Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DIENCEPHALON”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1990

Diencephalon as a cardinal neural structure for mediating 2 Hz- but not 100 Hz-electroacupuncture-induced tail flick reflex suppression.

Transections at two levels of the forebrain were undertaken in the rat to investigate the neural structures indispensable for the mediation of tail flick reflex suppression (TFRS) induced by low (2 Hz) and high (100 Hz) frequency electroacupuncture (EA) stimulation. Removal of the telencephalic structures did not affect TFRS produced by high frequency EA, although a mild and temporal attenuation was observed for low frequency EA-induced TFRS. Ablation of the whole forebrain (the telencephalon and diencephalon) resulted in a total abolishment of 2-Hz EA effect as measured 5, 24 and 72 h after surgery. In the meantime there was a moderate attenuation (-32.8%, P less than 0.05) of 100-Hz EA effect, which appeared 5 h after the operation and recovered after 24 h. The results indicate that (1) high frequency EA effect persisted in animals devoid of the whole forebrain structures; (2) an intact diencephalon is indispensable for the neural circuitry controlling low frequency EA-induced TFRS.

Animals↗
PubMed1996

An immunocytochemical mapping of ACTH/CLIP in the cat diencephalon.

Using an indirect immunoperoxidase technique, the location of cell bodies and fibres containing adrenocorticotropin hormone/corticotropin-like intermediate lobe peptide (ACTH/CLIP) was studied in the cat diencephalon. Immunoreactivity was observed in several diencephalic nuclei of the cat in which no immunoreactivity has been previously reported. In this sense, a low density of immunoreactive cell bodies was found in the nucleus ventromedialis hypothalami; a high density of immunoreactive fibres was found in the medial preoptic area; a moderate density in the lateral preoptic area and in the nuclei centralis thalami (pars medialis), interventralis thalami, interanteromedialis thalami, parafascicularis and praemamillaris (pars ventralis and pars dorsalis); a low density in the nuclei habenularis lateralis and reuniens thalami, and single fibres were found in the nuclei lateralis thalami (pars anterior), habenularis medialis, parataenialis, corpus geniculatum mediale, ventralis thalami (pars medialis) and in the fornix. Our results point to a more widespread distribution of ACTH/CLIP immunoreactive structures in the cat diencephalon in comparison with previous studies carried out in the same region of this feline.

Adrenocorticotropic Hormone↗
PubMed2005

Chiasmatic neurons in the ventral diencephalon of mouse embryos--changes in arrangement and heterogeneity in surface antigen expression.

We have investigated the changes in arrangement of the SSEA-1 immunoreactive chiasmatic neurons in the mouse ventral diencephalon from embryonic day (E) 9 to the end of gestation. A regionally specific staining of SSEA-1 was first detected in the ventricular layer of the caudal diencephalon at E10 and later at E11 on the cells in the subventricular layer. At E12, these cells formed the characteristic V-shaped configuration caudal to the optic axons in the chiasm. At E13-E15, this neuronal array changes gradually to a configuration that facilitates contact with the optic axons only at the midline and the initial segment of the optic tract. Colocalization studies showed that CD44 was localized strongly on the neurons in the central but not lateral domains of the array, suggesting existence of heterogeneity in these neurons in terms of surface antigen presentation. This difference between the central and lateral domains raises the possibility that the chiasmatic neurons may regulate the patterning of axon orders at the midline and the optic tract through presentation of distinct combination of guidance cues at these strategic positions in the optic pathway. Furthermore, exogenous Lewis-x/SSEA-1 inhibited neurite outgrowth from the E14 retinal explants; this inhibition was observed in neurites from both ventral temporal and dorsal nasal retina. These findings suggest an action of this surface carbohydrate on the control of axon growth and guidance in the mouse optic pathway.

Age Factors↗
PubMed2004

Close anatomical associations between beta-endorphin and luteinizing hormone-releasing hormone neuronal systems in the human diencephalon.

Endogenous opiates, such as beta-endorphin, inhibit the release of luteinizing hormone (LH) release in the pituitary gland of several species including rat, pig, sheep, and human. Although it is generally believed that beta-endorphin influences gonadal functions via the regulation of hypothalamic LH-releasing hormone (LHRH) release, the morphological substrate underlying this regulation in humans remains elusive. In the present series of experiments the beta-endorphin-immunoreactive (IR) and LHRH-IR neural elements, utilizing single label immunohistochemistry, were mapped. Following the superimposition of the maps of these systems, the overlapping sites were identified and examined in order to verify the putative juxtapositions between the beta-endorphin-IR and LHRH-IR structures. LHRH-IR elements were detected mainly in the medial basal hypothalamus, in the medial preoptic area and along the diagonal band of Broca. Beta-endorphin-IR perikarya were observed in the infundibular region/median eminence, whereas beta-endorphin-IR axon varicosities were detected periventricularly in the preoptic and tuberal regions, in the medial basal hypothalamus and around the mamillary bodies. Careful examination of the immunoreactive elements in the overlapping areas revealed close contacts between beta-endorphin-IR and LHRH-IR structures, which have been verified in semithin plastic sections. These putative beta-endorphin-LHRH juxtapositions were most numerous in the medial preoptic area and in the infundibulum/median eminence of the human diencephalon. In conclusion, the present paper is the first study that revealed close juxtapositions between the beta-endorphin-IR and LHRH-IR neural elements in the human diencephalon. These beta-endorphin-LHRH contacts may be functional synapses, and they may be the morphological substrate of the beta-endorphin control on gonadal functions in man.

Adult↗
PubMed1997

The preglomerular nucleus of gymnotiform fish: relay station for conveying information between telencephalon and diencephalon.

The preglomerular nucleus of teleost fishes, believed to be a lateral part of the posterior tuberculum in the diencephalon, receives input from several sensory areas. By employing an in vitro technique, the pattern of connectivity between this cell group and the telencephalon has been explored through retrograde and anterograde tracing in the gymnotiform fish Apteronotus leptorhynchus. Neurons of the preglomerular nucleus project to the following telencephalic areas: central division of dorsal forebrain, dorsal subdivision of dorsolateral telencephalon, posterior subdivision of dorsolateral telencephalon, dorsal posterior telencephalon, and probably, also subdivision 2 of dorsomedial telencephalon. Experiments in which tracer application was restricted to the lateral subdivision of the preglomerular nucleus, or in which tracer substance was placed into various regions of the telencephalon revealed a differential projection pattern of cells in the lateral and the medial subdivision of the preglomerular nucleus. Neurons in the central division of the dorsal forebrain, the dorsal posterior telencephalon, and likely, also in the subdivision 2 of the dorsomedial telencephalon and the ventricular zone of the intermediate subdivision of the ventral telencephalon project back to the preglomerular nucleus. Thus, a major function of the preglomerular nucleus appears to be to act as a relay station for conveying information between diencephalon and telencephalon.

Animals↗
PubMed1998

Acute intermittent nicotine treatment produces regional increases of basic fibroblast growth factor messenger RNA and protein in the tel- and diencephalon of the rat.

Several findings show a neuroprotective effect of nicotine treatment in different experimental models, and a negative correlation has been observed between cigarette smoking and the incidence of Parkinson's disease. It seems possible that nicotine may in part exert its neuroprotective actions by favouring the synthesis of neurotrophic factors. The aim of this study was to determine whether the nicotine treatment could be associated with the induction of a neurotrophic factor in brain regions with nicotinic receptors. Thus, we analysed by in situ hybridization and RNAse protection assay the effects of (-)nicotine on basic fibroblast growth factor messenger RNA and by immunocytochemistry fibroblast growth factor-2 protein in the tel- and diencephalon of rats following single or acute intermittent (-)nicotine treatment. The present results showed that acute intermittent (-)nicotine treatment (four i.p. injections at intervals of 30 min), but not single injections, lead to a substantial and dose-related (0.1-2 mg/kg) up-regulation of fibroblast growth factor-2 messenger RNA levels in the cerebral cortex, in the hippocampus, in the striatum and ventral midbrain. This induction of fibroblast growth factor-2 expression peaked 4 h after the first injection and returned to normal levels within 24 h. The change of fibroblast growth factor-2 messenger RNA levels was associated with increased fibroblast growth factor-2 immunoreactivity mainly localized to nerve cells. The treatment was effective also when repeated in the same animals three or five days after the first injection. The pre-treatment with the non-competitive (-)nicotine receptor antagonist mecamylamine blocked the (-)nicotine effects on fibroblast growth factor-2 messenger RNA levels. In the above areas, no changes were observed in the fibroblast growth factor-1, 2 and 3 receptor messenger RNA levels nor in brain-derived neurotrophic factor messenger RNA levels. The present data indicate an ability of intermittent (-)nicotine to increase fibroblast growth factor-2 in many tel- and diencephalic areas. In view of the trophic function of fibroblast growth factor-2, the previously observed neuroprotective effects of (-)nicotine may at least in part involve an activation of the neuronal fibroblast growth factor-2 signalling, and open up new avenues for treatment of Parkinson's disease and Alzheimer's disease based on the existence of nicotinic receptor subtypes enhancing fibroblast growth factor-2 signalling in many regions of the tel- and diencephalon.

Animals↗
PubMed2000

Distribution of met-enkephalin immunoreactivity in the diencephalon and the brainstem of the dog.

The endogenous opioid system, in particular the enkephalins, has been implicated in a vast array of neurological functions. The dog could be a suitable model for the study of complex interactions between behavioral state and regulatory physiology in which the opioid system appeared to be implicated. Moreover, opiate derivatives are currently used in veterinary clinic and sometimes pharmacologically tested in the dog. However, there are no anatomical data regarding the organization of the opioid system in this species. The present work represents the first attempt to map the distribution of Met(5)-enkephalin-like-immunoreactive (Met-enk-li) cell bodies and fibers in the diencephalon and the brainstem of the dog. In the diencephalon, labeled cells were present in all the mid-line and intralaminar thalamic nuclei; the lateral posterior, pulvinar and suprageniculate nuclei; the ventral nucleus of the lateral geniculate body and the medial geniculate body. Additionally, Met-enk-li cells were seen in every hypothalamic nucleus except in the supraoptic. Variable densities of labeled fibers were also seen in all these nuclei except in the medial geniculate body and in most areas of the lateral posterior and pulvinar nuclei. In the mesencephalon, positive cells were found in the periaqueductal gray, the Edinger-Westphal and interpeduncular nuclei, delimited areas of the superior and inferior colliculi and the ventral tegmental area. In the rhombencephalon, labeled cells were seen in the majority of the nuclei in the latero-dorsal pontine tegmentum, the nuclei of the lateral lemniscus, the trapezoid, vestibular medial, vestibular inferior and cochlear nuclei, the prepositus hypoglossal, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, the infratrigeminal nucleus and the caudal part of the spinal trigeminal nucleus and in the rhombencephalic reticular formation. The distribution of fibers included additionally the substantia nigra, all the trigeminal nerve nuclei, the facial nucleus and a restricted portion of the inferior olive. These results are discussed with regard to previous reports on the distribution of Met-enk in other species.

Animals↗
PubMed2001

Distribution of alpha-neoendorphin immunoreactivity in the diencephalon and the brainstem of the dog.

Alpha-neoendorphin (alpha-NE) is an opiate decapeptide derived from the prodynorphin protein. Its anatomical distribution in the brain of mammals other than the rat, particularly in carnivores, is less well known than for other opiate peptides. In the present work, we have charted the distribution of alpha-NE immunoreactive fibers and perikarya in the diencephalon and the brainstem of the dog. The highest densities of labeled fibers were found in the substantia nigra and in patches within the nucleus of the solitary tract. Moderate densities appeared in the arcuate nucleus (Ar), median eminence, entopeduncular nucleus, ventral tegmental area, retrorubral area, periaqueductal central gray, interpeduncular nucleus and lateral parabrachial nucleus. Groups of numerous labeled perikarya were localized in the magnocellular hypothalamic nuclei, Ar and in the central superior and incertus nuclei in the metencephalon. Moreover, less densely packed fibers and cells appeared widely distributed throughout many nuclei in the region studied. These results are discussed with regard to the pattern described in other species. In addition, the present results were compared with the distribution of met-enkephalin immunoreactivity in the diencephalon and the brainstem of the dog that we have recently described. Although the distributions of these two peptides overlap in many areas, the existence of numerous differences suggest that they form separate opiate systems in the dog.

Animals↗
PubMed2002

Cloning of two tryptophan hydroxylase genes expressed in the diencephalon of the developing zebrafish brain.

The monoamine serotonin (5-HT) exerts key neuromodulatory activities in all animal phyla, but the development and function of the serotonergic system is still incompletely understood. The zebrafish Danio rerio is an excellent model to approach this question since it is amenable to a combination of genetic, molecular and embryological studies. In order to characterize the organization of serotonergic neurons in the zebrafish we cloned two cDNAs encoding distinct forms of tryptophan hydroxylase (Tph), the rate-limiting enzyme in serotonin synthesis. We report here the pattern of expression of these two genes in relation with immunoreactive TH and 5-HT nuclei in the developing zebrafish embryo and early larva. tphD1 expression starts at 22 h post-fertilization (hpf) in the epiphysis and in basal spinal cells. Expression persists in the epiphysis until at least 4 days (dpf). Between 48 hpf and 3 dpf, tphD1 expression is initiated in retinal amacrine cells and in restricted preoptic and posterior tubercular nuclei within the basal diencephalon. At 3 and 4 dpf, tphD1 expression is newly initiated in the caudal hypothalamus and in branchial arches-associated neurons. tphD2 mRNA is detected transiently (between 30 somites and 32 hpf) in a restricted preoptic nucleus. All sites of tphD1 or D2 expression within the anterior central nervous system are also immunoreactive for 5-HT, but are not positive for TH. However, neither tphD gene is expressed in raphe nuclei, suggesting that additional tph gene(s) exist in zebrafish to account for 5-HT synthesis in that location. The co-expression of tphD1, tphD2 and 5-HT in the zebrafish diencephalon appears in striking contrast to the situation in mammals, where diencephalic serotonin results from re-uptake rather than from local production.

Animals↗
PubMed2002

Cloning of two tryptophan hydroxylase genes expressed in the diencephalon of the developing zebrafish brain.

The monoamine serotonin (5-HT) exerts key neuromodulatory activities in all animal phyla, but the development and function of the serotonergic system is still incompletely understood. The zebrafish Danio rerio is an excellent model to approach this question since it is amenable to a combination of genetic, molecular and embryological studies. In order to characterize the organization of serotonergic neurons in the zebrafish we cloned two cDNAs encoding distinct forms of tryptophan hydroxylase (Tph), the rate-limiting enzyme in serotonin synthesis. We report here the pattern of expression of these two genes in relation with immunoreactive TH and 5-HT nuclei in the developing zebrafish embryo and early larva. tphD1 expression starts at 22 h post-fertilization (hpf) in the epiphysis and in basal spinal cells. Expression persists in the epiphysis until at least 4 days (dpf). Between 48 hpf and 3 dpf, tphD1 expression is initiated in retinal amacrine cells and in restricted preoptic and posterior tubercular nuclei within the basal diencephalon. At 3 and 4 dpf, tphD1 expression is newly initiated in the caudal hypothalamus and in branchial arches-associated neurons. tphD2 mRNA is detected transiently (between 30 somites and 32 hpf) in a restricted preoptic nucleus. All sites of tphD1 or D2 expression within the anterior central nervous system are also immunoreactive for 5-HT, but are not positive for TH. However, neither tphD gene is expressed in raphe nuclei, suggesting that additional tph gene(s) exist in zebrafish to account for 5-HT synthesis in that location. The co-expression of tphD1, tphD2 and 5-HT in the zebrafish diencephalon appears in striking contrast to the situation in mammals, where diencephalic serotonin results from re-uptake rather than from local production.

Amino Acid Sequence↗
PubMed1972

Eating caused by 6-hydroxydopamine-induced release of noradrenaline in the diencephalon of the rat.

1. Although it is well established that exogenous noradrenaline injected into the diencephalon causes the satiated rat to eat, it is not known whether eating may be induced by release of endogenous diencephalic noradrenaline. In the present experiment 6-hydroxydopamine was injected into the diencephalon of the rat to release catecholamines and produce degeneration of catecholamine-containing neurones.2. Injection into the preoptic area of 0.01-16.0 mug of 6-hydroxydopamine caused satiated rats to eat.3. All doses of 6-hydroxydopamine above 0.01 mug produced long-lasting partial depletion of noradrenaline and dopamine in the region of the brain composed of septum, preoptic area and hypothalamus.4. Repeated injections of 8 mug 6-hydroxydopamine at intervals of several days caused progressively less eating.5. Eating in response to 6-hydroxydopamine was inhibited by pre-treatment with desmethylimipramine, or by pre-treatment with the adrenergic blocking agents phentolamine or MJ-1999.6. Water intake after 6-hydroxydopamine was reduced by pre-treatment with desmethylimipramine or MJ-1999 but was enhanced after pre-treatment with phentolamine.7. It is concluded that release of diencephalic catecholamines by injection of 6-hydroxydopamine causes eating in rats and that the catecholamine responsible for eliciting eating is noradrenaline.

Adrenergic beta-Antagonists↗
PubMed1977

The effect of some phenylethanolamine N-methyltransferase inhibitors on the adrenaline content in the domestic fowl diencephalon.

The concentration of adrenaline in the domestic fowl diencephalon was determined by a mass spectrometric or fluorimetric method. The values obtained were 701 and 803 ng/g, respectively. The administration of phenylethanolamine N-methyltransferase (PNMT) (EC 2.1.1.28) inhibitors (SK&F 7698 or SK&F 64139) to the domestic fowl produced a marked reduction in the diencephalic noradrenaline methylation (from 25% in the controls ot 7--8% in the PNMT-inhibitor-treated animals); the large decrease in adrenaline concentration (to 14--18% of controls) was accompanied by a moderate decrease in noradrenaline concentration (to 63--84% of controls). Reserpine, in contrast, produced a marked reduction of both adrenaline and noradrenaline (to 12 and 17% of controls, respectively) but did not affect the percentage of methylation. It would seem a reasonable assumption that in the domestic fowl diencephalon, adrenaline is formed by N-methylation of noradrenaline and functions there as a transmitter in some specific adrenergic neuronal pathways.

Animals↗
PubMed1989

Effects of synaptic blockade on thermosensitive neurons in rat diencephalon in vitro.

To identify the distribution of inherently thermosensitive and conditionally (i.e., synaptically dependent) thermosensitive neurons in the rat diencephalon, single-unit recordings (n = 88) were made in horizontal tissue slices during localized thermal stimulation before, during, and after reversible synaptic blockade. Inherently warm-sensitive neurons (n = 17) were found in 10 nuclei, the largest number occurring in the preoptic area-anterior hypothalamus (POAH). Inherently cold-sensitive neurons (n = 5) were encountered in three nuclei, with the highest number in the posterior hypothalamus (PH) and mammillary body (MB). Fifty-nine percent of the inherently thermosensitive neurons showed a change in spontaneous activity and/or thermosensitivity during synaptic blockade, indicating that these neurons undergo synaptic modulation. Conditionally warm-sensitive neurons (n = 14) were found in six nuclei with the majority of these neurons located in the accumbens nucleus, diagonal band of Broca, and PH-MB. Two conditionally cold-sensitive neurons were found in the POAH and one in the MB. Temperature-insensitive neurons (n = 49) were rarely affected by synaptic blockade. Thus inherently and conditionally thermosensitive neurons are found in many locations in the diencephalon. These thermosensitive neurons may belong to the neuronal networks responsible for thermo-regulation and the other homeostatic systems that are influenced by temperature.

Animals↗
PubMed1995

Discharge patterns of hippocampal theta-related cells in the caudal diencephalon of the urethan-anesthetized rat.

1. Single-unit discharge patterns of cells in specific nuclei of the caudal diencephalon were characterized in relation to simultaneously recorded field activity from the stratum moleculare of the dentate gyrus according to the criteria that have been used previously to classify cells in the hippocampal formation (including entorhinal cortex), medial septum, and cingulate cortex. Theta (theta)-related cells were classified as 1) tonic theta-ON, if they discharged nonrhythmically and increased their discharge rates during hippocampal theta relative to large, irregular hippocampal field activity (LIA); 2) tonic theta-OFF, if they discharged nonrhythmically and decreased their discharge rates during theta relative to LIA; or 3) phasic theta-ON, if they discharged rhythmically and in phase with ongoing theta, but nonrhythmically during LIA. Cells not meeting any of the above criteria were classified as nonrelated. 2. Recordings were obtained in a total of 127 cells from the caudal diencephalon. Recordings were made in 54 cells from the posterior hypothalamic nucleus (PH), 16 from the supramammillary nucleus (SuM), 20 from the PH/SuM border, and 23 from the medial mammillary nucleus (MM). Recordings were also made from nine cells from the central medial nucleus of the thalamus (CM) and five from the dorsomedial hypothalamic nucleus (DMH). 3. Of the 54 PH cells, 43 (80%) were classified as tonic theta-ON and 11 (20%) as nonrelated. Tonic theta-ON cells in the PH discharged at significantly higher rates during theta, either occurring spontaneously (9.6 +/- 1.7 Hz, mean +/- SE) or elicited with a tail pinch (TP theta; 10.6 +/- 1.9 Hz), than during LIA (3.6 +/- 1.4 Hz). Of the nine CM cells, seven (78%) were tonic theta-ON and two (22%) were nonrelated. Tonic theta-ON cells discharged at significantly higher rates during theta (17.5 +/- 7.8 Hz) or TP theta (18.0 +/- 7.1 Hz) than during LIA (7.3 +/- 4.8 Hz). All DMH cells were nonrelated. 4. Of the 20 PH/SuM border cells, 15 (75%) were classified as tonic theta-OFF and discharged at significantly higher rates during LIA (5.3 +/- 1.5 Hz) than during theta (0.8 +/- 0.4 Hz) or TP theta (0.4 +/- 0.3 Hz). Five (25%) cells in the PH/SuM border were nonrelated. 5. All of the 16 cells (100%) recorded from the body of the SuM were phasic theta-ON. The discharge rates of these cells did not change significantly across hippocampal field states (LIA = 8.3 +/- 1.6; theta = 7.3 +/- 1.6; TP theta = 8.6 +/- 1.7 Hz).(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗
PubMed1998

The diencephalon and pretectum of the white sturgeon (Acipenser transmontanus): a cytoarchitectonic study.

The cytoarchitecture of the diencephalon and pretectum of the white sturgeon, Acipenser transmontanus, was studied utilizing cresyl violet stained serial paraffin sections. The identified cell groups were assigned to the preoptic area, hypothalamus, thalamus and posterior tubercle, epithalamus, synencephalon and pretectum. The outlines of the diencephalic and pretectal nuclei were projected graphically onto a midsagittal section of the brain, thus providing a reconstruction of the relative positions of the major cell groups. This facilitated comparisons with the diencephalic and pretectal nuclei of other ray-finned fishes. Our cytoarchitectural analysis indicates that the diencephalon and pretectum of the white sturgeon is intermediate to that described for cladistians and neopterygians. The preoptic area in Acipenser is relatively conservative compared to other ray-finned fishes but lacks distinct subdivisions in the magnocellular periventricular preoptic nucleus and includes a unique migrated rostral accessory nucleus. The hypothalamic walls are rather thin, and due to the presence of extensive lateral and posterior recesses and the lack of migrated nuclei, they superficially resemble the condition seen in sharks. The dorsal and ventral thalamic nuclei do not exhibit much variation compared to other ray-finned fishes, except for the presence of a small lateral posterior thalamic nucleus, the absence of a distinct ventrolateral thalamic nucleus, and slight differences in the internal organization of the ventromedial thalamic nucleus. The posterior tubercle in Acipenser clearly comprises more migrated cell groups than that of Polypterus, however, these cell groups are considerably less well defined than in neopterygians. As in other nonteleost actinopterygians, the habenular nuclei are highly asymmetrical with the right side larger than the left side. The cytoarchitectonic complexity of the pretectum in Acipenser is intermediate to that observed in Polypterus and neopterygians in that a magnocellular component within the superficial pretectal nucleus is clearly present but cannot be delineated as a distinct magnocellular superficial pretectal nucleus. Also, the posterior pretectal nucleus which is absent in Polypterus but which has been identified as a small nucleus both in Lepisosteus and Amia is represented in Acipenser by a small group of scattered cells.

Animals↗
PubMed2000

Expression of Foxb1 reveals two strategies for the formation of nuclei in the developing ventral diencephalon.

Fork head b1 (Foxb1; also called Fkh5, HFH-e5.1, Mf3) is a winged helix transcription factor gene whose widespread early expression in the developing neural tube is soon restricted to the ventral and caudal diencephalon. During diencephalic neurogenesis, Foxb1 is expressed in one patch of neuroepithelium comprising a large mammillary portion and a smaller tuberal portion. The labeled cells coming from this patch contribute to nuclear formation by means of two different strategies: (1) caudally, the young neurons aggregate and settle immediately, giving rise to the nuclei of the mammillary body; (2) rostrally, the young neurons separate from the neuroepithelium forming a trail of cells which spans the mantle layer mediolaterally and which will give rise to two separate cell groups (the dorsal premammillary and part of the lateral hypothalamic area). Our results show the elaborate, regionalized histogenetic mechanisms necessary for the differentiation of the caudal diencephalon; moreover, they suggest that specifically labeled populations, arising from specifically labeled neuroepithelial patches and giving place to specific brain nuclei could be a common mechanism to build complex, nonlaminar regions of the forebrain.

Animals↗
PubMed2004

The distribution and morphological characteristics of catecholaminergic cells in the diencephalon and midbrain of the bottlenose dolphin (Tursiops truncatus).

The present study describes the distribution and cellular morphology of catecholaminergic neurons in the diencephalon and midbrain of the bottlenose dolphin (Tursiops truncatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these putatively dopaminergic neurons. The standard A1-A17, C1-C3, nomenclature is used for expediency; however, the neuroanatomical names of the various nuclei have also been given. Dolphins exhibit certain tyrosine hydroxylase immunoreactive (TH-ir) catecholaminergic neuronal groups in the midbrain (A8, A9, A10) and diencephalon (A11, A12, A14), however, no neuronal clusters clearly corresponding to the A13 and A15 groups could be identified. The subdivisions of these neuronal groups are in general agreement with those of other mammals, but there is a high degree of species specificity. First, three TH-ir neuronal groups not identified in other species were found: in the ventral lateral peri-aqueductal gray matter, posterior dorsal hypothalamus, and rostral mesencephalic raphe. Second, the normal components of the substantia nigra (A9 or pars compacta, A9 lateral or pars lateralis, A9 ventral or pars reticulata) were extremely cell sparse, but there was a substantial expansion of the A9 medial and A10 lateral subdivisions forming an impressive 'ventral wing' in the posterior substantia nigra. The findings of this and previous studies suggest a distinct evolutionary trend occurring in the neuromodulatory systems in mammals. The results are discussed in relation to motor control, thermoregulation, unihemispheric sleep, and dolphin cognition.

Animals↗
PubMedDate not supplied

Role of computerized transverse axial tomography on stereotactic surgery of the diencephalon. A preliminary report of 67 cases.

67 cases of various functional disorders of the diencephalon were examined by EMI scanner. The patients were composed of 38 cases of parkinsonism, 7 cases of thalamic syndrome, 6 cases of choreoathetoid movement, 2 cases of dystonia, 11 cases of involuntary movement of unknown etiology and 1 case of torticollis, tic, and ballismus, respectively. In parkinsonism, 79% showed diffuse cerebral atrophy, 5% had focal low density in the substantia nigra and the thalamus, whereas 16% remained normal. Pre- and postoperative assessment with CT scan was briefly discussed with reference to stereotactic surgery of the diencephalon.

Adult↗