Cholecystokinin Downregulates Psoriatic Inflammation by Its Possible Self-Regulatory Effect on Epidermal Keratinocytes.

Cholecystokinin (CCK) is a peptide hormone that functions in digestive organs and the CNS. We previously showed that CCK downregulates peripheral pruritus by suppressing degranulation of mast cells. In this study, we demonstrated that CCK octapeptide (CCK8) was constitutively expressed in the epidermis of normal skin, whereas its expression was lost in acanthotic lesions of psoriasis. In contrast, CCKA receptor (CCKAR), a high-affinity receptor for CCK, was constitutively expressed in the epidermis of psoriatic skin lesions. Expression of CCK was also reduced in skin lesions of an imiquimod (IMQ)-induced psoriatic mouse model. Notably, the expression level of CCK inversely correlated with the severity of epidermal inflammation, raising the possibility that CCK from epidermal keratinocytes suppresses the psoriatic inflammation. To verify this hypothesis, we investigated the effects of sulfated CCK octapeptide (CCK8S) on the development of IMQ-induced psoriatic inflammation. i.p. injection of CCK8S suppressed the IMQ-induced psoriatic inflammation accompanied by reduced mRNA expression of IL-17, IL-22, and IL-6 but not of IL-23. The suppressive effect of CCK8S was completely restored by administration of CCKAR antagonist. In vitro studies showed that exogenous CCK8S suppressed IL-6 production in CCKAR-expressing cultured human keratinocytes, and blocking the endogenous CCK signaling with CCKAR antagonist markedly enhanced IL-6 production. When keratinocytes were stimulated with IL-17, the expression of endogenous CCK was significantly decreased. These findings suggest that CCK physiologically functions as a negative regulator of keratinocyte-based inflammation in an autocrine or paracrine manner, although decreased CCK may pathologically contribute to continuous and aggravated skin lesions such as psoriasis.

SP-SR interneurones: a novel class of neurones of the CA2 region of the hippocampus.

The CA2 region of the hippocampus has distinctive properties and inputs and may be linked with the pathology of specific psychiatric and neurological disorders. It is, therefore, important to understand CA2 circuitry and its involvement in the circuitry of the hippocampus. Properties of CA2 basket cells have been reported. However, other classes of CA2 interneurones with cell bodies located in stratum pyramidale remained to be described. In this study, the unusual axonal arbors of a novel subclass of dendrite-preferring CA2 interneurones whose somata are located in the pyramidal cell layer was revealed following intracellular recordings and biocytin labeling. One to four apical dendrites emerged from the soma, branched in stratum radiatum (SR) forming a tuft, but rarely penetrated stratum lacunosum-moleculare (SLM). One or two basal dendrites branched close to the soma, the branches extended through stratum oriens (SO) and often reached the alveus. Unlike CA2 bistratified cells, the axons of these cells arborized almost exclusively in SR with few, if any, branches extending to stratum pyramidale (SP), SO, or SLM. These interneurones again, unlike bistratified cells, were immunonegative for parvalbumin and cholecystokinin. Electrophysiologically, they were similar to some CA2 basket and bistratified cells in that they presented a "sag" in response to hyperpolarizing current injections and displayed spike frequency adaptation. They targeted the apical dendrites of neighboring CA2 pyramidal cells and received inputs from them.

Supersensitive gastrin assay using antibodies raised against a cholecystokinin homolog.

Peptide hormones may occur in particularly low amounts in samples from small animals. Hence, in a rat microdialysis study conventional immunoassays were not sufficiently sensitive to measure gastrin in the dialysis samples. We therefore exploited the observation that antibodies raised against the homologous hormone cholecystokinin (CCK) occasionally bind gastrin peptides with significantly higher affinity than the proper ligand. The immunoassay thus established could detect 1.0 pmol/l in 15 µl microdialysate, which corresponds to 23 attomol gastrin. Such detection limit is five-fold lower than that obtained with the most avid conventional gastrin antibodies. The results may encourage similar approaches for other peptides using homologue-raised antibodies when supersensitivity is required.

Pseudopod-like basal cell processes in intestinal cholecystokinin cells.

Cholecystokinin (CCK) is secreted by neuroendocrine cells comprising 0.1%-0.5% of the mucosal cells in the upper small intestine. Using CCK promoter-driven green fluorescent protein (GFP) expression in transgenic mice, we have applied immunofluorescence techniques to analyze the morphology of CCK cells. GFP and CCK colocalize in neuroendocrine cells with little aberrant GFP expression. CCK-containing cells are either flask- or spindle-shaped, and in some cells, we have found dendritic processes similar to pseudopods demonstrated for gut somatostatin-containing D cells. Most pseudopods are short, the longest process visualized extending across three cells. Pseudopods usually extend to adjacent cells but some weave between neighboring cells. Dual processes have also been observed. Three-dimensional reconstructions suggest that processes are not unidirectional and thus are unlikely to be involved in migration of CCK cells from the crypt up the villus. Abundant CCK immunostaining is present in the pseudopods, suggesting that they release CCK onto the target cell. In order to identify the type of cells being targeted, we have co-stained sections with antibodies to chromogranin A, trefoil factor-3, and sucrase-isomaltase. CCK cell processes almost exclusively extend to sucrase-isomaltase-positive enterocytes. Thus, CCK cells have cellular processes possibly involved in paracrine secretion.

Cholecystokinin antibody injected in cerebral ventricles stimulates feeding in sheep.

The role of brain cholecystokinin peptides in satiety was further assessed by using antibody to cholecystokinin to reduce cholecystokinin activity in the cerebrospinal fluid of sheep. Food intakes were increased approximately 100 percent during the 2-hour continuous injection of antibody into the cerebrospinal fluid. This supports the hypothesis that, during feeding, cholecystokinin is released into the cerebrospinal fluid, which transports it to the receptors that elicit satiety.

Morphine analgesia potentiated but tolerance not affected by active immunization against cholecystokinin.

Administration of cholecystokinin was recently found to attenuate opiate analgesia. In the present study, the role of endogenous cholecystokinin in opiate analgesia was examined. Endogenously released cholecystokinin was sequestered by antibodies to cholecystokinin developed in response to an active immunization procedure. Morphine analgesia was potentiated and prolonged in rats immunized against cholecystokinin. The rate of development of morphine tolerance, however, was not affected by the antibodies. Endogenous cholecystokinin appears to function as a short-term modulator of opiate action.

Localization of cholecystokinin-like immunoreactivity in the central nervous system of Triatoma infestans (Insecta: Heteroptera).

The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.

Is the C-terminal flanking peptide of rat cholecystokinin double sulphated?

A specific radioimmunoassay was developed to the predicted nine amino acid C-terminal flanking peptide of cholecystokinin (peptide serine serine, PSS). In aqueous extracts of rat brain, PSS was undetectable unless the extracts were first treated with arylsulphatase, which also resulted in desulphation of cholecystokinin. The reverse-phase HPLC analysis of partially desulphated extracts showed the presence of two peaks intermediate to the naturally occurring and the completely desulphated forms. It is therefore proposed that the CCK-flanking peptide PSS has both tyrosine residues sulphated.

Isolation from chicken antrum, and primary amino acid sequence of a novel 36-residue peptide of the gastrin/CCK family.

A peptide that cross-reacted with C-terminal gastrin/CCK antisera was isolated from chicken antral extracts by a combination of gel filtration and reversed-phase HPLC. The sequence was: Phe-Leu-Pro-His- Val-Phe-Ala-Glu-Leu-Ser-Asp-Arg-Lys-Gly-Phe-Val-Gln-Gly-Asn-Gly-Ala- Val-Glu-Ala-Leu-His-Asp-His-Phe-Tyr-Pro-Asp-Trp-Met-Asp-Phe(NH2). Aside from the C-terminal tetrapeptide and the Tyr residue, the molecule does not resemble other known forms of gastrin or CCK. The peptide was a potent stimulus of avian gastric acid but not pancreatic secretion. The results have important implications for the structure-activity and evolutionary relationships of the gastrin/CCK family.

Heterogeneity of cholecystokinin/gastrin-like immunoreactivity in the nervous system of the nematode Ascaris suum.

A wholemount immunocytochemical method was used for the localization of cholecystokinin (CCK8)-like and gastrin-like immunoreactivity in Ascaris. The patterns of specific neuronal staining given by two antisera and four monoclonal antibodies made against CCK8, and one antiserum made against gastrin were investigated. Preabsorption of these antibodies with CCK8 or gastrin 17 resulted in complete loss of immunoreactivity in almost all of the neurons (two antisera also contained nonspecific antibodies), suggesting that all of the antibodies recognize epitopes, in Ascaris neurons, that include some or all of the C-terminal five amino acids that are identical in CCK8 and gastrin 17. However, the seven different antibodies showed immunoreactivity in different subpopulations of neurons, implying that there are at least seven different species of CCK-like molecules in Ascaris. Fractionation of Ascaris peptide extracts by high performance liquid chromatography (HPLC), monitoring fractions with a CCK8 radioimmunoassay (RIA), also shows heterogeneity of molecules immunologically related to CCK8.

Distribution of cholecystokinin-like immunoreactivity in the rat main olfactory bulb.

The anatomical localization of cholecystokinin-like immunoreactivity (CCK-I) within the rat main olfactory bulb was analyzed by using the peroxidase-antiperoxidase immunocytochemical technique. Neurons or neuronal processes containing CCK-I were localized within all laminae of the olfactory bulb except the olfactory nerve fiber layer. A large population of CCK-I neurons, with morphology, size, and distribution corresponding to that of the middle and external tufted cells, was observed within a zone extending from the deep periglomerular region through the superficial one-half to one-third of the external plexiform layer. A smaller number of immunoreactive perikarya were found in the deep external plexiform layer, the glomerular layer, and rarely within the inner plexiform layer. These CCK-I neurons appeared to correspond to internal tufted cells, periglomerular cells, and deep short-axon cells, respectively. Dense CCK-I staining of fibers and terminals was present within the internal plexiform layer and, less densely, within the neuropil of the granule cell layer. In addition, terminal-like CCK-I was localized within layer 1A of the anterior olfactory nucleus, the olfactory tubercle, and the most rostral piriform cortex. This observation provides corroboration for the identification of the principal CCK-I neuron in the rat olfactory bulb as the centrally projecting middle tufted cell. The present results, demonstrating the localization of CCK-I to both local circuit and projection neurons of the olfactory bulb and to terminal-like puncta in the internal plexiform and granule cell layers, suggest that CCK may be significantly involved in olfactory processing at several levels.

Cholecystokinin in hippocampal pathways.

The distribution of cholecystokininlike (CCK-L) immunoreactive cells and fibers in the rat hippocampal formation and its afferent and efferent connections was studied using the immunoperoxidase technique. In the hippocampal formation CCK-L immunoreactive perikarya were located in the polymorphic zone of the dentate hilus, all layers of Ammon's horn, the subiculum, the presubiculum, and the entorhinal cortex. Cholecystokininlike immunoreactive fibers extended from cell bodies or were located around the cell bodies in the entorhinal cortex, subiculum and stratum pyramidale of Ammon's horn, and among the granule cells and inner molecular layer of the dentate gyrus. The immunoreactive cells in the stratum oriens may be a type of basket cell, since processes from these cells extend into stratum pyramidale and collections of CCK-L immunoreactive fibers are seen around cell bodies in stratum pyramidale. Cholecystokininlike immunoreactive fibers were also observed in the alveus, ventral and lateral fimbria, and ventrolateral lateral septal nucleus. Some of these immunoreactive fibers, therefore, being to either an efferent or afferent hippocampal pathway(s) originating from CCK-L immunoreactive pyramidal cells in the hippocampal formation and/or from the hippocampal subcortical nuclei, the supramammillary nucleus, and the dorsomedial hypothalamic nucleus which contain CCK-L immunoreactive perikarya. The distribution of these immunoreactive fibers in the fimbria and lateral septal nucleus is most consistent with an anteriorly directed efferent hippocampal pathway.

Cholecystokinin concentrations and peptide immunoreactivity in the intact and deafferented medullary dorsal horn of the rat.

To further address the hypothesis that cholecystokinin (CCK) in the medullary dorsal horn (MDH) arises from intrinsic or higher-order neurons, CCK-8-specific radioimmunoassay (RIA) and immunohistochemical (IHC) experiments were carried out in adult rats after trigeminal tractotomy. RIA of punches from deafferented superficial layers of the MDH revealed no significant change in CCK levels vs. the control right side. In this same area, IHC revealed modest reductions in CCK, gastrin, and substance P staining. Calcitonin gene-related peptide (CGRP) staining was reduced substantially. Gastrin immunoreactive cell bodies, present normally in inner lamina II, were reduced in number. RIA and IHC methods were also used to assess MDH CCK concentrations in adult rats subjected to left infraorbital nerve section at birth. The left medulla contained significantly higher levels of CCK than the control right medulla (1.27 +/- 0.19 vs. 0.97 +/- 0.11 ng/mg protein). IHC revealed a dense band of CCK-like staining in laminae I and II ipsi- and contralateral to the lesion. Thus, neonatal deafferentation elevates medullary CCK. To determine if the neonatal lesion-induced increase in medullary CCK is due to primary afferent or higher-order reorganization, RIA and IHC experiments were run after infraorbital nerve section at birth and trigeminal tractotomy in adulthood. RIA revealed no significant change in CCK levels caudal to the tractotomy, although they were higher than control levels in 9 of 12 cases. IHC revealed modest reductions in CCK, substance P, and gastrin staining that resembled the reductions observed in tractotomy-alone cases. These data suggest that 1) most MDH CCK is of non-primary afferent origin, 2) gastrin immunoreactivity in layer II probably originates in CCK-containing cells intrinsic to layer II, the expression of which is dependent upon trigeminal primary afferent input, 3) neonatal V deafferentation induces increased CCK in the superficial MDH, reflecting reorganized intrinsic or higher-order inputs, and 4) higher-order substance P in the MDH is robust.

Pattern of substance P- and cholecystokinin-like immunoreactivity during regeneration of the neural complex in the ascidian Ciona intestinalis.

The neural ganglion of ascidians exhibits a novel and rapid pattern of regeneration whereby within approximately 28-35 days of total ablation an entirely new neural complex is formed. In normal adults, neuronal cell bodies expressing substance P- (SP-Li), neurokinin A-(NKA-Li), CCK/gastrin- (CCK-Li), and insulin-like immunoreactivity exhibit a clearly defined pattern of localization in the cortical rind of the ganglion with characteristic long processes arising from the perikarya running throughout the neuropile. CCK-Li cell bodies are particularly concentrated close to the points of exit of the main nerve trunks. We have used antisera raised against these peptides to monitor the process of regeneration up to postoperative (pa) day 35. Only SP and CCK antisera produced positive staining in the regenerating tissue. Immunoreactive cell bodies first appear following 14 days pa. At this time CCK-Li neurons are more abundant than SP-Li neurons and in contrast to the pattern found in the normal adult ganglion, immunoreactive cell bodies are located both peripherally and centrally in the core of the ganglion and processes were rarely seen. Later stages exhibited an increasing number of SP-Li neurons and at 35 days pa SP-Li cell bodies clearly predominate. CCK-Li neurons typically become clustered close to the points of emergence of the anterior nerve roots. The early expression of CCK-Li and SP-Li molecules during regeneration is considered in terms of their potential role in development and cell proliferation in the newly forming ganglion.

Cholecystokinin innervation of monkey prefrontal cortex: an immunohistochemical study.

Knowledge of the circuitry of chemically identified systems in primate prefrontal cortex is limited. Although cholecystokinin is very abundant in prefrontal cortex (Geola et al.: Journal of Clinical Endocrinology and Metabolism 53(2):270-275, 1981; Taquet et al.: Neuroscience 27(3):871-883, 1988), the organization of cholecystokinin-containing structures in primate prefrontal cortex has not been investigated. Using immunohistochemical and retrograde transport techniques, we characterized the cholecystokinin innervation of prefrontal cortex in macaque monkeys. The use of two antibodies directed against different portions of the cholecystokinin molecule revealed that distinct forms of the molecule were differentially localized in the same cortical neurons. These small, nonpyramidal cholecystokinin-positive neurons had a variety of somal morphologies and the density of labeled cells did not differ among cytoarchitectonic regions. Labeled neurons had a distinctive laminar distribution with the greatest density of cells present in layers II-superficial III. Labeled fibers also had a distinctive laminar pattern of distribution that differed from that of the immunoreactive neurons. In granular prefrontal cortex, terminal fields were evident in layers II, IV, and VI, with the greatest density in layer VI. Agranular area 24 exhibited a bilaminar pattern of immunoreactivity with a band in layer II and a very dense terminal field in layers V-VI. A high density of cholecystokinin-binding sites has been found in layers III-IV of prefrontal cortex and other association areas in the monkey; this finding has been attributed to possible cholecystokinin-containing afferents from the thalamus (Kritzer et al.: Journal of Comparative Neurology 263:418-435, 1987). The mediodorsal nucleus of the thalamus is known to be a source of afferents which terminate in layer IV of prefrontal cortex. However, combined retrograde transport and immunohistochemical techniques failed to reveal the presence of cholecystokinin-positive neurons in the mediodorsal nucleus of the thalamus that project to prefrontal cortex. These findings, and other observations, suggest that the terminal field in layer IV is formed by descending axons that arise from cholecystokinin-containing neurons in layers II and superficial III. This study demonstrates that the cholecystokinin innervation of prefrontal cortex has a laminar specific organization that is preserved across cytoarchitectonic regions. This distribution of immunoreactive structures suggests a distinctive role of cholecystokinin in cortical circuitry that is common to every region of prefrontal cortex.

Immunocytochemical survey of putative neurotransmitters in taste buds from Necturus maculosus.

To investigate synaptic mechanisms in taste buds and collect information about synaptic transmission in these sensory organs, we have examined taste buds of the mudpuppy, Necturus maculosus for the presence of neurotransmitters and neuromodulators. Immunocytochemical staining at the light microscopic level revealed the presence of serotonin-like and cholecystokinin-like (CCK) immunoreactivity in basal cells in the taste bud. Nerve fibers innervating taste buds were immunoreactive for vasoactive intestinal peptide-like (VIP), substance P-like, and calcitonin gene-related peptide-like (CGRP) or compounds closely related to these substances. Immunoreactivity for tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) in the taste cells and nerve fibers was absent. These data suggest that serotonin, CCK, VIP, substance P, and CGRP are involved in synaptic transmission or neuromodulation in the peripheral organs of taste. No evidence was found for cholinergic or adrenergic mechanisms on the basis of the absence of immunocytochemical staining for key enzymes involved in these two transmitter systems.

Distribution of cholecystokinin-like immunoreactivity within the stomatogastric nervous systems of four species of decapod crustacea.

The distribution of cholecystokinin-like immunoreactivity was studied in the stomatogastric nervous systems, pericardial organs, and haemolymph of four species of decapod crustacea, by using immunocytochemical and radioimmunoassay techniques. Whereas cholecystokinin-like immunoreactivity was found within the stomatogastric nervous systems of all four species, its distribution in each is unique. Two species (Panulirus interruptus and Homarus americanus) have cholecystokinin-like immunoreactivity within fibers and neuropil of the stomatogastric ganglion (STG); two other species (Cancer antenarius and Procambarus clarkii) do not. Further, the cholecystokinin-like immunoreactivity within the STGs of Panulirus and Homarus arise from distinct structures; from a projection of anterior ganglia in Panulirus, and from somata within the posterior motor nerves in Homarus. The staining in the other ganglia of the stomatogastric nervous system also shows some interspecies variability, although it appears to be more highly conserved than staining within the STG. These differences in staining were confirmed by measuring the amount of CCK-like peptide present in tissue extracts of ganglia by radioimmunoassay. In contrast to the variable staining within the STG, all four species have cholecystokinin-like immunoreactivity within the neurosecretory pericardial organs and thoracic segmental nerves. This cholecystokinin-like immunoreactivity is contained within fibers and within varicosities that coat the surface of these structures. The location of this staining and the presence of detectible levels of CCK-like peptide in the haemolymph suggests that CCK-like peptides in decapod crustacea may be utilized as neurohormones.

Ultrastructural localization of neurotensin-like immunoreactivity within dense core vesicles in perikarya, but not terminals, colocalizing tyrosine hydroxylase in the rat ventral tegmental area.

Within the rat ventral tegmental area (VTA), the parabrachial pigmentosus and paranigral subdivisions are known to differ in their functional responses to injected neurotensin. These subdivisions also vary in their connections with other brain regions and in their number of neurotensin-containing perikarya as seen by light microscopy. In both subdivisions, there may be intracellular as well as synaptic relations between dopamine and neurotensin. Dopaminergic neurons are known to be physiologically activated by neurotensin (NT) and may also contain this peptide. To characterize further the cellular relationships in each subdivision, we examined the ultrastructural immunocytochemical localization of a rat antiserum against NT and a rabbit antiserum against the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) in single sections. The NT antiserum was raised against the entire peptide sequence. Immunoblots showed that the antiserum recognized the original antigen as well as the related peptides neuromedin N and lysine 8- arginine 9- neurotensin 10-13 (LANT-6). In both the parabrachial pigmentosus and paranigral subdivisions, neurotensin-like immunoreactivity (NTLI) was localized predominantly in the large (80-100 nm) dense core vesicles using the peroxidase anti-peroxidase (PAP) method. In tissue labeled for NT by the PAP method and for TH by immunoautoradiography, serial section analysis revealed that all perikarya containing NTLI (n = 19) were also TH-positive. Three times as many perikarya colocalized NTLI and TH in the parabrachial pigmentosus subdivision (n = 15) as in the paranigral subdivision (n = 4). Occasionally, a perikaryon containing TH and NTLI could be found in direct apposition to a TH-labeled perikaryon without glial separation. In contrast to perikarya and dendrites, terminals showing NTLI (38 in parabrachial pigmentosus, 29 in paranigral) lacked detectable TH labeling. Of the terminals containing NTLI whose synaptic junctions could be identified, 48% were symmetric and 10% were asymmetric. The targets of these terminals included perikarya and dendrites lacking detectable immunoreactivity (69% in parabrachial pigmentosus, 55% in paranigral), immunolabeled for TH (26% in parabrachial pigmentosus, 38% in paranigral) or containing both NTLI and TH (5% in parabrachial pigmentosus, 7% in paranigral). Single terminals containing NTLI sometimes contacted more than one neuronal target, some of which were apposed to each other without glial separation. TH-labeled terminals synapsed onto double-labeled perikarya in the paranigral subdivision, but were not observed to do so in the parabrachial pigmentosus subdivision.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical analyses of the human olfactory bulb.

These studies explore the distribution of putative neuroactive peptides in the human olfactory bulb. Localization of synaptophysin-, serotonin-, cholecystokinin-, substance P-, and somatostatin-like staining was examined by immunocytochemical protocols. The results provide new insights into the composition and laminar segregation of subpopulations of neurons and neuronal processes in the human olfactory bulb. The prominent synaptophysin-like immunoreactivity observed in the glomeruli of the human olfactory bulb is consistent with the notion that the density of synapses, and hence the density of synaptic vesicles, is highest in the glomeruli. Serotonin-like immunoreactivity suggested a variable innervation of glomeruli ranging from a dense tangled ball of fibers within the glomerulus to a sparse innervation by a single immunoreactive fiber. There was no evidence of serotonin-like immunoreactive cell bodies in either the olfactory bulb proper, anterior olfactory nucleus, or proximal regions of the lateral olfactory tract. Cholecystokinin-like immunoreactivity was limited to fibers found largely in the juxtaglomerular region of the glomerular layer. In the deeper layers of the olfactory bulb, cholecystokinin-like immunoreactive fibers did not show any of branching or arborization that was evident in the juxtaglomerular region. Substance P-like immunoreactivity was seen in varicose fibers distributed in all of the human olfactory bulb laminae. In addition, stained multipolar neurons were found in the area of the anterior olfactory nucleus. Somatostatin-like immunoreactivity was similar to that of substance P in that a plexus of stained fibers was found in all laminae of the olfactory bulb. Also, somatostatin-like immunoreactive cell bodies were found in the area of the anterior olfactory nucleus. However, as compared to substance P, somatostatin had a less dense plexus of immunoreactive fibers in the olfactory bulb. These results increase our understanding of the fundamental organization of the human olfactory system. The current data, coupled with prior studies, provide a foundation from which to study the cellular pathology of diseases with known olfactory system sequelae such as Alzheimer's, Parkinson's, and schizophrenia.

Deafferentation-induced changes in neuropeptides of the adult rat dorsal horn following pronase injection of the sciatic nerve.

The effect of deafferentation on the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), somatostatin (SS), and cholecystokinin (CCK) in the lumbar dorsal horn of the adult rat was examined by the indirect immunohistochemical method. Deafferentation was induced by injecting the sciatic nerve of anesthetized rats with proteolytic enzymes (20 mg pronase), which cause selective death of the nerve's ganglion cells and degeneration of their terminal arborization in the spinal cord. The density of immunolabel of each peptide was determined by using a computerized densitometry analysis system in two animal groups, i.e., short-term (10-13 days after injection) and long-term (4-9 months). In both groups, the deafferentation produced a significant ipsilateral depletion of CGRP, SP, CCK, and SS immunoreactivity. This depletion was limited to the area occupied by the sciatic terminals in the dorsal horn. In the long-term group, the loss of CGRP and SP staining was significantly less than that in the short-term animals, thus indicating partial recovery. A similar, but not statistically significant, trend was observed for CCK and SS. The large decrease in CGRP and SP seen in short-term animals reflects the large contribution of the sciatic nerve to the lumbar dorsal horn. The partial recovery of peptides demonstrates the plasticity of the nervous system and may parallel sprouting of primary afferents from other nerves, such as the saphenous nerve, as we have demonstrated in previous studies.