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PubMed1995

Expression patterns of a glutamate-binding protein in the rat central nervous system: comparison with N-methyl-D-aspartate receptor subunit 1 in rat.

Using radioactive in situ hybridization histochemistry, we examined the topographical patterns of expression of the messenger RNA encoding a glutamate-binding protein (N-methyl-D-aspartate receptor glutamate-binding protein in rat; NMDARgbs) in the central nervous system of the rat. Expression patterns of N-methyl-D-aspartate receptor glutamate-binding protein were compared with those of N-methyl-D-aspartate receptor subunit 1 (NMDAR1) of the N-methyl-D-aspartate receptor on adjacent sections. N-methyl-D-aspartate receptor glutamate-binding protein is not expressed in glial cells. The expression of both N-methyl-D-aspartate receptor glutamate-binding protein and N-methyl-D-aspartate receptor subunit 1 was observed in virtually all neurons throughout the central nervous system. The mean level of N-methyl-D-aspartate receptor subunit 1 expression was higher than that of N-methyl-D-aspartate receptor glutamate-binding protein. Similar topographical patterns of expression of N-methyl-D-aspartate receptor glutamate-binding protein and N-methyl-D-aspartate receptor were observed in most regions, except in discrete thalamic, hypothalamic and brainstem nuclei. Concomitantly for N-methyl-D-aspartate receptor glutamate-binding protein and N-methyl-D-aspartate receptor subunit 1, the highest expression levels were distributed in the mitral layer of main and accessory olfactory bulbs, granule cell layer of the dentate gyrus, polymorphic and pyramidal layers of CA1-3 fields of Ammon's horn. A slightly less prominent expression was observed in the glomerular and granule cell layers of main and accessory olfactory bulbs, anterior olfactory nucleus, layer 2 of piriform cortex, olfactory tubercle and taenia tecta. In the cerebellum, the prominent level of N-methyl-D-aspartate receptor glutamate-binding protein expression was slightly higher in the Purkinje cell layer than in the granule cell layer, an opposite pattern being observed for N-methyl-D-aspartate receptor subunit 1. A moderately high expression level of both messenger RNAs was observed in the medial septal nucleus, nucleus of the diagonal band of Broca, dorsal part of the endopiriform nucleus, and in the anteroventral and anterolateral parts of the bed nucleus of the stria terminalis. In the neocortex, the mean expression level of N-methyl-D-aspartate receptor glutamate-binding protein is moderate, while the mean level of N-methyl-D-aspartate receptor subunit 1 expression is high. With both probes, layer IV is slightly less labeled than the other layers.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1997

Protein synthesis inhibitors delay transneuronal death in the piriform cortex of young adult rats.

It has been demonstrated that apoptotic cell death is an active process that is dependent on RNA and protein synthesis. The question remains as to whether neuronal death in adult, mammalian brains can also be demonstrated in vivo to be dependent on protein synthesis. To address this question we have analysed transneuronal death in the piriform (olfactory) cortex. Following unilateral olfactory bulb ablation in young adult rats, layer IIa of the piriform cortex undergoes rapid degeneration, that commences 12 h after ablation and that is almost complete at 48 h. In order to block protein synthesis, three to six subcutaneous injections of the short acting protein synthesis inhibitor anisomycin, were given at 2 h intervals beginning just before the ablation of the olfactory bulb. In other cases a single injection of the long acting protein synthesis inhibitor emetine were made intracerebrally just before or after olfactory bulb ablation. The number of dying cells was then counted in sections through the rostrocaudal extent of the piriform cortex. Both anisomycin and emetine injections markedly reduced the number of pyknotic cells in layer IIa of the piriform cortex after olfactory bulb ablation. The effect of anisomycin was dose-dependent, near lethal doses leading to an almost complete absence of cell death (six injections of 100 mg/kg). As the doses of anisomycin were reduced, more dying cells were observed. Emetine was only effective at near lethal doses (10 mg/kg) and showed a greater capacity to reduce the levels of cell death when injected into structures near the piriform cortex (e.g., accumbens nucleus) than when injected into more distant structures. To further confirm that the cell death observed was due to apoptosis, we analysed sections by tunel staining to demonstrate DNA fragmentation. We found that tunel-positive cells were also always pyknotic, one of the landmarks of apoptosis. The appearance of pyknotic cells labelled by the tunel method demonstrated that the dying cells in the piriform cortex did indeed undergo apoptosis.

Animals↗

PubMedDate not supplied

Number of correlates of membrane metabolism and long-term potentiation in rat brain slices.

Long-term potentiation was elicited in living slices of rat olfactory cortex by stimulation of the lateral olfactory tract. A group of interdependent parameters of membrane metabolism was studied, i.e., the kinetics of 45Ca metabolism, lipid peroxidation, and antioxidant defense; cytochemical measurements were made of Na+, K(+)-ATPase activity in neurons and glial cells; the functional (GTPase) activity of G-proteins was also studied. All parameters were compared with the bioelectrical activity of slices at three time points after tetanization, i.e., 3-5, 15, and 30 min. In most cases, regular phasic changes in metabolic parameters occurred, and their functional significance is discussed.

Acetylcholine↗

PubMed1983

Intrahippocampal bethanechol in rats: behavioural, electroencephalographic and neuropathological correlates.

Unilateral microinjections of bethanechol chloride into the CA3 subfield of the dorsal hippocampus in unrestrained rats produced a seizure-related type behavioural and disseminated brain damage syndrome. Injection of bethanechol in the dose of 50 micrograms resulted in locomotor activation, mouth movements, teeth chattering, chewing, wet dog shakes and mild limbic seizures. Shortly after intrahippocampal injection the electroencephalogram (EEG) showed an increase in the frequency of the theta rhythm in both hippocampi. Then EEG showed spiking activity of high frequency in the injected hippocampus, with rapid propagation to the lateral septum, amygdala, neocortex and contralateral hippocampus. The periods of spiking activity of high frequency were followed by depression in the background EEG rhythm with some interspersed spike and wave complexes of very low frequency. Histological examination of frontal forebrain sections revealed disseminated, apparently seizure-mediated pattern of brain damage. The patterning of distant damage after intrahippocampal injections of bethanechol involved the piriform cortex, entorhinal cortex, olfactory tubercle, anterior olfactory nucleus, subiculum, amygdaloid complex, temporoparietal cortex and hypothalamic nuclei. Neuropathological alterations were occasionally observed in the lateral septum and thalamus. These results seem to establish a causative relationship between excessive stimulation of cholinergic muscarinic receptors in the hippocampal formation and epileptic brain damage.

Acetylcholine↗

PubMed2003

Convergent and divergent effects of odors and emotions in depression.

The aim of the present study was to investigate the similarities and differences in the olfactory and visual processing of emotional stimuli in healthy subjects and in patients with major depressive disorder (MDD). Twenty-five inpatients were investigated after admission to the psychiatric clinic. Fifteen of them participated a second time, shortly before their discharge from the hospital. A group of healthy subjects, matched according to age and sex, served as a control. Chemsosensory event-related potentials (CSERPs) were recorded using the constant flow method. In addition, event-related potentials (ERPs), in response to colors and emotional slides, were obtained to control modality and emotion-specific effects. The subjects' task was to discriminate the colors (red/yellow) and odors (phenyl-ethylalcohol = rose/ isobutyraldehyde = rotten butter) according to their quality and to judge the valence of the emotional slides (IAPS slides). The EEG was recorded from 32 scalp locations. At the beginning of the therapy, visual stimulus processing was attenuated in depressive subjects at a relatively late processing level (reduced amplitudes of the P3 and pSW in response to colors and emotional slides), whereas olfactory stimulus processing had already been affected at an early level (reduced amplitudes of the P2 and P3-1 peaks in MDD patients). However, after successful medical treatment, ERPs did not differentiate between depressive patients and healthy controls. We discuss whether functional deviations within the primary olfactory cortex are responsible for the lower olfactory sensitivity, as well as for the altered emotional stimulus processing in MDD patients.

Adult↗

PubMed1995

Electron microscopic study of synaptogenesis and myelination of the olfactory centers in developing rats.

Development of the central olfactory system was studied in the rat with an electron microscope at three main structures: the olfactory bulb, the lateral olfactory tract, and the primary olfactory cortex (the piriform cortex). As a parameter of development, the synaptic density was examined quantitatively in the bulbar glomerulus and layer Ia (termination of bulbofugal fibers) of the piriform cortex. which are the key stations of the olfactory pathway. The synaptic densities in the glomerulus and those in layer Ia were 5.7% and 4.6% on embryonic day 19, 15.8% and 12.5% on postnatal day (P) 0, and 57.3% and 37.2% on P10, as compared with the adult (100%). As another parameter of development, the density of myelinated axons in the lateral olfactory tract was examined quantitatively. The densities of myelinated axons in the tract were 0% on P5, 15.1% on P10, and 73.5% on P21 of the adult density. Maturation in the tract was still progressing, even at P21, in terms of bundle formation and the thickness of myelin sheaths. The results show that synaptogenesis in the bulbar glomerulus is followed by synaptogenesis in layer Ia of the piriform cortex, and that myelination in the lateral olfactory tract occurs over a prolonged period, even in the stages after P21.

Aging↗

PubMed1985

Olfactory discrimination in rats with anterior amygdala lesions.

In Experiment 1, rats with posterior lateral olfactory tract/anterior amygdala lesions or with control neocortical lesions were tested for retention of a preoperatively learned odor detection task and for learning on new odor discrimination problems. All rats had perfect or near-perfect retention of the detection task, and there were no discernible differences between groups in learning on the new odor discrimination problems. In Experiment 2, an intensity-difference threshold for olfaction was determined in 4 rats before and after lesions of the posterior lateral olfactory tract and anterior amygdala. There were no apparent differences between pre- and postoperative performances on this psychophysical test. These results indicate that lateral olfactory tract projections to the amygdala and posterior olfactory cortex are not essential for normal performance on simple olfactory discrimination tasks.

Amygdala↗

PubMed1992

Localization of corticotropin-releasing factor-like immunoreactivity in monkey olfactory bulb and secondary olfactory areas.

Electrophysiological and anatomical observations suggest that terminals of olfactory bulb mitral cells ending in rat primary olfactory cortex exert certain postsynaptic effects via an excitatory amino acid neurotransmitter. Recent anatomical studies have shown that several peptides, most notably corticotropin-releasing factor (CRF) (Imaki et al., '89) Brain Res., 496: 35-44), are also localized within rat olfactory bulb projection neurons, thus raising the possibility that there is a peptide cotransmitter in this system. In contrast to the availability of data for rodents, very little is known about the distribution of peptides and other putative transmitters in the olfactory systems of primate species. In the present study, sections through the olfactory bulb and its target areas were obtained from two monkey species (Saimiri sciureus and Macaca fascicularis) and processed for immunohistochemistry with a well-characterized polyclonal antiserum directed against the human form of CRF. Virtually identical results were obtained in the two species. Within the olfactory bulb, nearly all mitral and many tufted cells contained CRF-like immunoreactivity. CRF-positive fibers were seen within the olfactory tract and olfactory stria, which contain the axons of mitral and tufted cells. Within the anterior olfactory nucleus and layer Ia of the olfactory tubercle and piriform cortex, immunoreactivity was seen within fine processes, as well as in coarse, varicose fibers and isolated puncta. CRF-positive cells were seen within layer III of the olfactory tubercle and piriform cortex. Immunoreactive fibers and varicosities were also seen within olfactory-recipient regions of the amygdala and entorhinal cortex. These observations suggest that CRF may act as a transmitter and/or neuromodulator in primate olfactory system.

Amygdala↗

PubMed2006

Exposure in fetus of methylazoxymethanol in the rat alters brain neurotrophins' levels and brain cells' proliferation.

Changes during gestation have been shown to induce brain maldevelopment associated with changes in neurotrophins as nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neuropsychiatric disorders in humans. A rat model of altered prenatal brain development resembling the onset of schizophrenia has been obtained by administering in fetus methylazoxymethanol (MAM) at gestational day 12 which impairs the growth of limbic pathways between the entorhinal cortex and the hippocampus. Using the MAM model we studied in young rats the brain levels of both NGF/BDNF and their main receptors, TrkA/TrkB, to investigate whether or not changes in neurotrophins could affect the presence of brain BrdU positive cells. We found increased NGF and BDNF protein levels, associated with elevated TrkA and TrkB expression, in the hippocampus, entorhinal cortex, olfactory lobes and subventricular zone (SVZ), brain areas playing a key role in the production and migration of new dividing cells. We also found higher levels of BrdU positive cells in the SVZ and hippocampus but not a significant potentiation in the entorhinal cortex and olfactory lobes. All together the findings indicate that prenatal MAM exposure in young rats may elicit both neurotrophins' elevation and cell proliferation in limbic brain areas.

Analysis of Variance↗

PubMed1998

Forebrain expression of c-fos due to active maternal behaviour in lactating rats.

To reveal brain sites simultaneously active during the expression of maternal behaviour in lactating rats, we used immunocytochemical visualization of the nuclear protein product Fos of the immediate-early gene c-fos as a marker of neuronal activity. After a 48 h separation from their litter, day 7 postpartum dams received a 1 h period of physical interaction with pups either capable or incapable of suckling, inaccessible pups in a wire-mesh box, an empty box, or no stimulation. Physical interaction with pups elicited high levels of pronurturant maternal behaviour (retrieval, licking, mouthing), and suckling elicited nursing behaviour as well. Exposure to the box, with or without pups, elicited high levels of investigatory sniffing, self-grooming, and general activity. Distal stimulation from pups did not differentially activate Fos in any of 20 sites, including olfactory-processing structures such as the piriform cortex and medial amygdala. Physical interaction with pups, with or without suckling, elicited higher levels of Fos-immunoreactive nuclei than that of other conditions in numerous sites, including many previously implicated in maternal behaviour (medial preoptic nucleus, nucleus accumbens, lateral septum, lateral habenula, and the bed nucleus of the stria terminalis). Similar group patterns of Fos expression also occurred in sites not previously implicated in maternal behaviour (somatosensory cortex and paraventricular thalamic nucleus). Interaction with nonsuckling pups elicited the highest levels of Fos in the cortical amygdala, whereas suckling did not activate higher Fos than nonsuckling interaction in any site included in this report, including hypothalamic nuclei involved in lactation (paraventricular, supraoptic, and arcuate). There was little or no Fos in cingulate cortex, olfactory tubercle, medial septum, medial habenula, or ventromedial hypothalamus. These data suggest that trigeminal stimuli received by lactating rats during the performance of pronurturant maternal behaviour promote cellular activity resulting in neuronal expression of c-fos in many forebrain sites including the medial preoptic nucleus, several sites connected with it that are part of the mesotelencephalic dopamine system, and in the somatosensory cortex. In contrast, in these forebrain sites suckling does not elicit greater levels of Fos than that seen in nonsuckled rats and distal stimuli from pups are ineffective in increasing Fos levels compared with non-stimulated controls.

Animals↗

PubMed1993

Functional consequences of acute cocaine treatment depend on route of administration.

The 2-[14C]deoxyglucose method was used to compare the effects of the acute administration of cocaine by two different routes, intravenous and intraperitoneal, on rates of local cerebral glucose utilization in freely moving rats. Doses were initially chosen on the basis of their ability to elicit equivalent increases in locomotor activity during the experimental procedure, and the time of cocaine administration relative to 2-[14C]deoxyglucose infusion was chosen so that the maximal behavioral effect occurred during maximal tracer incorporation. Changes in glucose utilization following the intraperitoneal administration of cocaine (10 mg/kg, 10 min before 2-deoxyglucose infusion) were restricted to the nigrostriatal system and related structures involved in the production of movement. Increased activity was observed in the substantia nigra pars reticulata, globus pallidus, and sensorimotor cortex. In contrast, intravenous cocaine administration (1 mg/kg, 2 min before tracer infusion) produced more widespread changes in rates of glucose utilization including portions of both the mesocorticolimbic and nigrostriatal systems. Areas in which metabolic activity was altered included the caudate-putamen, globus pallidus, substantia nigra pars reticulata, sensorimotor cortex, olfactory tubercle, nucleus accumbens, and medial prefrontal cortex. Both intravenous and intraperitoneal cocaine produced similar increases in locomotor activity. Additional studies indicated that the absence of metabolic activation in the mesocorticolimbic system following acute intraperitoneal cocaine was not the result of the specific dose chosen or the length of time between cocaine administration and radiotracer infusion, as no changes in metabolic activity in mesocorticolimbic structures were evident when these parameters were varied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Dopamine transporter: deglycosylation with exo- and endoglycosidases.

The dopamine transporter from rat caudate-putamen was photolabeled with [125I]DEEP as previously described. Treatment of photolabeled membranes with neuraminidase and N-glycanase reduced the molecular weight of the [125I]DEEP photolabeled dopamine transporter complex, whereas treatment with alpha-mannosidase had no effect. The solubilized [125I]DEEP photolabeled dopamine transporter complex readily bound to wheat-germ agglutinin but not to concanavalin-A sepharose columns. These results suggest that the carbohydrate moiety of the dopamine transporter is N-linked and contains significant quantities of sialic acid but not high mannose residues. A DEEP binding protein was readily detectable in other brain regions including the nucleus accumbens and olfactory tubercle, but not in the prefrontal cortex, olfactory bulb or hypothalamus under similar conditions. The DEEP binding protein in the other brain regions was similar to that in the striatum.

Animals↗

PubMed1990

Localization of aldolase C mRNA in brain cells.

The expression of aldolase C and aldolase A mRNA was assessed by Northern blot hybridization using RNAs purified from cultured rat and mouse brain neurons and astroglial cells. Neurons were found to contain about 4-fold more aldolase C mRNA and about twice as much aldolase A mRNA than astroglia. Analysis of the cellular localization of aldolase C mRNA by in situ hybridization to brain slices showed a predominantly neuronal labeling with an irregular distribution. A strong signal was observed in Purkinje cell somata and a weaker signal in subpopulations of neurons in cerebral cortex, striatum, hippocampus, hypothalamic nuclei and primary olfactory cortex.

Animals↗

PubMed1992

Induction of brain ornithine decarboxylase after systemic or intrastriatal administration of kainic acid.

The activity of ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis, dramatically increases after different types of brain injuries. The role of this induction is still unclear. We report here data on the temporal pattern of ODC induction caused by the excitotoxin kainic acid. After systemic administration, ODC activity increases severalfold peaking at 8 h in the prefrontal cortex and at 16 h in the olfactory cortex and hippocampus. After intrastriatal injection, the peak of induction is reached at 32 h, while a smaller and more transient increase is also observed in the contralateral, saline-injected striatum. We suggest that ODC induction is initially linked to overactivation of neural circuits and, later on, to the development of widespread neural damage.

Animals↗

PubMed1994

Neuroanatomical pathways linking vision and olfaction in mammals.

Retinal projections to several telencephalic structures have been demonstrated in a wide range of mammalian species following intraocular injections of tritiated amino acids and cholera toxin subunit-B conjugated to horseradish peroxidase. Since these regions are also innervated by olfactory fibers, we investigated the distribution of convergent projections using simultaneous injections of different anterograde tracers in the eye and olfactory bulbs. Convergent projections from the retina and from the olfactory bulbs were observed in the piriform cortex, olfactory tubercle, the cortical region of the medial amygdala, lateral hypothalamus, and the bed nucleus of the stria terminalis. A few retinal fibers also invade the nucleus of the lateral olfactory tract, the bed nucleus of the accessory olfactory bulb and the diagonal band of Broca. Injections of retrograde tracers in the medial amygdala, the bed nucleus or the lateral hypothalamus shows that the visuo-olfactory convergence mainly involves projections originating from the accessory olfactory bulb, and to a lesser extent from the ventromedial region of the main olfactory bulb. Fewer than 20 retinotelencephalic ganglion cells were identified in the retina, mainly located contralateral to the injection site. Ganglion cells were medium sized and possessed two long slender opposing dendrites. These retinal and olfactory projections could provide an anatomical substrate for the modulation of gonadotropin hormone levels and the olfactory influence on light mediated rhythms related to reproductive physiology.

Animals↗

PubMed2006

Tissue manganese concentrations in young male rhesus monkeys following subchronic manganese sulfate inhalation.

High-dose human exposure to manganese results in manganese accumulation in the basal ganglia and dopaminergic neuropathology. Occupational manganese neurotoxicity is most frequently linked with manganese oxide inhalation; however, exposure to other forms of manganese may lead to higher body burdens. The objective of this study was to determine tissue manganese concentrations in rhesus monkeys following subchronic (6 h/day, 5 days/week) manganese sulfate (MnSO(4)) inhalation. A group of monkeys were exposed to either air or MnSO(4) (0.06, 0.3, or 1.5 mg Mn/m(3)) for 65 exposure days before tissue analysis. Additional monkeys were exposed to MnSO(4) at 1.5 mg Mn/m(3) for 15 or 33 exposure days and evaluated immediately thereafter or for 65 exposure days followed by a 45- or 90-day delay before evaluation. Tissue manganese concentrations depended upon the aerosol concentration, exposure duration, and tissue. Monkeys exposed to MnSO(4) at > or = 0.06 mg Mn/m(3) for 65 exposure days or to MnSO(4) at 1.5 mg Mn/m(3) for > or = 15 exposure days developed increased manganese concentrations in the olfactory epithelium, olfactory bulb, olfactory cortex, globus pallidus, putamen, and cerebellum. The olfactory epithelium, olfactory bulb, globus pallidus, caudate, putamen, pituitary gland, and bile developed the greatest relative increase in manganese concentration following MnSO(4) exposure. Tissue manganese concentrations returned to levels observed in the air-exposed animals by 90 days after the end of the subchronic MnSO(4) exposure. These results provide an improved understanding of MnSO(4) exposure conditions that lead to increased concentrations of manganese within the nonhuman primate brain and other tissues.

Animals↗

PubMed2006

Influence of toluene intoxication on the number of mitral and granular neurons in olfactory bulbs of rats.

In the last years, implementation of the volatile solvents in order to get a narcotic high, used via inhalation (sniffing), increased significantly, especially in the youth. Substances containing these agents induce hallucinations and euphoric state. In the present study the influences of toluene intoxication on quantity of the mitral and granular cells in olfactory bulbs was analyzed in young and adult rats. An inhalation route of intoxication was used in our experiments - animal inhaled toluene until attaining a sidewise laying position. This procedure was performed in the closed glass container, in which air was beforehand saturated with the toluene vapours. Experiments was carried out on two age groups (n=20 animals): one - and two months age rats. Inhalation period was 40 days. Each age group consisted of ten animals and was divided into the two subgroups: I - control animals (n=5), II - experimental animals (n=5). Assessment of the neurons' quantity in different structures was made according to the fractional approach method proposed by M. West (1999). The results obtained showed that number of mitral neurons in the olfactory bulb of the Subgroup II of the rats, sniffing since the age of one and two months, significantly decreased by 43% (p<0,05) and by 28% (p<0,01), respectively. Meanwhile, the granular cells remained unaltered in experimental animals of both age groups. Decrease of the projection mitral neurons, in its turn, results in disruption of the projections to olfactory cortex and hampers proper functioning of the olfactory analyzer.

Animals↗

PubMed1989

Bursting induces persistent all-or-none EPSPs by an NMDA-dependent process in piriform cortex.

Burst responses to stimulation of excitatory fiber tracts in olfactory cortex slices after removal of extracellular Mg2+ or decreases in extracellular Cl-, resulted in long-lasting changes in response properties of neurons following a return to normal bathing medium. After bursting activity, the response of pyramidal cells to stimulation of afferent or associational fiber systems consisted of the normal graded depolarizing postsynaptic potential and a new, high-amplitude depolarizing potential that followed the graded potential at a variable latency. The new late potential had a waveform that resembled the initial graded response, but it occurred in an all-or-none fashion with a discrete threshold and persisted for many hours. Threshold for the late potential was similar for different cells in the same slice and was not affected by intracellular current injection, indicating that a synchronized interaction among a large number of cells is involved in its generation. Properties of the late potential indicate that it is an EPSP. NMDA receptor antagonists (APV and ketamine) had little effect on the late potential but prevented its development if present during bursting activity. The possible relevance of these findings to the study of the neuronal substrate for long-term memory and epilepsy is discussed.

2-Amino-5-phosphonovalerate↗