Periventricularis Magnocellularis Research Articles

Androgen Receptor Immunolocalization in Brains of Courting and Brooding Male and Female Ring Doves (Streptopelia risoria)

Nuclear androgen receptors (ARs) were localized immunocytochemically in the brains of courting and brooding male and female ring doves (Streptopelia risoria). AR immunoreactivity (AR-ir) in courting birds was localized in cell nuclei in the telencephalon, diencephalon, and mesencephalon. In the anterior hypothalamus, high density of AR-ir was concentrated in several nuclei including the nucleus lateralis hypothalami, nucleus periventricularis magnocellularis, nucleus preopticus anterior, nucleus preopticus medialis, and nucleus preopticus paraventricularis magnocellularis. In the posterior hypothalamus, areas showing high density of AR-ir included the nucleus lateralis hypothalami posterioris, nucleus medialis hypothalami posterior, nucleus ectomamillaris, nucleus mamillaris lateralis, and nucleus tuberis. No sex differences in the density or localization of AR-ir were observed. Compared to brains from courting birds, AR-ir density was either extremely low or absent in most brain regions of brooding birds. It is concluded that in the dove, central ARs are closely associated with the sexual stages of the reproductive cycle.

Immunohistochemical localization of chicken gonadotropin‐releasing hormones I and II (cGnRH I and II) in turkey hen brain

The distribution of cells and fibers immunoreactive (ir) for either chicken gonadotropin-releasing hormone I (cGnRH I; [Gln8]GnRH) or II ([His5,Trp7,Tyr8]GnRH) was determined in brains of turkey hens to reveal whether these peptides occur in separate neuronal systems. ir-cGnRH I cells were located: along the medial aspect of the ventriculus lateralis, nucleus accumbens, and bed nucleus of the stria terminalis; ventral to the tractus septomesencephalicus and extending medially to the third ventricle, and caudally into the lateral hypothalamic area; and in a diffuse band extending from the nucleus preopticus medialis to the nucleus dorsomedialis anterior thalami. cGnRH I fibers were evident in these areas in addition to the hippocampus, nucleus subhabenularis medialis, nucleus ventromedialis hypothalami, and median eminence. Two groups of ir-cGnRH II cells were observed: a magnocellular group lying between the substantia grisea centralis and the nucleus ruber; and a parvicellular group lying medial to the nucleus of the basal optic root and extending into the lateral hypothalamic area. ir-cGnRH II fibers were prominent in limbic structures (cortex piriformis, lateral to nucleus taeniae, hippocampus); olfactory areas (tuberculum olfactorium, nucleus subhabenularis lateralis, nucleus septalis lateralis); areas that in other avian species have steroid-concentrating cells or receptors (medial edge of lobus parolfactorius, nucleus septalis medialis, nucleus periventricularis magnocellularis, nucleus dorsomedialis posterior thalami); and areas containing ir-GnRH I cells or fibers but not in median eminence. These results suggest that cGnRH I and II occur in separate neuronal systems and that cGnRH II does not directly promote pituitary gonadotropin secretion.

Distribution and hypothalamic projection of tyrosine‐hydroxylase containing neurons of the nucleus of the solitary tract in the pigeon

The avian nucleus of the solitary tract has an extensive subnuclear organization. Several subnuclear cell groups can be distinguished on the basis of cytoarchitectonic criteria. In general, the subnuclei of the medial division of the nucleus of the solitary tract receive gastrointestinal afferents, whereas the subnuclei of the lateral division of the nucleus of the solitary tract receive cardiopulmonary afferents. Forebrain afferents to the nucleus of the solitary tract are segregated to medial and lateral subnuclei, which are located at the periphery of the nucleus. These peripheral subnuclei of the nucleus of the solitary tract are also the source of ascending axonal projections to the forebrain. In this study, the tyrosine hydroxylase (initial enzyme for catecholamine synthesis) content of the anteromedial hypothalamic projecting neurons of the nucleus of the solitary tract is determined by use of a combined retrograde fluorescent dye-immunofluorescence method. Fast Blue implanted into the anteromedial hypothalamus (in the region of the nucleus periventricularis magnocellularis) resulted in the retrograde labeling of neurons in the caudal two-thirds of the nucleus of the solitary tract. At levels rostral to the obex, dye-labeled cells were mostly observed in the dorsally located subnuclei medialis superficialis pars posterior and lateralis dorsalis pars posterior and in the ventrally located subnucleus medialis ventralis pars posterior. More centrally located subnuclei contained few labeled cells, if any. For example, subnucleus medialis intermedius pars posterior only had a few retrogradely labeled cells, whereas the centrally located subnucleus medialis dorsalis pars posterior was almost devoid of labeled cells. At levels caudal to the obex, many retrogradely labeled neurons of the nucleus of the solitary tract were observed. Neurons immunoreactively labeled for tyrosine hydroxylase were mostly found within subnuclei, which contain anteromedial hypothalamic projection neurons. In subnuclei medialis superficialis pars posterior and lateralis dorsalis pars posterior, 87% of the retrogradely dye-labeled cells were also immunoreactively labeled, whereas in the caudal nucleus of the solitary tract (at levels caudal to the obex), 68% of the retrogradely labeled cells were immunoreactively labeled. Not all tyrosine hydroxylase containing cells had projections to the implantation site in the anteromedial hypothalamus since only 40% of the immunoreactive cells in the caudal nucleus of the solitary tract and 59% of the immunoreactive cells in the subnucleus medialis superficialis pars posterior were retrogradely labeled with Fast Blue.(ABSTRACT TRUNCATED AT 400 WORDS)

Autoradiographic localization of progestin‐concentrating cells in the brain of the zebra finch

The production of song in passerine birds is under the control of steroid hormones, and brain regions involved in song production have been shown to contain androgen and/or estrogen receptors. Studies to date, however, have not considered the possible role of progestins in this behavior. As one approach to this question, the autoradiographic method was used to investigate the distribution of progestin-concentrating cells in the brain of the adult male zebra finch (Poephila guttata) after injection of the radiolabeled synthetic progestin [17 alpha-methyl-3H]-promegestone. In the telencephalon, identifiable groups of progestin-accumulating cells were found in the hyperstriatum dorsale, at the medial edge of the lobus parolfactorius, and in the medial septum. In the diencephalon, labeled groups of cells were found in the preoptic area, through much of the medial hypothalamus--including nucleus periventricularis magnocellularis, nucleus medialis hypothalami posterialis, and area infundibularis--and in the medial spiriform nucleus and dorsomedial thalamus. In the myelencephalon, labeled cells are described at the dorsal edge of the medulla and scattered lateral to nXII. These findings offer no support for the hypothesis that progestin acts on any of the known song regions, but do suggest areas of progestin action in the avian central nervous system outside of the known song system. Not surprisingly, these include many areas of the medial hypothalamus and other midline structures.

Ascending vocalization pathways in the female ring dove: Projections of the nucleus intercollicularis

Nest-coo (courtship) vocalization is an estrogen-dependent component of a sequence of behaviors leading to egg-laying in the ring dove ( Streptopelia risoria). Implantation of estrogen in the nucleus intercollicularis of ovariectomized females restores the ability to produce nest-coos. Lesion of n. intercollicularis specifically disrupts nest-cooing and inhibits follicular development. We used anterograde transport of tritiated leucine to identify regions that receive input from n. intercollicularis. As a control, isotope was injected in an auditory nucleus (nucleus mesencephalicus lateralis, pars dorsalis) neighboring the n. intercollicularis. A strong projection to the nucleus was observed, demonstrating a potential interaction between auditory and vocalization systems at the level of the midbrain. Local projections of n. intercollicularis were observed in midbrain and hind brain nuclei including the nucleus tegmenti pedunculo-pontinus, pars compacta and nucleus papillioformis. A conspicuous projection ascended centrally via the mesencephalic central gray. Proceeding rostrally, this pathway was traced to the nucleus periventricularis magnocellularis and tissue surrounding it. At its rostral extent, the pathway was found to project to the nucleus preopticus medialis, the anterior medial hypothalamus, and the lateral hypothalamus. These results are consistent with the possibility of a nucleus intercollicularis projection to regions that regulate reproductive function.

Effect of acute stress on catecholamine content in the hypothalamic nuclei of Japanese quail.

Concentration of noradrenaline, adrenaline and dopamine in eight hypothalamic nuclei or areas (nucleus hypothalamicus medialis anterior, n. periventricularis magnocellularis, n. hypothalamicus lateralis anterior, n. hypothalamicus medialis posterior, n. hypothalamicus lateralis posterior, eminentia medialis, n. tuberis, area hypothalamica posterior) have been determined by a sensitive radioenzymatic micromethod in male Japanese quail restrained for 30 min. In control quail the highest concentrations were found in the a. hypothalamica posterior, n. periventricularis magnocellularis and n. hypothalamicus medialis anterior; the lowest was in the n. hypothalamicus medialis posterior. After restraint, noradrenaline concentrations decreased in the n. periventricularis magnocellularis and n. hypothalamicus medialis posterior. However, the concentration of adrenaline increased in the n. tuberis under the same conditions. In stressed animals the dopamine concentration was lower than in controls in the n. periventicularis and higher in the n. tuberis.

Distribution of catecholamines in individual hypothalamic nuclei of Japanese quail.

The dissection of eight hypothalamic nuclei or areas of Japanese quail brain (nucleus hypothalamicus medialis anterior, nucleus periventricularis magnocellularis, nucleus hypothalamicus lateralis anterior, nucleus hypothalamicus medialis posterior, nucleus hypothalamicus lateralis posterior, eminentia medialis, nucleus tuberis and area hypothalamica posterior) and a subsequent radioenzymatic measurement of the basic concentrations of noradrenaline, adrenaline and dopamine in these structures of female Japanese quail were demonstrated in this study. Individual hypothalamic nuclei were identified according to the histological map prepared. All the above mentioned structures were isolated from serial 200 micrometers thick frozen coronal sections of the hypothalamus under a stereomicroscope by means of a needle punch of 500 micrometers or 300 micrometers internal diameter. The highest levels of all biogenic amines measured were found in the area hypothalamica posterior which significantly differed from all other nuclei examined. Their lowest concentrations occurred in the nucleus hypothalamicus medialis posterior and in the nucleus hypothalamicus lateralis posterior. The results present the first picture of the quantitative distribution of catecholamines in the hypothalamus of the female Japanese quail.

Long descending projections of the hypothalamus in the pigeon, Columba livia.

An autoradiographic analysis was performed on the descending projections of nucleus periventricularis magnocellularis (PVM) of the hypothalamus in the pigeon. A PVM-medullospinal pathway was observed coursing posteriorly through the lateral hypothalamus, ventrolateral midbrain tegmentum, and into the spinal lemniscus (ls) in the ventrolateral pons and medulla. In the pons, some fibers course dorsomedially from ls and terminate at the lateral border of the locus coeruleus. At medullary levels, fibers from ls sweep dorsomedially in the plexus of Horsley and project to certain regions of the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus (NX). Specifically, PVM fibers project heavily into NTS subnuclei medialis superficialis, medialis ventralis, and lateralis (sulcalis) dorsalis as well as into the ventral parvocellular subnucleus of NX. Fibers in ls were traced caudally into the lateral funiculus as far as upper cervical levels of the spinal cord. Although autoradiographs of lower cervical or thoracic spinal cord sections were not available, PVM fibers do descend to thoracic spinal cord levels, as evidenced by the retrograde transport of horseradish peroxidase. In addition to the medullospinal pathway, the autoradiographs demonstrated PVM projections to septum, diencephalon, and midbrain. Labeled PVM fibers are found in the lateral septal nucleus, nucleus of the anterior pallial commisure, dorsomedial thalamic nucleus, dorsolateral anterior thalamic nucleus (pars ventralis), median eminence, medial and lateral hypothalamus, medial mammillary area, and nucleus intercollicularis and central gray of the midbrain. The projection of fibers to medullospinal regions and median eminence suggests that PVM is homologous to the mammalian paraventricular nucleus. These projections to specific subnuclei of NTS and NX denote hypothalamic control over certain autonomic functions.

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.

An autoradiographic study of the localization of androgen concentrating cells in the chaffinch

The distribution of labeled cells in the chaffinch brain has been examined by autoradiography after an intramuscular injection of [ 3H]testosterone. In the telencephalon labeled cells were particularly concentrated in nucleus magnocellularis neostriatalis anterioris, nucleus septalis lateralis, and hyperstriatum ventrale, pars caudale. In the diencephalon the nucleus periventricularis magnocellularis, the nucleus magnocellularis posterioris and the area infundibularis contained many heavily labeled cells. In the mesencephalon and medulla, labeled cells were found in the nucleus intercollicularis and in the nucleus nervi hypoglossi, respectively. Measurements of the density of grains per cell revealed (1) clear quantitative differences in the extent of labeling in different regions of the brain and (2) a wide variation in the density of labeling of individual cells within a region. The relationship between these sites of hormone binding and known sites of androgen action in the avian brain is discussed.

Hormone concentrating cells in vocal control and other areas of the brain of the zebra finch ( Poephila guttata).

Using the autoradiographic method in the zebra finch (poephila guttata), areas of the brain were identified which contain cells which accumulate testosterone. Among these areas are the caudal nucleus of the hyperstriatum ventrale, nucleus intercollicularis of the midbrain, and the tracheosyringeal portion of the hypoglossal nucleus of the medulla (nXIIts). These three are known to control or influence androgen dependent song and other vocalizations of passeriform birds, and nXIIts is composed of the motoneurons innervating the vocal (syringeal) muscles. Other areas containing hormone-concentrating cells are the medial preoptic area, nucleus periventricularis magnocellularis of the hypothalamus, dorsal infundibular layers, dorsomedial thalamus, lateral septum, magnocellular nucleus of the anterior neostriatum, periventricular medial neostriatum, nucleus taeniae of the archistriatum, and ventral paleostriatum augmentatum. Accumulation by cells in the preoptic area, hypothalamus, and limbic forebrain is consistent with a general vertebrate pattern of distribution of brain cells which accumulate sex steroids. Some of these same areas may be involved in the control of androgen dependent events such as courtship, copulation, aggression, and feedback regulation of the hypophysis.