nigrostriatal dopaminergic system. Ann Neurol 27, 157-161 DeKeyser J, DeBacker JP, Vauquelin G,

44

MS Aldrich et al

Ebinger G (1990b) The effect of aging on the DI d o p a m i n e r e c e p t o r s in human frontal cortex. Brain Res 528, 308-310 Erlich SS, Itabashi HH (1986) Narcolepsy: a n e u r o p a t h o l o g i c s t u d y . Sleep 9, 126-132 Faull KF, Zeller-DeAmicis LC, Radde L e t al (1986) Biogenic amine concentrations in the brains of normal and narcoleptic canines: current status. Sleep 9, 107-110 F r u h s t o r f e r B, M i g n o t E, B o w e r s o x S, Nishino S, Dement WC, Guilleminault C (1989) Canine narcolepsy is associated with an e l e v a t e d n u m b e r o f a l p h a - 2 receptors in the locus cceruleus. Brain Res 500, 209-14 Hall H, Ogren SO (1981) Effects of antidepressant drugs on different receptors in the brain. Eur J Pharmaco170, 393-407 Howlett DR, Nahorski SR (1978) Acute and c h r o n i c a m p h e t a m i n e treatments modulate striatal dopamine binding sites. Brain Res 161,173-178 Jouvet M (1972) The role of monoamine and acetylcholine containing neurones in the regulation of the sleep-waking cycle. Ergebn Physiol 64, 166-307 Kilduff TS, Bowersox SS, Kaitin KI, Baker TL, Ciaranello RD, Dement WC (1986) Muscarinic cholinergic receptors and the canine m o d e l of narcolepsy. Sleep 9, 102-106 Kish S J, Mamelak M, Slimovitch C, et al (1992) Brain neurotransmitter changes in h u m a n n a r c o l e p s y . N e u r o l o g y 42, 229-234 Kosten TR (1990) Neurobiology of abused drugs. Opioids and stimulants. J Nerv Ment Dis 178, 217-227 Leverenz J, Petito CK, Morgello S (1988) Neuropathologic change in a patient with narcolepsy. Neurology 38, 307 Levy AD, Kim JJ, Ellison GD (1988) Cba'onic amphetamine alters D-2 but not D-1 agonist induced behavioral responses in rats. Life Sci 43, 1207-1213

M e f f o r d IN, Baker TL, B o e h m e R et al (1983) Narcolepsy: biogenic amine deficits in an animal model. Science 220, 629-632 Mereu GP, Scarnati E, Paglietti E, Pellegrini-Quarantotti B, Chessa P, DiChiara G, Gessa GL (1979) Sleep induced b y low doses of apomorphine in rats. Elect r o e n c e p h a l Clin N e u r o p h y s i o l 46, 214-219 Mignot E, Guilleminault CG, Bowersox S, Rappaport A, Dement WC (1988a) Role of central alpha-1 adrenoceptors in canine narcolepsy. J Clin Invest 82, 885-94 Mignot E, Guilleminault CG, Bowersox S, R a p p a p o r t A, D e m e n t W C ( 1 9 8 8 b ) Effect of a 1 adrenoceptors blockade with prazosin in canine noa-colepsy. Brain Res 444, 184-8 Miller JD, Faull KF, Bowersox SS, Dement WC (1990) CNS monoamines and their metabolites in canine nm'colepsy: a replication study. Brain Res 509, 169-171 Montplaisir J, de Champlain J, Young SN et al (1982) Narcolepsy and idiopathic hypersonmia: biogenic amines and related compounds in CSF. Neurology 32, 1299-1302 N i s h i n o S, Haak L, Shepherd H (1990) Effects of central alpha-2 a d r e n e r g i c c o m p o u n d s on c a n i n e n a r c o l e p s y , a disorder of rapid eye movement sleep. J Pharmacol Exp Ther 253, 1145-1152 N i s h i n o S, A r r i g o n i J, V a l t i e r D et al ( 1 9 9 i ) Dopamine D-2 mechanisms in c a n i n e n a r c o l e p s y . J N e u r o s c i 11, 2666-2671 Ongiui E, Caporali MG, Massotti M (1985) Stimulation of dopamine D-1 recpetors by SKF 38393 induces EEG desynchronisation and behavioral arousal. Life Sci 37, 2327-2333 Parkes JD, Fenton G, Struthers G e t al (1974) Narcolepsy and cataplexy. Clinical features, treatment and cerebrospinal fluid findings. QJ Med 43,525-526

Autoradiographic studies R i c h f i e l d EK, Y o u n g A B , P e n n e y JB (1986) P r o p e r t i e s o f D-2 d o p a m i n e receptor autroradiography: high percentage o f high affinity agonist sites and increased nucleotide sensitivity in tissue sections. Brain Res 383, 121-128 R i c h f i e l d EK, D e B o w e y D, Penney JB, Young AB (1987a) Basal ganglia and cerebral cortical distribution of dopamine D- 1 and D-2 receptors in neonatal and a d u l t cat b r a i n . N e u r o s c i Lett 73, 203-208 R i c h f i e l d EK, Y o u n g A B , P e n n e y JB (1987b) Comparative distribution of dopamine D-1 and D-2 receptors in the basal ganglia of turtles, pigeons, rats, cats, and monkeys. J Comp Neurol 262, 446-463 Rinne JO, Lonnberg P, Marjamaki P (1990) Age-dependent decline in human brain dopamine D1 and D2 receptors. Brain Res 508, 349-352 Robertson HA (1986) Cerebral decortication reverses the effect of amphetamine on striatal D2 dopamine binding site density. Neurosci Lett 72, 325-329 Robertson HA (1982) Chronic phencyclidine, like amphetamine produces a decrease in [3H] spriroperidol binding in rat s t r i a t u m . E u r J P h a r m a c o l 78, 363-365

45

Roseboom PH, Gnegy ME (1989) Acute in vivo amphetamine produces a homologous desensitization of dopamine receptor-coupled adenylate cyclase activities and decreases agonist binding to the D 1 site. Mol Pharmacol 35, 139-147 Sims KS, Williams RS (1990) The human a m y g d a l o i d complex: a cytologic and histochemical atlas using Nissl, myelin, acetylcholinesterase and nicotinamide adenine dinucleotide phosphate diaphorase staining. Neuroscience 36,449-472 Suhura/T, Inoue O, K o b a y a s i K (1990) E f f e c t o f d e s i p r a m i n e on d o p a m i n e r e c e p t o r b i d i n g in vivo. Life Sci 47, 2119-2126 Svensson K, Alfoldi P, Hajos M, Rubicsek G, Johansson AM, Carlsson A, Obal F (1987) Dopamine autoreceptor antagonists: effects of sleep-wake activity in the rat. P h a r m a c o l B i o c h e m Behai~ 26, 123-129 Trulson ME, Crisp T (1985) Chronic administration o f D - a m p h e t a m i n e increases [3H] spiroperidol bindin'g in cat brain. Eur J Pharmacol 117, 267-270 Willner P (1983) Dopamine and depression: a review o f recent evidence. III. The effects o f a n t i d e p r e s s a n t treatments. Brain Res 287, 237-246 e