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At least 127 records · Page 7Linked to original sources
PubMed2004

Developmental regulation of the 5-HT7 serotonin receptor and transcription factor NGFI-A in the fetal guinea-pig limbic system: influence of GCs.

Fetal exposure to excess glucocorticoids (GCs) programs the developing hypothalamo-pituitary-adrenal (HPA) axis, and may predispose offspring to adult-onset disease. During development, serotonin (5-HT) influences transcription of hippocampal GR mRNA via the 5-HT7 receptor. The effect of 5-HT on GR involves the transcription factor NGFI-A. Given the developmental changes which we have previously reported in hippocampal GR mRNA expression, we hypothesized that (1) there are progressive developmental changes in 5-HT7 receptor and NGFI-A mRNA expression in the fetal guinea-pig limbic system, and (2) repeated exposure to synthetic GC treatment will significantly modify developmental expression of these genes. 5-HT7 receptor mRNA was highly expressed in the hippocampus and thalamus at gestational day (gd) 40 (term approximately 70 days), and significantly decreased (P < 0.05) with advancing gestation. Conversely, NGFI-A mRNA expression in the hippocampus and frontal cortex was almost undetectable at gd40, but was dramatically elevated (P < 0.05; 8-fold) near term. Changes in mRNA were refelected by NGFI-A protein levels. These changes were significantly correlated to hippocampal GR expression and fetal plasma cortisol concentrations. Synthetic GC treatment increased NGFI-A mRNA levels in CA1 and the cingulate cortex, but had no effect on 5-HT7 receptor expression. In conclusion our results suggest that (1) limbic 5-HT7 receptor expression is not directly linked to maturation of hippocampal GR in late gestation; (2) the up-regulation of NGFI-A expression near term is driven by glucocorticoid; and (3) premature exposure to synthetic glucocorticoid significantly increases NGFI-A-related transcriptional activity in the fetal limbic system.

Animals↗
PubMed1994

Participation of the limbic system and its associated areas in the dementia of amyotrophic lateral sclerosis.

The topographic distribution of degenerative changes in large brain sections from five sporadic amyotrophic lateral sclerosis (ALS) patients with dementia and three without dementia was examined. The dementia characteristics were impaired shifting from one line of thinking to another, perseveration, and emotional disinhibition as well as impairment of cognition, and judgment. Neuropathological examinations showed definite ALS changes in all the patients studied. In addition, the five patients with dementia showed neuronal loss, gliosis, and sponginess of the superficial layers throughout the cerebral cortices, predominantly in the dorsomedial cortex of the temporal tip and the parahippocampal, ambiens, anterior cingulate, rectal, orbital, and insular gyri as well as neuronal loss in the basolateral nucleus of the amygdala, nucleus accumbens, and subiculum of the hippocampus. Ubiquitin-immunoreactive inclusions were present in some neurons in the granular cell layers of the hippocampus. Fibrous gliosis was extensive in the subcortical and deep white matter of the frontotemporal lobes. The affected regions take in the limbic system and its associated areas which are the sources of the psychological problems, including emotional disturbance, experienced by these ALS patients. The psychological problems of ALS need to be investigated in relation to the involvement of the limbic system.

Adult↗
PubMed1978

Pituitary-adrenal response to stimulation of the limbic system and lateral hypothalamus in the rhesus monkey (Macacca mulatta).

Various sites within the limbic system, frontal lobe and lateral hypothalamus of the rhesus monkey brain were electrically stimulated using chronically implanted electrodes. Increases in plasma cortisol was observed after stimulation of the lateral hypothalamic area, basolateral amygdala, pyriform cortex, hippocampus, certain sites in the cingulate gyrus and orbital part of the frontal lobe. Inactive sites included the caudate nucleus, putamen and white matter in the frontal lobe.

Amygdala↗
PubMed2005

Depression in Parkinson's disease: loss of dopamine and noradrenaline innervation in the limbic system.

The reason for the high frequency of depression and anxiety in Parkinson's disease is poorly understood. Degeneration of neurotransmitter systems other than dopamine might play a specific role in the occurrence of these affective disorders. We used [11C]RTI-32 PET, an in vivo marker of both dopamine and noradrenaline transporter binding, to localize differences between depressed and non-depressed patients. We studied eight and 12 Parkinson's disease patients with and without a history of depression matched for age, disease duration and doses of antiparkinsonian medication. The depressed Parkinson's disease cohort had lower [11C]RTI-32 binding than non-depressed Parkinson's disease cases in the locus coeruleus and in several regions of the limbic system including the anterior cingulate cortex, the thalamus, the amygdala and the ventral striatum. Exploratory analyses revealed that the severity of anxiety in the Parkinson's disease patients was inversely correlated with the [11C]RTI-32 binding in most of these regions and apathy was inversely correlated with [11C]RTI-32 binding in the ventral striatum. These results suggest that depression and anxiety in Parkinson's disease might be associated with a specific loss of dopamine and noradrenaline innervation in the limbic system.

Adult↗
PubMedDate not supplied

[Glutamate decarboxylase and GABA transaminase activity in the mitochondrial fraction of the dog brain limbic system during postnatal development].

Overall glutamate decarboxylase (GDCase) activity in the initial mitochondrial fraction of the limbic structure is found to be regionally different it increases from the moment of birth up to 1 year, the midbrain reticular formation (RF), where the enzyme activity in the mitochondrial decreases in pups aged 3 month and reincreases in 1 year old dogs being the exception. Overall GABA-transaminase (GABA-T-ase) activity reaches the "adult" level and is the highest: in the hypothalamic and hippocampal mitochondria on the 1st postnatal day; in the limbic cortex (l1 and l2 fields), amygdala and midbrain RF--on the 12-16th postnatal days. During the period from 12-16 postnatal days up to the age of 1 year GABA-T-ase activity in the dog limbic system decreases reliably.

4-Aminobutyrate Transaminase↗
PubMed2000

Similar increases in extracellular lactic acid in the limbic system during epileptic and/or olfactory stimulation.

Previous studies have shown that physiological stimulation of brain activity increases anaerobic glucose consumption, both in humans and in experimental animals. To investigate this phenomenon further, we measured extracellular lactate levels within different rat brain regions, using microdialysis. Experiments were performed comparing the effects of natural, physiological olfactory stimulation of the limbic system with experimental limbic seizures. Olfactory stimulation was carried out by using different odors (i.e. both conventional odors: 2-isobutyl-3-methoxypyrazine, green pepper essence; thymol; and 2-sec-butylthiazoline, a sexual pheromone). Limbic seizures were either induced by systemic injection of pilocarpine (200-400 mg/kg) or focally elicited by microinfusions of chemoconvulsants (bicuculline 118 pmol and cychlothiazide 1.2 nmol) within the anterior piriform cortex. Seizures induced by systemic pilocarpine tripled lactic acid within the hippocampus, whereas limbic seizures elicited by focal microinfusion of chemoconvulsants within the piriform cortex produced a less pronounced increase in extracellular lactic acid. Increases in extracellular lactate occurring during olfactory stimulation with the sexual pheromone (three times the baseline levels) were non-significantly different from those occurring after systemic pilocarpine. Increases in lactic acid following natural olfactory stimulation were abolished both by olfactory bulbectomy and by the focal microinfusion of tetrodotoxin, while they were significantly attenuated by the local application of the N-methyl-D-aspartate antagonist AP-5. Increases in hippocampal lactate induced by short-lasting stimuli (olfactory stimulation or microinfusion of subthreshold doses of chemoconvulsants, bicuculline 30 pmol) were reproducible after a short delay (1 h) and cumulated when applied sequentially. In contrast, limbic status epilepticus led to a long-lasting refractoriness to additional lactate-raising stimuli and there was no further increase in lactate levels when the olfactory stimulation was produced during status epilepticus. Increases in lactic acid following olfactory stimulation occurred with site specificity in the rhinencephalon (hippocampus, piriform and entorhinal cortex) but not in the dorsal striatum. Site specificity crucially relied on the quality of the stimulus. For instance, other natural stimuli (i.e. tail pinch) produced a similar increase in extracellular lactate in all brain areas under investigation. The major conclusion of this work is that the presentation of an odor known to be a rat pheromone results in lactate production as great as that induced by the systemic convulsant pylocarpine (maximum: 2.286+/-0.195 mM and 1.803+/-0.108 mM, respectively). This supports the notion that the great magnitude of lactate production known to accompany seizures can result from the intensified neural activity per se ("aerobic gycolysis"), not merely from local anoxia or other pathological changes.

2-Amino-5-phosphonovalerate↗
PubMed2004

Alterations of myelin basic protein and ultrastructure in the limbic system at the early stage of trauma-related stress disorder in dogs.

BACKGROUND: The secondary injury and related complications after trauma are still the focus of trauma research. However, whether the remote effects on the central nervous system could be induced by high-energy missile extremity impact remains unclear. Also, the possible biomarker for brain damage in traumatic stress disorder has not been determined. METHODS: Forty-two healthy adult dogs were divided into three groups: the control group (n = 12), the high-speed trauma group (n = 15), and the low-speed trauma group (n = 15). Bilateral thighs of dogs were wounded with a smoothbore 6.2-mm rifle at a speed of 1,368 m/s (1.03-g steel bullet) for the high-speed trauma group and 625 m/s for the low-speed trauma group. The expression of myelin basic protein (MBP) in cerebrospinal fluid (CSF), hypothalamus and hippocampus of the limbic system, and temporoparietal cortex was investigated by enzyme-linked immunosorbent assay and dot-blot analysis. Also, the ultrastructure of the above areas was observed with light and electron microscopy. RESULTS: Neuronal degeneration and nerve fiber demyelination were seen in the hypothalamus and hippocampus in the high-speed trauma group at 8 hours after impact. The MBP level was markedly increased in the CSF (p < 0.01) in the two trauma groups, in the hypothalamus of the low-speed trauma group (p < 0.05), and in both the hypothalamus and the hippocampus of the high-speed trauma group (p < 0.01). The expression of MBP mRNA was also significantly enhanced in these areas at the same time. The increase of MBP content in the CSF was positively correlated with the elevation of MBP concentration in the hypothalamus and hippocampus. CONCLUSION: The hypothalamus and hippocampus of the limbic system in the central nervous system are vulnerable to damage after high-energy missile extremity impact, indicating that it might be one of the important pathologic bases involved in the development of trauma-related complications. Meanwhile, the MBP level in the CSF may be a sensitive biological indicator for brain damage at the early stage of trauma-related stress disorder.

Animals↗
PubMed1976

Lack of effect of various endocrine manipulations on tryptophan hydroxylase activity of individual nuclei of the hypothalamus, limbic system, and midbrain of the rat.

The tryptophan hydroxylase activity of individual nuclei of the limbic system, hypothalamus, and midbrain was determined after various endocrine manipulations in an attempt to identify specific endocrine-responsive serotonergic structures in the rat brain. Following adrenalectomy, thyroidectomy, castration, or treatment with pharmacological doses of dexamethasone, testosterone, or thyroxine, no changes in tryptophan hydroxylase activity occurred in any of the areas of brain examined. Furthermore, in large sections of the hypothalamus and midbrain, total tryptophan hydroxylase activity was unaltered, and no changes in Km for substrate or co-factor were found after adrenalectomy. This study, therefore, has failed to detect any hormonally responsive tryptophan hydroxylase activity in the rat brain. These findings suggest that endocrine-induced alterations in serotonin turnover, if they occur, do so without measurable changes in the activity or kinetic properties of tryptophan hydroxylase.

Adrenal Glands↗
PubMed1997

Crystallization and preliminary X-ray analysis of neuropsin, a serine protease expressed in the limbic system of mouse brain.

Neuropsin (M(r) 25032) is a serine protease expressed in the limbic system of mouse brain. It has been implicated in various neurological processes including formation of memory and may be important as a drug target in the treatment of epilepsy. The recombinant protein was produced using a baculovirus expression system and was purified. Two crystal forms were obtained by a hanging-drop vapor-diffusion method with polyethylene glycol. Preliminary X-ray crystallographic analysis revealed that crystal form I belongs to triclinic space group P1 with unit cell dimensions a = 97.16 A, b = 97.12 A, c = 46.75 A and alpha = 99.17 degrees, beta = 99.77 degrees, gamma = 117.35 degrees. Self-rotation function analysis of these data of form I indicates the position of a noncrystallographic threefold axis. There are six molecules in the crystallographic asymmetric unit. Crystal form II also belongs to triclinic space group P1 but has unit cell dimensions of a = 38.40 A, b = 55.16 A, c = 65.37 A and alpha = 95.38 degrees, beta = 89.98 degrees, gamma = 110.46 degrees with two molecules in the crystallographic asymmetric unit. Form II has a noncrystallographic twofold axis. Intensity data to 3.1 A resolution for form I and to 2.2 A resolution for form II have been collected.

Amino Acid Sequence↗
PubMed2005

GABAergic control of the ascending input from the median raphe nucleus to the limbic system.

The median raphe nucleus (MRN) is the primary source of serotonergic afferents to the limbic system that are generally considered to suppress hippocampal theta oscillations. GABA receptors are expressed in the MRN by serotonergic and nonserotonergic cells, including GABAergic and glutamatergic neurons. This study investigated the mechanisms by which the fluctuating GABA tone in the MRN leads to induction or suppression of hippocampal theta rhythm. We found that MRN application of the GABA(A) agonist muscimol (0.05-1.0 mM) or GABA(B) agonist baclofen (0.2 mM) by reverse microdialysis had strong theta promoting effects. The GABA(A) antagonist bicuculline infused in low concentrations (0.1, 0.2 mM) eliminated theta rhythm. A short period of theta activity of higher than normal frequency preceded hippocampal desynchronization in 46% of rats. Bicuculline in larger concentrations (0.5, 1.0, 2.0 mM) resulted in a biphasic response of an initial short (<10 min) hippocampal desynchronization followed by stable theta rhythm that lasted as long as the infusion continued. The frequency and amplitude of theta waves were higher than in control recordings and the oscillations showed a conspicuous intermittent character. Hippocampal theta rhythm elicited by MRN administration of bicuculline could be completely (0.5 mM bicuculline) or partially (1.0 mM bicuculline) blocked by simultaneous infusion of the GABA(B) antagonist CGP35348. Our findings suggest that the GABAergic network may have two opposing functions in the MRN: relieving the theta-generators from serotonergic inhibition and regulating the activity of a theta-promoting circuitry by the fluctuating GABA tone. The two mechanisms may be involved in different functions.

Afferent Pathways↗
PubMed1982

The telencephalic limbic system and experimental gastric pathology: a review.

The effects of lesions and stimulations of the telencephalic limbic system on experimental gastric ulcers and erosions are reviewed. It is concluded that the centromedial amygdala and the anterior cingulate gyrus are facilitatory structures, whereas the medial prefrontal cortex, posterior cingulate cortex, entorhinal cortex, hippocampus and posterolateral amygdala are inhibitory areas during stressful experiences, e.g., immobilization. Both the centromedial amygdala and the anterior cingulate gyrus may be part of an "ancillary" pain system, mediating the affective components of aversive experiences. The inhibitory structures, on the other hand, are assumed to be part of a "preventive" mechanism which is initiated by the selective nuclear binding of glucocorticoids when under stress.

Amygdala↗
PubMed1998

Large-scale functional connectivity in associative learning: interrelations of the rat auditory, visual, and limbic systems.

Large-scale functional connectivity in associative learning: interrelations of the rat auditory, visual, and limbic systems. J. Neurophysiol. 80: 3148-3162, 1998. Functional relations between specialized parts of the brain may be important determinants of learned behaviors. To study this, we examined the interrelations of the auditory system with several extraauditory structures in two groups of rats having different behavioral histories. Both groups were trained to associate a tone conditional stimulus (CS) with an aversive unconditional stimulus (US). For one group, a light presented with the tone predicted the absence of the US (group TL-). In the other group, the light was a neutral stimulus (group TL0). Fluorodeoxyglucose (FDG) incorporation was measured in the presence of the tone-light compound. Because the tone-light compound was physically identical for both groups, neural differences between groups reflected differences in the learned associative properties of the stimuli. Covariances of FDG uptake in the auditory system and extraauditory structures were examined using partial least squares. Three strong covariance or functional connectivity patterns were identified. The first pattern mainly reflected similarities between groups, with strong interrelations between the subcortical auditory system and the thalamocortical visual system, cerebellum, deep cerebellar nuclei, and midline thalamus. This pattern of interactions may represent part of a common circuit for relaying the associative value of the tone CS to the cerebellum and the midline thalamus. The external nucleus of the inferior colliculus and medial division of the medial geniculate nucleus were associated more strongly with this pattern for group TL-, which was interpreted as representing the change of the associative value of the tone by the light, mediated through extraauditory influences on these two regions. A second pattern involved midbrain auditory regions, superior colliculus, zona incerta, and subiculum and was stronger for group TL0. The relations between midbrain structures may represent the excitatory conditioned response (CR) evoked by the tone in this group. The final pattern was strongest in group TL- and involved interrelations of the thalamocortical auditory system with hippocampus, basolateral amygdala, and hypothalamus. This pattern may represent the learned inhibition of the CR to the tone in the presence of the light. These findings are consistent with behavioral studies suggesting that at least two types of associations are formed during associative learning. One is the sensory relation of the stimuli and another is the relation between the CS and the affective components of the US. These behavioral associations are mapped to the patterns of functional connectivity between auditory and extraauditory regions.

Acoustic Stimulation↗
PubMed1999

Environmental influences on neural plasticity, the limbic system, emotional development and attachment: a review.

The effects of early environmental influences on neural plasticity, the limbic system, and social and emotional development are reviewed and an illustrative case study is briefly discussed. Deprived or abnormal rearing conditions induce severe disturbance in all aspects of social and emotional functioning, and effect the growth and survival of dendrites, axons, synapses, interneurons, neurons, and glia. The amygdala, cingulate, and septal nuclei develop at different rates which correlate with the emergence of wariness, fear, selective attachments, play behavior, and the oral and phallic stages of development. These immature limbic nuclei are "experience-expectant," and may be differentially injured depending on the age at which they suffer deprivation. The medial amygdala and later the cingulate and septal nuclei are the most vulnerable during the first three years of life. If denied sufficient stimulation these nuclei may atrophy, develop seizure-like activity or maintain or form abnormal synaptic interconnections, resulting in social withdrawal, pathological shyness, explosive and inappropriate emotionality, and an inability to form normal emotional attachments.

Affective Symptoms↗
PubMed2003

Altered levels of POMC, AgRP and MC4-R mRNA expression in the hypothalamus and other parts of the limbic system of mice prone or resistant to chronic high-energy diet-induced obesity.

The melanocortinergic system plays an important role in promoting negative energy balance and preventing excessive fat deposition. This study has investigated the levels of mRNA expression of proopiomelanocortin (POMC), agouti-related protein (AgRP) and the melanocortin-4 receptor (MC4-R) in diet-induced obese (DIO) and diet-resistant (DR) mice. Thirty C57 mice were used in this study. Twenty-four mice were fed with a high-fat diet (HF: 40% of calories from fat, 20% from saturated fat) for 4 weeks and then classified as DIO and DR according to their body weight gain. Six mice were placed on a low-fat diet (LF: 10% of calories from fat, 1% from saturated fat) and were used as controls. After 22 weeks of feeding, visceral fat deposits were more than twice as heavy in the DIO mice as in the DR and LF mice, while the latter two groups had no significant difference. Using quantitative in situ hybridization techniques, this study found that the DIO mice had a significantly lower level of Arc POMC (-29%) and AgRP (-31%) mRNA expression than the DR and LF mice, respectively. The mice on high-fat diets had higher levels of AgRP mRNA expression in the bed nucleus of stria terminalis (BST), and ventral part of the lateral septal nucleus (LSV) than the LF mice. Furthermore, the DIO mice had a 40% higher level of MC4-R mRNA expression in the ventromedial hypothalamic nucleus (VMH) and posterodorsal part of the medial amygdaloid nucleus (MePD) than the LF mice. In conclusion, this study has demonstrated that differential expression of POMC, AgRP and MC4-R mRNA levels exists in DIO, DR and LF mice. These differences were shown to occur in the specific nuclei of the hypothalamus and other parts of the limbic system. These findings may assist in understanding the involvement of the melanocortinergic system in the regulation of body weight via the autonomic and limbic systems.

Agouti-Related Protein↗