Processing of thyrotropin-releasing hormone (TRH) prohormone in the rat olfactory bulb generates novel TRH-related peptides.

Based on the deduced amino acid sequence of rat TRH prohormone (pro-TRH), proteolytic processing of this polyprotein precursor is expected to produce, beside TRH, several other novel peptides. These peptides should correspond to connecting segments flanking the repeated TRH progenitor sequence and to various C- and/or N-terminally extended forms of TRH. The profile of the endogenous products of the TRH system was studied in rat brain using multiple RIAs coupled to molecular sieve filtration and HPLC separations. In extracts from the rat hypothalamus, TRH and two pro-TRH-connecting peptides, prepro-TRH-(160-169) and prepro-TRH-(178-199) were detected in molar ratios corresponding to those expected for a nearly complete processing of the prohormone molecule. In the olfactory bulb, pro-TRH is processed differently, since peptides containing TRH at their N-termini, [pGlu172] prepro-TRH-(172-199) and [pGlu154]prepro-TRH-(154-169), were found to be major end products along with prepro-TRH-(160-169) and prepro-TRH-(178-199). The dissimilarity in tissue content suggests that differential processing of TRH precursor by various enzymatic pathways may act as a regulating mechanism for TRH and TRH-related activities. The cellular localization of C-terminally extended forms of TRH in rat olfactory bulb was examined by the indirect immunoperoxidase method, using antisera directed against prepro-TRH-(160-169) and pre-pro-TRH-(178-199). Cell bodies and nerve fibers were detected in the glomerular and external plexiform layers of the main olfactory bulb. The presence of extended forms of TRH in interneurons and middle tufted cells of the main olfactory bulb suggests that in light of the recent biological properties described for prepro-TRH-(160-169), these peptides may act as neuromodulators for olfactory epithelium inputs or neurotransmitters within more rostrally located olfactory areas in the forebrain.

Molecular cloning and expression of the gene for a human D1 dopamine receptor.

The diverse physiological actions of dopamine are mediated by its interaction with two basic types of G protein-coupled receptor, D1 and D2, which stimulate and inhibit, respectively, the enzyme adenylyl cyclase. Alterations in the number or activity of these receptors may be a contributory factor in diseases such as Parkinson's disease and schizophrenia. Here we describe the isolation and characterization of the gene encoding a human D1 dopamine receptor. The coding region of this gene is intronless, unlike the gene encoding the D2 dopamine receptor. The D1 receptor gene encodes a protein of 446 amino acids having a predicted relative molecular mass of 49,300 and a transmembrane topology similar to that of other G protein-coupled receptors. Transient or stable expression of the cloned gene in host cells established specific ligand binding and functional activity characteristic of a D1 dopamine receptor coupled to stimulation of adenylyl cyclase. Northern blot analysis and in situ hybridization revealed that the messenger RNA for this receptor is most abundant in caudate, nucleus accumbens and olfactory tubercle, with little or no mRNA detectable in substantia nigra, liver, kidney, or heart. Several observations from this work in conjunction with results from other studies are consistent with the idea that other D1 dopamine receptor subtypes may exist.

Distribution of dopamine-immunoreactive neuronal perikarya and fibres in the brain of a teleost, Gasterosteus aculeatus L. comparison with tyrosine hydroxylase- and dopamine-beta-hydroxylase-immunoreactive neurons.

The distribution of dopamine in the brain of the teleost Gasterosteus aculeatus L. was demonstrated with the indirect peroxidase-antiperoxidase immunohistochemical method using highly specific antibodies against a dopamine-glutaraldehyde-thyroglobulin conjugate. Dopamine-immunoreactive (DAir) neuronal somata were observed in all main brain regions. In the forebrain, DAir neurons were located in a continuous cell column extending from the caudal part of the olfactory bulbs to the preoptic area. The neurons lie lateral to the dorsal (and caudally to the subcommissural) portion of the ventral telencephalic area, and ventromedial to the central nuclei of the dorsal area. In the diencephalon, cerebrospinal fluid-contacting neurons were located in the paraventricular organ and in the subependymal layers of the dorsal and caudal zones of the periventricular hypothalamus. Small DAir neurons were observed in the suprachiasmatic nucleus, in the parvocellular preoptic nucleus and in the ventromedial thalamic nucleus, while large perikarya were observed dorsolateral to the dorsal zone of the periventricular hypothalamus ('PVO-accompanying cells'), in the posterior tuberal nucleus and in the most rostral portion of the mammillary bodies. Numerous small DAir neurons were located in the periventricular pretectal nucleus. In the brainstem, DAir neurons were observed in the isthmus region, in the dorsal raphe nucleus and in the lateral parts of the nucleus of the solitary tract. DAir perikarya were also observed in the area postrema. Direct comparison with the distribution of tyrosine hydroxylase- and dopamine-beta-hydroxylase-immunoreactivity (THir and DBHir) gave the following results: THir neurons were found in all areas where DAir neurons were located, except for the paraventricular organ and the dorsal and caudal zones of the periventricular hypothalamus, which were devoid of THir. DBHir (putatively noradrenergic or adrenergic) neurons were observed in the lateral parts of the nucleus of the solitary tract, and in the isthmus region. The DBHir neurons in the isthmus region, which have previously been shown to be noradrenergic, appeared to be identical with the THir and DAir neurons of the same area. DAir axons were found in high numbers in most parts of the brain. Especially dense innervation was found in the ventrolateral and posterior parts of the dorsal telencephalic area, the region surrounding the lateral recesses of the third ventricle, the interpeduncular nucleus, the dorsal and median raphe nuclei (the rostral raphe nuclei), and in the nucleus of the solitary tract.(ABSTRACT TRUNCATED AT 400 WORDS)

Olfactory neurons express a unique glycosylated form of the neural cell adhesion molecule (N-CAM).

mAb-based approaches were used to identify cell surface components involved in the development and function of the frog olfactory system. We describe here a 205-kD cell surface glycoprotein on olfactory receptor neurons that was detected with three mAbs: 9-OE, 5-OE, and 13-OE. mAb 9-OE immunoreactivity, unlike mAbs 5-OE and 13-OE, was restricted to only the axons and terminations of the primary sensory olfactory neurons in the frog nervous system. The 9-OE polypeptide(s) were immunoprecipitated and tested for cross-reactivity with known neural cell surface components including HNK-1, the cell adhesion molecule L1, and the neural cell adhesion molecule (N-CAM). These experiments revealed that 9-OE-reactive molecules were not L1 related but were a subset of the 200-kD isoforms of N-CAM. mAb 9-OE recognized epitopes associated with N-linked carbohydrate residues that were distinct from the polysialic acid chains present on the embryonic form of N-CAM. Moreover, 9-OE N-CAM was a heterogeneous population consisting of subsets both with and without the HNK-1 epitope. Thus, combined immunohistochemical and immunoprecipitation experiments have revealed a new glycosylated form of N-CAM unique to the olfactory system. The restricted spatial expression pattern of this N-CAM glycoform suggests a possible role in the unusual regenerative properties of this sensory system.

The gonadotropin-releasing hormone neuronal system of the male Djungarian hamster: distribution from the olfactory tubercle to the medial basal hypothalamus.

The neuroanatomical distribution and morphology of neurons that produce gonadotropin-releasing hormone (GnRH) in the brain of the postpubertal male Djungarian hamster was studied using light microscopic immunocytochemistry. Analysis of every section from the rostral olfactory tubercle to the medial basal hypothalamus indicate 356 +/- 37 immunoreactive GnRH perikarya per brain (mean +/- SE; n = 4 brains). Over 90% of GnRH cell bodies were found in 6 brain regions; the largest number of somata were located in the medial preoptic area followed by the diagonal band, lateral hypothalamus, lateral preoptic area, lateral septum and anterior hypothalamus. Morphologically, two predominant types of GnRH neurons were identified: unipolar GnRH cells with an ovoid soma and only a single distinct process (about 40% of all GnRH neurons), and bipolar cells with a fusiform-shaped perikaryon. Overall and in most brain regions, the ratio of unipolar to bipolar GnRH perikarya was 2:3 or greater. A significant proportion of GnRH neurons had an unusually "thick" process(es) that exited the soma and tapered gradually. GnRH fibers were evident in most sections, forming dense plexuses in the arcuate nucleus-median eminence, the periventricular region of the third ventricle and organum vasculosum of the lamina terminalis. These findings indicate that the Djungarian hamster is similar to other rodent species, especially the white-footed mouse, in the neuroanatomical distribution of GnRH neurons. The present report provides a working atlas for the rostral ventral forebrain of the postpubertal Djungarian hamster.(ABSTRACT TRUNCATED AT 250 WORDS)

[Immunohistochemical study on the primary olfactory neuron of rat and suncus].

Carnosine (beta-alanyl-L-histidine), a putative neurotransmitter, was identified immunohistochemically in the primary olfactory neuron, using newly developed anti-carnosine antiserum. Similar results were obtained in the rat and suncus. Carnosine-like immunoreactivity was observed in the olfactory cells and its apical dendrites of the olfactory epithelium. The olfactory nerve and glomerular layer of the olfactory bulb showed positive reaction. At electron microscopic level, carnosine-immunoreactive end products widely spread out in the cytoplasm of olfactory nerve cells and also on microtubules of olfactory cilia. In the glomerular layer, reaction products were found diffusely in many axon terminals. These terminals had small spherical vesicles and often made asymmetric synaptic contacts to the second neuron. Unilateral closure of the olfactory naris resulted lower immunoreactivity of tyrosine hydroxylase in periglomerular cells, which are dopaminergic interneurons and are thought to regulate neurotransmission of olfactory input. In contrast no remarkable changes were seen on carnosine immunoreactivity in olfactory bulb. The present results suggest that carnosine may play some important roles in the olfactory mucosa. The functional role of carnosine remarks to be further examined.

[Transplantation of embryonic brain tissue into newborn rats after unilateral bulbectomy]. / Transplantácie embryonálneho mozgového tkaniva neonatálnym krysám po unilaterárnej bulbektómii.

Embryonic tissue (E14-E16) of the olfactory bulb and substantia nigra resp. was transplanted to neonatal rats into cavities formed by partial or total unilateral bulbectomy. After 40 days of survival the animals were perfused with Bouin's fluid and processed for histological examination. Complete series of 10 microns horizontal or sagittal sections were stained with Gill haematoxylin and Bodian's silver method. To demonstrate the olfactory protein immunohistochemical staining with peroxidase-antiperoxidase was used. After bulbectomy degeneration of the axons of the olfactory cells occur, which subsequently regenerate, penetrate into the transplant and form typical glomerular structures in the latter. By immunohistochemical staining in both types of transplants olfactory structures were reliably differentiated from non-olfactory elements.

Regional distribution of neuropeptide Y and its receptor in the porcine central nervous system.

The regional distribution of neuropeptide Y (NPY) immunoreactivity and receptor binding was studied in the porcine CNS. The highest amounts of immunoreactive NPY were found in the hypothalamus, septum pellucidum, gyrus cinguli, cortex frontalis, parietalis, and piriformis, corpus amygdaloideum, and bulbus olfactorius (200-1,000 pmol/g wet weight). In the cortex temporalis and occipitalis, striatum, hippocampus, tractus olfactorius, corpus mamillare, thalamus, and globus pallidus, the NPY content was 50-200 pmol/g wet weight, whereas the striatum, colliculi, substantia nigra, cerebellum, pons, medulla oblongata, and medulla spinalis contained less than 50 pmol/g wet weight. The receptor binding of NPY was highest in the hippocampus, corpus fornicis, corpus amygdaloideum, nucleus accumbens, and neurohypophysis, with a range of 1.0-5.87 pmol/mg of protein. Intermediate binding (0.5-1.0 pmol/mg of protein) was found in the septum pellucidum, columna fornicis, corpus mamillare, cortex piriformis, gyrus cinguli, striatum, substantia grisea centralis, substantia nigra, and cerebellum. In the corpus callosum, basal ganglia, corpus pineale, colliculi, corpus geniculatum mediale, nucleus ruber, pons, medulla oblongata, and medulla spinalis, receptor binding of NPY was detectable but less than 0.5 pmol/mg of protein. No binding was observed in the bulbus and tractus olfactorius and adenohypophysis. In conclusion, immunoreactive NPY and its receptors are widespread in the porcine CNS, with predominant location in the limbic system, olfactory system, hypothalamoneurohypophysial tract, corpus striatum, and cerebral cortex.

Origin of luteinizing hormone-releasing hormone neurons.

Neurons expressing luteinizing hormone-releasing hormone (LHRH), found in the septal-preoptic nuclei and hypothalamus, control the release of gonadotropic hormones from the anterior pituitary gland and facilitate reproductive behaviour. LHRH-expressing neurons are also found in the nervus terminalis, a cranial nerve that is a part of the accessory olfactory system and which projects directly from the nose to the septal-preoptic nuclei in the brain. During development, LHRH-immunoreactivity is detected in the peripheral parts of the nervus terminalis before it is found in the brain. Using a combination of LHRH immunocytochemistry and tritiated thymidine autoradiography in fetal mice, we show that LHRH neurons originate in the medial olfactory placode of the developing nose, migrate across the nasal septum and enter the forebrain with the nervus terminalis, arching into the septal-preoptic area and hypothalamus. Clinically, this migratory route for LHRH-expressing neurons could explain the deficiency of gonadotropins seen in 'Kallmann's syndrome' (hypogonadotropic hypogonadism with anosmia).

Glutamate-like immunoreactivity revealed in rat olfactory bulb, hippocampus and cerebellum by monoclonal antibody and sensitive staining method.

Although there is good evidence favoring L-glutamate as a major excitatory amino acid transmitter, relatively little is known about the distribution of nerve terminals using this substance. A method visualizing glutamate-like immunoreactivity at the light microscopic level by means of a monoclonal antibody, mAb 2D7, is described. --The antigen used for immunization was a glutaraldehyde-linked glutamate-BSA conjugate, and hybridomas were differentially screened by ELISA for production of antibodies recognizing glutamate- but not aspartate-BSA. The crossreactivity of 'anti-glutamate' mAb 2D7 as estimated in absorption tests was low even with conjugates closely related to glutamate-BSA.--Semithin sections from rapidly perfusion-fixed, plastic-embedded rat brain tissues were etched and stained by a combination of the peroxidase-antiperoxidase method and silver enhancement of the diaminobenzidine reaction product. Only this amongst several other immunohistochemical methods tried produced labeling patterns which showed terminal-like elements in brain regions such as olfactory bulb, hippocampus and cerebellum, and which were mostly consistent with already available information on systems using glutamate as neurotransmitter. Particularly striking was the staining of elements reminiscent of mossy fiber terminals in hippocampus and cerebellum as well as of cerebellar parallel fiber terminals.

Mercury accumulation in tissues from dental staff and controls in relation to exposure.

Samples, mainly from occipital cortex and pituitary gland, but also from rental cortex, olfactory bulbs, thyroid gland and liver were collected from autopsies of 8 dental staff cases and 27 controls. These samples were analysed for total mercury content using radiochemical neutron activation analyses. The results revealed high mercury concentrations (median 815, range 135-4,040 micrograms Hg/kg wet weight) in pituitaries from the dental staff cases compared to controls (N = 23, median 23 range 6-1, 170 micrograms Hg/kg). In occipital cortex, the cases had a median of 17, range of 4-300 micrograms Hg/kg and the controls (N = 20) had a median of 10, range 2-29 micrograms Hg/kg. A few samples from olfactory bulbs show low mercury concentrations for both cases and controls. Renal cortex was analysed from three cases and contained clearly higher concentrations (945, 1,545, 2,110 micrograms Hg/kg) compared to controls (N = 12, median 180, range 21-810 micrograms Hg/kg). There is no control material for the other analysed samples, but one thyroid sample had an extremely high concentration of 28,000 micrograms Hg/kg.

An immunochemical analysis of the distribution of a brain-specific polypeptide, PEP-19.

Immunochemical and immunohistochemical techniques were used to map the tissue distribution and cellular localization of a rat brain-specific polypeptide, termed PEP-19. PEP-19 was found to be abundant in the cerebellum and olfactory bulbs but was present at much lower levels in other gross brain regions. It was undetectable in all nonneural tissues examined but was present in the cerebellum of several vertebrates, including rat, mouse, guinea pig, monkey, and human. Immunohistochemical analysis revealed that PEP-19 was localized to the soma, axon, and dendritic processes of rat cerebellar Purkinje cells with no demonstrable immunoreactivity in nonneuronal cell types. Furthermore, mutant mice showing degeneration of Purkinje cells exhibit markedly decreased levels of PEP-19. Because PEP-19 appears during the final stages of maturation of Purkinje cells, it may be utilized as a probe to monitor the development of these neurons in vivo.

Oxyntomodulin and glicentin: brain-gut peptides in the rat.

Glucagon-like materials and glucagon have been identified by immunoassay and immunocytochemistry in the mammalian central nervous system. However, the molecular forms relevant to brain glucagon-like immunoreactivity (GLI) have not been precisely defined. In the rat small intestine, more than 90% of GLI is constituted by two peptides: oxyntomodulin (OXM) and glicentin. This work was initiated to characterize and determine the concentrations of these two peptides and glucagon in the rat central nervous system and to compare their relative proportions with those found in the gut. Different regions from the adult rat brain were analyzed by HPLC in association with RIA, using a central glucagon antiserum and an antibody directed toward the C-terminal end of OXM and glicentin. The elution profiles of hypothalamus extracts were constituted by two main peaks, both detected by the two antibodies used and displaying the same retention times as glicentin and OXM, respectively. A third small peak, which coeluted with glucagon, was constantly recorded with the central glucagon antiserum. The percentages of glicentin, OXM, and glucagon in 10 hypothalami were 37 +/- 1%, 55 +/- 1%, and 8 +/- 2%, respectively (n = 8). This distribution was quite similar to that in small intestinal extracts (38 +/- 1%, 59 +/- 1%, and 1.3 +/- 0.1%, respectively; n = 7); however, the peptide concentrations were almost 50-fold greater in intestine than in hypothalamus. In the medulla oblongata, the same peptide ratio was observed, with 10-fold lower concentrations compared to those in hypothalamus. In olfactory bulb, cerebellum, and cortex the concentrations were close the the detection limit, whereas they could be not detected in the pituitary. The combination of HPLC and specific RIAs allowed us to unambiguously characterize OXM and glicentin as the major components of GLI in the rat hypothalamus and medulla oblongata. The same proportion of these two peptides in the central nervous system and the gut indicates that a similar posttranslational processing exists in these rat tissues, another example of the brain-gut axis.

Characterization and localization of a novel neuroreceptor for the peptide sarafotoxin.

We have recently shown that the rat atrium and brain contain specific high affinity receptors for the novel snake vasoconstrictor peptide sarafotoxin-b (SRTXb), and demonstrated toxin-induced phosphoinositide hydrolysis. Here we report on the characteristics of 125I-SRTXb receptors and their regional distribution in rat brain. 125I-SRTX receptors in the rat brain bind the toxin rapidly and with high affinity. The binding was not inhibited by ligands of known neurotransmitter receptor and ion channels. 125I-SRTX receptors have a distinctive regional distribution. The highest densities were observed in the cerebellum, thalamus and hypothalamus (850, 550 and 450 fmol/mg protein, respectively) and the lowest densities in the caudate and cerebral cortex (82 and 62 fmol/mg protein, respectively). Taken together our results suggest that mammalian brains contain a hitherto undetected neuroreceptor that may operate in neurotransmission with a "SRTX-like" brain peptide, similar to the SRTX homologous vasoconstrictor peptide of the mammalian endothelium endothelin.

Post-translational processing of thyrotropin-releasing hormone precursor in rat brain: identification of 3 novel peptides derived from proTRH.

The sequence of rat hypothalamic pro-thyrotropin releasing hormone, deduced by sequencing of cDNA, in addition to 5 TRH progenitor sequences contains leader, trailer and 4 intervening sequences separated by paired basic amino acid sequences. We have developed radioimmunoassays to synthetic peptides corresponding to portions of these cryptic proTRH sequences and have used these assays to identify and partially characterize proTRH peptides, distinct from TRH, in extracts of rat brain. Two of these peptides correspond closely in size to one intervening sequence and the carboxy-terminal sequence of proTRH. Three other peptides correspond to the intact amino-terminal leader sequence and two peptides formed by a further cleavage of the leader sequence at an internal paired basic amino acid sequence.

Neuropeptide Y-like immunoreactive neurons in the human olfactory bulb.

Neuropeptide Y-like (NPY) immunoreactivity was localized in the adult human olfactory bulb by the unlabeled antibody enzyme (peroxidase anti-peroxidase; PAP) technique in vibratome sections. The majority of NPY-immunoreactive somata was localized in the white matter surrounding the anterior olfactory nucleus. Immunoreactive neurons were less numerous within the anterior olfactory nucleus and within the olfactory bulb layers. NPY-immunoreactive fibres were present in the white matter, the anterior olfactory nucleus, and in the olfactory bulb layers. Fibres within the white matter were generally aligned in a straight path parallel to the long axis of the olfactory bulb and tract. Fibres within the anterior olfactory nucleus showed no clear orientation and displayed numerous branching points. Coiled plexus of NPY-immunoreactive fibres were present in the glomerular layer of the olfactory bulb. Additional characteristics of the NPY-immunoreactive neurons were studied after decolouring the chromogen and restaining the sections with aldehydefuchsin to demonstrate the presence of lipofuscin granules and also with gallocyanin chrome alum to stain the Nissl substance. This analysis showed that the neurons belong to the class of non-pigmented nerve cells.

Localization of the GABAA receptor in the rat brain with a monoclonal antibody to the 57,000 Mr peptide of the GABAA receptor/benzodiazepine receptor/Cl- channel complex.

The mAb 62-3G1 to the GABAA receptor/benzodiazepine receptor/Cl- channel complex was used with light-microscopy immunocytochemistry for studying the localization of the GABAA receptors (GABAR) in the rat brain. The results have shown a receptor distribution identical to the one obtained by others using 3H-muscimol binding in combination with autoradiographic techniques. The external plexiform layer of the olfactory bulb, cerebral cortex, granule cell layer of the cerebellum, hippocampus, dentate gyrus, substantia nigra, dorsolateral and medium geniculate nuclei, and the lateral posterior thalamic nucleus, among other areas, were rich in GABAA receptor immunoreactivity. In the cerebellum the granule cell layer had more immunoreactivity than did the molecular layer. In the hippocampus the receptor was most abundant in the stratum oriens and in the molecular layer of the dentate gyrus. The immunocytochemical techniques have also allowed us to study the distribution of the GABAA receptor with high-resolution light microscopy. These studies have shown that the GABAA receptors are localized in neuronal membranes and concentrated in structures rich in GABAergic synapses, such as the cerebellar and olfactory glomeruli and the external plexiform layer of the olfactory bulb, the deep cerebellar nuclei, and the substantia nigra. The mAb 62-3G1 was generated by immunizing mice with the affinity-purified GABAA receptor/benzodiazepine receptor (BZDR) complex. This mAb bound to the 57,000 Mr peptide but not to the benzodiazepine binding 51,000 Mr peptide. The distribution of the GABAR immunoreactivity in the rat brain colocalized better with 3H-muscimol than with 3H-benzodiazepine binding. Therefore, it is suggested that (1) the 57,000 Mr peptide that is recognized by the mAb 62-3G1 is the muscimol (GABAA receptor agonist) binding subunit of the receptor complex, (2) there is an important population of brain GABAA receptors that is not functionally coupled to the benzodiazepine receptors, and (3) both the BZDR-coupled and uncoupled forms of the GABAA receptor are immunologically similar, if not identical.

Somatostatin-14-like immunoreactive neurons and fibres in the human olfactory bulb.

This study describes the morphological features and the distribution pattern of neurons in the human olfactory bulb which are immunoreactive for an antiserum against the neuropeptide somatostatin-14. Immunoreactive nerve cell bodies were mainly found in the white matter surrounding the cell clusters of the anterior olfactory nucleus. Some immunoreactive neurons were also found scattered throughout the anterior olfactory nucleus and the deeper parts of the inner granule cell layer. Only a few immunoreactive neurons were localized in the glomerular layer and the outer granule cell layer. Immunoreactive fibres were found in all layers of the olfactory bulb. In addition, an impressive number of coiled and kinked immunoreactive fibres were localized within the anterior olfactory nucleus forming a dense plexus. Accumulations of twisted and coiled branches of immunoreactive fibres were rarely found either surrounding or within the olfactory glomerula. The characteristics of somatostatin-14 immunoreactive neurons as seen in the combined pigment-Nissl preparation were studied after decolourizing the chromogen and restaining the preparations with aldehydefuchsin in order to demonstrate the lipofuscin pigment and gallocyanin chrome alum for Nissl material. About 90% of the immunoreactive neurons studied in this manner turned out to be devoid of lipofuscin granules. The remaining 10% displayed different patterns of pigmentation. These findings suggest the presence of different types of somatostatin-14-like immunoreactive neurons in the olfactory bulb of the human adult.

Carnosine-like immunoreactivity in the olfactory bulb of the rat: an electron microscopic study.

Carnosine-immunoreactive primary olfactory nerve terminals are demonstrated in the glomerular layer of the rat olfactory bulb by immunoelectron microscopy. Asymmetrical synapses between dendrites of mitral/tufted cells and that of periglomerular cells could be observed. In the accessory olfactory system, carnosine-like immunoreactivity is also detected in the vomeronasal neurons.

Possible coexistence of amino acid (gamma-aminobutyric acid), amine (dopamine) and peptide (substance P); neurons containing immunoreactivities for glutamic acid decarboxylase, tyrosine hydroxylase and substance P in the hamster main olfactory bulb.

The coexistence of immunoreactivities for glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) and substance P (SP) was revealed in the hamster main olfactory bulb, using the peroxidase-antiperoxidase immunohistochemical method. Adjacent 40 micron thick Vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning were identified at the paired surfaces of two consecutive sections. The coexistence of the immunoreactivities for 1) TH and GAD, 2) TH and SP and 3) GAD and SP in the same cells could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. About 70% of TH-like immunoreactive (TH-LI) neurons in the periglomerular region also contained GAD-like immunoreactivity, whereas about 45% of GAD-LI ones were also TH-like immunoreactive. Furthermore, almost all (more than 95%) of SP-LI neurons contained both GAD-like and TH-like immunoreactivities. These observations indicate that in the periglomerular region of the hamster main olfactory bulb, some neurons (about 9% of all neurons containing TH-like and/or GAD-like immunoreactivities) may contain three different categories of neuroactive substances, that is, amino acid (GABA), amine (dopamine) and peptide (SP).