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PubMed1997

Expression of the cell adhesion molecule axonin-1 in neuromeres of the chicken diencephalon.

Axonin-1/TAG-1, a member of the immunoglobulin (Ig) superfamily of adhesion molecules, has been shown to be selectively expressed by a subset of neurons and fiber tracts in the developing nervous system of vertebrates. Axonin-1/TAG-1 is thought to play a role in the outgrowth, guidance, and fasciculation of neurites. In the present study, we map the expression of axonin-1 in the diencephalon of the chicken brain at early and intermediate stages of development [2-8 days of incubation; embryonic day (E)2-E8] by immunohistochemical methods. Results show that axonin-1 is first expressed at about E2.5 by postmitotic neurons scattered throughout most of the diencephalon. During the neuromeric stage of brain development (about E3-E5), axonin-1+ nerve cell bodies are predominantly found in two neuromeric subdivisions: 1) in the alar plate of the precommissural pretectum and dorsal thalamus and 2) in the posterior preoptic region of the hypothalamus. The axonin-1+ fiber bundles emerging from these areas grow across segmental boundaries. For example, axonin-1+ neurites originating in the dorsal thalamus cross the zona limitans intrathalamica at a right angle to project to the striatum. Later, the axonin-1+ neuromere areas give rise to particular axonin-1+ gray and white matter structures. Most of these structures correspond to the structures described to express TAG-1 in rodents. In conclusion, axonin-1 can be used as a marker to study aspects of the transition from the early neuromeric structure to the mature anatomy of the chicken brain.

Animals↗
PubMed2003

Catecholaminergic systems in the zebrafish. IV. Organization and projection pattern of dopaminergic neurons in the diencephalon.

In the diencephalons of the adult zebrafish brain, all catecholamine-containing neurons are dopaminergic. The organization and projection pattern of these neurons are studied using tyrosine hydroxylase immunocytochemistry. By their locations, 3 neuronal complexes and 17 cell groups are identified on the bases of their morphology, staining intensity, and projection pattern: 1) the preoptic complex (5 groups); 2) the posterior tuberal complex (4 groups); and 3) the hypothalamic complex (5 groups). In addition, three other groups can be distinguished: one group in the ventral thalamus; one in the pretectal area, and one found in the postoptic commissure and above the pituitary stalk in a few brains. Two dopaminergic pathways are defined: 1) the preoptico-hypophyseal tract runs in close association with the lateral forebrain bundle along the base of the brain between the preoptic area and the pituitary stalk, and neurons of the preoptic complex are major contributors to this pathway; additional fibers come from the large periventricular organ-associated neurons of the posterior tuberal; 2) the endohypothalamic tract links neurons of the hypothalamic complex and consists mainly of processes from hypothalamic neurons. Axons from neurons of the suprachiasmatic, periventricular organ-associated, and posterior tuberal nuclei also join this pathways after entering the hypothalamus. Several groups of neurons contact the cerebrospinal fluid. These appear to be primarily local neurons because none have processes that join the two major pathways. The preoptic area, dorsal thalamus, tuberal and hypothalamic areas, optic tectum, and pituitary are the major targets of diencephalic dopaminergic neurons. The dorsal telencephalon does not receive input from these cells. The large periventricular organ-accompanying neurons have descending projections beyond the diencephalon and isthmus. Some cells of this group terminate in the crista cerebellaris. A few axons also exit the medulla via a branch of the octavolateralis nerve.

Animals↗
PubMed1982

Ontogeny of somatostatin-containing neuron system of the rat: immunohistochemical analysis. II. Forebrain and diencephalon.

The ontogeny of the somatostatin (SRIF) neuron system in the forebrain and diencephalon the rat was investigated by means of the indirect immunofluorescence method. SRIF-positive cells first appear in the primordium of the hypothalamus surrounding the fasciculus mammillothalamicus of the fetus at gestational day 14 (10-12-mm embryo). At gestational days 16-17 (14-17-mm embryo, SRIF-positive cells appear in the developing piriform cortex and entopeduncular nucleus. The fetus at gestational days 18-19 (17-26-mm embryos) showed a remarkable increase in the number of SRIF-positive cells and numerous groups of such cells are detectable in various forebrain and diencephalic areas such as the hypothalamic periventricular zone, zona incerta, area lateral to the commissura posterior (ACP), area between the optic tract and capsula interna, pars retrolenticularis (AOR), n. caudatus putamen, hippocampus, somatic sensory cortex, and n. accumbens, etc. At gestational day 20, SRIF-positive cells newly appear in the septum, olfactory bulb, diagonal band of Broca, claustrum, lateral preoptic area, and lateral habenular nucleus. The majority of SRIF-positive structures found in the forebrain and diencephalon increase in number during the perinatal stage (between gestational day 21 and postnatal day 2) and more or less maintain their immunoreactivity even in adult rats. However, SRIF-positive cells located in the AOR, ACP, and lateral septal area, etc., begin to decrease in number during the perinatal stage and no or only a few SRIF-containing cells are identified in these areas of infant and adult rats.

Animals↗
PubMed1982

The localization of vasotocin and neurophysin neurons in the diencephalon of the pigeon, Columba livia.

Vasotocin (VT)- and neurophysin (NP)-synthesizing neurons were demonstrated by immunocytochemistry in the diencephalon of the pigeon, Columba livia. Three diencephalic regions contain VT-NP cells: (1) periventricular preoptic area and hypothalamus, including nucleus periventricularis magnocellularis (PVM); (2) lateral preoptic area and hypothalamus; and (3) dorsal diencephalon. The immunoreactive cells in each of these three regions were divided into groups based on cytology and topography. No differences were found in the location of VT and NP cell groups. The periventricular region contains three continuous cell groups (P1-P3) extending from the posteroventral preoptic area to the anterodorsal hypothalamus and PVM. The lateral region has two cell groups composed of medium- to large-sized cells associated with the quintofrontal tract (L1) or with the optic tract (L2), while a third group (L3) lies between these two cell groups. Two accessory cell groups reside in the dorsolateral hypothalamus; L4 contains scattered cells of varied size, whereas L5 has small- to medium-sized cells clumped together. The dorsal diencephalic cell groups are found in the following locations: (1) lateral and dorsal to the lateral forebrain bundle (DD1); (2) in the area ventral to the dorsomedial anterior thalamic nucleus and dorsolateral to PVM (DD2); and (3) at the dorsolateral border of nucleus rotundus (DD3). To avoid potentially inaccurate mammalian homologies, the cell group nomenclature denotes topographic position. Nevertheless, the presence of VT-NP cells in PVM and projections to the brainstem and spinal cord suggest a homology between PVM and some of the parvocellular subnuclei of the mammalian paraventricular nucleus.

Animals↗
PubMed1988

Cell death in suboptic necrotic centers of chick embryo diencephalon and their topographic relationship with the earliest optic fiber fascicles.

The structural features of suboptic necrotic centers (SONCs) in the floor of the chick embryo diencephalon were studied. These necrotic areas were observed lateral to the prospective zone of the optic chiasm through developmental stages 14 to 24. The relationship between SONCs and the earliest optic fiber fascicles also was studied in an attempt to determine the possible significance of these cell death areas in the mechanism of optic pathway development. In SONCs, healthy neuroepithelial cells contain primary lysosomes and phagocytose fragments of dead cells. Discrete regions within the cytoplasm of some cells show electron-transparent vacuoles in contact with dense contents of ruptured lytic bodies. The cytoplasm of dying cells and dead cell fragments are notably electron dense, with numerous secondary lysosomes and electron-transparent vacuoles. These observations are interpreted on the assumption that after autophagic processes, condensation and fragmentation take place in dying cells of the SONCs. In the ventricular lumen adjacent to the SONCs, numerous more or less spherical bodies are observed that appear to be shed from the tip of the cells constituting the SONCs. Three different types of intraventricular bodies can be distinguished: loose, moderately dense, and highly dense. The first type appears to originate from apical portions of cells that undergo autolytic processes. Moderately dense fragments are interpreted as originating from dying cells in which the cytoplasm is undergoing condensation. Finally, highly dense intraventricular bodies appear to be fragments of dead cells that are shed into the ventricular lumen. SONCs separate the prospective area of the optic chiasm from lateral regions of the diencephalic floor. Extracellular spaces are poorly developed within the wall of the SONCs, whereas the neuroepithelium of the presumptive optic chiasm and regions located rostral and caudal to SONCs show abundant and extensive extracellular spaces. These are bounded by long marginal processes of neuroepithelial cells. Sagittal sections of embryonic heads at stages 22-24 reveal optic fiber fascicles penetrating the SONCs asymmetrically, as they are found only in its caudal half. These observations suggest that the SONCs function as doorways made of compact neuroepithelium, to be traversed by the earliest optic fibers before they reach the middle zone of the floor of the diencephalon through which they travel to the contralateral optic tract within large extracellular spaces.

Animals↗
PubMed1989

GABA-like immunoreactivity of neurons in the chicken diencephalon and mesencephalon.

The chick brain is a useful model system for studying the ontogeny and phylogeny of neural circuitry, especially that of the visual system. In this study the distribution of cells and processes showing GABA-like immunoreactivity (GABA+) in the diencephalon and mesencephalon of the posthatch chick was determined immunohistochemically with a polyclonal antibody to GABA and compared with the results of similar studies in mammals. Most of the small GABA+ cells were found in the chick visual centers such as the nucleus lateralis anterior, suprachiasmatic nucleus, ventral lateral geniculate, optic tract, dorsolateralis anterior pars lateralis, lentiformis mesencephali, ectomammillary nucleus, area pretectalis, and the optic tectum. Large GABA+ cells were found in the following nuclei: reticularis superior, posteroventralis thalami, subpretectalis, isthmi pars magnocellularis, interstitio-pretectosubpretectalis, mesencephalicus lateralis pars dorsalis. These large cell-containing nuclei receive projections from visual or auditory centers. GABA+ axons were found throughout the diencephalon and mesencephalon but were especially prominent in the ansa lenticularis, fasciculus medialis longitudinalis, and optic tract. The distribution of GABA+ cells in the chick is more widespread than in rodents and exhibits an increased association with the visual centers suggesting a correlation with the specialized visual requirements of the bird.

Animals↗
PubMed1991

Immunohistochemical localization of serotoninergic, enkephalinergic, and catecholaminergic cells in the brainstem and diencephalon of a cartilaginous fish, Hydrolagus colliei.

We localized serotonin (5-HT), leu-enkephalin (LENK), and tyrosine hydroxylase (TH) immunoreactive cells in the brain of a holocephalian, Hydrolagus colliei, by use of antibodies made in rabbit and the peroxidase-antiperoxidase technique. Only three locations contained TH+ cells, the caudal myelencephalon, the locus coeruleus, and the diencephalon. Of these locations, the diencephalon contained the most cells and the locus coeruleus the least cells. The caudal TH+ myelencephalic cells formed a single large group that spanned both the dorsal and ventral portions of the brain (A1A2). The diencephalic TH+ cells were located in the posterior tuberculum, in the ventromedial and ventrolateral thalamic nuclei, and in the inferior lobe of the hypothalamus. Hydrolagus differed from mammals and the elasmobranchs, their sister group, in that no substantia nigra (A9), ventral tegmental area (A10), or A5 cell group was found. Distribution of LENK+ and 5-HT+ cells were similar to each other; the raphe nuclei contained most of the 5-HT+ and LENK+ cells. These 5-HT+ and LENK+ cells were found at all rostrocaudal levels of the myelencephalon. The nucleus reticularis magnocellularis, reticularis paragigantocellularis lateralis, the ventral met- and mesencephalon (B7 and B9 cell groups), the hypothalamus, and the pretectal area contained additional 5-HT+ and LENK+ cells. The solitary complex contained LENK+ cells but not but 5-HT+ cells. A dorsal raphe nucleus, which is the largest 5-HT+ cell group in mammals, was absent in Hydrolagus. A dorsal raphe nucleus is present in one galeomorph shark radiation but is absent in three radiations of batoids (rays, skates, and guitarfish). Thus even within cartilaginous fish, there are differences in the distribution of neurochemicals and possibly nuclei within their brains.

Animals↗
PubMed1992

Immunohistochemical localization of nicotinic acetylcholine receptor subunits in the mesencephalon and diencephalon of the chick (Gallus gallus).

Monoclonal antibodies against two alpha-bungarotoxin-binding subunits (alpha 7 and alpha 8) of the nicotinic acetylcholine receptors (nAChRs) were used as immunohistochemical probes to map their distribution in the chick diencephalon and mesencephalon. The distribution of the alpha 7 and alpha 8 nAChR subunits was compared to the distribution of immunoreactivity produced by a monoclonal antibody against the beta 2 structural subunit of the nAChRs. Structures that contained high numbers of alpha 7-like immunoreactive (LI) somata included the intergeniculate leaflet, nucleus intercalatus thalami, nucleus ovoidalis, organum paraventricularis, nucleus rotundus, isthmic nuclei, nucleus trochlearis, oculomotor complex, nucleus interstitio-pretecto-subpretectalis, stratum griseum centrale of the optic tectum, and nucleus semilunaris. Neuropil staining for alpha 7-LI was intense in the nucleus dorsomedialis hypothalami, nucleus geniculatus lateralis ventralis, griseum tecti, isthmic nuclei, nucleus lentiformis mesencephali, nucleus of the basal optic root, and stratum griseum et fibrosum superficiale of the tectum. High numbers of alpha 8-LI somata were found in the stratum griseum et fibrosum superficiale of the tectum and the nucleus interstitio-pretecto-subpretectalis, and intense neuropil staining for alpha 8-LI was found in the dorsal thalamus, nucleus geniculatus lateralis ventralis, lateral hypothalamus, griseum et fibrosum superficiale of the tectum. High numbers of beta 2-LI somata were found only in the nucleus spiriformis lateralis, whereas neuropil staining for beta 2-LI was intense in the nucleus geniculatus lateralis ventralis, nucleus suprachiasmaticus, nucleus lateralis anterior, nucleus habenularis lateralis, area pretectalis, griseum tecti, nucleus lentiformis mesencephalis, nucleus externus, and nucleus interpeduncularis, and in the stratum griseum centrale, stratum griseum et fibrosum superficiale, and stratum opticum of the tectum. These results indicate that there are major disparities in the localization of the alpha-bungarotoxin-binding alpha 7 and alpha 8 nAChR subunits and the beta 2 structural nAChR subunit in the chick diencephalon and mesencephalon. These nAChR subunits appear, however, to coexist in several regions of the chick brain.

Animals↗
PubMed1995

Organization of permanent and transient neuropeptide Y-immunoreactive neuron groups and fiber systems in the developing hamster diencephalon.

The development of neuropeptide Y-immunoreactive (NPY-IR) cell and fiber systems in the hamster diencephalon was studied. Eight perinatal groups of NPY-IR neurons develop into 12 distinct sets in nuclei of the adult diencephalon and mesencephalon. NPY-IR neurons of the thalamic precommissural nucleus, nucleus of the optic tract, and olivary pretectal nucleus are derived from the superior group. Those in the adult magnocellular nucleus of the posterior commissure and deep mesencephalic nucleus are from the dorsal group. An arcuate group contributes neurons to the arcuate nucleus and median eminence and a mammillary group transiently exists in the mammillary region. A medial group gives rise to two sets of neurons, one that migrates to the intergeniculate leaflet and another that develops in the medial nucleus reuniens. A very large ventral group provides NPY-IR neurons to the adult medial zona incerta and caudal reticular thalamus. Groups of NPY-IR neurons also appear in the bed nucleus of the stria terminalis and centromedian thalamic nucleus. Superior group neurons may undergo apoptosis. In several groups, neurons become fewer during development, and NPY-IR may disappear. NPY-IR neurons of several groups initially migrate away from the neuroepithelial zone with later emergence of a distinct, persistent set of NPY-IR neurons in the same neuroepithelial region. The data show that neuropeptide content can be used to identify particular sets of neurons early in development, thereby allowing migration patterns to be followed and principles of brain development to be elucidated.

Animals↗
PubMed1992

Histochemical distribution of zinc in the brain of the rainbow trout, Oncorhynchos myciss. II. The diencephalon.

The distribution of zinc in the diencephalon of the rainbow trout, Oncorhynchos myciss, is described in the present paper, which is the second in a series of three reporting for the first time the distribution of a heavy metal in the fish brain. The Neo-Timm method was used for the histochemical demonstration of zinc. The staining was essentially confined to the neuropil, in all probability representing stained axon terminals, but stained nerve cell bodies were observed in the nucleus lateralis geniculatus and the nucleus cerebellosus hypothalami. Stained fibers were never seen. The staining gave rise to a consistent, specific distribution pattern, which accorded well with the diencephalic nuclei defined on the basis of cytoarchitectural criteria. The diencephalon was in general stained with much higher intensity than the telencephalon, in surprising contrast to the state of affairs in the mammalian, reptilian, and avian brain. In species of these classes, high staining intensities are observed almost exclusively in the telencephalon. The Neo-Timm staining was predominantly distributed in the nuclei of the periventricular zone, but some internal (migrated) nuclei did show a positive staining reaction, namely the nucleus lateralis geniculatus, the anterior thalamic nucleus, the nucleus diffusus tori lateralis, and the nucleus cerebellosus hypothalami. The zinc distribution pattern has been compared with the terminal fields of afferent projections, known from experimental studies, and with the distribution of substance P. The possible function of zinc in synaptic vesicles is considered.

Animals↗
PubMed1992

Development of the tectum and diencephalon in relation to the time of arrival of the earliest optic fibres in Xenopus.

The development of the tectum and diencephalon in Xenopus has been investigated in relation to recent descriptions of the establishment of the retinotectal projection. Tritiated thymidine autoradiography and bromodeoxyuridine immunohistology were used to identify the stages at which cells became postmitotic. Cells in the diencephalon were found to become postmitotic before cells in the tectum. At the time of arrival of the first optic fibres (stage 37/38) no postmitotic cells appeared to be present in the tectal precursor region. The first postmitotic cells which could be definitely assigned to the tectum appeared between stages 41 and 45. The results suggest that the initial retinotopic ordering of optic fibres observed from stage 37/38 relates to the position of fibres in the optic tract and not the tectum.

Animals↗
PubMed1996

Comparative distribution of NADPH-diaphorase activity and tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the domestic chicken (Gallus domesticus).

We described the distribution of NADPH-diaphorase-containing neurons in relation to tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the chicken. In the diencephalon, both markers were found in the lateral hypothalamus, dorsal hypothalamic area, hypothalamic periventricular nucleus, paraventricular nucleus and mamillary area. A close examination showed that the fine distribution of these markers differed slightly, so that they were never observed in the same neurons. In the mesencephalon, NADPH-diaphorase and tyrosine hydroxylase immunoreactivity were found in the ventral pedunculopontine area (nucleus tegmenti pedunculopontinus pars compacta, adjacent areas surrounding the quintofrontal tract and the nucleus mesencephalicus profundus ventralis), the coeruleus complex (locus coeruleus, ventral and dorsal subcoeruleus nuclei), the ventral tegmental area and the central gray. The majority of these neurons contained either diaphorase or tyrosine hydroxylase. Nevertheless, in a few cases both markers appeared to colocalize in the same neuron, typically in large perikarya of the ventral pedunculopontine area.

Animals↗
PubMed1994

Activation of noradrenergic neurons projecting to the diencephalon following central administration of histamine is mediated by H1 receptors.

The effect of histamine on the activity of noradrenergic neurons terminating in discrete regions of the diencephalon was examined in male rats. Noradrenergic neuronal activity was estimated by measuring the concentration of norepinephrine and its metabolite 3-methoxy-4-hydroxyphenylethyleneglycol [MHPG] in the medial zona incerta [MZI] and in the dorsomedial [DMN], periventricular [PeVN] and medial preoptic hypothalamic nuclei [MPN]. The intracerebroventricular administration of histamine effected a time-related increase in MHPG concentrations in the MZI, DMN, PeVN and MPN; these effects were blocked by the H1 antagonist mepyramine but not the H2 antagonist zolantidine. Neither mepyramine nor zolantidine affected basal MHPG concentrations in any of the brain regions examined. These results indicate that central administration of histamine increases the activity of noradrenergic neurons projecting to the diencephalon via an action at H1 but not H2 receptors.

Animals↗
PubMed1991

Substituted piperazine and indole compounds increase extracellular serotonin in rat diencephalon as determined by in vivo microdialysis.

In vivo microdialysis was used to examine the effects of 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU24969) and 1-(m-trifluoromethylphenyl)piperazine (TFMPP) on extracellular 5-hydroxytryptamine (5-HT) in the diencephalon of unanesthetized rats. Both RU24969 and TFMPP are potent 5-HT autoreceptor agonists but both compounds caused a dose-dependent increase in extracellular 5-HT, when infused into the diencephalon at micromolar concentrations. The piperazine compound, TFMPP, also caused an increase in 5-HT when administered peripherally (2.5-10 mg/kg i.p.). In contrast, peripheral administration of RU24969 (2.5 mg/kg i.p.) caused a decrease in extracellular 5-HT. Since the effects of local infusion with RU24969 and TFMPP were not additive with the increase produced by the inhibitor of the uptake of 5-HT, fluoxetine, these compounds may be acting at the site of the membrane carrier. These results suggest that direct 5-HT1 agonist activity is not the only factor involved in the physiological and behavioral consequences of peripheral administration of TFMPP.

Animals↗
PubMed1991

Somatostatin-28 (1-12)-like immunoreactivity in the cat diencephalon.

Using an indirect immunoperoxidase technique, the location of somatostatin-28 (1-12)-like immunoreactive fibres and cell bodies in the cat diencephalon was studied. The hypothalamus was richer in somatostatin-28 (1-12)-like immunoreactive structures than the thalamus. A high density of immunoreactive fibres was observed in the nuclei habenularis lateralis, paraventricularis anterior (its caudal part), filiformis, hypothalami ventromedialis, and regio praeoptica, whereas a moderate density was found in the nuclei paracentralis, supraopticus, supra chiasmaticus, hypothalamus posterior and area hypothalamica dorsalis. The nuclei lateralis dorsalis, lateralis posterior, medialis dorsalis, rhomboidens, centralis medialis, ventralis medialis, reuniens, anterior dorsalis, parataenialis, interanteromedialis, hypothalamus lateralis, hypothalamus dorsomedialis and arcuatus had the lowest density of immunoreactive fibres. In addition, a high or moderate density of somatostatin-28 (1-12)-like immunoreactive cell bodies was observed in the nuclei paraventricularis hypothalami, supraopticus, supra chiasmaticus, area hypothalamics dorsalis, subparafascicularis, hypothalamus posterior and hypothalamus anterior, whereas scarce immunoreactive perikarya were visualized in the nuclei lateralis dorsalis and parafascicularis. The distribution of somatostatin-28 (1-12)-like immunoreactive structures is compared with the location of other neuropeptides in the cat diencephalon.

Animals↗
PubMed1990

Translingual approach of the basal surface of the diencephalon of the rat and retrograde labeling from the median eminence.

A unique surgical procedure is described by which the basal surface of the diencephalon can be exposed without cannulation of the trachea. The basal surface of the diencephalon is exposed through a midsagittal incision by splitting the oral diaphragm, tongue, and soft palate respectively. Then a small hole is drilled in the base of the skull. After manipulation on the base of the brain is completed, the hole in the skull is plugged with Histoacryl and the soft palate and tongue are sutured. Rats having such interventions survive in excellent condition for days without the need of intensive medical care.

Animals↗
PubMed1988

Ontogeny of calcitonin gene-related peptide-immunoreactive structures in the rat forebrain and diencephalon.

Ontogeny of the calcitonin gene-related peptide (CGRP)-containing structures was investigated in the forebrain and diencephalon of the rat by means of indirect immunofluorescence. CGRP-like immunoreactive (CGRP-IR) fibers first appeared at gestational day 18 (E18) in the primordia of the bed nucleus of the stria terminalis, central amygdaloid nucleus and posterolateral portion of the lateral hypothalamic nucleus. CGRP-IR fibers gradually increased in immunoreactivity and in number in these nuclei toward birth. A pronounced increase of CGRP-like immunoreactive fibers was found after birth in these nuclei and made very dense plexuses of fibers in adult animals. A few CGRP-IR fibers first appeared at the perinatal stage in the lateral septum, the most caudal portion of the caudate-putamen, and ventromedial and ventroposterior thalamic nuclei. Then the immunoreactive fibers increased and dense plexuses were present in these brain areas of the adult. A small number of immunoreactive fibers appeared at postnatal day 4-7 (P4-7) in the caudal insular cortex and ventromedial hypothalamic nucleus. A significant number of fibers was present in these areas of the adult. On the other hand, CGRP-like immunoreactivity in cell bodies was first detected with faint immunofluorescence at P4 in the anteromedial parts of the lateral hypothalamic area and ventromedial and ventroposterior thalamic nuclei. Thereafter CGRP-IR cells increased in immunoreactivity, and a significant number of cells was noted in these nuclei of the adult. In addition, CGRP-IR cells are identified in the medial amygdaloid nucleus, and medial preoptic area at P14. In conclusion, in the forebrain and diencephalon (1) CGRP-like immunoreactivity appears in fibers earlier than in cell bodies, suggesting that at least some of immunoreactive fibers originate from the lower brainstem, and (2) high density of CGRP-IR structures present in the brain at embryonic and early postnatal stages may indicate that CGRP could be an important factor involved in the developmental organization of the central nervous system.

Aging↗
PubMed1991

Postnatal ontogeny of mineralocorticoid and glucocorticoid receptor gene expression in regions of the rat tel- and diencephalon.

In situ hybridization was used to study the neuroanatomical distribution of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) gene expression during development in the rat. This study was based on incubation of adjacent sections of brains from 2-, 8-, 12-, 16-day-old and adult (3 months) rats with 35S-labelled cRNA probes. These probes are transcribed from 513 and 500 basepair cDNA fragments with little homology from rat brain MR and rat liver GR respectively. Different patterns of expression were found in the brain of MR and GR during ontogeny. At postnatal day (pnd) 2, a high density of labelled MR mRNA was found in all pyramidal (CA1-4) and granular (dentate gyrus) cell fields of the hippocampal structure, the anterior hippocampus and indusium griseum, and cortex layer II. Modest to high labelling of MR mRNA was observed in the subfornical organ and the anterior hypothalamus. A variety of other telencephalic regions anterior and posterior of bregma exhibited modest to weak intensity of labelled MR mRNA. The diencephalon virtually lacked labelled MR mRNA. At older postnatal ages including the adult age, this regional distribution of radiolabelled MR mRNA did not change. At pnd 2, abundant radiolabelled GR mRNA was found widespread over the tel- and diencephalon, with the highest density observed in cell field CA1 and CA2 of the hippocampus and the parvocellular division of the hypothalamic paraventricular nucleus. Modestly labelled GR mRNA was observed in various hypothalamic and thalamic nuclei, basal ganglia, the lateral septum and the amygdala. At older postnatal ages and in adulthood, the intensity of labelled GR mRNA became progressively stronger in the hippocampus. Moreover, we observed a trend towards a more condensed and narrow band of cell bodies in the hippocampus for both MR and GR mRNA during ontogeny. A semi-quantitative comparison of the intensity of both labelled mRNA's performed at each age revealed a significantly lower expression of GR than MR mRNA in the CA3 cell field at pnd 2. At pnd 8 and 12, the amount of GR mRNA was significantly lower in the dentate gyrus and the CA3, whereas in adulthood, less GR mRNA was measured in all pyramidal and granular cell fields. The present study demonstrates that MR and GR genes are expressed in early postnatal development in a pattern resembling that in adulthood. As is the case in the adult brain, there is more MR than GR mRNA in the hippocampus during ontogeny, especially in the CA3 cell field and the DG.

Aging↗