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5-hydroxyindoleacetic acid in cerebrospinal fluid - methodological and clinical aspects
Life Sciences, Vol. 41, pp. 821-824 Printed in the U.S.A.
Pergamon Journals
5 - H Y D R O X Y I N D O L E A C E T I C A C I D IN C E R E B R O S P I N A L METHODOLOGICAL AND CLINICAL ASPECTS
FLUID
-
Leif Bertilsson Department
of C l i n i c a l P h a r m a c o l o g y at the K a r o l i n s k a Institute, H u d d i n g e H o s p i t a l , S-141 86 H u d d i n g e , S w e d e n
F e w m e t h o d s are a v a i l a b l e to m e a s u r e c e n t r a l s e r o t o n i n f u n c t i o n in the living h u m a n brain. One i n d i r e c t t e c h n i q u e is to d e t e r m i n e the c o n c e n t r a t i o n of the s e r o t o n i n m e t a b o l i t e 5 - h y d r o x y i n d o l e a c e t i c a c i d (5-HIAA) in the c e r e b r o s p i n a l fluid (CSF). Our e x p e r i e n c e w i t h such m e a s u r e m e n t s is r e v i e w e d here. Analytical
methods
for the q u a n t i t a t i o n
of 5 - H I A A
in CSF.
W h e n w e s t a r t e d our i n v e s t i g a t i o n s in 1970 only f l u o r o m e t r i c m e t h o d s w e r e a v a i l a b l e to m e a s u r e 5 - H I A A in CSF. We t h e r e f o r e d e v e l o p e d a m a s s f r a g m e n t o g r a p h i c m e t h o d for q u a n t i t a t i o n (i). This m e t h o d has d u r i n g the y e a r s b e e n i m p r o v e d (2). The use of d i d e u t e r i u m l a b e l l e d 5 - H I A A as i n t e r n a l standard, e n s u r e s a h i g h d e g r e e of r e p r o d u c i b i l i t y . T h i s a l o n g w i t h the h i g h s p e c i f i c i t y has b e e n a p r e r e q u i s i t e for the r e s u l t s o b t a i n e d in our c l i n i c a l i n v e s t i g a t i o n s d e s c r i b e d below. U s i n g m a s s f r a g m e n t o g r a p h y as a r e f e r e n c e m e t h o d , s e v e r a l s t u d i e s have s h o w n t h a t f l u o r o m e t r i c d e t e r m i n a t i o n of 5 - H I A A in CSF does not have a s a t i s f a c t o r y s p e c i f i c i t y (3,4). M a n y h i g h p e r f o r m a n c e liquid c h r o m a t o g r a p h i c (HPLC) m e t h o d s have b e e n d e v e l o p e d to m e a s u r e b i o g e n i c a m i n e s and t h e i r m e t a b o l i t e s . S c h e i n i n et al (5) h a v e d e v e l o p e d an HPLC m e t h o d w i t h e l e c t r o c h e m i c a l d e t e c t i o n that can s i m u l t a n e o u s l y d e t e r m i n e 5-HIAA, homovanillic acid (HVA) and 4 - h y d r o x y - 3 - m e t h o x y p h e n y l glycol (HMPG) in CSF. The s p e c i f i c i t y of this m e t h o d seems to be h i g h and only a small v o l u m e of CSF is required. L a t e l y the p a r e n t t r a n s m i t t e r s e r o t o n i n also has b e e n d e t e r m i n e d in CSF by HPLC (6,7). The c o n c e n t r a t i o n of s e r o t o n i n in CSF is m u c h lower t h a n that of 5 - H I A A a n d little is k n o w n a b o u t the r e l e v a n c e of m e a s u r i n g this amine in c l i n i c a l studies. Factors
influencing
levels
of 5 - H I A A
in CSF.
As s h o w n in table i, s e v e r a l factors i n f l u e n c e the c o n c e n t r a t i o n of 5 - H I A A in h u m a n l u m b a r CSF. B e c a u s e of the p r o n o u n c e d g r a d i e n t b e t w e e n v e n t r i c u l a r , c i s t e r n a l and lumbar CSF, it is i m p o r t a n t to s t a n d a r d i z e the l u m b a r p u n c t u r e for the v o l u m e drawn. We m e a s u r e d a m i n e m e t a b o l i t e levels in four c o n s e c u t i v e 3-ml f r a c t i o n s of CSF d r a w n from d e p r e s s e d p a t i e n t s and h e a l t h y c o n t r o l s (8). T h e r e w a s a fairly steep c o n c e n t r a t i o n g r a d i e n t for b o t h 5 - H I A A and HVA, but o n l y a s l i g h t one for HMPG. T h e r e w a s no d i f f e r e n c e in the slope of the g r a d i e n t s b e t w e e n p a t i e n t s and controls. We also found that it is i m p o r t a n t to s t a n d a r d i z e the site of lumbar p u n c t u r e (9). W h e n lumbar p u n c t u r e s w e r e p e r f o r m e d at two d i f f e r e n t level-s 0024-3205/87$3.00 + .00 Copyright (c) 1987 Pergamon Journals Ltd.
822
5-HIAA in Cerebrospinal Fluid
Vol. 41, No. 7, 1987
three w e e k s a p a r t in 7 males, the 5 - H I A A and H V A c o n c e n t r a t i o n s w e r e lower in the c a u d a l than in the m o r e r o s t r a l sample (Fig i). These r e s u l t s are p r o b a b l y r e l a t e d to the CSF g r a d i e n t s of these two m e t a b o l i t e s . IAA
11(:
HVA
30(
HMPG
10(
8C
"3
20(;
"6 E
=" 5(:1
100
U
2O
0
111 i
i
L3 L4
FIG.
L4- L5
LsS 1
L3L 4
L4-L5
L5S1
1
C o n c e n t r a t i o n of u n c o n j u g a t e d 5-HIAA, HVA and H M P G in lumbar CSF (6 ml CSF was drawn) in 7 h e a l t h y m a l e s at two d i f f e r e n t sites of lumbar p u n c t u r e (From ref 9). TABLE
1
Factors influencing 5-HIAA concentration s t a n d a r d i z a t i o n of lumbar p u n c t u r e
in
Factors
Standardization
Motor activity V o l u m e of CSF d r a w n Site of lumbar p u n c t u r e Diet Circadian variation Drug t r e a t m e n t
Bed rest for 8 hours T o t a l volume: 12 ml B e t w e e n L. and L F a s t i n g ~or 8 h~urs Early m o r n i n g sample
CSF and
Seasonal variation Age Sex Body h e i g h t Disease
N e i t h e r s e r o t o n i n nor 5 - H I A A p a s s e s the b l o o d - b r a i n b a r r i e r to any s i g n i f i c a n t degree. On the o t h e r h a n d the p r e c u r s o r t r y p t o p h a n i n c r e a s e s the p r o b e n e c i d - i n d u c e d a c c u m u l a t i o n of 5 - H I A A in CSF (10). Diet is thus also of i m p o r t a n c e . N i c o l e t t i et al (I0) found a circadian variation, w h e r e the 5 - H I A A in v e n t r i c u l a r CSF i n c r e a s e d d u r i n g the day and p e a k e d at m i d n i g h t , w h e n it w a s 100% h i g h e r than at 6 a.m. In our i n v e s t i g a t i o n s w e have s t a n d a r d i z e d
Vol. 41, No. 7, 1987
5-HIAA in Cerebrospinal Fluid
823
the lumbar p u n c t u r e to include b e d rest and fasting for at least 8 hours. A total v o l u m e of 12 ml is d r a w n w i t h the n e e d l e i n s e r t e d b e t w e e n L 4 and L 5. The lumbar p u n c t u r e is p e r f o r m e d at about 8 a.m. The c o n c e n t r a t i o n of 5 - H I A A v a r i e s w i t h season and i n c r e a s e s w i t h i n c r e a s i n g age (Table i). There is a n e g a t i v e c o r r e l a t i o n b e t w e e n the level of 5 - H I A A in CSF and the body h e i g h t (Ii). The sex d i f f e r e n c e o b s e r v e d is p r o b a b l y due to the fact that m e n u s u a l l y are t a l l e r t h a n women. These factors have to be considered, w h e n c o m p a r i n g levels of amine m e t a b o l i t e s in CSF in p a t i e n t s w i t h a c e r t a i n d i s e a s e and in h e a l t h y controls. Effect
of drug
treatment
on amine m e t a b o l i t e
levels
in CSF.
T r e a t m e n t w i t h p s y c h o t r o p i c drugs o f t e n a f f e c t s levels of amine m e t a b o l i t e s in CSF. For example, n o r t r i p t y l i n e , a p o t e n t i n h i b i t o r of n o r a d r e n a l i n e uptake, d e c r e a s e s the level of H M P G m o r e than that of 5 - H I A A (12). C o n v e r s e l y , the s e r o t o n i n u p t a k e b l o c k e r z i m e l d i n e d e c r e a s e s 5 - H I A A m o r e than H M P G in CSF (13). C h a n g e s of m e t a b o l i t e levels in CSF m a y be u s e d to q u a n t i t a t e the e f f e c t s of drugs on d i f f e r e n t n e u r o n a l systems in man. Obviously, it is important that subjects are drug free w h e n investigating d i f f e r e n c e s in amine m e t a b o l i t e s b e t w e e n d e p r e s s e d p a t i e n t s and controls. Do 5 - H I A A
levels
in CSF reflect
serotonergic
activity
in brain?
The a n s w e r to this q u e s t i o n is: We don't know! Studies in the cat i n d i c a t e that the level of 5 - H I A A in lumbar CSF r e f l e c t s m e t a b o lism of s e r o t o n i n in the spinal cord (14). A m o r e p o s i t i v e study was r e c e n t l y p u b l i s h e d by Stanley et al (15), w h o m e a s u r e d c o n c e n t r a t i o n s of 5 - H I A A in lumbar CSF and in the c e r e b r a l cortex o b t a i n e d s i m u l t a n e o u s l y from 48 i n d i v i d u a l s at autopsy. The strong correlation (r=0.78; p<0.001) b e t w e e n the two p a r a m e t e r s , shows that lumbar CSF levels of 5 - H I A A r e f l e c t b r a i n levels. The authors suggest the results p r o v i d e e v i d e n c e that CSF m e a s u r e s can be u s e d as indices of m e t a b o l i s m in the living b r a i n (15). 5 - H I A A in CSF of h e a l t h y controls.
depressed
and
suicida_l
patients
compared
to
In 1973 we found that the c o n c e n t r a t i o n of 5 - H I A A in CSF w a s b i m o d a l l y d i s t r i b u t e d in d e p r e s s e d p a t i e n t s (16). This m a t e r i a l w a s s u b s e q u e n t l y e x t e n d e d to include 83 p a t i e n t s w i t h d e p r e s s i o n w h o w e r e c o m p a r e d w i t h 66 h e a l t h y c o n t r o l s (17). A f t e r a d j u s t m e n t by a n a l y s i s of c o v a r i a n c e for d i f f e r e n c e s b e t w e e n the subject groups in b o d y height, age, and sex d i s t r i b u t i o n , significantly (p<0.001) lower c o n c e n t r a t i o n s of 5 - H I A A (and also of HVA) w e r e found in the d e p r e s s e d p a t i e n t s t h a n in the controls. Using our published data (17) and m a x i m u m l i k e l i h o o d g a u s s i a n m i x t u r e analysis, G i b b o n s and Davis (18) showed that there is s t a t i s t i c a l e v i d e n c e for a b i o l o g i c a l subtype of depression, c h a r a c t e r i z e d by a b n o r m a l l y low CSF 5 - H I A A and CSF HVA. No e v i d e n c e for m i x t u r e d i s t r i b u t i o n s was found in our controls. In the s u b g r o u p of d e p r e s s e d p a t i e n t s w i t h low CSF levels of 5-HIAA, A s b e r g et al (19) found that suicide a t t e m p t s w e r e s i g n i f i c a n t l y m o r e c o m m o n than in the r e m a i n d e r of the d e p r e s s e d patients. In a f o l l o w - u p study we c o n f i r m e d that suicide
824
5-HIAA in Cerebrospinal Fluid
Vol. 41, No. 7, 1987
a t t e m p t e r s had a s i g n i f i c a n t l y lower CSF 5 - H I A A level than in h e a l t h y controls, e s p e c i a l l y those who had m a d e m o r e v i o l e n t attempts (20). T h e s e and o t h e r studies s u g g e s t a d i s t u r b e d s e r o t o n e r g i c t r a n s m i s s i o n in a s u b g r o u p of d e p r e s s e d p a t i e n t s and in s u i c i d a l b e h a v i o u r of the v i o l e n t type. Acknowledgements Our studies r e v i e w e d heze w e r e s u p p o r t e d by the S w e d i s h M e d i c a l R e s e a r c h C o u n c i l (3902 and 5454), the Bank of S w e d e n T e r c e n t e n a r y F o u n d a t i o n (83/38) and the K a r o l i n s k a Institute.
References i.
2.
L. B E R T I L S S O N , A. J. A T K I N S O N , Jr., J. R. ALTHAUS, A. H~RFAST, J.-E. L I N D G R E N and B. H O L M S T E D T , Anal. Chem. 44 1 4 3 4 - 1 4 3 8 (1972). L. B E R T I L S S O N , in C l i n i c a l P h a r m a c o l o g y in P s y c h i a t r y , E. Usdin, ed., pp. 59-71, E l s e v i e r - N o r t h Holland, N e w Y o r k
(1981). 3. 4.
5. 6.
7. 8 9 i0 ]i 12 13 14 15. 16. 17.
18. 19. 20.
B. S J O Q U I S T and B. J O H A N S S O N , J. N e u r o c h e m , 31 621-625 (1978). L. F. MAJOR, D. L. MURPHY, S. L I P P E R and E. GORDON, J. N e u r o c h e m . 32 229-231 (1979). M. SCHEININ, W.-H. CHANG, D. C. J I M E R S O N and M. LINNOILA, Anal. Biochem. 132 165-170 (1983). F. ARTIGAS, M. J. SARRIAS, E. ~ R T I N E Z and E. GELPI, Life Sci. 37 441-447 (1985). M. LINNOILA, K. A. JACOBSON, T. H. M A R S H A L L , T. L. M I L L E R and K. L. KIRK, Life Sci. 38 687-694 (1986). L. B E R T I L S S O N , M. ASBERG, O. LANTTO, G.-P. S C A L I A - T O M B A , L. T R ~ S K M A N - B E N D Z and G. TYBRING, Psych. Res. 6 77-83 (1982) C. NORDIN, B. SIWERS and L. B E R T I L S S O N , Arch. Gen. P s y c h i a t r y 39 1445 (1982). F. K. GOODWIN, R. M. POST, D. L. D U N N E R and E. K. GORDON, Am. J. P s y c h i a t r y 130 73-79 (1973). B. W O D E - H E L G O D T and G. SEDVALL, Commun. P s y c h o p h a r m a c o l . 2 177-183 (1978). C. NORDIN, L. B E R T I L S S O N and B. SIWERS, Clin. Pharmacol. Therap. In press (1987). L. B E R T I L S S O N , J. R. T U C K and B. SIWERS, Europ. J. clin. Pharmacol. 18 483-487 (1980). M. B U L A T and B. ZIVCOVIC, S c i e n c e 173 738-740 (1971). M. STANLEY, L. T R ~ S K M A N - B E N D Z and K. D O R O V I N I - Z I S , Life Sci. 37 1279-1286 (1985). M. ASBERG, L. B E R T I L S S O N , D. TUCK, B. C R O N H O L M and F. SJOQVIST, Clin. Pharmacol. Therap. 14 277-286 (1973). M. A S B E R G , L. B E R T I L S S O N , B. M A R T E N S S O N , G.-P. S C A L I A - T O M B A , P. T H O R E N and L. T R ~ S K M A N - B E N D Z , Acta Psychiatr. Scand. 69 201-218 (1984). R.D. G i b b o n s and J.M. DAVIS, A c t a Psychiatr. Scand. 74 8-12 (1986). M. ASBERG, L. T R ~ S K M A N and P. THOREN, Arch. Gen. P s y c h i a t r y 33 1193-1197 (1976). L. TR~SKMAN, M. ASBERG, L. B E R T I L S S O N and L. SJOSTRAND, Arch. Gen. P s y c h i a t r y 38 631-636 (1981).
Pergamon Journals
5 - H Y D R O X Y I N D O L E A C E T I C A C I D IN C E R E B R O S P I N A L METHODOLOGICAL AND CLINICAL ASPECTS
FLUID
-
Leif Bertilsson Department
of C l i n i c a l P h a r m a c o l o g y at the K a r o l i n s k a Institute, H u d d i n g e H o s p i t a l , S-141 86 H u d d i n g e , S w e d e n
F e w m e t h o d s are a v a i l a b l e to m e a s u r e c e n t r a l s e r o t o n i n f u n c t i o n in the living h u m a n brain. One i n d i r e c t t e c h n i q u e is to d e t e r m i n e the c o n c e n t r a t i o n of the s e r o t o n i n m e t a b o l i t e 5 - h y d r o x y i n d o l e a c e t i c a c i d (5-HIAA) in the c e r e b r o s p i n a l fluid (CSF). Our e x p e r i e n c e w i t h such m e a s u r e m e n t s is r e v i e w e d here. Analytical
methods
for the q u a n t i t a t i o n
of 5 - H I A A
in CSF.
W h e n w e s t a r t e d our i n v e s t i g a t i o n s in 1970 only f l u o r o m e t r i c m e t h o d s w e r e a v a i l a b l e to m e a s u r e 5 - H I A A in CSF. We t h e r e f o r e d e v e l o p e d a m a s s f r a g m e n t o g r a p h i c m e t h o d for q u a n t i t a t i o n (i). This m e t h o d has d u r i n g the y e a r s b e e n i m p r o v e d (2). The use of d i d e u t e r i u m l a b e l l e d 5 - H I A A as i n t e r n a l standard, e n s u r e s a h i g h d e g r e e of r e p r o d u c i b i l i t y . T h i s a l o n g w i t h the h i g h s p e c i f i c i t y has b e e n a p r e r e q u i s i t e for the r e s u l t s o b t a i n e d in our c l i n i c a l i n v e s t i g a t i o n s d e s c r i b e d below. U s i n g m a s s f r a g m e n t o g r a p h y as a r e f e r e n c e m e t h o d , s e v e r a l s t u d i e s have s h o w n t h a t f l u o r o m e t r i c d e t e r m i n a t i o n of 5 - H I A A in CSF does not have a s a t i s f a c t o r y s p e c i f i c i t y (3,4). M a n y h i g h p e r f o r m a n c e liquid c h r o m a t o g r a p h i c (HPLC) m e t h o d s have b e e n d e v e l o p e d to m e a s u r e b i o g e n i c a m i n e s and t h e i r m e t a b o l i t e s . S c h e i n i n et al (5) h a v e d e v e l o p e d an HPLC m e t h o d w i t h e l e c t r o c h e m i c a l d e t e c t i o n that can s i m u l t a n e o u s l y d e t e r m i n e 5-HIAA, homovanillic acid (HVA) and 4 - h y d r o x y - 3 - m e t h o x y p h e n y l glycol (HMPG) in CSF. The s p e c i f i c i t y of this m e t h o d seems to be h i g h and only a small v o l u m e of CSF is required. L a t e l y the p a r e n t t r a n s m i t t e r s e r o t o n i n also has b e e n d e t e r m i n e d in CSF by HPLC (6,7). The c o n c e n t r a t i o n of s e r o t o n i n in CSF is m u c h lower t h a n that of 5 - H I A A a n d little is k n o w n a b o u t the r e l e v a n c e of m e a s u r i n g this amine in c l i n i c a l studies. Factors
influencing
levels
of 5 - H I A A
in CSF.
As s h o w n in table i, s e v e r a l factors i n f l u e n c e the c o n c e n t r a t i o n of 5 - H I A A in h u m a n l u m b a r CSF. B e c a u s e of the p r o n o u n c e d g r a d i e n t b e t w e e n v e n t r i c u l a r , c i s t e r n a l and lumbar CSF, it is i m p o r t a n t to s t a n d a r d i z e the l u m b a r p u n c t u r e for the v o l u m e drawn. We m e a s u r e d a m i n e m e t a b o l i t e levels in four c o n s e c u t i v e 3-ml f r a c t i o n s of CSF d r a w n from d e p r e s s e d p a t i e n t s and h e a l t h y c o n t r o l s (8). T h e r e w a s a fairly steep c o n c e n t r a t i o n g r a d i e n t for b o t h 5 - H I A A and HVA, but o n l y a s l i g h t one for HMPG. T h e r e w a s no d i f f e r e n c e in the slope of the g r a d i e n t s b e t w e e n p a t i e n t s and controls. We also found that it is i m p o r t a n t to s t a n d a r d i z e the site of lumbar p u n c t u r e (9). W h e n lumbar p u n c t u r e s w e r e p e r f o r m e d at two d i f f e r e n t level-s 0024-3205/87$3.00 + .00 Copyright (c) 1987 Pergamon Journals Ltd.
822
5-HIAA in Cerebrospinal Fluid
Vol. 41, No. 7, 1987
three w e e k s a p a r t in 7 males, the 5 - H I A A and H V A c o n c e n t r a t i o n s w e r e lower in the c a u d a l than in the m o r e r o s t r a l sample (Fig i). These r e s u l t s are p r o b a b l y r e l a t e d to the CSF g r a d i e n t s of these two m e t a b o l i t e s . IAA
11(:
HVA
30(
HMPG
10(
8C
"3
20(;
"6 E
=" 5(:1
100
U
2O
0
111 i
i
L3 L4
FIG.
L4- L5
LsS 1
L3L 4
L4-L5
L5S1
1
C o n c e n t r a t i o n of u n c o n j u g a t e d 5-HIAA, HVA and H M P G in lumbar CSF (6 ml CSF was drawn) in 7 h e a l t h y m a l e s at two d i f f e r e n t sites of lumbar p u n c t u r e (From ref 9). TABLE
1
Factors influencing 5-HIAA concentration s t a n d a r d i z a t i o n of lumbar p u n c t u r e
in
Factors
Standardization
Motor activity V o l u m e of CSF d r a w n Site of lumbar p u n c t u r e Diet Circadian variation Drug t r e a t m e n t
Bed rest for 8 hours T o t a l volume: 12 ml B e t w e e n L. and L F a s t i n g ~or 8 h~urs Early m o r n i n g sample
CSF and
Seasonal variation Age Sex Body h e i g h t Disease
N e i t h e r s e r o t o n i n nor 5 - H I A A p a s s e s the b l o o d - b r a i n b a r r i e r to any s i g n i f i c a n t degree. On the o t h e r h a n d the p r e c u r s o r t r y p t o p h a n i n c r e a s e s the p r o b e n e c i d - i n d u c e d a c c u m u l a t i o n of 5 - H I A A in CSF (10). Diet is thus also of i m p o r t a n c e . N i c o l e t t i et al (I0) found a circadian variation, w h e r e the 5 - H I A A in v e n t r i c u l a r CSF i n c r e a s e d d u r i n g the day and p e a k e d at m i d n i g h t , w h e n it w a s 100% h i g h e r than at 6 a.m. In our i n v e s t i g a t i o n s w e have s t a n d a r d i z e d
Vol. 41, No. 7, 1987
5-HIAA in Cerebrospinal Fluid
823
the lumbar p u n c t u r e to include b e d rest and fasting for at least 8 hours. A total v o l u m e of 12 ml is d r a w n w i t h the n e e d l e i n s e r t e d b e t w e e n L 4 and L 5. The lumbar p u n c t u r e is p e r f o r m e d at about 8 a.m. The c o n c e n t r a t i o n of 5 - H I A A v a r i e s w i t h season and i n c r e a s e s w i t h i n c r e a s i n g age (Table i). There is a n e g a t i v e c o r r e l a t i o n b e t w e e n the level of 5 - H I A A in CSF and the body h e i g h t (Ii). The sex d i f f e r e n c e o b s e r v e d is p r o b a b l y due to the fact that m e n u s u a l l y are t a l l e r t h a n women. These factors have to be considered, w h e n c o m p a r i n g levels of amine m e t a b o l i t e s in CSF in p a t i e n t s w i t h a c e r t a i n d i s e a s e and in h e a l t h y controls. Effect
of drug
treatment
on amine m e t a b o l i t e
levels
in CSF.
T r e a t m e n t w i t h p s y c h o t r o p i c drugs o f t e n a f f e c t s levels of amine m e t a b o l i t e s in CSF. For example, n o r t r i p t y l i n e , a p o t e n t i n h i b i t o r of n o r a d r e n a l i n e uptake, d e c r e a s e s the level of H M P G m o r e than that of 5 - H I A A (12). C o n v e r s e l y , the s e r o t o n i n u p t a k e b l o c k e r z i m e l d i n e d e c r e a s e s 5 - H I A A m o r e than H M P G in CSF (13). C h a n g e s of m e t a b o l i t e levels in CSF m a y be u s e d to q u a n t i t a t e the e f f e c t s of drugs on d i f f e r e n t n e u r o n a l systems in man. Obviously, it is important that subjects are drug free w h e n investigating d i f f e r e n c e s in amine m e t a b o l i t e s b e t w e e n d e p r e s s e d p a t i e n t s and controls. Do 5 - H I A A
levels
in CSF reflect
serotonergic
activity
in brain?
The a n s w e r to this q u e s t i o n is: We don't know! Studies in the cat i n d i c a t e that the level of 5 - H I A A in lumbar CSF r e f l e c t s m e t a b o lism of s e r o t o n i n in the spinal cord (14). A m o r e p o s i t i v e study was r e c e n t l y p u b l i s h e d by Stanley et al (15), w h o m e a s u r e d c o n c e n t r a t i o n s of 5 - H I A A in lumbar CSF and in the c e r e b r a l cortex o b t a i n e d s i m u l t a n e o u s l y from 48 i n d i v i d u a l s at autopsy. The strong correlation (r=0.78; p<0.001) b e t w e e n the two p a r a m e t e r s , shows that lumbar CSF levels of 5 - H I A A r e f l e c t b r a i n levels. The authors suggest the results p r o v i d e e v i d e n c e that CSF m e a s u r e s can be u s e d as indices of m e t a b o l i s m in the living b r a i n (15). 5 - H I A A in CSF of h e a l t h y controls.
depressed
and
suicida_l
patients
compared
to
In 1973 we found that the c o n c e n t r a t i o n of 5 - H I A A in CSF w a s b i m o d a l l y d i s t r i b u t e d in d e p r e s s e d p a t i e n t s (16). This m a t e r i a l w a s s u b s e q u e n t l y e x t e n d e d to include 83 p a t i e n t s w i t h d e p r e s s i o n w h o w e r e c o m p a r e d w i t h 66 h e a l t h y c o n t r o l s (17). A f t e r a d j u s t m e n t by a n a l y s i s of c o v a r i a n c e for d i f f e r e n c e s b e t w e e n the subject groups in b o d y height, age, and sex d i s t r i b u t i o n , significantly (p<0.001) lower c o n c e n t r a t i o n s of 5 - H I A A (and also of HVA) w e r e found in the d e p r e s s e d p a t i e n t s t h a n in the controls. Using our published data (17) and m a x i m u m l i k e l i h o o d g a u s s i a n m i x t u r e analysis, G i b b o n s and Davis (18) showed that there is s t a t i s t i c a l e v i d e n c e for a b i o l o g i c a l subtype of depression, c h a r a c t e r i z e d by a b n o r m a l l y low CSF 5 - H I A A and CSF HVA. No e v i d e n c e for m i x t u r e d i s t r i b u t i o n s was found in our controls. In the s u b g r o u p of d e p r e s s e d p a t i e n t s w i t h low CSF levels of 5-HIAA, A s b e r g et al (19) found that suicide a t t e m p t s w e r e s i g n i f i c a n t l y m o r e c o m m o n than in the r e m a i n d e r of the d e p r e s s e d patients. In a f o l l o w - u p study we c o n f i r m e d that suicide
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5-HIAA in Cerebrospinal Fluid
Vol. 41, No. 7, 1987
a t t e m p t e r s had a s i g n i f i c a n t l y lower CSF 5 - H I A A level than in h e a l t h y controls, e s p e c i a l l y those who had m a d e m o r e v i o l e n t attempts (20). T h e s e and o t h e r studies s u g g e s t a d i s t u r b e d s e r o t o n e r g i c t r a n s m i s s i o n in a s u b g r o u p of d e p r e s s e d p a t i e n t s and in s u i c i d a l b e h a v i o u r of the v i o l e n t type. Acknowledgements Our studies r e v i e w e d heze w e r e s u p p o r t e d by the S w e d i s h M e d i c a l R e s e a r c h C o u n c i l (3902 and 5454), the Bank of S w e d e n T e r c e n t e n a r y F o u n d a t i o n (83/38) and the K a r o l i n s k a Institute.
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2.
L. B E R T I L S S O N , A. J. A T K I N S O N , Jr., J. R. ALTHAUS, A. H~RFAST, J.-E. L I N D G R E N and B. H O L M S T E D T , Anal. Chem. 44 1 4 3 4 - 1 4 3 8 (1972). L. B E R T I L S S O N , in C l i n i c a l P h a r m a c o l o g y in P s y c h i a t r y , E. Usdin, ed., pp. 59-71, E l s e v i e r - N o r t h Holland, N e w Y o r k
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