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Reduced amounts of immunoreactive somatostatin in the temporal cortex in senile dementia of Alzheimer type
Neuroscience Letters, 20 (1980) 373-377
373
© Elsevier/North-HoLland Scientific Publishers Ltd.
R E D U C E D AMOUNTS OF I M M U N O R E A C T I V E S O M A T O S T A T I N IN T H E T E M P O R A L CORTEX IN SENILE D E M E N T I A OF A L Z H E I M E R TYPE
M.N. ROSSOR, P.C. EMSON, C.Q. MOUNT JOY, SIR MARTIN ROTH and L.L. IVERSEN
MRC Neurochemical Pharmacology Unit, Department of Neurological Surgery and Neurology and (C.Q.M. and M.R.) Department of Psychiatry, Addenbrooke's Hospital, Cambridge (U.K.) (Received July 14th, 1980; Accepted August 19th, 1980)
Post-mortem brain tissue from 15 patients dying with a diagnosis of senile dementia of Alzheimer type (SDAT) was compared with tissue obtained from 16 control patients at routine post-mortem. A significant fall in choline acetyltransferase (CHAT) activity was observed in the cortex, hippocampus and amygdala of the SDAT cases and was maximal in the temporal cortex. The fall in ChAT activity observed in the temporal cortex was accompanied by a significant reduction (47°70) in immunoreactive somatostatin.
There have been a number of reports of a cholinergic deficit in senile dementia of Alzheimer type (SDAT). Choline acetyltransferase (CHAT) [8, 16, 28] and acetylcholine [20] are reduced in post-mortem cerebral cortex and ChAT and acetylcholine synthesis are reduced in biopsied temporal cortex [23]. These cholinergic indices correlate with the degree of dementia at the time of death [17, 23]. Dopamine, noradrenaline, 5-hydroxytryptamine and 7-aminobutyric acid systems have also been examined (for review see ref. 27), and apart from a modest fall in monoamines [1] the significant changes have been confined to the cholinergic system. Recently a number o f peptides have been described which are found in mammalian central neurones and which may act as neurotransmitters or neuromodulators (for review see refs. 9 and 10). Somatostatin, a hypothalamic tetradecapeptide which was found to inhibit growth hormone release [4] is also found in substantial quantities in the rat cerebral cortex and hippocampus [5, 12], areas of the brain which show the most marked histological changes in SDAT. Furthermore, immunohistochemical studies [2] have demonstrated somatostatin within the cell bodies in the cerebral cortex, indicating that some of these somatostatin neurones are intrinsic to the cortex, and the study of Petrusz et al. [19] suggests that somatostatin in the hippocampus may also be confined to local interneurones. In this study, we have measured the levels of immunoreactive somatostatin in post-mortem tissue from SDAT and control cases to assess whether this population of cortical and hippocampal neurones is affected in SDAT.
374
Fifteen brains were examined from patients dying with a diagnosis of SDAT (4 males, 11 females; mean age + S.D. = 80 _ 8 years; mean autopsy delay +_ S.D. = 39 +_ 23 h, range 7-77 h). All patients had been assessed during life on a dementia scale and an i n f o r m a t i o n - c o n c e n t r a t i o n - m e m o r y test [22]. In addition, all cases were confirmed histologically by the presence of widespread cortical plaques and neurofibrillary tangles, although two cases were included in which there were low numbers of plaques but abundant tangles. The control group comprised 16 brains from patients dying without a history of neurological or psychiatric illness or of intellectual impairment (8 males, 8 females; mean age _+ S.D. = 78 _+ 8 years; mean autopsy delay _ S.D. = 54 +_ 25 h, range 24-108 h). All control cases were normal on histological examination. Following removal, the brains were divided mid-sagittally and one half fixed in formalin for histological examination, and the other half frozen at - 7 0 ° C for biochemical studies. Six brain areas were examined: Brodmann areas 10 (frontal cortex), 7 (parietal cortex), 21 (temporal cortex), amygdala, hippocampus and putamen. Details of storage and dissection have been reported previously [24]. Tissue samples for ChAT assays were homogenized in water and assayed by the method of Fonnum [11]. Tissue samples for somatostatin assays were extracted in boiling 1 M acetic acid for 10 min, the homogenates centrifuged, and the supernatants freeze-dried. The dried samples were reconstituted in assay buffer and their somatostatin content determined by the radioimmunoassay procedure of P e n m a n et al. [14]. Protein determinations were performed according to Lowry et al. [13]. The values for ChAT and somatostatin determinations are shown in Table I. A significant fall in ChAT was apparent in the cerebral cortex, hippocampus and amygdala and the reduction was most marked in the temporal lobe (62O7o). The somatostatin content of the temporal cortex (Brodmann area 21) also showed a highly significant reduction of 47°7o in the SDAT group. The somatostatin content of the remaining areas in the dementia brain did not differ significantly from that of control brain although there was a tendency in all areas for the values to be lower. The mean delay to autopsy differed in the two groups (39 h in the SDAT group and 54 h in the control group), and it is possible that post-mortem losses of somatostatin and ChAT in the two groups may have differed. However, using the mouse brain cooling model of Spokes and Koch [25] no losses of somatostatin (Penman and Wass, personal communication) or of C h A T [25] were apparent up to 72 h post-mortem. Moreover, we were unable to demonstrate any significant correlation between the levels of somatostatin and autopsy delay (r = 0.28, ns, for the S D A T group and r = - 0 . 1 9 , ns, for the control group) or between the values for C h A T activity and autopsy delay (r = - 0.08, ns, for the SDAT group and r = - 0 . 2 3 , ns, for the control group). The reduction of C h A T in the temporal cortex is similar to that reported for the whole temporal lobe by Bowen et al. [3]. In general, however, the reductions
(CHAT) A C T I V I T Y I N C O N T R O L A N D S D A T B R A I N S
B r o d m a n n area 10 B r o d m a n n area 7 B r o d m a n n area 21 Amygdala Posterior hippocampus Putamen
C e r e b r a l cortex:
Brain area
60.4 44.3 70.7 254.6 59.4 116.7
_+ _+ _+ _+ _+ _+
6.2 3.8 6.3 26.5 4.9 12.6
Control
47.3 34.4 37.3 193.5 46.4 94.6
_+ 4.7 ___ 3.1 _+ 2.6** + 17.8 _+ 4.0(13) + 12.0
SDAT
6.75 4.69 8.19 50.10 20.59 338.2
_+ _+ _+ _+ __. _+
0.36 0.40 0.57 6.00 1.66 30.1
Control
+ + _+ + _+ _
0.36** 0.35* 0.45** 4.46* 1.31(13)** 33.9
SDAT
3.99 2.93 3.14 22.70 8.33 285.0
ChAT ( ~ m o l / h / g protein)
Somatostatin ( p m o l / g tissue)
Figures are m e a n s _+ S . E . M . for 15 control and 15 S D A T b r a i n s except w h e r e i n d i c a t e d in b r a c k e t s . B r o d m a n n area 10 = p r e f r o n t a l cortex; B r o d m a n n area 7 = parietal cortex; B r o d m a n n area 21 = m i d d l e t e m p o r a l gyrus. The p r o t e i n c o n t e n t s o f the c o n t r o l a n d S D A T g r o u p did not d i f f e r significantly. * P < 0.01 ; • * P < 0.001, S t u d e n t ' s t-test (two-tailed).
SOMATOSTATIN CONTENT AND CHOLINE ACETYLTRANSFERASE
TABLE I
376
reported here are less profound than those reported by Perry [15] and Davies [7]. The absence of any change in the putamen indicates that the loss of ChAT activity is confined to certain brain areas. The reduction in ChAT probably reflects loss of afferent cholinergic terminals rather than intrinsic neocortical and hippocampal neurones [15, 18, 21]. Indeed, the claim that there are substantial losses of cortical neurones in SDAT [6] has been disputed by others [26]. However, the loss of somatostatin in the temporal lobe suggests that this population of intrinsic neocortical neurones is affected in SDAT, although to what extent this may represent a late feature of the disorder is unknown. We would like to thank the many clinicians and pathologists involved in the collection of tissue. We also acknowledge the excellent technical assistance of Mr. N. Garrett and Mr. P. Horsefield.
1 2 3
4
5 6 7 8 9 10 11 12 13 14
15
Adolfsson, R., Gottfries, C.G., Roos, B.E. and Winblad, B., Changes in brain catecholamines in patients with dementia of Alzheimer type, Brit. J. Psychiat., 135 (1979) 216-223. Bennett-Clarke, C., Romagnano, M.A. and Joseph, S.A., Distribution of somatostatin in the rat brain: telencephalon and diencephalon, Brain Res., 188 (1980) 473-486. Bowen, D.M., White, P., Spillane, J.A., Goodhardt, M.J., Curzon, G., lwangoff, P., Meier-Ruge, W. and Davison, A.N., Accelerated ageing or selective neuronal loss as an important cause of dementia? Lancet, i (1979) 11 14. Brazeau, P., Vale, W., Burgus, R., Ling, N., Butcher, M., Rivier, J. and Guillemin, R., Hypothalamic polypeptide that inhibits the secretion of immunoreactive pituitary growth hormone, Science, 179 (1973) 77-79. Brownstein, M., Arimura, A., Sato, H., Schally, A.V. and Kizer, J.S., The regional distribution of somatostatin in the rat brain, Endocrinology, 96 (1975) 1456-1461. Colon, E.J., The cerebral cortex in presenile dementia: a quantitative analysis, Acta neuropath. (Berl.),23 (1973) 281 290. Davies, P., Neurotransmitter-related enzymes in senile dementia of the Alzheimer type, Brain Res., 171 (1979) 319 327. Davies, P. and Maloney, A.J., Selective loss of central cholinergic neurones in Alzheimer's disease, Lancet, ii (1976) 1403. Emson, P.C., Peptides as neurotransmitter candidates in the mammalian CNS, Progr. Neurobiol., 13 (1979) 61-116. Emson, P.C. and kindvall, O., Distribution of putative neurotransmitters in the neocortex, Neuroscience, 4 (1979) l 30. Fonnum, F., Radiochemical microassays for the determination of choline acetyltransferase and acetylcholinesterase activities, Biochem. J., 115 (1969) 465-472. Kobayashi, R.M., Brown, M. and Vale, W., Regional distribution of neurotensin and somatostatin in rat brain, Brain Res., 126 (1977) 584-588. Lowry, O.H., Rosebrough, N.J., Farr, A.L. and Randall, R.J., Protein measurement with the Folin phenol reagent, J. biol. Chem., 193 (1951) 265 275. Penman, E., Wass, J.A.H., Lund, A., Lowry, P.J., Stuart, J., Dawson, A.M., Besser, G.M. and Rees, L.H., Development and validation of a specific radioimmunoassay for somatostatin in human plasma, Ann. clin. Biochem., in press. Perry, E.K., The cholinergic system in old age and Alzheimer's disease, Age and Ageing, 9 (1980) I-8.
377 16 Perry, E.K., Perry, R.H., Blessed, G. and Tomlinson, B.E., Necropsy evidence of central cholinergic deficits in senile dementia, Lancet, i (1977) 189. 17 Perry, E.K., Tomlinson, B.E., Blessed, G., Bergmann, K., Gibson, P.H. and Perry, R.H., Correlation of cholinergic abnormalities with senile plaques and mental test scores in senile dementia, Brit. med. J., 2 (1978) 1457-1459. 18 Perry, R.H., Blessed, G., Perry, E.K. and Tomlinson, B.E., Histochemical observations on cholinesterase activities in the brains of elderly normal and demented (Alzheimer-type) patients, Age and Ageing, 9 (1980) 9-16. 19 Petrusz, P., Sar, M., Grossman, G.H. and Kizer, J.S., Synaptic terminals with somatostatin-like immunoreactivity in the rat brain, Brain Res., 137 (1977) 181-187. 20 Richter, J.A., Perry, E.K. and Tomlinson, B.E., Acetylcholine and choline levels in post-mortem human brain tissue: preliminary observations in Alzheimer's disease, Life Sci., 26 (1980) 1683-1689. 21 Rossor, M., Fahrenkrug, J., Emson, P., Mountjoy, C., Iversen, L. and Roth, M., Reduced cortical choline acetyltransferase activity in senile dementia of Alzheimer type is not accompanied by changes in vasoactive intestinal polypeptide, Brain Res., in press. 22 Roth, M. and Hopkins, B., Psychological test performance in patients over sixty. 1. Senile psychosis and the affective disorders of old age, J. ment. Sci., 99 (1953) 439-450. 23 Sims, N.R., Bowen, D.M., Smith, C.C.T., Flack, R.H.A., Davison, A.N., Snowden, J.S. and Neary, D., Glucose metabolism and acetylcholine synthesis in relation to neuronal activity in Alzheimer's disease, Lancet, i (1980) 333-335. 24 Spokes, E.G.S., An analysis of factors influencing measurements of dopamine, noradrenaline, glutamate decarboxylase and choline acetylase in human post-mortem brain tissue, Brain, 102 (1979) 333-346. 25 Spokes, E.G.S. and Koch, D.J., Post mortem stability of dopamine, glutamate decarboxylase and choline acetyltransferase in the mouse brain under conditions simulating the handling of human autopsy material, J. Neurochem., 31 (1978) 381-383. 26 Terry, R.D., Senile dementia, Fed. Proc., 37 (1978) 2837-2840. 27 Terry, R.D. and Davies, P., Dementia of the Alzheimer type, Ann. Rev. Neurosci., 3 (1980) 77-95. 28 White, P., Goodhardt, M.J., Keat, J.P., Hiley, C.R., Carrasco, L.H., Williams, I.E. and Bowen, D.M., Neocortical neurons in elderly people, Lancet, i (1977) 668-671.
373
© Elsevier/North-HoLland Scientific Publishers Ltd.
R E D U C E D AMOUNTS OF I M M U N O R E A C T I V E S O M A T O S T A T I N IN T H E T E M P O R A L CORTEX IN SENILE D E M E N T I A OF A L Z H E I M E R TYPE
M.N. ROSSOR, P.C. EMSON, C.Q. MOUNT JOY, SIR MARTIN ROTH and L.L. IVERSEN
MRC Neurochemical Pharmacology Unit, Department of Neurological Surgery and Neurology and (C.Q.M. and M.R.) Department of Psychiatry, Addenbrooke's Hospital, Cambridge (U.K.) (Received July 14th, 1980; Accepted August 19th, 1980)
Post-mortem brain tissue from 15 patients dying with a diagnosis of senile dementia of Alzheimer type (SDAT) was compared with tissue obtained from 16 control patients at routine post-mortem. A significant fall in choline acetyltransferase (CHAT) activity was observed in the cortex, hippocampus and amygdala of the SDAT cases and was maximal in the temporal cortex. The fall in ChAT activity observed in the temporal cortex was accompanied by a significant reduction (47°70) in immunoreactive somatostatin.
There have been a number of reports of a cholinergic deficit in senile dementia of Alzheimer type (SDAT). Choline acetyltransferase (CHAT) [8, 16, 28] and acetylcholine [20] are reduced in post-mortem cerebral cortex and ChAT and acetylcholine synthesis are reduced in biopsied temporal cortex [23]. These cholinergic indices correlate with the degree of dementia at the time of death [17, 23]. Dopamine, noradrenaline, 5-hydroxytryptamine and 7-aminobutyric acid systems have also been examined (for review see ref. 27), and apart from a modest fall in monoamines [1] the significant changes have been confined to the cholinergic system. Recently a number o f peptides have been described which are found in mammalian central neurones and which may act as neurotransmitters or neuromodulators (for review see refs. 9 and 10). Somatostatin, a hypothalamic tetradecapeptide which was found to inhibit growth hormone release [4] is also found in substantial quantities in the rat cerebral cortex and hippocampus [5, 12], areas of the brain which show the most marked histological changes in SDAT. Furthermore, immunohistochemical studies [2] have demonstrated somatostatin within the cell bodies in the cerebral cortex, indicating that some of these somatostatin neurones are intrinsic to the cortex, and the study of Petrusz et al. [19] suggests that somatostatin in the hippocampus may also be confined to local interneurones. In this study, we have measured the levels of immunoreactive somatostatin in post-mortem tissue from SDAT and control cases to assess whether this population of cortical and hippocampal neurones is affected in SDAT.
374
Fifteen brains were examined from patients dying with a diagnosis of SDAT (4 males, 11 females; mean age + S.D. = 80 _ 8 years; mean autopsy delay +_ S.D. = 39 +_ 23 h, range 7-77 h). All patients had been assessed during life on a dementia scale and an i n f o r m a t i o n - c o n c e n t r a t i o n - m e m o r y test [22]. In addition, all cases were confirmed histologically by the presence of widespread cortical plaques and neurofibrillary tangles, although two cases were included in which there were low numbers of plaques but abundant tangles. The control group comprised 16 brains from patients dying without a history of neurological or psychiatric illness or of intellectual impairment (8 males, 8 females; mean age _+ S.D. = 78 _+ 8 years; mean autopsy delay _ S.D. = 54 +_ 25 h, range 24-108 h). All control cases were normal on histological examination. Following removal, the brains were divided mid-sagittally and one half fixed in formalin for histological examination, and the other half frozen at - 7 0 ° C for biochemical studies. Six brain areas were examined: Brodmann areas 10 (frontal cortex), 7 (parietal cortex), 21 (temporal cortex), amygdala, hippocampus and putamen. Details of storage and dissection have been reported previously [24]. Tissue samples for ChAT assays were homogenized in water and assayed by the method of Fonnum [11]. Tissue samples for somatostatin assays were extracted in boiling 1 M acetic acid for 10 min, the homogenates centrifuged, and the supernatants freeze-dried. The dried samples were reconstituted in assay buffer and their somatostatin content determined by the radioimmunoassay procedure of P e n m a n et al. [14]. Protein determinations were performed according to Lowry et al. [13]. The values for ChAT and somatostatin determinations are shown in Table I. A significant fall in ChAT was apparent in the cerebral cortex, hippocampus and amygdala and the reduction was most marked in the temporal lobe (62O7o). The somatostatin content of the temporal cortex (Brodmann area 21) also showed a highly significant reduction of 47°7o in the SDAT group. The somatostatin content of the remaining areas in the dementia brain did not differ significantly from that of control brain although there was a tendency in all areas for the values to be lower. The mean delay to autopsy differed in the two groups (39 h in the SDAT group and 54 h in the control group), and it is possible that post-mortem losses of somatostatin and ChAT in the two groups may have differed. However, using the mouse brain cooling model of Spokes and Koch [25] no losses of somatostatin (Penman and Wass, personal communication) or of C h A T [25] were apparent up to 72 h post-mortem. Moreover, we were unable to demonstrate any significant correlation between the levels of somatostatin and autopsy delay (r = 0.28, ns, for the S D A T group and r = - 0 . 1 9 , ns, for the control group) or between the values for C h A T activity and autopsy delay (r = - 0.08, ns, for the SDAT group and r = - 0 . 2 3 , ns, for the control group). The reduction of C h A T in the temporal cortex is similar to that reported for the whole temporal lobe by Bowen et al. [3]. In general, however, the reductions
(CHAT) A C T I V I T Y I N C O N T R O L A N D S D A T B R A I N S
B r o d m a n n area 10 B r o d m a n n area 7 B r o d m a n n area 21 Amygdala Posterior hippocampus Putamen
C e r e b r a l cortex:
Brain area
60.4 44.3 70.7 254.6 59.4 116.7
_+ _+ _+ _+ _+ _+
6.2 3.8 6.3 26.5 4.9 12.6
Control
47.3 34.4 37.3 193.5 46.4 94.6
_+ 4.7 ___ 3.1 _+ 2.6** + 17.8 _+ 4.0(13) + 12.0
SDAT
6.75 4.69 8.19 50.10 20.59 338.2
_+ _+ _+ _+ __. _+
0.36 0.40 0.57 6.00 1.66 30.1
Control
+ + _+ + _+ _
0.36** 0.35* 0.45** 4.46* 1.31(13)** 33.9
SDAT
3.99 2.93 3.14 22.70 8.33 285.0
ChAT ( ~ m o l / h / g protein)
Somatostatin ( p m o l / g tissue)
Figures are m e a n s _+ S . E . M . for 15 control and 15 S D A T b r a i n s except w h e r e i n d i c a t e d in b r a c k e t s . B r o d m a n n area 10 = p r e f r o n t a l cortex; B r o d m a n n area 7 = parietal cortex; B r o d m a n n area 21 = m i d d l e t e m p o r a l gyrus. The p r o t e i n c o n t e n t s o f the c o n t r o l a n d S D A T g r o u p did not d i f f e r significantly. * P < 0.01 ; • * P < 0.001, S t u d e n t ' s t-test (two-tailed).
SOMATOSTATIN CONTENT AND CHOLINE ACETYLTRANSFERASE
TABLE I
376
reported here are less profound than those reported by Perry [15] and Davies [7]. The absence of any change in the putamen indicates that the loss of ChAT activity is confined to certain brain areas. The reduction in ChAT probably reflects loss of afferent cholinergic terminals rather than intrinsic neocortical and hippocampal neurones [15, 18, 21]. Indeed, the claim that there are substantial losses of cortical neurones in SDAT [6] has been disputed by others [26]. However, the loss of somatostatin in the temporal lobe suggests that this population of intrinsic neocortical neurones is affected in SDAT, although to what extent this may represent a late feature of the disorder is unknown. We would like to thank the many clinicians and pathologists involved in the collection of tissue. We also acknowledge the excellent technical assistance of Mr. N. Garrett and Mr. P. Horsefield.
1 2 3
4
5 6 7 8 9 10 11 12 13 14
15
Adolfsson, R., Gottfries, C.G., Roos, B.E. and Winblad, B., Changes in brain catecholamines in patients with dementia of Alzheimer type, Brit. J. Psychiat., 135 (1979) 216-223. Bennett-Clarke, C., Romagnano, M.A. and Joseph, S.A., Distribution of somatostatin in the rat brain: telencephalon and diencephalon, Brain Res., 188 (1980) 473-486. Bowen, D.M., White, P., Spillane, J.A., Goodhardt, M.J., Curzon, G., lwangoff, P., Meier-Ruge, W. and Davison, A.N., Accelerated ageing or selective neuronal loss as an important cause of dementia? Lancet, i (1979) 11 14. Brazeau, P., Vale, W., Burgus, R., Ling, N., Butcher, M., Rivier, J. and Guillemin, R., Hypothalamic polypeptide that inhibits the secretion of immunoreactive pituitary growth hormone, Science, 179 (1973) 77-79. Brownstein, M., Arimura, A., Sato, H., Schally, A.V. and Kizer, J.S., The regional distribution of somatostatin in the rat brain, Endocrinology, 96 (1975) 1456-1461. Colon, E.J., The cerebral cortex in presenile dementia: a quantitative analysis, Acta neuropath. (Berl.),23 (1973) 281 290. Davies, P., Neurotransmitter-related enzymes in senile dementia of the Alzheimer type, Brain Res., 171 (1979) 319 327. Davies, P. and Maloney, A.J., Selective loss of central cholinergic neurones in Alzheimer's disease, Lancet, ii (1976) 1403. Emson, P.C., Peptides as neurotransmitter candidates in the mammalian CNS, Progr. Neurobiol., 13 (1979) 61-116. Emson, P.C. and kindvall, O., Distribution of putative neurotransmitters in the neocortex, Neuroscience, 4 (1979) l 30. Fonnum, F., Radiochemical microassays for the determination of choline acetyltransferase and acetylcholinesterase activities, Biochem. J., 115 (1969) 465-472. Kobayashi, R.M., Brown, M. and Vale, W., Regional distribution of neurotensin and somatostatin in rat brain, Brain Res., 126 (1977) 584-588. Lowry, O.H., Rosebrough, N.J., Farr, A.L. and Randall, R.J., Protein measurement with the Folin phenol reagent, J. biol. Chem., 193 (1951) 265 275. Penman, E., Wass, J.A.H., Lund, A., Lowry, P.J., Stuart, J., Dawson, A.M., Besser, G.M. and Rees, L.H., Development and validation of a specific radioimmunoassay for somatostatin in human plasma, Ann. clin. Biochem., in press. Perry, E.K., The cholinergic system in old age and Alzheimer's disease, Age and Ageing, 9 (1980) I-8.
377 16 Perry, E.K., Perry, R.H., Blessed, G. and Tomlinson, B.E., Necropsy evidence of central cholinergic deficits in senile dementia, Lancet, i (1977) 189. 17 Perry, E.K., Tomlinson, B.E., Blessed, G., Bergmann, K., Gibson, P.H. and Perry, R.H., Correlation of cholinergic abnormalities with senile plaques and mental test scores in senile dementia, Brit. med. J., 2 (1978) 1457-1459. 18 Perry, R.H., Blessed, G., Perry, E.K. and Tomlinson, B.E., Histochemical observations on cholinesterase activities in the brains of elderly normal and demented (Alzheimer-type) patients, Age and Ageing, 9 (1980) 9-16. 19 Petrusz, P., Sar, M., Grossman, G.H. and Kizer, J.S., Synaptic terminals with somatostatin-like immunoreactivity in the rat brain, Brain Res., 137 (1977) 181-187. 20 Richter, J.A., Perry, E.K. and Tomlinson, B.E., Acetylcholine and choline levels in post-mortem human brain tissue: preliminary observations in Alzheimer's disease, Life Sci., 26 (1980) 1683-1689. 21 Rossor, M., Fahrenkrug, J., Emson, P., Mountjoy, C., Iversen, L. and Roth, M., Reduced cortical choline acetyltransferase activity in senile dementia of Alzheimer type is not accompanied by changes in vasoactive intestinal polypeptide, Brain Res., in press. 22 Roth, M. and Hopkins, B., Psychological test performance in patients over sixty. 1. Senile psychosis and the affective disorders of old age, J. ment. Sci., 99 (1953) 439-450. 23 Sims, N.R., Bowen, D.M., Smith, C.C.T., Flack, R.H.A., Davison, A.N., Snowden, J.S. and Neary, D., Glucose metabolism and acetylcholine synthesis in relation to neuronal activity in Alzheimer's disease, Lancet, i (1980) 333-335. 24 Spokes, E.G.S., An analysis of factors influencing measurements of dopamine, noradrenaline, glutamate decarboxylase and choline acetylase in human post-mortem brain tissue, Brain, 102 (1979) 333-346. 25 Spokes, E.G.S. and Koch, D.J., Post mortem stability of dopamine, glutamate decarboxylase and choline acetyltransferase in the mouse brain under conditions simulating the handling of human autopsy material, J. Neurochem., 31 (1978) 381-383. 26 Terry, R.D., Senile dementia, Fed. Proc., 37 (1978) 2837-2840. 27 Terry, R.D. and Davies, P., Dementia of the Alzheimer type, Ann. Rev. Neurosci., 3 (1980) 77-95. 28 White, P., Goodhardt, M.J., Keat, J.P., Hiley, C.R., Carrasco, L.H., Williams, I.E. and Bowen, D.M., Neocortical neurons in elderly people, Lancet, i (1977) 668-671.