The comparative distribution of enkephalin, dynorphin and substance P in the human globus pallidus and basal forebrain

The distribution of substance P in the cerebral cortex and hippocampal formation: an immunohistochemical study in the monkey and rat

The distribution of substance P-containing fibers in the cerebral cortex and the hippocampal formation of the Japanese monkey (Macaca fuscata fuscata) was studied by immunohistochemistry using a monoclonal antibody raised against substance P. The results were compared with the distribution in homologous regions of the rat brain. Substance P-containing fibers and cell bodies were observed in all regions of the cerebral cortex. In deep layers of the neocortex (IV-VI), substance P-immunoreactive fibers formed arrays that ran perpendicular to the surface. These immunoreactive fibers tended to branch as they approached the cortical surface in layers II and III, at which point they were oriented in many directions. The molecular layer (I) of the monkey neocortex contained many granular, substance P-immunoreactive structures, resembling terminal boutons. In contrast to the monkey, rat cortical areas contained substantially fewer substance P-containing fibers. The immunoreactive profiles, mostly fine dot-like structures, were seen uniformly in layers II and IV of the rat neocortex, although in the medial prefrontal cortex many thick, varicose fibers were also observed. Substance P-containing fibers were seen throughout the hippocampal formation of the monkey, including the subiculum and the parahippocampal regions. The regional distribution of immunoreactive fibers was most dense in the molecular layers of dentate gyrus, in the stratum moleculare of the CA1 region, and in the stratum pyramidalis of the CA2 region. In the rat, the hippocampus and dentate gyrus contained fewer immunoreactive fibers. Moderate densities were observed in the rat subiculum and entorhinal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Pattern formation in the striatum: developmental changes in the distribution of striatonigral projections

The mammalian striatum (the major subcortical structure in the telencephalon) can be divided into two compartments, the patch and the matrix, on the basis of various neurochemical and hodological markers expressed in the adult. The primary efferent target of striatal neurons is the substantia nigra. We have previously shown that the patch compartment sends projections to the substantia nigra embryonically; whereas the matrix does not form a similar projection until the early postnatal period (Fishell and van der Kooy, J. Neurosci., 7 (1987) 1969-1978). The projection of patch neurons to the substantia nigra is the earliest developmental marker for the patch compartment. Here we ask about the early distribution of patch projections and their possible relation to striatal compartmentalization. Embryonic anterograde axonal tracing of the striatonigral pathway can take advantage of the temporal separation of patch versus matrix projections to reveal the terminal distribution of patch striatonigral neurons independent of the nigral terminal distribution from the striatal matrix. The anterograde tracer rhodamine isothiocyanate was shown in a model system to persist in labeled neurons for more than a week, but to be available for uptake into these neurons for a few days after injection at the most. These properties of rhodamine isothiocyanate were combined experimentally with short and long term survival periods. This allowed assessment of the changing developmental distribution of nigral fibers from specifically the striatal patch compartment. In all experimental cases the anterogradely labeled sections of the substantia nigra were also stained with antibodies to tyrosine hydroxylase, which permitted differentiation of the dopamine cell rich pars compacta from the dopamine cell poor pars reticulata. The results show that in the adult the majority of patch and matrix striatonigral projections are confined to the substantia nigra pars reticulata. Furthermore, their fiber distribution within the pars reticulata is overlapping rather than complementary. Most interestingly, in the late embryonic period (most noticeably at embryonic day 19) there is a marked overlap between patch striatonigral fibers and nigral dopamine perikarya. By early postnatal times, when the matrix compartment begins to form its striatonigral projection, the overlap of patch striatonigral fibers and dopamine cells has largely disappeared. The results suggest that a transient interaction between patch striatonigral fibers and dopamine neurons (which is concomitant with the formation of striatal compartments), may be an important developmental event in the phenotypic maturation of striatal pa

Chemoanatomic compartments in the human bed nucleus of the stria terminalis

Recent studies have indicated that peptidergic inputs to the bed nucleus of the stria terminalis are more developed in man than in rodents. To facilitate interspecies comparisons, the definition of the chemoanatomical subdivisions of the human bed nucleus of the stria terminalis was attempted. The immunocytochemistry of synenkephalin, [Met]enkephalin, somatostatin, and tyrosine hydroxylase was analysed on four verticofrontal levels in five control subjects. Four principal sectors were identified in the bed nucleus of the stria terminalis: (1) lateral, displaying an irregular patchy terminal innervation overlapping for the four markers studied; (2) central, characterized by a high density of somatostatin neurons, by pericellular basket-like formations for all markers, and by a shell of dense somatostatin innervation; (3) medial, characterized by a less dense aminergic and peptidergic innervation; and (4) lateroventral, where peptidergic (somatostatin and enkephalin) peridendritic plexuses were prominent. Double-labeling analyses showed that the somatostatin, enkephalin and tyrosine hydroxylase-like immunoreactive terminals rarely converged on the same soma or dendrite even in areas where they appeared closely interdigitated. The differences and similarities of these sectors with those defined in the rat are discussed; a marked development of the lateral and ventral bed nucleus of the stria terminalis is emphasized in man. Islands with dense peptidergic innervation, similar to the ventral bed nucleus of the stria terminalis, extended into the sublenticular substantia innominata (intercalated between the ventral pallidum and the basal magnocellular nucleus). This supports the existence of an extended amygdaloid complex from the amygdala to the bed nucleus of the stria terminalis in the human brain, as has been proposed in the rat. In relation to the literature, the present findings suggest the increasing importance of the central and lateral amygdaloid-bed nucleus of the stria terminals components and of their cortical connections in man while the medial amygdala-bed nucleus of the stria terminalis nuclei, which are preferentially connected to the olfactory system, appear less developed.

Synaptic organization of the globus pallidus

The synaptic organization of the globus pallidus is reviewed with respect to present knowledge about neurons, fibers, axon terminals, and their intrinsic synaptic relationships. Information derived from studies employing Nissl stains, Golgi impregnations, lesion degeneration techniques, immunohistochemistry, and anterograde axonal labeling in various species are presented along with ultrastructural data. Studies indicate that the globus pallidus contains a principal efferent neuron with smooth or spiny dendrites and simple or complex terminal dendritic arborizations. This cell type receives convergent inputs from intrinsic and extrinsic sources and uses gamma-aminobutyric acid as a transmitter. A smaller and separate population of pallidal projection neurons contains acetylcholine. Two other less frequent neuronal types, of small and medium size, have also been recognized. Three to six types of axonal boutons forming synaptic contacts with pallidal neurons have been recognized in various studies. Among these, three types (types I, II, and III) are the most prevalent. Studies indicate that the most frequent category (type I) originates from neostriatal neurons via radial fiber projections and contains immunoreactive GABA and enkephalins. The synaptic architecture of the globus pallidus is dominated by a mosaic-like arrangement of long dendrites that are ensheathed by longitudinally oriented axons making synapses en passant. Triadic synapses involving dendrites that are pre- and postsynaptic are encountered infrequently. Because both striatopallidal and pallidothalamic connections are inhibitory, pallidal target neurons in the thalamus may be "disinhibited" when the neostriatum is activated.

Autoradiographic localization of delta opiate receptors in rat and human brain

In vitro quantitative receptor autoradiography was performed on frozen sections of rat and human brain to visualize delta opiate receptors using the specific ligand [3H][D-Pen2, D-Pen5]enkephalin. For comparison, rat brain sections were also labelled with [3H]D-Ala2, D-Leu5-enkephalin. Compounds which block mu and kappa binding were included to make the [3H]D-Ala2, D-Leu5-enkephalin binding more specific. The two ligands had similar, but not identical, distributions in rat forebrain sections. Sites labelled with [3H][D-Pen2,D-Pen5]enkephalin were distributed heterogeneously within the layers of the frontal and parietal cerebral cortex, with high densities in the superficial and deep cortical layers. The claustrum and striatum had the most delta sites, whereas the globus pallidus had no delta binding. The distribution of [3H]D-Ala2,D-Leu5-enkephalin binding sites was similar to that of [3H][D-Pen2,D-Pen5]enkephalin, except that there was less heterogeneity in the frontal cortex. In the human brain regions studied, the highest delta binding was in caudate, putamen, temporal cortex and amygdala. There was less heterogeneity in the binding of [D-Pen2,D-Pen5]enkephalin in the human cortex than in the rat. No delta binding was seen in the medial and lateral segments of the globus pallidus. In both species, a discrepancy between the high enkephalin content of the globus pallidus and the absence of delta binding was apparent.

New perspectives in basal forebrain organization of special relevance for neuropsychiatric disorders: the striatopallidal, amygdaloid, and corticopetal components of substantia innominata

The basal forebrain is critically involved in functions representing the highest levels of integration. Only recently has a relatively clear anatomical picture of this important area begun to emerge. The territory that has generally been referred to as the "substantia innominata" appears to be composed of portions of three recognizable forebrain structures: the ventral striatopallidal system, the extended amygdala and the magnocellular corticopetal system. (1) Rostrally, the striatopallidal system reaches ventrally to the base of the brain. (2) Caudal to the ventral extension of the striatopallidal system elements of the centromedial amygdala and bed nucleus of the stria terminalis are merged so that these two areas together with this subpallidal corridor form a large forebrain unit that might be described as an "extended amygdala". (3) Large cholinergic and non-cholinergic corticopetal neurons form a more or less continuous aggregate that is interwoven with the striatopallidal and extended amygdala systems in basal forebrain. Consideration of morphological and connectional characteristics of basal forebrain suggests that the corticopetal cell groups, together with magnocellular elements of the striatum, serve similar functional roles for the striatopallidal system, the extended amygdala, and the septal-diagonal band complex. Specifically, the output of medium spiny neurons in striatum, extended amygdala, and lateral septum are directed toward somewhat larger sparsely or moderately spiny neurons with radiating dendrites which in turn project to diencephalon and brainstem or provide either local feedback (e.g. in striatum) or distal feedback to cortex. The functional implications of this parallel processing of descending forebrain afferents are discussed.

Ventral striatopallidal parts of the basal ganglia in the rat: I. Neurochemical compartmentation as reflected by the distributions of neurotensin and substance P immunoreactivity

The distribution of neurotensin immunoreactivity in the basal ganglia of the adult rat was evaluated by studying alternate serial vibratome sections that were exposed to antiserum against neurotensin, substance P, or cholecystokinin. It was observed that a heterogeneous distribution of neurotensin-immunoreactive fibers and terminals contributes to the neurochemical compartmentation of the ventral pallidum and ventral striatum, and that significant numbers of neurotensin-immunoreactive neurons occupy striatal districts of the olfactory tubercle, nucleus accumbens, and ventromedial caudate-putamen. An intense band of pallidal neurotensin immunoreactivity characterizes the medial part of the ventral pallidum adjacent to the nucleus accumbens, whose medial boundary is conveniently defined in sections incubated with cholecystokinin antiserum. Electron microscopic studies showed that the pallidal plexus of neurotensin-immunoreactive elements consists primarily of boutons, which contact large dendrites in arrangements that in all respects appear to be of the classical striatopallidal variety. A gradual decrease in immunolabel was observed approaching the lateral parts of the ventral pallidum, which display sparse neurotensin immunoreactivity. The results thus indicate the existence of a significant neurotensinergic striatopallidal pathway confined primarily, if not exclusively, to the medial part of the ventral striatopallidal system. The contribution of neurotensin-immunoreactive fibers and terminals to the compartmentation of ventral striatum is expressed most vividly in their exclusion from clusters of tightly packed medium-sized neurons, many of which are intensely substance P immunoreactive. Such clusters appear identical with those previously described as rich in opiate receptors and poor in acetylcholinesterase activity. In the ventral striatal region where the nucleus accumbens and ventromedial caudate-putamen merge, neurotensin-immunoreactive neurons are organized in clusters. Further rostral in the nucleus accumbens, they are more evenly distributed. Few were found in the dorsolateral quadrant of the neostriatum.

Immunocytochemical studies on the basal ganglia and substantia nigra in Parkinson's disease and Huntington's chorea

The basal ganglia and substantia nigra, taken from control human brain and from patients dying with a diagnosis of Parkinson's disease or Huntington's chorea, were analysed with histochemical and biochemical techniques. The pigmented neurons of the substantia nigra pars compacta possess tyrosine hydroxylase immunoreactivity and are disposed in three major layers, alpha, beta and gamma. This pattern became obscured in choreic brains by the severe shrinkage of the nigra, but total numbers of pigmented neurons were within the normal range. In contrast, pigmented neurons were lost from all layers of the substantia nigra in Parkinson's disease, although examination of cases with minimal cell loss suggested that an internal part of the lateral alpha sub-layer was most severely and consistently affected. A dopaminergic projection between this internal part of the alpha sub-layer and the putamen was suggested by the preferential loss of catecholamines from the putamen in Parkinson's disease. The distribution of the peptides, substance P, methionine-enkephalin and dynorphin 1-17 were mapped immunohistochemically within the substantia nigra. The different patterns of immunoreactive axons and terminals were found to be extensive, at least partially overlapping, and largely avoided the region of the pigmented perikarya of the alpha sub-layer and nucleus paranigralis. All peptides were depleted in choreic substantia nigra, reflecting the degeneration of the striatonigral pathway. However, concentrations of enkephalin-like immunoreactivity were increased within the interpeduncular nucleus. In Parkinson's disease there was a loss of enkephalin- and dynorphin-like immunoreactivity from the substantia nigra but a fall in substance P-like immunoreactivity was only detected by radioimmunoassay, not by immunocytochemistry. Peptide immunoreactivity was also reduced within choreic basal ganglia. However, no gross changes were found in peptide staining of the parkinsonian basal ganglia. In summary we have reported a number of changes in peptide-containing pathways in human degenerative disorders that may reflect the degeneration of neuronal pathways either as a primary event or secondary to initial lesion. We have also emphasized the sensitivity of the alpha sub-layer of nigral neurons to damage in Parkinson's disease. We suggest that the lower density of peptidergic fibres in the area of the perikarya may contribute to the susceptibility of these neurons to damage.

Multiple benzodiazepine receptors in the human basal ganglia: a detailed pharmacological and anatomical study

The pharmacological characteristics and anatomical distribution of benzodiazepine receptors in the striatum (dorsal striatum, comprising the caudate nucleus and putamen, and ventral striatum) and globus pallidus (dorsal pallidum, comprising the external and internal segments, and ventral pallidum) of the human basal ganglia were examined in twelve cases aged 4-71 years. The pharmacology of the receptors was studied using computerized, non-linear least-squares regression analysis of [3H]flunitrazepam displacement by flunitrazepam, CL218,872 and ethyl beta-carboline-3-carboxylate binding to membranes. The results showed that the dorsal striatum (caudate nucleus and putamen) contained higher concentrations of receptors than the dorsal pallidum (external and internal segments). The dorsal striatum contained equal numbers of sites with high affinity (Type I) and low affinity (Type II) for CL218,872 and ethyl beta-carboline-3-carboxylate whereas the globus pallidus contained sites with only high affinity (Type I) for these ligands. The anatomical localization of the benzodiazepine receptor subtypes (Type I and II) was studied using quantitative autoradiography following in vitro labelling of cryostat sections with [3H]flunitrazepam in the absence or presence of the discriminating ligand CL218,872. The autoradiograms showed that benzodiazepine receptors were distributed throughout all regions of the human striatum in a heterogeneous fashion, i.e. high-density patches of receptors were set against a background matrix of lower receptor densities. The highest densities of receptors were seen in the ventral striatum where the patches were particularly extensive and showed densities 56% higher than the receptor densities in the dorsal striatal patches. Quantitative analysis showed that the patches in all striatal regions contained mainly Type II receptors (83%-86%) whereas the matrix regions in the ventral and dorsal striatum contained different proportions of the receptor subtypes; Type I receptors predominated (60%) in the matrix of the ventral striatum and Type II receptors predominated (67%-71%) in the matrix of the dorsal striatum. By contrast, the autoradiograms showed that the globus pallidus contained considerably lower concentrations of receptors than the striatum. The highest density of receptors in the globus pallidus was present in the ventral pallidum with successively lower concentrations in the external (26% less) and internal (66% less) segments of the dorsal pallidum. In agreement with the membrane binding studies the receptors in the globus pallidus were mainly of the Type I variety.(ABSTRACT TRUNCATED AT 400 WORDS)

Subtraction autoradiography of opiate receptor subtypes in human brain

Opiate binding sites in sections of human brain were labelled with [3H]etorphine. Many brain areas contained high levels of [3H]etorphine binding sites although the globus pallidus was an exception. Subtraction autoradiography was performed using selective displacement of [3H]etorphine with opioid agonists to visualise mu-, delta- and kappa-opiate receptor subtypes. mu-Receptors were most abundant in the thalamus, caudate nucleus, putamen and the superficial layers of the cerebral cortex. Kappa receptors were concentrated in the deep layers of the cortex, the claustrum and the caudate nucleus. Human brain contained very few delta-receptors. Some brain areas with high concentrations of endogenous opioid peptides have many receptors, but in other areas, for example the globus pallidus, there is a mismatch between peptide concentration and receptor density.

Somatostatin 28 and neuropeptide Y innervation in the septal area and related cortical and subcortical structures of the human brain. Distribution, relationships and evidence for differential coexistence

Somatostatin 28- and neuropeptide Y-containing innervations were mapped in the human medial forebrain (eight control brains) with immunohistochemistry, using the sensitive avidin-biotin-peroxidase method. Peptidergic perikarya and fibers had an extensive distribution: they were densest in the ventral striatum (nucleus accumbens, olfactory tubercle and bed nucleus of the stria terminalis) and infralimbic cortex, of intermediate density in the medial septal area and of lowest density in the dorsal and caudal lateral septal nucleus. Somatostatin-like immunoreactive perikarya and fibers were generally more numerous than the neuropeptide Y-like immunoreactive ones, but more faintly labeled. Their pattern of distribution was strikingly similar in some of the limbic structures studied but clearly distinct in others. Excellent overlap of neuropeptide Y and somatostatin-like immunoreactivity was detected in: (1) the medial septal area, where innervation occasionally formed perivascular clusters; (2) the nucleus accumbens and olfactory tubercle, characterized by dense patchy innervation; and (3) the laterodorsal septal nucleus, scarcely innervated. In the latter structures, most peptidergic neurons were double-labeled. On the other hand, both peptidergic innervations clearly differed in the lateroventral septal nucleus and the bed nucleus of the stria terminalis which contained distinct clusters of somatostatin-like immunoreactive neurons devoid of neuropeptide Y-like immunoreactivity. Also, the perineuronal and peridendritic axonal plexuses ('woolly fibers') present in these structures were only labeled with somatostatin. In the infralimbic cortex, the relation between the peptides varied according to the cortical laminae. Coexistence of somatostatin and neuropeptide Y frequently occurred in layer VI and in the subcortical white matter, whereas layer V and particularly layers II and III contained a contingent of neurons labeled only with somatostatin. Dense horizontal terminal networks in layers I and VI however were similar for both peptides. These findings support the existence of two different types of somatostatin-like immunoreactive perikarya as regards colocalization with neuropeptide Y. Their particular topographical segregation within the cortical and subcortical structures analysed suggest that they could have different connections and functional properties.(ABSTRACT TRUNCATED AT 400 WORDS)

Subset of neurons characterized by the presence of NADPH-diaphorase in human substantia innominata

The substantia innominata encompasses an area of the basal forebrain that is ventral to the lenticular nucleus and anterior commissure, medial to the claustrum and external capsule, and lateral to the hypothalamus. The nucleus basalis of Meynert consists primarily of large acetylcholinesterase (AchE)-positive neurons embedded within the substantia innominata. Damage to these neurons may be important in the pathogenesis of cortical dysfunction in Alzheimer's disease. In order to characterize other neuronal elements in the substantia innominata and their relationship to the nucleus basalis, we chose to study a biochemically distinct neuronal subset containing the enzyme nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d). The substantia innominata was blocked from six normal brains obtained postmortem and fixed in neutral-buffered formalin at 4 degrees C for 48 hours. Free-floating 50-micron sections from several levels were stained for NADPH-d or AchE activities. Selected sections were double stained for NADPH-d and AchE. NADPH-d activity was present in a network of pleomorphic neurons that extended through all levels of the substantia innominata and into the striatum and amygdala. NADPH-d neurons were particularly numerous at the level of the anterior commisure and were closely associated with the cholinergic neurons of the nucleus basalis. They were not seen in the ventral pallidum, or the vertical limb of the diagonal band of Broca or in the islands of Calleja. The cell bodies of NADPH-d neurons were quite varied in shape, ranging from ovoid to fusiform, and about half the cells were bipolar. Where neuronal density was high, their dendrites formed an interlacing pattern. NADPH-d-positive fibres were seen coursing through the external capsule, hypothalamus, and amygdala. This novel set of neurons in the substantia innominata may be part of a more extensive network that interacts with the magnocellular basal forebrain system at the level of the nucleus basalis. Whether other neurotransmitters are present within these neurons and whether NADPH-d neurons are involved in Alzheimer's disease remain to be elucidated.

Preprotachykinin messenger RNA detected by in situ hybridization in striatal neurons of the human brain

Sections from postmortem human brain were processed for in situ hybridization histochemistry using a 35S-labelled RNA probe transcribed from a cDNA coding for the human preprotachykinin which contains both substance P and K. Labelled neurons were observed in the caudate nucleus and the putamen but not the cerebellum. The labelled cells were of medium size and their distribution and morphology were compatible with previous data on substance P-like immunoreactivity in the human brain. The results confirm the presence of preprotachykinin mRNA in a subpopulation of striatal neurons in the human and show that in situ hybridization can be used to detect specific neurotransmitter-related mRNAs in postmortem tissue from normal and diseased humans.

Anatomical relationship between the basal ganglia and the basal nucleus of Meynert in human and monkey forebrain

Previous immunohistochemical studies have provided evidence that the external segment of the globus pallidus extends ventrally beneath the transverse limb of the anterior commissure into the area of the substantia innominata. Enkephalin-positive staining in the form of "woolly fibers" has been used as a marker for the globus pallidus and its ventral extension. Acetylcholinesterase staining of both fibers and cell bodies, frequently used as a marker for the basal nucleus of Meynert, is also found in the area of the substantia innominata. This study describes the differential distribution of enkephalin-positive woolly fibers and acetylcholinesterase staining on adjacent sections in both the monkey and human basal forebrain area in an attempt to define the relationship between the basal ganglia and the basal nucleus of Meynert. The results show that while both occupy large regions of the basal forebrain, they overlap very little. In both species investigated, dense concentrations of acetylcholinesterase-positive neurons lie, for the most part, outside the boundaries of the pallidal fibers. However, some scattered acetylcholinesterase cells do lie within the confines of the dorsal pallidum, and a more prominent group is found in the subcommissural ventral pallidum. These cells may constitute a group separate from the more densely packed acetylcholinesterase-positive cells in woolly fiber-free regions in that they may receive direct striatal input.

Gilles de la Tourette's syndrome. A postmortem neuropathological and immunohistochemical study

Immunocytochemical studies of the human forebrain have shown that enkephalin-like, dynorphin-like and substance-P-like immunoreactivity (respectively ELI, DLI, and SPI) normally present in unique pattern (now termed woolly fibers) in the globus pallidus and substantia nigra, in which their concentration is at its densest. Quantitative determinations moreover indicate that the levels of all 3 peptides are higher in the globus pallidus and substantia nigra than in any other region of the brain. We report here the distribution of immunoreactivity of these 3 peptides in the brain of a patient showing the typical clinical manifestations of Gilles de la Tourette's syndrome (TS); a disease for which no characteristic or consistent neuropathological features have been discerned. In the case described here neuropathological examination by means of the usual histopathological methods showed no abnormalities to which the patient's illness could be ascribed. ELI- and SPLI-positive woolly fibers were densely stained and of normal distribution. DLI-staining was, however, considerably less dense throughout the brain than normal. The most striking finding was the total absence of DLI-positive woolly fibers in the dorsal part of the external segment of the globus pallidus; the ventral pallidum showed very faint staining. These observations, which indicate a decrease of dynorphin in striatal fibers projecting to the globus pallidus, are, to our knowledge, the first evidence of a distinct pathological change in the brain in TS.

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.

An immunohistochemical study of endopeptidase-24.11 ("enkephalinase") in the pig nervous system

Endopeptidase-24.11, a plasma membrane ectoenzyme with the ability to hydrolyse a variety of neuropeptides, has been localized in the pig nervous system by an immunoperoxidase technique. The endopeptidase was mapped in cryostat sections of the fore and mid-brain to the following structures: caudate-putamen, globus pallidus, olfactory tubercle, nucleus interpeduncularis and substantia nigra. Endopeptidase-24.11-like immunoreactivity was also found in the pia mater, choroid plexus and ependymal lining of the central canal. In the spinal cord, weak staining was observed in the dorsal horn, but strong staining was found in the dorsal root ganglia and nerve roots. Within the central nervous system, endopeptidase immunoreactivity was confined to gray matter and within the positive areas of the striatum densely staining areas, corresponding to striosomes, were discernible. These well-defined structures were exploited in serial sections to examine the alignment of the enzyme-rich patches of neuropil with correspondingly strong staining for other antigens. A consistent match was observed with a monoclonal antibody to neurofilament protein, but there was a poor correlation with a polyclonal antibody to glial fibrillary acidic protein. Substance P-like and [Leu]enkephalin-like immunoreactivity were also studied in sections adjacent to those stained for the endopeptidase. Good matching between enzyme-rich and peptide-rich areas was observed, but some enkephalin-rich areas did not align with enzyme staining and indeed endopeptidase-rich areas were not necessarily matched with areas rich in either peptide. These findings suggest a neuronal rather than an astrocytic location for endopeptidase-24.11 in the CNS and lend support to the view that it plays a central role in neuropeptide metabolism at membrane surfaces. In the peripheral nervous system, the endopeptidase was located in Schwann cell membranes surrounding dorsal root ganglion cells and nerve fibres, while in the pituitary the main concentration was in the adenohypophysis, where only a proportion of the endocrine cells were found to be immunoreactive.

Opioid peptides in Huntington's disease: alterations in prodynorphin and proenkephalin system

The concentrations of dynorphin A1-8 and Met-enkephalin-Arg6-Gly7-Leu8 were measured in the basal ganglia of postmortem brains from patients with Huntington's disease (HD) and from control subjects. A significant reduction of dynorphin A1-8 concentration was found in caudate nucleus, putamen, external globus pallidus and substantia nigra of HD brains. Levels of Met-enkephalin-Arg6-Gly7-Leu8 were reduced in HD caudate nucleus, putamen, internal and external globus pallidus. These data indicate that both the prodynorphin and proenkephalin opioid peptide system are affected in the basal ganglia in HD.

Prodynorphin peptide immunocytochemistry in rhesus monkey brain

The present study describes the immunocytochemical distribution of peptides derived from the prodynorphin precursor in the brain of the rhesus monkey (Macaca mulatta). Animals were treated with colchicine (intracerebroventricularly) prior to perfusion to enhance the observation of perikaryal immunoreactivity. Using antisera generated against dynorphin A(1-17), dynorphin B(1-13), and prodynorphin(186-208) (or bridge peptide), the anatomical distribution of dynorphin systems was mapped. The results indicate a widespread neuronal localization of immunoreactivity from the cerebral cortex to the caudal medulla. Anti-dynorphin B and anti-bridge peptide sera proved useful for the demonstration of neuronal perikarya, while the dynorphin A antiserum was best for localizing terminal projection fields. Immunoreactive perikarya are located in numerous brain loci, including the cingulate cortex, caudate nucleus, amygdala, hypothalamus (especially the magnocellular nuclei), thalamus, substantia grisea centralis, parabrachial nucleus, nucleus tractus solitarius, and other nuclei. In addition, fiber and terminal immunoreactivity are seen in varying densities in the striatum and pallidum, substantia innominata, hypothalamus, substantia nigra pars reticulata, parabrachial nucleus, spinal trigeminal nucleus, and other areas. The distribution of prodynorphin peptides in the brain of the monkey is similar to that described for the rat brain; however, significant differences also exist. Other interspecies differences in the anatomy of prodynorphin and proenkephalin neuronal systems in the monkey and human brain are further discussed.