Neocortical substance P neurons in the baboon: an immunohistochemical finding

Intraventricular administration of substance p increases the dendritic arborisation and the synaptic surfaces of Purkinje cells in rat's cerebellum

Substance P was infused in the lateral ventricles of twenty Lewis rats for twenty days. On the twentieth day the animals were sacrificed and the cerebellar cortex was processed for electron microscopy. The ultrastructural morphometric analysis revealed that the Purkinje cell dendritic arborisation and the number of the synapses between the parallel fibres and the Purkinje cell dendritic spines were much higher than in control animals. Numerous unattached spines of the secondary and tertiary dendritic branches of the Purkinje cells were also seen in the molecular layer either free or surrounded by astrocytic sheath. The increased number of synapses between the Purkinje cell dendrites and the parallel fibres in the animals, which received substance P intraventricularly, in correlation to control animals, supports a neurotrophine-like activity of the substance P in the mammalian cerebellum, enforcing the pre-programmed capability of the Purkinje cells to develop new synaptic surfaces.

Characterization of neocortical non-pyramidal neurons expressing preprotachykinins A and B: a double immunofluorescence study in the rat

Neurons expressing preprotachykinin A and preprotachykinin B, which are the precursor prepropeptides of substance P and neurokinin B (neuromedin K), respectively, were characterized immunocytochemically in the rat neocortex. Antibodies raised against C-terminal portions of preprotachykinins were used for labeling cell bodies of preprotachykinin-producing neurons. Neurons immunoreactive for preprotachykinin B were encountered four times more frequently in the neocortex than those immunoreactive for preprotachykinin A. Preprotachykinin A-immunoreactive neurons were scattered more frequently in the deep cortical layers (layers IV-VI) than in the superficial layers (layers I-III), whereas preprotachykinin B-immunoreactive neurons were distributed more frequently in the superficial layers than in the deep layers. Almost all preprotachykinin-expressing neurons were immunoreactive for GABA, suggesting that they were non-pyramidal cells. However, co-expression of the two preprotachykinin immunoreactivities in single neurons was not found. Preprotachykinin-expressing neocortical neurons were further examined with markers for subpopulations of GABAergic cortical neurons. Immunoreactivities for parvalbumin, calbindin and somatostatin were found in 69%, 27% and 11%, respectively, of preprotachykinin A-immunoreactive neurons. Conversely, preprotachykinin A-immunoreactive neurons constituted only 6% of parvalbumin-immunoreactive neurons, 4% of calbindin-immunoreactive neurons and 1% of somatostatin-immunoreactive neurons. Immunoreactivities for calretinin, choline acetyltransferase, vasoactive intestinal polypeptide, corticotropin-releasing factor and cholecystokinin were detected in 13-39% of preprotachykinin B-immunoreactive neurons. Preprotachykinin B immunoreactivity was seen in 33% of calretinin-positive neurons, 45% of cholinergic neurons, 47% of vasoactive intestinal polypeptide-positive neurons, 59% of corticotropin-releasing factor-positive neurons and 83% of cholecystokinin-positive neurons. These results indicate that preprotachykinin A- and preprotachykinin B-expressing neurons constitute separate populations of GABAergic non-pyramidal neurons in the neocortex. Since receptors for substance P and neurokinin B are expressed in GABAergic neurons [Kaneko T. et al. (1994) Neuroscience 60, 199-211] and pyramidal neurons [Ding Y. Q. et al. (1996) J. comp. Neurol. 364, 290-310], respectively, cortical neurons may use two separate lines of tachykinin signals; substance P serves as a signal between GABAergic non-pyramidal neurons, whereas neurokinin B acts as a signal of GABAergic neurons to pyramidal neurons.

Morphological and chemical characteristics of substance P receptor-immunoreactive neurons in the rat neocortex

Substance P receptor-expressing neurons in the rat cerebral neocortex were examined by single- and double-immunolabeling methods with an affinity-purified specific antibody to substance P receptor. Substance P receptor immunoreactivity was observed exclusively in non-pyramidal neurons. About a quarter of these substance P receptor-positive neocortical neurons showed intense immunoreactivity, and the other three quarters displayed weak substance P receptor immunoreactivity. The neurons showing intense substance P receptor immunoreactivity were large multipolar cells with a few long aspiny or sparsely-spiny dendrites, and were scattered throughout the neocortical layers except for layer I, and also in the underlying white matter. The weakly immunoreactive neurons were medium-sized multipolar cells with oval to round somata and aspiny varicose dendrites, and were distributed in all cortical layers with a bias to layers II-III and the superficial part of layer V. The double-immunofluorescence study revealed that almost all substance P receptor-positive neurons were immunoreactive for GABA, but negative for glutaminase. Substance P receptor immunoreactivity in GABAergic neocortical neurons were further examined by the double-immunofluorescence method with antibodies to markers for subgroups of GABAergic neurons. Somatostatin immunoreactivity was found in 89% of neurons with intense substance P receptor immunoreactivity, and in 1.5% of neurons with weak substance P receptor immunoreactivity. Neuropeptide Y immunoreactivity was also observed in 92% of neurons with intense immunoreactivity for substance P receptor, and in 1.6% of neurons with weak immunoreactivity for substance P receptor. In contrast, parvalbumin immunoreactivity was seen in 1.3% of neurons with intense substance P receptor immunoreactivity, and in 59% of weak substance P receptor immunoreactivity. Calbindin D28k immunoreactivity was found in 12 and 19% of neurons, respectively, with weak and intense immunoreactivities for substance P receptor. Virtually no cells showing substance P receptor immunoreactivity displayed immunoreactivity for vasoactive intestinal polypeptide or choline acetyltransferase. These results indicate that the neocortical neurons expressing substance P receptor constitute a subpopulation of GABAergic non-pyramidal cells, and are segregated into neurons with intense immunoreactivity and those with weak immunoreactivity for substance P receptor; the vast majority of neurons with intense substance P receptor immunoreactivity contain somatostatin and neuropeptide Y, and the majority of neurons with weak substance P receptor immunoreactivity have parvalbumin.

Differential regulation of substance P and somatostatin in Martinotti cells of the developing cat visual cortex

In order to determine their morphological development and ontogenetic fate, Martinotti neurons immunoreactive for substance P and somatostatin have been analysed in the cat visual cortex. Martinotti neurons are located in layers V and VI. They are multipolar to bitufted, and most dendrites remain in layers V and VI. Their typical features is the ascending axon, which emerges from an apical dendrite or from the upper pole of the soma. A number of collaterals branch off in layer V, forming a local terminal plexus. The axon then branches into 2-8 collaterals, which ascend as a bundle to layers III and II, where a second terminal plexus is formed. Some collaterals ascend to layer I where they adopt a horizontal course. Horizontal collaterals in the terminal layers V, III, II, and in layer I may reach up to 400 microns in length. Martinotti neurons begin to differentiate perinatally. The quantitative analysis reveals that the initial time course of differentiation of Martinotti cells is very similar in material stained for substance P and for somatostatin. Double immunofluorescence then confirms that the two peptides are colocalized in Martinotti cells of layers V and VI during the early postnatal period. Further, substance P is colocalized with GABA. Substance P expression in Martinotti cells can be observed only in the immature visual cortex. After postnatal day 15, the Martinotti neuron system becomes less and less detectable by substance P immunoreactivity. It declines to virtually undetectable levels after the third postnatal month. The adult visual cortex is almost devoid of substance P-immunoreactive cell bodies, processes and axon terminals. In situ hybridization confirms this finding, revealing beta-preprotachykinin mRNA-expressing cell bodies in layers V and IV at postnatal day (P)6 and P12, but not in the adult cortex. This suggests a downregulation of the substance P expression at the transcriptional level. In contrast, somatostatin-immunoreactive Martinotti cells, most of which have coexpressed substance P during early postnatal life, can still be observed in the adult cortex. Thus, the Martinotti neurons constitute a persisting cell type, although many individual neurons of this type disappear during the second postnatal month by degeneration and cell death. In summary, while somatostatin is permanently expressed in Martinotti neurons in the cat visual cortex, substance P peptide and mRNA are transiently expressed during an early postnatal period, and apparently are downregulated later in development.

A comparison of the development of neuropeptide and MAP2 immunocytochemical labeling in the macaque visual cortex during pre- and postnatal development

The appearance of Substance P (SP) and Neuropeptide Y (NPY) has been studied using light microscopic immunocytochemical labeling throughout the complete developmental span of Macaca nemestrina monkey striate cortex. In the adult, 80% of the NPY+ neurons occur in the white matter (WM) and most of the remainder are medium to large multipolar neurons in layer 2. Fibers occur in all layers except 4C and are very numerous, given the relatively small number of NPY+ cell bodies. NPY+ neurons first were seen at embryonic day (E) 75. Most neurons were in the intermediate zone (IZ), but a few were in the immature cortical plate (CP). An adult-like distribution was present by E125 for neurons and by birth for fibers, but fiber staining intensity and number increased to postnatal year 1 (P1yr). In adult cortex, numerous SP+ nonpyramidal neurons were present in layers 2-6 and WM, but SP+ fibers were surprisingly infrequent. During development, significant numbers of SP+ neurons were not seen in the CP until E113-125. Later prenatal ages had a prominent plexus of SP+ cell bodies and fibers at the layer 5/6 border. This plexus disappeared by P12wk due to either down-regulation of SP or cell death. SP+ neurons in IZ/WM were very sparse until birth after which they increased in number and staining intensity up to P1yr, suggesting a postnatal up-regulation of SP in a preexisting WM subpopulation. Cell densities were determined for SP, NPY, and the neuron-specific marker microtubule-associated protein 2 (MAP2) to clarify the developmental dynamics of IZ/WM neurons. MAP2+ cell densities in WM peaked around birth and then declined 20% in the outer half and 77% in the inner half of WM. SP+ cell density rose 57% from birth to P20wk and then declined 20% into adulthood. NPY+ cell density was fairly constant prenatally and then rose 300% by adulthood. Neuropeptide cell density changes took place predominantly in the outer WM. These data indicate that cell death does occur in the general population of monkey striate cortical WM neurons. In contrast, both SP+ and NPY+ cells are characterized by minimal cell death and a late expression of neuropeptides which causes an increase in neuropeptide+ cell density in postnatal WM.

The presence of neuropeptides in GABAergic and cholinergic rat cerebrocortical synaptosome sub-populations

GABAergic and cholinergic synaptosomes from rat cerebral cortex were isolated by a magnetic immunoaffinity technique, i.e. immunomagnetophoresis. These subpopulations were extracted and subjected to radioimmunoassay for four neuropeptides: Neuropeptide Y (NPY); vasoactive intestinal peptide (VIP); substance P (SP); and somatostatin (SRIF). In each of the sub-populations three of the four peptides were enriched in the sorted fraction compared with the mother fraction with respect to the cytosolic marker lactate dehydrogenase (LDH). In the GABAergic sub-population the order was SP > SRIF > NPY > or = VIP whilst in the cholinergic sub-population they were enriched in the order VIP > or = NPY > SP > SRIF. The presence of NPY has not previously been reported in cortical cholinergic neurons.

Substance P-containing pyramidal neurons in the cat somatic sensory cortex

Light and electron microscopic immunocytochemical methods were used to verify the possibility that neocortical pyramidal neurons in the first somatic sensory cortex of cats contain substance P. At the light microscopic level, substance P-positive neurons accounted for about 3% of all cortical neurons, and the vast majority were nonpyramidal cells. However, 10% of substance P-positive neurons had a large conical cell body, a prominent apical dendrite directed toward the pia, and basal dendrites, thus suggesting they are pyramidal neurons. These neurons were in layers III and V. At the electron microscopic level, the majority of immunoreactive axon terminals formed symmetric synapses, but some substance P-positive axon terminals made asymmetric synapses. Labelled dendritic spines were also present. Combined retrograde transport-immunocytochemical experiments were also carried out to study whether substance P-positive neurons are projection neurons. Colloidal gold-labelled wheat germ agglutinin conjugated to enzymatically inactive horseradish peroxidase was injected either in the first somatic sensory cortex or in the dorsal column nuclei. In the somatic sensory cortex contralateral to the injection sites, a few substance P-positive neurons in layers III and V also contained black granules, indicative of retrograde transport. This indicates that some substance P-positive neurons project to cortical and subcortical targets. We have therefore identified a subpopulation of substance P-positive neurons that have most of the features of pyramidal neurons, are the probable source of immunoreactive axon terminals forming asymmetric synapses on dendritic spines, and project to the contralateral somatic sensory cortex and dorsal column nuclei. These characteristics fulfill the criteria required for classifying a cortical neuron as pyramidal.

VVA-labelled cells in monkey visual cortex are double-labelled by a polyclonal antibody to a cell surface epitope

The staining patterns produced by the lectin Vicia villosa and by a commercially available polyclonal antibody generated to substance P were analysed and compared in monkey visual cortex at the light and electron microscopic levels. Vicia villosa lectin labels the cell surface of a subpopulation of cortical cells, producing a meshlike pattern over the soma and proximal dendrites. The polyclonal antibody labels three distinct elements in the cortex: a pericellular epitope present on a subpopulation of non-pyramidal cells, and putative intracellular sites in a type of small pyramidal cell located at the layer 5/6 border, and in a small number of non-pyramidal cells in the underlying white matter. Because of the similarity of the appearance of the Vicia villosa lectin labelling and the pericellular labelling produced by the polyclonal antibody, further experiments were conducted to determine the relationship between the cell surface sites recognized by these markers. Double-labelling experiments show that both sites are present on the same population of cells, and at the ultrastructural level both markers appear to outline the intersynaptic cell membrane, sometimes extending around presynaptic elements. However, preadsorption experiments indicate that the markers recognize different sites on the cell membrane. Preadsorption experiments also show that the pericellular epitope recognized by the polyclonal antibody is unlikely to be substance P, but it may be structurally similar to keyhole limpet haemocyanin. Comparison of cortical and subcortical staining patterns produced with the polyclonal antibody and with a commonly used monoclonal antibody to substance P reveal that one of the putative intracellular epitopes recognized by the polyclonal antibody is likely to be substance P.

Intraventricular administration of substance P induces unattached Purkinje cell dendritic spines in rats

Substance P was infused in the lateral ventricles of twenty Lewis rats for twenty days. The animals under the influence of the substance P demonstrated grooming of the head, the body and the forepaws. On the twentieth day the animals were sacrificed and the cerebellar cortex was processed for electron microscopy. The ultrastructural analysis revealed that although the granule cells, the parallel fibers and the systems of the afferent fibers were intact, numerous unattached Purkinje cell dendritic spines were seen embedded in the soma of the astrocytes, demonstrating postsynaptic differentiation. Numerous unattached spines of the secondary and tertiary dendritic branches of the Purkinje cells were also seen in the molecular layer surrounded by astrocytic sheath. Free unattached spines were also seen not surrounded by any astrocytic process, which did not demonstrate any postsynaptic specialization. The development of unattached Purkinje cell dendritic spines, in an otherwise intact cerebellar cortex, following the intraventricular administration of substance P, suggests that it may act as local growth factor, enforcing the preprogrammed-capability of the Purkinje cells in developing new synaptic surfaces.

A transitory population of substance P-like immunoreactive neurones in the developing cerebral cortex of the mouse

Immunocytochemical methods were used to investigate the developmental expression of substance P (SP) in mouse cerebral cortex. SP-like-immunoreactive cells were first detected at postnatal day 0 (P0), their numbers being notably increased by P2. Immunopositive cells were especially abundant in layer VIb and in the subjacent future white matter, although they were also present in layer V. Between P5 and P8 the number of SP-like-immunoreactive cells gradually decreased, being almost completely absent by P12. At these stages cells were only observed in the deepest cortical layers. From P16 onwards, the adult pattern of SP-like immunoreactivity emerged with a few immunopositive cells scattered throughout the cortical layers. The present data show a transitory population of SP-like-immunoreactive cells present in the mouse cerebral cortex during the first postnatal week. On the basis of close correlations of SP-like expression with the distribution or transitory populations and the timing of cell death in rodents, we propose that most of the SP-like-immunoreactive cells reported here would probably disappear by cell death.

The bed nucleus-amygdala continuum in human and monkey

The cytoarchitecture and distributions of seven neuropeptides were examined in the the bed nucleus of the stria terminalis (BST), substantia innominata (SI), and central and medial nuclei of the amygdala of human and monkey to determine whether neurons of these regions form an anatomical continuum in primate brain. The BST and centromedial amygdala have common cyto- and chemo-architectonic characteristics, and these regions are components of a distinct neuronal complex. This neuronal continuum extends dorsally, with the stria terminalis, from the BST and merges with the amygdala; it extends ventrally from the BST through the SI to the centromedial amygdala. The cytoarchitectonics of the BST-amygdala complex are heterogeneous and compartmental. The BST is parcellated broadly into anterior, lateral, medial, ventral, supracapsular, and sublenticular divisions. The central and medial nuclei of the amygdala are also parcellated into several subdivisions. Neurons of central and medial nuclei of the amygdala are similar to neurons in the lateral and medial divisions of the BST, respectively. Neurons in the SI form cellular bridges between the BST and amygdala. The BST, SI, and amygdala share several neuropeptide transmitters, and patterns of peptide immunoreactivity parallel cytological findings. Specific chemoarchitectonic zones were delineated by perikaryal, peridendritic/perisomatic, axonal, and terminal immunoreactivities. The results of this investigation demonstrate that there is a neuronal continuity between the BST and amygdala and that the BST-amygdala complex is prominent and discretely compartmental in forebrains of human and monkey.

Distribution of GABA and neuropeptides in the human cerebral cortex. A light and electron microscopic study

Antibodies were used to identify neurons in human frontal and temporal cortex that were immuno-positive to gamma-aminobutyric acid (GABA) and the neuropeptides vasoactive intestinal polypeptide (VIP), substance P (SP) and somatostatin (SOM). Specimens were taken at surgical biopsy and fixed immediately after removal. The results described for both light and electron microscopy were obtained when relatively high concentrations of glutaraldehyde (2.5-3%) were present in the fixative. Specimens were examined from three adults and an infant aged 5 months. GABAergic neurons were present in all cortical layers, with fewest in layers I, deep III and V, and were mainly small, and round or oval. No labelled pyramidal neurons were detected. GABAergic puncta were common in the neuropil, probably representing axonal profiles. VIP-neurons were also found in all layers, including layer I, and were approximately twice as numerous as GABA-cells. SP-positive cells were found throughout the layers, but were sparse in layers I and VI. They were about three times commoner than GABAergic neurons. SOM-reactivity was demonstrated in about the same number of cells as that for SP. Again, this involved all layers, but layer I least. Peptidergic neurons were larger, on the average, than GABAergic cells, and were frequently pyramidal in character. In the infant, the distribution, size and frequency of immunoreactive neurons were similar to those in the adult. However, GABAergic puncta were commoner.

Substance P-like immunoreactive neurons are depleted in Alzheimer's disease cerebral cortex

We studied the morphology and distribution of substance P-like immunoreactive elements in normal and Alzheimer's disease brain with a monoclonal anti-substance P antibody. Bands of prominent terminal-like staining were found in the dentate gyrus of normal brain. Multipolar substance P-immunoreactive neurons were seen in dentate polymorphic layer and CA4 and prominent fiber staining was present in the CA fields of the hippocampus and adjacent allocortex. Reactive perikarya, concentrated in deep cortex and infracortical white matter, were found in all isocortical regions. Greatest density was in frontal and parietal association cortex; lowest in visual cortex. Fiber density was generally greatest in layers I and II. In Alzheimer's disease, staining intensity was reduced in the dentate gyrus. Hilar neurons were unaffected but other CA field neurons were distorted with pruned dendritic trees. Isocortical perikarya and fibers were significantly depleted and distorted in all regions. Globular deposits consisting of distorted neurites or dissolving perikarya were frequently seen. Double staining methods showed that the vast majority of isocortical, but not hippocampal, substance P-like immunoreactive neurons are nicotinamide adenine dinucleotide phosphate diaphorase-positive. Despite the modest quantitative depletion of substance P in Alzheimer's disease cortex as measured by radioimmunoassay compared to somatostatin, there is a significant depletion of substance P-like immunoreactive perikarya. This disparity may be due to persistence of afferent projections which make a major contribution to substance P concentrations in cerebral cortex or to the high substance P content of dystrophic fibers in Alzheimer's disease cortex.

Ontogeny of substance P-immunoreactive structures in the primate cerebral neocortex

The distribution and the ontogeny of substance P (SP)-immunoreactive structures were investigated in the various cortical areas of macaque monkey cerebrum at embryonic day 120 (E120), embryonic day 140 (E140), newborn (Nb), postnatal day 30, postnatal day 60 (P60) and adult stages, using an immunohistochemical method. SP-immunoreactive cell bodies and fibers were detectable at E120 and the cell number increased until Nb stage. At E140, many immunoreactive cells were present in the upper part of layer V. Some of them seemed to be developing pyramidal cells which ascended their fibers toward layer I. After Nb stage, the number of immunoreactive structures decreased. By P60, the distribution patterns of SP-immunoreactive structures reached the adult level. Between Nb and P60, we occasionally observed structures which were presumably degenerated neurons and fibers. The distribution and developmental ontogeny of immunoreactivities were different among the various cortical areas. In areas OC and FA (von Bonin and Bailey), we observed the high densities of immunoreactive fibers and terminals, in spite of low numbers of cell somatas. While, in the association areas (areas FD, PE, TA and TE), there existed larger numbers of immunoreactive cells at E140 and newborn stages, following the decrease of cell number until P60. Our present study shows the transient increase and the following decrease of the numbers of SP-immunoreactive cells. Since we observed SP-immunoreactive pyramidal cells and degenerating cells during development, the decrease of immunoreactivities may be due to both cell death and change in phenotype.

Pyramidal neurons are immunopositive for peptides, but not GABA, in the temporal cortex of the macaque monkey (Macaca fascicularis)

Areas 20, 21 and 22 of the temporal neocortex of the macaque monkey (Macaca fascicularis) were studied with immunocytochemical and electron-microscopic techniques to localise neurons immunoreactive to the neuropeptides vasoactive intestinal polypeptide, substance P and somatostatin, and to gamma-aminobutyric acid (GABA). GABAergic neurons were found in all cortical layers, but especially in layers II, IV and VI. They were all of non-pyramidal morphology, comprising small round cells, and bipolar or multipolar forms. Presumed GABAergic axon terminals were also common. Peptidergic neurons were also found in all layers, but they consisted of cells of many morphological types, including pyramidal cells. Compared with previous descriptions in other cortical areas and in other animals, we find a greater proportion of peptidergic temporal cortical neurons compared to the GABAergic population. The immunopositive neurons were easily recognisable ultrastructurally from non-reactive neurons by the dense labelling of the cytoplasm and nucleus. Immunopositive and negative neuronal somata were often contiguous, providing evidence for the specificity of the immune reaction. Stem dendrites were often labelled for a short distance from the soma, and other strongly reacting dendritic segments were found in the neuropil, as were labelled axons. Neurons labelled for GABA had features typical of non-pyramidal cells, but neuropeptides were also found in cells with pyramidal characteristics.

Substance P-like immunoreactivity in brains with pathological features of Parkinson's and Alzheimer's diseases

Substance P is found in both the basal ganglia and cerebral cortex in mammalian brain. In the present study postmortem concentrations of substance P-like immunoreactivity (SP-LI) were measured in the globus pallidus, substantia nigra and 22 cortical regions in a group of demented patients with neuropathological features of both Parkinson's disease (PD) and Alzheimer's disease (AD), and from neurologically normal controls. There were no significant changes in the globus pallidus but concentrations were significantly reduced by 44% in the substantia nigra compacta in the PD patients. In cerebral cortex small (20-30%) significant reductions of SP-LI were found in the PD patients in 7 of 22 cortical regions examined. These results are similar to changes found in AD alone and provide further evidence that the dementia of PD is frequently related to the coincidence of PD and AD.

Substance P and somatostatin coexist within neuritic plaques: implications for the pathogenesis of Alzheimer's disease

In recent years the present authors and others have sought to determine the neurochemical composition of the dilated neuronal processes found within neuritic plaques of patients with Alzheimer's disease. To date a number of neurotransmitter and neuropeptide systems have been observed within different plaques, yet at present it is unclear whether individual human plaques contain more than one transmitter substance. In the present study a highly sensitive dual-immunolabeling procedure was employed and it was demonstrated that substance P and somatostatin-immunoreactive profiles coexist within single senile plaques of patients with Alzheimer's disease. Coexistence of somatostatin and substance P immunoreactivity within plaques was observed in the hippocampus and amygdala but not in the neocortex, although the latter region contained plaques within which somatostatin and substance P existed alone. The frequency with which we observed one or more neuropeptide within plaques was relatively low and in fact most plaques contained neither substance P nor somatostatin immunoreactivity. In addition, a large number of swollen peptidergic processes were observed outside of plaques. The significance of these observations with respect to the pathogenesis of Alzheimer's disease is discussed.

A detailed examination of substance P in pathologically graded cases of Huntington's disease

Substance P concentrations have been found to be reduced in the basal ganglia in Huntington's disease (HD). In order to further examine this finding in the present study we measured substance P-like immunoreactivity (SPLI) in cases of HD which had been graded as to the severity of pathological changes in the striatum. Marked significant reductions of SPLI were found in all striatal nuclei which were significantly correlated with the percentage of neuronal loss in the varying pathologic grades. Similar changes were found in the projection sites of striatal substance P neurons, the globus pallidus interna and the substantia nigra. These changes are consistent with a loss of striatal substance P containing projection neurons in HD. Significant reductions in SPLI were also found in the external pallidum, bed nucleus of the stria terminalis and the subthalamic nucleus. Small significant increases in SPLI (20-30%) were found in 3 frontal cortical regions (Brodmann areas 6, 8 and 9). The finding of neurochemical changes in the subthalamic nucleus is of particular interest since lesions in this nucleus are known to result in chorea and therefore might contribute to the chorea which is a cardinal symptom of HD.

Substance P neuronal cell bodies in the human brain: complete mapping by immunohistofluorescence

The localization of substance P-immunoreactive (SP-IR) cells was studied in 5 postmortem brains from aged human subjects using technical improvements combined with the indirect immunofluorescence method. The presence of various forms of SP-IR cells was observed in paleocortical and neocortical areas as well as in the basal ganglia, the brainstem and the spinal cord. The distribution of these SP-IR cell bodies was transposed onto our previous mapping of SP-IR fibers and terminals. The morphological differences between SP-containing cell bodies or areas of human and rat central nervous systems and the SP-changes in various states of human pathology are shortly discussed.

Substance P in the human brain

The distribution of substance P immunoreactive sites was investigated by immunoenzymatic methods in a large series of paraffin embedded human brain sections from the collection assembled by Oscar and Cécile Vogt several decades ago, as well as from more recent post-mortem material. These studies demonstrated that substance P immunoreactivity was preserved in archival material permitting a detailed account of the localization of immunoreactive cell bodies, fibre networks and tracts in the human brain. Previous observations made on experimental animals and man were confirmed and extended. Additionally, substance P immunoreactive cell bodies were seen in most cortical areas and novel features were noted in the distribution of substance P-containing elements in the tuberal region, corpus striatum, substantia nigra (particularly in relationship to blood vessels) and in association with melanin-containing cells. Reconstruction of some substance P pathways was attempted by the analysis of semi-serial sections in more than one plane. Immunocytochemistry, in combination with image analysis, enabled some measurements of the differential concentrations of substance P immunoreactive material to be made and allowed a close correlation of this with defined anatomical landmarks or enkephalin immunoreactive sites.

The distribution of cholecystokinin-8 in the central nervous system of turtles: an immunohistochemical and biochemical study

Immunohistochemical techniques, radioimmunoassay (RIA) and high performance liquid chromatography (HPLC) were used to: (1) determine the regional distribution and amounts of cholecystokinin-8 (CCK8)-like immunoreactivity in the turtle central nervous system, and (2) chemically characterize the CCK8-like material present in the turtle central nervous system. High levels of CCK8-like immunoreactivity were found in the turtle central nervous system, with the highest levels being present in the hypothalamus and neurohypophysis. Moderate levels of the CCK8-like material were found in all other regions of the turtle nervous system except the cerebellum, the olfactory bulbs and the dorsal ventricular ridge of the telencephalon, which contained low levels. The bulk (87%) of the CCK8-like material in turtle central nervous system co-eluted with CCK8-sulfate in gradient elution HPLC. The distribution of CCK8-like immunoreactivity (CCK8LI) observed using immunohistochemistry was consistent with the results of the RIA studies. Numerous CCK8LI-containing neurons and fibers were observed in the hypothalamus and neurohypophysis. Neurons and fibers containing CCK8 were, however, more sparsely distributed outside the hypothalamus. The immunohistochemical data provided evidence for the existence of two major CCK8-containing pathways in turtles that have been previously described in mammals: a pathway from the supraoptic and paraventricular magnocellular nuclei to the external zone of the median eminence and neurohypophysis and a pathway from dorsal root ganglia to the dorsal horn of the spinal cord. Overall, the present results, in conjunction with several previous studies, indicate that CCK8 has had a relatively stable evolutionary history as a CNS neuropeptide among land vertebrates. The molecular structure of CCK8 appears to have been largely (if not entirely) conserved, as has its concentration in many brain regions. A noteworthy exception to such conservatism in the localization of CCK8 is that the concentration of CCK8 in the telencephalon, particularly in the telencephalic cortex, is much lower in turtles than in mammals. The present results therefore suggest that CCK8 may not have become a prominent peptide in the telencephalic cortex (or its anatomical equivalents) until the evolution of neocortex in the mammalian lineage.

Substance P immunoreactivity within neuritic plaques

In the present immunocytochemical study we examined brain tissue of patients with Alzheimer's disease in order to determine the relationship of substance P (SP)-labeled processes to neuritic plaques. Swollen neuropeptidergic processes were consistently observed within a relatively small percentage of the plaques. These data provide a morphologic correlate to the biochemical finding that SP levels are reduced in the brain tissue of patients with Alzheimer's disease, and further indicate that Alzheimer's disease affects multiple neurotransmitter and neuropeptide systems.