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Decreased somatostatin immunoreactivity but not neuropeptide Y immunoreactivity in cerebral cortex in senile dementia of Alzheimer type
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Decreased somatostatin immunoreactivity but not neuropeptide Y immunoreactivity in cerebral cortex in senile dementia of Alzheimer type D. D a w b a r n , M . N . Rossor, C.Q. M o u n t j o y , M. R o t h and P.C. E m s o n MR(" Neurochemical Pharmacolo~,y Unit, Medical Research Council Centre, Cambridge ( l ".K. ) [Received 5 March 1986; Revised version received and accepted 16 May 1986) K~,v wortZs" Alzheimer's disease
Neuropeptide Y
Somatostatin
Cerebral cortex
Plaque
Tangle
The content of two neuropeptides, somatoslatin (SR1F) and neuropeptide Y (NPY) has been determined in two cerebral cortical areas o1"Alzheimer's disease brain and in age-matched control brains. The content of SRI F-like immunoreactivity (SRIF-L1) was found to be decreased in Alzheimer temporal cortex (Brodmann area 21) compared to control temporal cortex. The decreased content of SRIF was signiticantly correlated with the observed number of neuritic plaques and neurofibrillary tangles. No difference was observed in NPY-LI between Alzheimer cerebral cortex and control cortex. Furthermore, no correlalions were observed between NPY content and plaque count, neurofibrillary tangle estimate or SR1F conlent despite widespread reports of N P Y / S R I F coexistence.
Alzheimer's disease is the commonest cause of dementia and is characterized by the presence of neuritic plaques and neurofibrillary tangles throughout the brain. particularly in the temporal cortex and hippocampus. Histological and biochemical studies on postmortem tissue have shown selective cell loss in Alzheimer's disease. Several studies have shown a decreased activity of the enzyme choline acetyltransferase (CHAT) [26, 28] in the cerebral cortex in Alzheimer's disease. This loss of enzyme activity is believed to be due to degeneration of the ascending cholinergic fibers which arise in the nucleus basalis of Meynert [11, 28, 37]. In addition to the cholinergic deficit there is also evidence of a loss of the ascending noradrenergic projection in Alzheimer's disease [1, 12]. The noradrenergic projection to the cerebral cortex arises in the locus coeruleus and a dramatic cell loss has been reported from this nucleus in Atzheimer's disease [7]. Other studies have examined the content of markers of intrinsic cortical neurones in Alzheimer's disease. The contents of vasoactive intestinal polypeptide and cholecystokinin have been reported to be normal in Alzheimer's disease [29, 32]. However, reduced concentrations of 7-aminobutyric acid and somatostatin (SRIF) have been observed, particularly in temporal c o r t e x [4, 18~ 28, 29].
Corre:pondence: D. Dawbarn. Present address: Department of Medicine, British Royal Infirmary, Bristol BS2 8HW, U.K. 0304-3940/86,'$ 03.50 cO 1986 Elsevier Science Publishers B.V. (Biomedical Division)
155
lmmunohistochemical studies in rat cerebral cortex have shown that some SRIFcontaining cells also contain neuropeptide Y-like immunoreactivity (NPY-LI) [19, 36]. Similar results have been demonstrated for cat, monkey and human cerebral cortex [19, 20, 35]. NPY is a 36-amino-acid peptide which has recently been isolated and sequenced from porcine brain [33, 34]. Subsequent sequencing from human phacochromocytoma has shown that human NPY differs from porcine NPY by one amino acid [10]. The distribution of NPY in the human brain has been demonstrated both by radioimnaunoassay and immunocytochemistry. A high cortical content was lkmnd together with an interneuronal location [8, 16]. hnmunocytochemical studies in Alzheimer's disease cortex have shown an apparent reduction in the number of NPYcontaining cells particularly in the temporal cortex [9]. However, radioimmunoassay of NPY content in Alzheimer's disease has shown no reduction in content compared to age-matched control samples [3]. The aim of this present study was to measure both the contents of SRIF and NPY in the same cortical samples in Alzheimer's disease and in age-matched control brains. Furthermore, the numbers of plaques and tangles in the same Brodmann areas (Ba) in the opposite cerebral hemisphere have been estimated in order to ex.aluate any possible correlations between neuropeptide content and plaque and tangle count.
The collection, dissection and storage of human postmortem brains has been described previously [5]. Briefly, brains were obtained at autopsy and bisected sagittally. One half of the brain was dissected into appropriate regions and these were then frozen at - 7 0 ' C . The other half of the brain was fixed for 6 months in saline formalin. For NPY and SRI F assays 40 samples (20 control and 20 Alzheimer's) of temporal cortex BA_,~ and frontal cortex BA]0 were weighed and then extracted by boiling in I ml of 1 M acetic acid for 10 min followed by homogenization and a further 5 min in boiling acetic acid. The extracts were centrifuged and the supernatants removed, freeze-dried and stored until assay. The S R I F and NPY radioimmunoassays haxe previously been described in detail [I 5, 17]. For histological examination, sections, 16 l~m in thickness, of BArn and BA:I were cut and stained with the Glees-Marsland modification of the Bielschowsky silver method. These sections were then examined microscopically to estimate the number of neurofibrillary tangles and to make counts of the number of neuritic plaques. The method of making plaque counts has been described previously [25]. Briefly this method depended on two methods of counting. The first depended on counts along two lines drawn at random at right angles to the cortical surface. The second on making counts along two lines made at right angles to the surface in the region of maximum density of plaques. The reasons for making the counts in this way were to overcome the selectivity of other methods while not allowing absence of plaques m a random count to give erroneous results. This method produced high correlation coefficients between random and selected counts and gave correlation coefficients [23. 24] of a similar order to those lkmnd by other authors in respect of dementia score and ChAT activity [6, 27].
t 56
TABLE I S O M A T O S T A T I N A N D NEUROPIZ.PT1DE Y IN A L Z t t E I M E R ' S
DISEASE
Values are means ± S. E. M. of logarithmicalb transformed data from peptide immunoreactivities (pmol g tissue) with medians of untransformed data in parentheses, n - 2 0 ; *P<0.01. NPY-LI and SRIF-LI were determined on the same samples. 1]rail1 a r e a
('ontrol
Alzheimer
NPY Frontal cortex Temporal cortex
1.27 +_0.02 (18.3) 1.08 + 0,04 ( 10.3t
1.24_+ 0.02 (18.4) 1.19_+0.03 (14.7)
SRIF Frontal cortex Temporal cortex
1.84-+ 0.03 (64.4) 2. t 2 + 0.06 (150.0)
1.80_+0.04 (65.6) 1.84+_0.07" (68. I)
An estimate of the frequency of neurofibrillary change was made for each slide on a 4-point scale (0, absent; l, slight; 2, moderate; 3, severe). The content of S R I F - L I was found to be significantly reduced in the temporal cortex, BA21 but not in the frontal cortex, BAi0 (Table 1). The content of SRIF-LI was found to be significantly inversely correlated with the numbers of both plaques and tangles (Fig. 1). In contrast no change was found in N P Y - L I content between control and Alzheimer's disease cerebral cortical areas (Table I). N o significant correlation (n = 40) was observed between N P Y content and plaque and tangle counts in either temporal or frontal cortex. The Pearson correlation coefficients for NPY with plaques and tangles, respectively, in BA2t were 0.2762 and 0.1556. In BAi0 the correlation coefficients were 0.008 and -0.0568. Furthermore the contents of S R I F - L I and N P Y - L ! were compared in each sample in both BA10 and BA21. No correlation was observed between SRIF and N P Y in either cortical area (BAI0: n = 40, r = 0.0541; BA2~: n = 39, r = -0.1286). These results agree with previously published data showing a decrease in temporal cortex S R I F content in Alzheimer's disease [13, 28-30]. We did not find a reduction in frontal cortical S R I F content in Alzheimer's disease. This is in contrast to earlier studies [4, 13] which found a more widespread reduction in S R I F in Alzheimer's disease. However, one study has shown that the reduction in frontal cortex S R I F content is confined to patients who have died at less than 79 years [31]. This view is opposed to the results of Beal et al. [4] where the average age of the subjects was 77. In this study we also show that the loss o f S R I F in the temporal cortex can be significantly correlated with plaque and tangle counts in the contralateral temporal cortex. In addition, our data demonstrate that in Alzheimer's disease there is no change in the cortical content of NPY-LI. Neither is there a correlation between N P Y content and S R I F content, plaque or tangle number. These are surprising results in view of a reported reduction in the number of NPY-containing cells in the temporal cortex in Alzheimer's disease [9]. It is possible that dendritic sprouting in these remaining
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I:ig. I. ('orrelation of SRIF in the temporal cortex with (A) plaque count and (B) ncurolibrillary langle estimate. In both cases the data have been transformed as indicated on the graphs. Thc circles represent control brains and the squares Alzheimer's disease brains.
cells accounts for the unchanged content of NPY-LI in Alzheimer's disease temporal cortex. It has also been recently shown that NPY-containing neurones are spared in Huntington's disease caudatc nucleus and putamen [15] suggesting that NPY-containing neurones are resistant to degenerative disease processes. Also one other study has tkmnd no change in NPY content in Alzheimer's disease cerebral cortex, although they had a much smaller sample number than our study [3]. It has been suggested that NPY and S R I F coexist within neurones in the cerebral cortex in animal and human brains [19, 20, 35, 36] although the studies in human cortex are not extensive. It is likely that there is only a small population of cells showing coexistence of S R I F and NPY and it is these that are lost in Alzheimer's disease. One other possibility is that the synthesis of S R I F is reduced while the synthesis of NPY is either unaffected or increased. Both of these possibilities remain to be explored by using double staining methods and by quantification of S R I F and NPY mRNA. S R I F and NPY have both been demonstrated in neuritic plaques [14. 22]. The significance of these findings is not known but it is unlikely that neurotransmitter or neuropcptide specific plaques exist since histochemical techniques have now demonstrated acetylcholinesterase [26] substance P [2] and tyrosine hydroxylase [21] m plaques. Further studies will be necessary to see if SRIF and NPY coexist in the same neuritic plaques. Dr. l)awbarn acknowledges support from the Hereditary Disease Foundation. Postmortem brain was kindly supplied by Dr. G. Reynolds.
I AdollTson, R., Gottfries, C.G., Roos, B.T. and Winblad, B.. Changes in brain catecholammes in patients with dementia of Alzheimer type, Br. J. Psychiat., 135 (1979) 2[6 223, 2 Armstrong, D.M. and Terry, R.D., Substance P immunoreactivily within neuritic plaques, Neurosci. Lelt.. 58 (1985) 139 144. 3 Allen. J.M., Ferrier, I.N., Roberts, (LW.. Cross, A..1., Adrian, T.E., Crow, T.J. and Bloom, S.R., t-,It
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xaiion of neuropeptidc Y (NI'Y) in substantia nmominata in Alzheimer's type dcmemla, J. Neuloi Sci.. 64 (1984) 325 331. Beal, M.t:., Mazurek. M.F.. Tran, V.T., Chatlha, G., Bird, E.D. and Martin, J.B., Reduced number~ of somalostatin receptors in the cerebral cortex in Alzheimer's disease, Science, 229 (1985) 289 293. Bird, E.D. and lxersen, L.L., Huntington's chorea posl-mortem measurements of glutamic acid decarboxylase, choline acetyl transferase and dopamine in basal ganglia, Brain, 97 (1974) 457 472 Blessed. G.. Tomlinson, B,E. and P,oth, M., The association between quantitative measures ofdcmentia and of senile change in the cerebra[ grey matler of elderly subjects, Br. J. Psychiat., 114 (1968) 797 811. Bondarell, W., Mountjoy, C.Q. and Rolh, M., Loss of neurones of origin of the adrenergic projection to cerebral cortex (nucleus locus coeruleus) in senile dementia, Neurology, 32 (1982) 164 168. Chan-Palay, V.. Allen, Y.S., Lang, W.. Haester, U. and Polak, J.M., I., Cytology and distribution in normal human cerebra[ corlex of neurons immunoreactive with antisera against neuropeptidc Y, J ('omp. Neurol., 238 (1985) 382 389. Chan-Palay, V,, Lang, W., Allen, Y.S., Haesler, V. and Polak, J.M., II. Cortical neurones immunoreactive with anlisera against neuropeptide Y are altered in Alzheimer type dementia, J. Comp. Neurol., 238 (1985) 390 400. ('order, R., Emson, P.C and Lowry, P.,I., Puritication and characterization o[" human neuropcptidc Y from adrenal medullary phaeochromocytoma tissue, Biochem. J., 219 {1984) 699 707. Coyle, T.J., Price, D.L. and Delong, M.R., Alzheimer's disease: a disorder of cortical cholinergic innerration, Science, 219(1983) 1184 1190. Cross, A.J., Crow, T.J., Perry, E.K., Perry, R.H., Blessed, G. and Tomlinson, B.E., Reduced dopamine-//-hydroxylase activity m Alzheimer's disease, Br. Med. J., 282 (1981) 93 94. Davies, P., Katzman, R. and Terry. R.D., Reduced somatostatin-like immunoreactivity in cerebral cortex from cases of Alzheimer's disease and Alzheimer senile dementia, Nature (London), 288 (1980) 279 280. Dawbarn, D, and Emson, P.C., Neuropeptide Y-like immunoreactivity in neuritic plaques of Alzheimer's disease, Biochem. Biophys. Res. Commun., 126 0985) 289 294. Dawbarn, D., de Quidt, M. and Emson, P.C, Survival of basal ganglia neuropeptide Y:somatostatin neurones in Huntington's disease, Brain Res., 340 (1985) 251 260. Dawbarn, D., Hunt, S.P. and Emson, P.C., Neuropeptide Y: regional distribution chromatographic characlerization and immunohistochemical demonstration in post-morlem human brain, Brain Res.. 296(1984) 168 173. de Quidt, M. and Emson. P.C.. Distribution of neuropeptide Y-like immunoreactivity m the rat central nervous system, I. Radioimmunoassay and chromatographic characterisation, Neuroscience, in press. Ferrier. J.N., Cross, A.J., Johnson, J.A., Roberts, G.W., Crow, T.J., Corsellis, J.A.N., Lee, Y+C., O'Shaughnessy, D., Adrian, T.E., McGregor, G.P., Baracese-Hamilton, A.J. and Bloom, S,R., Neuropepiides in Alzheimer type dementia, J. Neurol. Sci., 62 (1983) 159 170. Hendry, S.H.C,, Jones, E.G. and Emson, P.C., Morphology, distribution and synaptic relations of somatostatin and neuropeptide Y immunoreactive neurones in rat and monkey neocortex, J. Neurosci., 4 (1984) 2497 2517. ttendry, S.H('., Jones, ]~.O., DeFelipe, J., Brandon, C. and Emson, D.C., Neuropeptide-containing neurones of the cerebral cortex are also GABA-ergic, Proc. Natl. Acad. Sci. U.S.A., 81 ([984) 6526 6530. Kilt, C.A., Struble, R.G,, Cork, L.C., Mobley, W.C., Walker, LC., Job, T.H. and Price, D.L., Catecholaminergic neurites in senile plaques in prefrontal cortex of aged nonhuman primate, Neuroscience. 16(1985) 69t 699. Morrison. J.H., Rogers, J.. Scherr, S., Benoit, R. and Bloom, F., Somatostatin immunoreactivity in neuritic plaques of Alzheimer's patients, Nature (London), 314 (1985) 90-92. Mountjoy, C.Q., Rossor, M.N., Evans, N.JR., Reynolds, G.P., Evans, H., Roth, M., lversen, L.L. and Emson, P.C., Biochemical and neuropathological changes in the brain and their correlation to the severity of dementia in Alzheimer's disease, Biol. Psychiatr., in press.
159 24 Mountjoy, C.Q., Rossor, M.N., lversen, L,L. and Roth, M., Correlation of cortical cholinergic and (IABA delieits with quantitative neuropathological findings m senile dementia. Brain. 107 (1984) 507 519. 25 Motllltjox. ('.Q.. Roth, M., Evans. N.J.R. and Evans. It., ('orlical neuronal cotlnls ill normal ehlerl', controls and demented patients, Neurobio]. Aging, 4 (1983) I 11. 26 Pcrr}, E.K. and Perry, R.H.. The cholinergie system in Alzheimer's disease. In P.J. Roberts ([{d.), Biochemistry of Dementia, John Wiley and Sons, Chichester, 1980, pp. 135 183. 27 Pert',,. E.K., Perry, R.I[., Blessed, G. and Tomlinson, B.I!., Neurotransmitter enz}me abnormalities m ~,cnile dementia choline acetyltransferase and glutamic acM decarboxylase in necropsy brain lissue. J Neurol. Sci..34(1977) 247 265. 28 Rossor, M.N., Neurotransmittcrs in ('NS disease: dcmentia, Lancet, ii (1982) 100 204. 29 Rossor. M.N.. Emson. P.('., lversen, L.L., Mountjoy, ('.Q.. Roth, M.. Hawthorn. tl., Ang, V I . Y . , Jenkins, J.S. and Fahrenkrug, J., Neuropeptides in senile dementia ot'Alzheimer type: studies on somatostatin, vasoactive intestinal polypeptide and vasopressin. In F. Clifford-Rose (Ed.), Metabolic Disorders o f l h e Nervous System. Pitman, London, (1981) pp. 418 429. 30 P,ossor. M.N., Emson, P.C., Mountjoy, C.Q., Roth, M. and lversen, k i . , Reduced a m o u n t s of immunorcacti',e somalostatin in the temporal cortex in senile dementia of Alzheimer type. Neurosci. l.cu.. 2011980) 373 377, 31 Rossor. M.N., lversen, L.L., Reynolds, G.P., Mountjoy, C.Q. and Roth. M., Neuroehemical characteristics of earl5 and late onset types of Al/heimer's diseasc, Br. Med. J., 228 (1984) 961 964. 32 Rossor, M.N.. Rehfeld, ,I.V., Emson, P.C., Mountjoy, C.(,),, Roth, M. and lversen, k.k., Normal cortical concentration of cholccystokinin-like immunoreactivity with reduced choline acetyltransfcrasc acti,,it,, in senile dementia of Alzheimer type, Life Sci., 29 (1981) 405 410. :;3 Tatemoto, K., Neuropeplide Y: complete amino acid sequence of the brain peptide, Proc. Nail. Acad. Sci. USA, 79(1982) 5485 5489. 34 "latemoto. K., ('arlquist, M. and Mutt, V., Neuropeptide Y a novel brain peptide wilh struclurat similarities to peptide YY and pancreatic polypeptide, Nature (London), 296 (I982) 659 660. 35 Vincenl. S.R,. Johansson, O., tt6kfeh, T., Meyerson, B., Sachs, C., Elde. R.P.. Terenius, [.. and Kim reel. J.. Ncuropeptidc coexistence in h u m a n cortical neurones, Nature (London), 298 (I 982) 65 (~7. 36 Vincent, S.R., Skirboll, k., H6kfelt, T., Johansson, O., Lundberg, J.M., Elde, R.P., Terenius. I. and Kilnmcl J.. Co-existence of somatostatin and avian pancreatic polypeptide (APP)-likc immunoreac ti,,ity m some forebrain neuroncs, Neuroscience. 7 (1982)439 466. 37 Whilehouse. P.,l., Price, D.L., Struble, R.G., Clark, A.W., ('oyle, T J . and Dclong, M,R., Alzhcimcr's discase and senilc dcmentia loss o f n e u r o n c s in the basal forebndrL Science, 215(1982) 1237 1239.
154
NSL (14097
Decreased somatostatin immunoreactivity but not neuropeptide Y immunoreactivity in cerebral cortex in senile dementia of Alzheimer type D. D a w b a r n , M . N . Rossor, C.Q. M o u n t j o y , M. R o t h and P.C. E m s o n MR(" Neurochemical Pharmacolo~,y Unit, Medical Research Council Centre, Cambridge ( l ".K. ) [Received 5 March 1986; Revised version received and accepted 16 May 1986) K~,v wortZs" Alzheimer's disease
Neuropeptide Y
Somatostatin
Cerebral cortex
Plaque
Tangle
The content of two neuropeptides, somatoslatin (SR1F) and neuropeptide Y (NPY) has been determined in two cerebral cortical areas o1"Alzheimer's disease brain and in age-matched control brains. The content of SRI F-like immunoreactivity (SRIF-L1) was found to be decreased in Alzheimer temporal cortex (Brodmann area 21) compared to control temporal cortex. The decreased content of SRIF was signiticantly correlated with the observed number of neuritic plaques and neurofibrillary tangles. No difference was observed in NPY-LI between Alzheimer cerebral cortex and control cortex. Furthermore, no correlalions were observed between NPY content and plaque count, neurofibrillary tangle estimate or SR1F conlent despite widespread reports of N P Y / S R I F coexistence.
Alzheimer's disease is the commonest cause of dementia and is characterized by the presence of neuritic plaques and neurofibrillary tangles throughout the brain. particularly in the temporal cortex and hippocampus. Histological and biochemical studies on postmortem tissue have shown selective cell loss in Alzheimer's disease. Several studies have shown a decreased activity of the enzyme choline acetyltransferase (CHAT) [26, 28] in the cerebral cortex in Alzheimer's disease. This loss of enzyme activity is believed to be due to degeneration of the ascending cholinergic fibers which arise in the nucleus basalis of Meynert [11, 28, 37]. In addition to the cholinergic deficit there is also evidence of a loss of the ascending noradrenergic projection in Alzheimer's disease [1, 12]. The noradrenergic projection to the cerebral cortex arises in the locus coeruleus and a dramatic cell loss has been reported from this nucleus in Atzheimer's disease [7]. Other studies have examined the content of markers of intrinsic cortical neurones in Alzheimer's disease. The contents of vasoactive intestinal polypeptide and cholecystokinin have been reported to be normal in Alzheimer's disease [29, 32]. However, reduced concentrations of 7-aminobutyric acid and somatostatin (SRIF) have been observed, particularly in temporal c o r t e x [4, 18~ 28, 29].
Corre:pondence: D. Dawbarn. Present address: Department of Medicine, British Royal Infirmary, Bristol BS2 8HW, U.K. 0304-3940/86,'$ 03.50 cO 1986 Elsevier Science Publishers B.V. (Biomedical Division)
155
lmmunohistochemical studies in rat cerebral cortex have shown that some SRIFcontaining cells also contain neuropeptide Y-like immunoreactivity (NPY-LI) [19, 36]. Similar results have been demonstrated for cat, monkey and human cerebral cortex [19, 20, 35]. NPY is a 36-amino-acid peptide which has recently been isolated and sequenced from porcine brain [33, 34]. Subsequent sequencing from human phacochromocytoma has shown that human NPY differs from porcine NPY by one amino acid [10]. The distribution of NPY in the human brain has been demonstrated both by radioimnaunoassay and immunocytochemistry. A high cortical content was lkmnd together with an interneuronal location [8, 16]. hnmunocytochemical studies in Alzheimer's disease cortex have shown an apparent reduction in the number of NPYcontaining cells particularly in the temporal cortex [9]. However, radioimmunoassay of NPY content in Alzheimer's disease has shown no reduction in content compared to age-matched control samples [3]. The aim of this present study was to measure both the contents of SRIF and NPY in the same cortical samples in Alzheimer's disease and in age-matched control brains. Furthermore, the numbers of plaques and tangles in the same Brodmann areas (Ba) in the opposite cerebral hemisphere have been estimated in order to ex.aluate any possible correlations between neuropeptide content and plaque and tangle count.
The collection, dissection and storage of human postmortem brains has been described previously [5]. Briefly, brains were obtained at autopsy and bisected sagittally. One half of the brain was dissected into appropriate regions and these were then frozen at - 7 0 ' C . The other half of the brain was fixed for 6 months in saline formalin. For NPY and SRI F assays 40 samples (20 control and 20 Alzheimer's) of temporal cortex BA_,~ and frontal cortex BA]0 were weighed and then extracted by boiling in I ml of 1 M acetic acid for 10 min followed by homogenization and a further 5 min in boiling acetic acid. The extracts were centrifuged and the supernatants removed, freeze-dried and stored until assay. The S R I F and NPY radioimmunoassays haxe previously been described in detail [I 5, 17]. For histological examination, sections, 16 l~m in thickness, of BArn and BA:I were cut and stained with the Glees-Marsland modification of the Bielschowsky silver method. These sections were then examined microscopically to estimate the number of neurofibrillary tangles and to make counts of the number of neuritic plaques. The method of making plaque counts has been described previously [25]. Briefly this method depended on two methods of counting. The first depended on counts along two lines drawn at random at right angles to the cortical surface. The second on making counts along two lines made at right angles to the surface in the region of maximum density of plaques. The reasons for making the counts in this way were to overcome the selectivity of other methods while not allowing absence of plaques m a random count to give erroneous results. This method produced high correlation coefficients between random and selected counts and gave correlation coefficients [23. 24] of a similar order to those lkmnd by other authors in respect of dementia score and ChAT activity [6, 27].
t 56
TABLE I S O M A T O S T A T I N A N D NEUROPIZ.PT1DE Y IN A L Z t t E I M E R ' S
DISEASE
Values are means ± S. E. M. of logarithmicalb transformed data from peptide immunoreactivities (pmol g tissue) with medians of untransformed data in parentheses, n - 2 0 ; *P<0.01. NPY-LI and SRIF-LI were determined on the same samples. 1]rail1 a r e a
('ontrol
Alzheimer
NPY Frontal cortex Temporal cortex
1.27 +_0.02 (18.3) 1.08 + 0,04 ( 10.3t
1.24_+ 0.02 (18.4) 1.19_+0.03 (14.7)
SRIF Frontal cortex Temporal cortex
1.84-+ 0.03 (64.4) 2. t 2 + 0.06 (150.0)
1.80_+0.04 (65.6) 1.84+_0.07" (68. I)
An estimate of the frequency of neurofibrillary change was made for each slide on a 4-point scale (0, absent; l, slight; 2, moderate; 3, severe). The content of S R I F - L I was found to be significantly reduced in the temporal cortex, BA21 but not in the frontal cortex, BAi0 (Table 1). The content of SRIF-LI was found to be significantly inversely correlated with the numbers of both plaques and tangles (Fig. 1). In contrast no change was found in N P Y - L I content between control and Alzheimer's disease cerebral cortical areas (Table I). N o significant correlation (n = 40) was observed between N P Y content and plaque and tangle counts in either temporal or frontal cortex. The Pearson correlation coefficients for NPY with plaques and tangles, respectively, in BA2t were 0.2762 and 0.1556. In BAi0 the correlation coefficients were 0.008 and -0.0568. Furthermore the contents of S R I F - L I and N P Y - L ! were compared in each sample in both BA10 and BA21. No correlation was observed between SRIF and N P Y in either cortical area (BAI0: n = 40, r = 0.0541; BA2~: n = 39, r = -0.1286). These results agree with previously published data showing a decrease in temporal cortex S R I F content in Alzheimer's disease [13, 28-30]. We did not find a reduction in frontal cortical S R I F content in Alzheimer's disease. This is in contrast to earlier studies [4, 13] which found a more widespread reduction in S R I F in Alzheimer's disease. However, one study has shown that the reduction in frontal cortex S R I F content is confined to patients who have died at less than 79 years [31]. This view is opposed to the results of Beal et al. [4] where the average age of the subjects was 77. In this study we also show that the loss o f S R I F in the temporal cortex can be significantly correlated with plaque and tangle counts in the contralateral temporal cortex. In addition, our data demonstrate that in Alzheimer's disease there is no change in the cortical content of NPY-LI. Neither is there a correlation between N P Y content and S R I F content, plaque or tangle number. These are surprising results in view of a reported reduction in the number of NPY-containing cells in the temporal cortex in Alzheimer's disease [9]. It is possible that dendritic sprouting in these remaining
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cells accounts for the unchanged content of NPY-LI in Alzheimer's disease temporal cortex. It has also been recently shown that NPY-containing neurones are spared in Huntington's disease caudatc nucleus and putamen [15] suggesting that NPY-containing neurones are resistant to degenerative disease processes. Also one other study has tkmnd no change in NPY content in Alzheimer's disease cerebral cortex, although they had a much smaller sample number than our study [3]. It has been suggested that NPY and S R I F coexist within neurones in the cerebral cortex in animal and human brains [19, 20, 35, 36] although the studies in human cortex are not extensive. It is likely that there is only a small population of cells showing coexistence of S R I F and NPY and it is these that are lost in Alzheimer's disease. One other possibility is that the synthesis of S R I F is reduced while the synthesis of NPY is either unaffected or increased. Both of these possibilities remain to be explored by using double staining methods and by quantification of S R I F and NPY mRNA. S R I F and NPY have both been demonstrated in neuritic plaques [14. 22]. The significance of these findings is not known but it is unlikely that neurotransmitter or neuropcptide specific plaques exist since histochemical techniques have now demonstrated acetylcholinesterase [26] substance P [2] and tyrosine hydroxylase [21] m plaques. Further studies will be necessary to see if SRIF and NPY coexist in the same neuritic plaques. Dr. l)awbarn acknowledges support from the Hereditary Disease Foundation. Postmortem brain was kindly supplied by Dr. G. Reynolds.
I AdollTson, R., Gottfries, C.G., Roos, B.T. and Winblad, B.. Changes in brain catecholammes in patients with dementia of Alzheimer type, Br. J. Psychiat., 135 (1979) 2[6 223, 2 Armstrong, D.M. and Terry, R.D., Substance P immunoreactivily within neuritic plaques, Neurosci. Lelt.. 58 (1985) 139 144. 3 Allen. J.M., Ferrier, I.N., Roberts, (LW.. Cross, A..1., Adrian, T.E., Crow, T.J. and Bloom, S.R., t-,It
158
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