Distribution of calretinin, calbindin-D28k, and parvalbumin in the rat thalamus.

The localization of three calcium-binding proteins, calretinin, calbindin-D28k, and parvalbumin, in the rat thalamus was immunohistochemically examined. a) Some thalamic regions revealed cells almost exclusively containing one of the calcium-binding proteins. For example, almost only calretinin-stained cells were found in the central medial and paraventricular nuclei. Calbindin-D28k-stained cells were mostly found in the centrolateral, interanteromedial, anteromedial, and posterior nuclei. Only parvalbumin-positive cells were found in the central part of the reticular nucleus. b) Other regions expressed overlap between the distributions of two cell components composed of different calcium-binding proteins. For example, both calretinin-stained cells and calbindin-D28k-labeled cells were found in the lateroposterior, intermediodorsal, rhomboid, and reuniens nuclei. c) Other regions showed no cells stained for any of the calcium-binding proteins. For example, generally no calcium-binding protein was detected in neurons of the anterodorsal, anteroventral, ventrolateral, ventral posterolateral, ventral posteromedial, or gelatinosus nuclei, or of the central part of the mediodorsal nucleus. These three proteins serve as useful marker for localizing subpopulations of neurons within the thalamus.

Heterogeneity in calbindin-D28k expression in oxytocin-containing magnocellular neurons of the rat hypothalamus.

We have used a double-labeling immunofluorescence method to examine whether oxytocin-containing magnocellular neurons possess a calcium-binding protein, calbindin-D28k, in the hypothalamus of the rat. In the supraoptic nucleus, most oxytocin-immunoreactive cells were also stained for calbindin-D28k. However, in the magnocellular part of the paraventricular nucleus nearly all oxytocin-labeled cells were devoid of calbindin-D28k. In the anterior commissural nucleus, approximately one-third of oxytocin-stained cells were also calbindin-D28k-immunoreactive, but the other cells were negative for calbindin-D28k. This study indicates that there may be distinct chemical features between oxytocin-containing magnocellular neurons of the supraoptic nucleus compared to those of the paraventricular nucleus.

Colocalization of calbindin-D28k with vasopressin in hypothalamic cells of the rat: a double-labeling immunofluorescence study.

By use of a double-labeling immunofluorescence method, we examined whether vasopressin-containing cells possess a calcium-binding protein, calbindin-D28k, in the hypothalamus of the rat. Subpopulations of vasopressin-containing cells varied in their ability to possess calbindin-D28k immunoreactivity in different regions. In the supraoptic nucleus, most vasopressin-immunoreactive cells were also stained for calbindin-D28k. By contrast, in the magnocellular part of the hypothalamic paraventricular nucleus, all vasopressin-labeled cells lacked calbindin-D28k. In the suprachiasmatic nucleus, no calbindin-D28k was found in vasopressin-stained cells. This study shows a further characterization of vasopressin-containing cells of the rat hypothalamus.

Calretinin distribution in the thalamus of the rat: immunohistochemical and in situ hybridization histochemical analyses.

The distribution of calretinin-containing cells was examined by in situ hybridization histochemistry and compared with the immunohistochemical mapping of calretinin in the thalamus of the rat. Results revealed a close correspondence between the immunohistochemical localization of cell bodies and the messenger RNA label produced by the calretinin oligonucleotide probe. Calretinin cells were most prominent in the midline (paraventricular, reuniens, rhomboid) and intralaminar (central medial, paracentral) nuclei and in a group of cells along the rostral central gray which appeared continuous with the caudal extent of the midline nuclei. A subpopulation of calretinin cell bodies was also identified in the reticular nucleus. The mediorostral lateral posterior nucleus, subparafascicular, lateral geniculate and habenular nuclei also contained calretinin messenger RNA probe label. In contrast, no positive cells were found in the anterior, ventral or posterior thalamic nuclei. The distribution of calretinin cells did not correspond directly with that of other histochemical markers. Thus, the in situ hybridization histochemical and immunohistochemical results revealed calretinin as a unique identifying marker for distinct sets of thalamic neurons.

Immunohistochemical localization of calretinin in the rat hindbrain.

The localization of calretinin in the rat hindbrain was examined immunohistochemically with antiserum against calretinin purified from the guinea pig brain. Calretinin immunoreactivity was found within neuronal elements. The distribution of calretinin-immunoreactive cell bodies and fibers is presented in schematic drawings and summarized in a table. Major calretinin-immunoreactive neurons were found in the lateral and medial geniculate nuclei, substantia nigra, ventral tegmental area, interpeduncular nucleus, periaqueductal gray, mesencephalic trigeminal nucleus, superior and inferior colliculi, pontine nuclei, parabrachial nucleus, dorsal and laterodorsal tegmental nuclei, cochlear nuclei, vestibular nuclei, medullary reticular nuclei, nucleus of the solitary tract, area postrema, substantia gelatinosa of the spinal trigeminal nucleus, and cerebellum. These results show that distinct calretinin-immunoreactive neurons are widely distributed in the rat hindbrain.

Hypothalamic galanin-immunoreactive neurons projecting to the posterior lobe of the rat pituitary: a combined retrograde tracing and immunohistochemical study.

UNLABELLED: To identify the galanin-immunoreactive neurons projecting to the posterior lobe of the pituitary in the rat hypothalamus, a retrograde tracer (complex of wheat germ agglutinin-enzymatically inactive horseradish peroxidase-colloidal gold) was injected into the posterior lobe of the pituitary. Sections of the hypothalamus were treated with a combination of silver enhancement of retrogradely transported tracer and immunohistochemistry of galanin. Of the total number of hypothalamic cells doubly labeled with retrograde tracing and galanin-immunostaining, 56-60% were found in the supraoptic nucleus, 18-23% in the retrochiasmatic nucleus, 8-10% in the lateral magnocellular portion of the paraventricular nucleus. The ratio of (number of doubly labeled cells/number of galanin-immunoreactive cells) in each of the above regions was similar to the ratio of (number of retrogradely labeled cells/number of Nissl-stained cells) in the supraoptic nucleus. Of all retrogradely labeled cells in the hypothalamus, 51-56% also contained galaninlike immunoreactivity. IN CONCLUSION: (1) galanin-immunoreactive fibers in the posterior lobe of the pituitary originate mainly in the supraoptic nucleus, retrochiasmatic nucleus, and lateral magnocellular portion of the paraventricular nucleus, (2) most of galanin-immunoreactive cells in these regions project to the posterior lobe of the pituitary, and (3) about half the neurons constituting the hypothalamo-neurohypophyseal system contain galaninlike immunoreactivity.

Origin of the met-enkephalinergic innervation of the lateral septum in the rat.

The location of the cells giving rise to the methionine-enkephalin (Met-Enk)-ergic innervation of the lateral septal nucleus has been investigated in the rat by combining immunohistochemistry and retrograde axonal tracing. Small volumes (0.06 microliter) of apo-horseradish peroxidase (Apo-HRP) conjugated to wheat-germ agglutinin (WGA) and coupled with colloidal gold particles (WGA-ApoHRP-gold) were injected into the lateral septum. The retrogradely labeled cell bodies were visualized by silver intensification of the gold particles on Vibratome sections that were subsequently processed for immunohistochemistry for Met-Enk. Cells labeled with WGA-ApoHRP-gold were observed in the septal area, throughout the hypothalamus (mainly in the perifornical and lateral nuclei) and in the mesencephalon. The localization of Met-Enk-immunoreactive cells was as previously described. With the exception of a few septal cells close to the injection site, doubly labeled cells were found only in the perifornical nucleus of the hypothalamus. Almost all perifornical magnocellular cells were doubly labeled ipsilateral to the injection site, whereas on the opposite side, only about 25% of the Met-Enk-immunoreactive cells contained WGA-ApoHRP-gold. Other brain regions containing retrogradely labeled or Met-Enk-immunoreactive cells (particularly the raphe nuclei) did not show double-labeled neurons. This study demonstrates, using a new and sensitive technique for specific neurochemical tracing of tracts, that the origin of the Met-Enk-ergic innervation of the rat lateral septal nuclei lies in the magnocellular perifornical nuclei of the hypothalamus. The precise involvement of this pathway in limbic functions remains to be determined.