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PubMed1994

Effects of intranigral injections of colchicine on the expression of some neuropeptides in the rat forebrain: an immunohistochemical and in situ hybridization study.

In the present study, we describe the neurochemical effects of intranigral injections of colchicine in the rat forebrain using immunohistochemistry and in situ hybridization. The observations on the injected side are compared to the contralateral one and to the sham-operated rats. We demonstrate that such injections are able to strongly enhance the immunoreactivity for Met-enkephalin (ME), substance P (SP) and neuropeptide Y (NPY) in numerous nerve cell bodies of the limbic system (injected side), whereas the levels of the corresponding mRNAs are differently modified according to the region examined. A clear correlation between the enhancement of the immunostaining for ME and SP and that of the preproenkephalin (PPA) and preprotachychinin gene transcripts was observed in neuronal perikarya of the medial amygdaloid nucleus (SP), of the dorsolateral hypothalamus (ME) and of the ventromedial hypothalamic nucleus (SP). These observations are interpreted as an induction--or increased expression--of neuropeptide genes in neuronal perikarya postsynaptic to nerve fibers originating in the midbrain and brain stem. In this case, colchicine is thought to block the electrophysiological activity of ascending nerve fibers (anterograde and postsynaptic effect). In the case where the enhancement of the immunoreactivity for the studied neuropeptides was associated with no change or a decreased expression of the corresponding genes in the same brain areas, colchicine may have blocked the axoplasmic transport of peptides in nerve fibers projecting to the midbrain and/or brain stem (6). This may result in a retrograde accumulation of peptides in the nerve cell bodies of origin and, eventually, in a negative feedback regulation of the corresponding encoding genes in these perikarya (retrograde and presynaptic effect of colchicine). The drastic behavioral effects of bilateral intranigral injections of colchicine, on ingestive behavior in particular, have been studied in a following paper.

Animals↗
PubMed2004

LIM genes parcellate the embryonic amygdala and regulate its development.

The mechanisms that regulate the development of the amygdaloid complex are as yet poorly understood. Here, we show that in the absence of the LIM-homeodomain (LIM-HD) gene Lhx2, a particular amygdaloid nucleus, the nucleus of the lateral olfactory tract (nLOT), is selectively disrupted. LIM family members are well suited for multiple roles in the development of complex structures because they participate in regulatory interactions that permit a diversity of function. To investigate the possible role for other LIM-HD genes as well as LIM-only (Lmo) genes in the developing amygdala, we examined their expression in the embryo. We show that amygdaloid nuclei upregulate distinct patterns of LIM gene expression from embryonic stages. This supports the hypothesis that LIM genes may participate in the mechanisms that control the development of the amygdala. The disruption of the nLOT in the Lhx2 mutant is the first evidence of a role for LIM-HD genes in the development of the amygdaloid complex. The combinatorial expression patterns of LIM genes suggest a comprehensive mechanism for patterning this structure.

Amygdala↗
PubMed1979

Afferent connections to the amygdaloid complex of the rat and cat. I. Projections from the thalamus.

By the use of the retrograde transport of horseradish peroxidase (HRP), the projections from the thalamus to the amygdala were investigated in the rat and cat, with main emphasis on the former species. HRP was injected stereotactically by microiontophoresis in the various amygdaloid nuclei. Several control procedures including the use of different approaches for the introduction of the micropipette were undertaken to eliminate the possibility of misinterpretation due to uptake of the protein by adjacent structures or fibers en passant. The paraventricular and paratenial nuclei of the thalamus were found to project throughout the entire amygdaloid complex. The medial geniculate complex and the basal nucleus of the ventromedial complex (the thalamic taste relay) mainly project to the centromedial part of the amygdala. The basolateral nucleus is the main recipient of a hitherto undescribed bilateral thalamo-amygdaloid pathway originating in the interanteromedial nucleus. The parafasciculare nucleus projects to the central nucleus of the amygdala; in the cat mainly to the lateral subdivision of the central nucleus. The findings are discussed in relation to previous anatomical and electrophysiological studies centered on the amygdaloid complex. Special reference is made to the possible role of the thalamo-amygdaloid connections in the conveyance of sensory information to the amygdala.

Afferent Pathways↗
PubMed1984

The neurotoxicity of trimethyltin chloride in hamsters, gerbils and marmosets.

Trimethyltin chloride (TMT) was given to Syrian hamsters, gerbils and marmosets, and the changes in the brain were studied 1 day to 7 weeks later by light and electron microscopy. Within the marmoset brain, TMT was found to be uniformly distributed, similar to that in the rat. In all three species, signs of poisoning included whole-body tremors and prostration, while death might occur in 3-4 days; in marmosets ataxia, agitation, aggression and occasional fits were also observed. Bilateral symmetrical neuronal necrosis and chromatolysis were seen in the majority, which involved the hippocampus, pyriform cortex, amygdaloid nucleus, neocortex, various brain stem nuclei and in marmosets the retina. The probably lethal dose of TMT in all three species is approximately 3 mg kg-1, while the LD50 for the rat is 12.6 mg kg-1. The lower figure is probably related to lack of binding to haemoglobin in contrast to the binding in the rat. TMT does not bind to human haemoglobin and thus the predicted lethal dose for humans may be about 3 mg kg-1 (15.1 mumol kg-1), while the dose required to produce neuronal damage could well be less.

Animals↗
PubMed1984

Changes in subcortical visual and auditory evoked potentials following amygdaloid kindling in cats.

In this study we dealt with the changes in visual and auditory evoked potentials following kindling, to reveal the distant effects of epileptic activity. The experiments were performed using cats. Visual and auditory evoked potentials were obtained initially. Daily stimulation of 60 Hz (rectangular wave, 1 ms in duration, 500 microA in peak current, 2-s train) was given to the right amygdala, for kindling. After the completion of kindling, evoked responses were recorded again. In the auditory system the changes of responses in the cortex, medial geniculate nucleus, and cochlear nucleus were distinguished. The changes of potentials in the subcortex were larger than those at the cortical level. For visual evoked potentials there was a discrepancy between stimulation with light and electrical stimulation of the optic chiasm. There was no significant change in amplitude of visual evoked potentials by flash. In the case of optic chiasm stimulation, an enlargement of evoked responses was obtained. These results indicate modality-specific change of the auditory system and widespread subcortical change. These results might be caused by some vulnerability of the auditory system in the case of amygdaloid kindling, as a result of the epileptogenic process.

Amygdala↗
PubMed1981

Dipropylacetate-induced quasi-morphine abstinence behaviour in the rat: involvement of amygdaloid and thalamic structures.

Quasi-morphine abstinence behaviour induced by di-n-propylacetate (DPA) in rats is thought to be caused by an increased GABAergic activity in the CNS. Behavioural responses after intracerebral injections of DPA were studied to gain insight into the centre median-parafascicularis (Cm-Pf) resulted in a large number of body shakes and greater locomotor activity when compared to other brain areas. Injection of DPA into the central amygdala (Ac) resulted in an enhanced number of chewing episodes. Administration of bicuculline methiodide (BMI) into the Cm-Pf, 5 min after intraperitoneal administration of DPA, suppressed by body shakes but had only minor effects on horizontal activity, whereas injection of morphine into the same structure suppressed both behavioural symptoms. It is concluded that GABAergic and opioid mechanisms in the Cm-Pf are involved in the DPA-induced behaviour. Injection of BMI into the central amygdala shortly after i.p. injection of DPA resulted in an increase in the number of body shakes, whereas no effect was observed on activity. Morphine applied to this structure slightly potentiated the locomotor activity, but had no effect on the body shakes induced by DPA. The present results suggest a facilitatory role for a GABAergic system in the Cm-Pf on body shakes, while in the central amygdala a GABAergic system exerts an inhibitory influence on this symptom of abstinence.

Amygdala↗
PubMed1997

In situ hybridization histochemical localization of prodynorphin messenger RNA in the central nervous system of the rat.

The distribution of preprodynorphin messenger RNA-containing perikarya in the central nervous system of the rat was determined with in situ hybridization histochemistry using a 35S-labelled complementary RNA probe. All of the regions of the central nervous system reported by other investigators to contain perikarya that synthesize prodynorphin-derived peptides, except the pedunculopontine tegmental nucleus, the accessory trigeminal nucleus, and the ventral nucleus of the trapezoid body, also contained perikarya that synthesize preprodynorphin messenger RNA. However, the olfactory bulb, the anterior olfactory nucleus, the islands of Calleja, the CA1-CA3 fields of the hippocampus, the septohippocampal nucleus, the diagonal band of Broca, the basal and cortical amygdaloid nuclei, the entopeduncular nucleus, the subthalamic nucleus, the superior colliculus, the Edinger-Westphal nucleus, the dentate nucleus, the raphes linearis and pontis, the dorsal cochlear nucleus, the medial vestibular nucleus, the inferior olive, and the dorsal motor nucleus of the vagus nerve also contained preprodynorphin messenger RNA-synthesizing perikarya. These observations suggest that prodynorphin-derived peptides have a much more pervasive role in central nervous system function than previously suspected. However, before the physiological significance of these observations can be judged, it will be necessary to determine whether all of the novel sites of preprodynorphin messenger RNA synthesis are sites of prohormone synthesis and conventional processing.

Animals↗
PubMed2004

The thalamic paraventricular nucleus relays information from the suprachiasmatic nucleus to the amygdala: a combined anterograde and retrograde tracing study in the rat at the light and electron microscopic levels.

The relationship between efferents of the hypothalamic suprachiasmatic nucleus (SCN) and neurons of the thalamic paraventricular nucleus (PVT) projecting to the amygdala was investigated in the rat using tract tracing in light and electron microscopy. Biotinylated dextran amine was used to label anterogradely SCN efferents. These fibers were found to reach the thalamic midline, terminating in PVT, through three pathways: anterodorsally through the preoptic region, dorsally through the periventricular hypothalamus, and through the contralateral medial hypothalamic and preoptic areas after crossing the midline in the optic chiasm. Preterminal and terminal-like elements labeled from the SCN were distributed throughout the rostrocaudal extent of PVT, with an anteroposterior gradient of density. Labeled terminal elements were densest in the dorsal portion of PVT beneath the ependymal lining and some of them entered the ependyma. Anterograde tracing of SCN fibers was combined with injections of retrograde tracers in the amygdala. Numerous retrogradely labeled cell bodies were seen throughout PVT, with a prevalence in its anterodorsal portion. Overlap was detected between puncta labeled from the SCN and retrogradely labeled neurons, especially in the anterodorsal sector of PVT, where numerous puncta were in close apposition to thalamo-amygdaloid cells. Electron microscopy revealed that boutons labeled from the SCN established synaptic contacts with dendritic profiles of PVT neurons labeled from the amygdala. The findings demonstrate that information processed in the biological clock is conveyed to the amygdala through PVT, indicating that this nucleus plays a role in the transfer of circadian timing information to the limbic system.

Amygdala↗
PubMed1998

Local cerebral glucose utilization in the AS/AGU rat: a mutant with movement disorders.

The AS/AGU mutant rat is characterized by a wide staggering gait and a movement disorder of the hindlimbs. Local cerebral glucose utilization in the brain was investigated using the [14C]2-deoxyglucose autoradiographic technique to map any functional alterations in the mutant AS/AGU (agu/agu) compared with Albino Swiss controls (+/+). Locomotor tests were also performed to confirm the phenotypic assignment of the animals. Statistically significant reductions in glucose utilization were apparent in 12 of the 44 regions examined in the AS/AGU animals. The regions showing the most significant differences (P < 0.01) from the control AS strain were the substantia nigra pars compacta (-23%) and medial geniculate body (-17%). Statistically significant decreases (P < 0.05 and P < 0.02) in glucose utilization ranging from -15 to -26% were also displayed in the superior colliculus superficial layer, auditory cortex, ventroposterior nucleus of the thalamus, molecular layer of the hippocampus, dentate gyrus, medial amygdaloid nucleus, median raphe nucleus, subthalamic nucleus, medial preoptic area of the hypothalamus and anterior hypothalamus. In no region studied was the mean value of glucose use in the AS/AGU rat greater than in the control animals. The results of this study complement previous behavioural and neurochemical characterization studies of this mutant, confirm that the disorder involves functional disturbances of the basal ganglia, and demonstrate the involvement of the limbic system and some sensory systems.

Animals↗
PubMed2006

Role of the stria terminalis in food intake and body weight in rats.

Previous studies have shown that lesions of the posterodorsal amygdala result in hyperphagia and obesity in female rats. In the present study, lesions of the stria terminalis at its most dorsal point (before it separates into dorsal and ventral components) also resulted in hyperphagia and excessive weight gains in female rats compared to female rats with sham lesions, as did coronal knife cuts anterior to the ventromedial hypothalamus. Identical lesions and knife cuts did not elevate food intake or weight gains in male rats compared to male control animals. Examination of the anterograde degeneration with the amino-cupric-silver method in the brains of two female rats with hypothalamic knife cuts revealed degenerating terminals in the capsule of the ventromedial hypothalamus and in the premammillary nuclei, two classic indicators of damage to the dorsal component of the stria terminalis. No degenerating axon terminals were observed in the paraventricular nucleus. Differences from previous studies that used male rats were attributed to a sex difference for the effects of amygdaloid and ventromedial hypothalamic lesions. It is proposed that the posterodorsal amygdala, dorsal component of the stria terminalis, and ventromedial hypothalamus are part of an inhibitory pathway in the regulation of feeding behavior.

Amygdala↗
PubMed1985

The anatomy of neuropeptide-Y-containing neurons in rat brain.

The distribution of neuropeptide Y in the central nervous system of adult male rats was investigated using indirect immunofluorescence, the peroxidase-antiperoxidase technique and by radioimmunoassay of microdissected brain regions. The different methods were in good agreement and showed that neuropeptide Y had a widespread distribution and was present in extremely high concentrations. The highest concentrations of neuropeptide Y were found in the paraventricular hypothalamic nucleus and hypothalamic arcuate nucleus, which also contained the highest density of immunoreactive fibers and numbers of perikarya, respectively. The suprachiasmatic nucleus, median eminence, dorsomedial hypothalamic nucleus and paraventricular thalamic nucleus showed high concentrations as well as high densities of fibers. Moderate concentrations were found in the bed nucleus of the stria terminalis, although a high density of fibers was found. Areas with moderate concentrations and densities of fibers were the medial preoptic area, anterior hypothalamic area, periventricular nucleus, posterior hypothalamus and the medial amygdaloid nucleus. The nucleus of the solitary tract contained a low concentration of neuropeptide Y although a high number of immunoreactive perikarya was found in colchicine-treated rats. Low concentrations were also measured in the cerebral cortex, yet relatively high numbers of cell bodies and fibers were found dispersed through the cortex. The extremely high concentrations and widespread distribution of neuropeptide Y in the central nervous system suggests a number of important physiological roles for this neurotransmitter candidate.

Animals↗
PubMed1990

Chromogranin A in the olfactory system of the rat.

The olfactory bulb of the rat contains chromogranin A at a similar level as the adrenal gland or the hypophysis as revealed by immunoblots. Olfactory chromogranin A also displays the same size as chromogranin A of endocrine cells. In the hippocampus and other brain regions, we could not detect chromogranin A by immunoblotting. In contrast, chromogranin A messenger ribonucleic acid (using S1 nuclease protection assays) was observed in all brain regions examined, including the olfactory bulb. By in situ hybridization histochemistry with a complementary ribonucleic acid probe (280 nucleotides), and by immunocytochemistry, chromogranin A synthesis could be localized to cell bodies of the mitral cell layer, of the external plexiform layer and of the periglomerular region of the olfactory bulb. Immunocytochemically, chromogranin A was also detected in the central projection areas of mitral and tufted cells in the primary olfactory cortex and the anterior amygdaloid area but not in the olfactory glomeruli, where the incoming olfactory nerve fibers of the primary olfactory neurons establish synaptic contacts. Taken together the data show that chromogranin A, following biosynthesis in the perikarya of the mitral and tufted cells, is specifically transported into their axonal terminals but not into their primary dendrites. We propose that the rat olfactory system could serve as a model for the study of chromogranin A regulation and function in neurons.

Adrenal Glands↗
PubMed1993

Identification of putative nitric oxide producing neurons in the rat amygdala using NADPH-diaphorase histochemistry.

Putative nitric oxide-containing neurons in the rat amygdala were studied using reduced nicotinamide adenine dinucleotide phosphate diaphorase histochemistry. All nuclei of the amygdala contained subpopulations of diaphorase-positive neurons, but the staining intensity of different subpopulations varied. Intensely stained neurons exhibited labeling of the cell body and the entire dendritic arborization. The lateral nucleus had the greatest concentration of intensely labeled cells. Many intensely labeled neurons were located along nuclear boundaries and fiber bundles. In addition to neuronal staining, there was a differential staining of the neuropil in different amygdaloid nuclei. In the basolateral and cortical nuclei the diaphorase-positive cells were non-pyramidal neurons that resembled those containing somatostatin and neuropeptide Y. The distribution and neuronal morphology of labeled neurons in the central nucleus and anterior amygdaloid area suggests that diaphorase-positive cells in these areas may be cholinergic. Recent studies have shown that the enzyme responsible for neuronal diaphorase activity is actually the synthetic enzyme for the newly discovered neurotransmitter nitric oxide. Since there is evidence that nitric oxide plays an important role in excitotoxic neuronal degeneration, the neurons identified in the present study may be involved in degenerative diseases of the amygdala.

Amygdala↗
PubMed2005

Afferent connections of the subparafascicular area in rat.

The subparafascicular nucleus and the subparafascicular area are the major sites of synthesis of the recently discovered neuropeptide, tuberoinfundibular peptide of 39 residues (TIP39). Better knowledge of the neuronal inputs to the subparafascicular area and nucleus will facilitate investigation of the functions of TIP39. Thus, we have injected the retrograde tracer cholera toxin B subunit into the rostral, middle, and caudal parts of the rat subparafascicular nucleus. We report that the afferent projections to the subparafascicular nucleus and area include the medial prefrontal, insular, and ectorhinal cortex, the subiculum, the lateral septum, the anterior amygdaloid area, the medial amygdaloid nucleus, the caudal paralaminar area of the thalamus, the lateral preoptic area, the anterior, ventromedial, and posterior hypothalamic nuclei, the dorsal premamillary nucleus, the zona incerta and Forel's fields, the periaqueductal gray, the deep layers of the superior colliculus, cortical layers of the inferior colliculus, the cuneiform nucleus, the medial paralemniscal nucleus, and the parabrachial nuclei. Most of these regions project to all parts of the subparafascicular nucleus. However, the magnocellular subparafascicular neurons, which occupy the middle part of the subparafascicular nucleus, may not receive projections from the medial prefrontal and insular cortex, the medial amygdaloid nucleus, the lateral preoptic area, and the parabrachial nuclei. In addition, double labeling of cholera toxin B subunit and TIP39 revealed a remarkable similarity between input regions of the subparafascicular area and the brain TIP39 system. Neurons within regions that contain TIP39 cell bodies as well as regions that contain TIP39 fibers project to the subparafascicular area. Overall, the afferent connections of the subparafascicular nucleus and area suggest its involvement in central reproductive, visceral, nociceptive, and auditory regulation.

Afferent Pathways↗
PubMed1997

Close relationship between spongiform change and ubiquitin-positive granular structures in diffuse Lewy body disease.

The origin of spongiform change seen in diffuse Lewy body disease (DLBD) cases was elucidated, as compared with Alzheimer-type dementia (ATD) cases. Spongiform change was composed of numerous vacuoles in the neuropil, predominantly in layers II-IIIab of the transentorhinal cortex and in the intermediate area of the accessory basal amygdaloid nucleus. The distribution of spongiform change was identical to that of ubiquitin-positive granular structures (UPG) in non-demented cases. The degree of spongiform change was correlated with loss of the large pyramidal neurons in layers IIIc and V of the transentorhinal cortex and with the disappearance of their ubiquitin-positive granular processes. With electron microscopy, the early vacuoles of spongiform change appeared to arise in the presynaptic terminals as well as in the postsynaptic terminals and dendritic processes. These findings indicate that the vacuoles derive from degeneration of terminal axons of the large pyramidal neurons. The occurrence of spongiform change characteristic to DLBD suggests that the large pyramidal neurons degenerate more rapidly in DLBD than in ATD.

Aged↗
PubMed1989

Localization of proopiomelanocortin (POMC) immunoreactive neurons in the forebrain of the pig.

The distribution of proopiomelanocortin (POMC)-immunoreactive neurons was examined in the forebrains of nine sexually mature female pigs by indirect biotin-avidin horseradish peroxidase immunocytochemistry. Primary antiserum against ovine beta-endorphin (Bioflex #BF-EP-3-1) yielded positive staining of neuronal perikarya and processes. Adjacent control sections treated either with primary antiserum preabsorbed with beta-endorphin or substituted with normal rabbit serum lacked specific staining. POMC-immunoreactive cells were located in the anterior and intermediate lobe of the pituitary gland. POMC-immunoreactive perikarya were located in the arcuate nucleus and periarcuate area. The pituitary stalk/median eminence contained sparsely distributed POMC-immunoreactive fibers, which were confined to the zona interna. POMC-immunoreactive fibers were located in the arcuate nucleus and extended rostrally from the arcuate nucleus into the telencephalon coursing adjacent to the wall of the third ventricle as well as through the anterior hypothalamus, suprachiasmatic, supraoptic nuclei and preoptic areas to the nucleus accumbens, diagonal band of Broca, olfactory tubercle, bed nucleus of the stria terminalis and the ventro-lateral aspect of the septum. Caudal projections extended along the wall of the third ventricle to the level of the mammillary bodies and also coursed dorsally, passing through the periventricular, paraventricular, and dorsal medial nuclei of the hypothalamus to the midline thalamic nuclei and habenular nucleus. Lateral projections extended from the arcuate nucleus along the dorsal aspect of the optic tract and terminated in the amygdaloid complex. The distribution of POMC-immunoreactive perikarya and fibers is similar to that of the luteinizing hormone-releasing hormone (LHRH) fiber network. Therefore the opportunities exist, anatomically, for interactions between the POMC and the LHRH systems.

Animals↗