Paraventricularis Magnocellularis Research Articles

Anatomical distribution of NPY-like immunoreactivity in the domestic chick brain (Gallus domesticus).

Neuropeptide Y-immunoreactive (NPY-ir) fibers and neurons in the brain of the domestic chick (Gallus domesticus) were described using an immunohistochemical technique. NPY-ir neurons were seen in the lobus parolfactorius; hyperstriatum, neostriatum, paleostriatum, and archistriatum; hippocampal and parahippocampal areas; dorsolateral corticoid area; piriform cortex; two thalamic areas contiguous to the n. rotundus; n. dorsolateralis anterior thalami, pars lateralis, and pars magnocellularis; n. periventricularis hypothalami; n. paraventricularis magnocellularis; regio lateralis hypothalami; n. infundibuli; inner zone of the median eminence; dorsal and lateral portions of the n. opticus basalis; n. raphes; and n. reticularis paramedianus. NPY-ir fibers were seen throughout the entire chick brain, but were more abundant in the hypothalamus where they formed networks and pathways. They were also observed in some circumventricular organs. The anatomical data of the present study regarding the distribution of NPY ir in the chick brain, together with the physiological findings of other studies, suggest that NPY plays a key role in the regulation of the neuroendocrine, vegetative, and sensory systems of birds by acting as a neuromodulator and/or neurotransmitter.

The distribution of neuropeptide Y gene expression in the chicken brain

Neuropeptide Y (NPY) is demonstrated to play an important role in central control of voluntary feed intake (FI) of a variety of species. The commercial broiler chicken has been intensively selected over generations for increased body weight, achieved largely through increased FI. This has resulted in a contemporary animal that does not regulate FI to maintain energy balance, and represents a model for hyperphagia and obesity if allowed unrestricted access to feed. In the present study, the distribution of NPY mRNA was mapped in the brain of juvenile, broiler-strain chicken, and results interpreted in the context of previous data for strains that do not exhibit hyperphagia. NPY mRNA was widely distributed in the broiler brain, and highly expressed in the hippocampus, nucleus commissurae pallii, infundibular hypothalamic nucleus, nucleus pretectalis pars ventralis and neurons around the nucleus rotundus. Moderately labeled neurons were found in the lateral septal organ, nucleus periventricularis hypothalamus and nucleus paraventricularis magnocellularis. The pallium exhibited only sparse labeling. Generally, the distribution of cell groups expressing NPY mRNA was consistent with those regions exhibiting NPY immunoreactivity, and also matches the distribution of receptor binding sites reported in the literature for the chicken brain. This suggests that NPY may be involved in functions controlled by these regions. The observation of NPY gene expression in brain regions involved in appetite regulation is consistent with the recognized importance of NPY in FI regulation in a variety of species, and with the chronic hyperphagia, characteristic of the broiler.

Colocalization of arginine-vasotocin and chicken luteinizing hormone-releasing hormone-I (cLHRH-I) in the preoptic–hypothalamic region of the chicken

To characterize a possible relationship between chicken luteinizing hormone-releasing hormone-I (cLHRH-I) and arginine-vasotocin (AVT) we performed immunocytochemical double-stainings throughout the preoptic–hypothalamic region of the chicken brain. This study clearly reveals a partial colocalization between both neuropeptides. Single-labeled neurons, containing either cLHRH-I or AVT are found intermingled with double stained cells, immunoreactive (ir) for both peptides. A significant number of double-labeled perikarya is found in the preoptic area, more specifically in the ventral and external portion of the supraoptic nucleus (SOv and SOe) and in the medial preoptic nucleus (MPOv). At the level of the anterior hypothalamus, double-labeled cells are predominantly observed near the third ventricle in the nucleus paraventricularis magnocellularis (PVN) and the nucleus periventricularis hypothalami (PHN). Next to this colocalization, a number of cLHRH-I-ir cell bodies are found in close apposition to AVT-ir fiber profiles in the very same areas. Taken together, these data are the first to provide morphological evidence indicating that the AVT system might be involved in the regulation of cLHRH-I release and thus of reproductive functions in birds.

Thyrotropin-releasing hormone concentrations in different regions of the chicken brain and pituitary: an ontogenetic study

The regional distribution of thyrotropin-releasing hormone (TRH) was studied in the chicken brain. The hypothalamus and the brain stem contained the highest concentration of TRH. Lower amounts were present in the telencephalon, the optic lobes and the cerebellum. Within the hypothalamus, TRH was most abundant in the median eminence. Other important TRH sites were the nucleus paraventricularis magnocellularis, nucleus periventricularis hypothalami, nucleus ventromedialis hypothalami, nucleus dorsomedialis hypothalami and nucleus preopticus periventricularis. On the 14th day of embryonic development (E14), TRH was mostly found in the brain stem. Towards hatching, TRH concentrations increased gradually in both the hypothalamic area and the brain stem. TRH concentrations in the telencephalon, optic lobes and cerebellum remained low. Pituitaries from E14 to E16 chickens were characterized by a high TRH concentration, whereas hypophyseal TRH concentrations dropped towards hatching. Our results support the hypothesis that TRH exerts both endocrine and neurocrine actions in the chicken. On the other hand, high pituitary TRH concentrations were present when hypothalamic concentrations were low and vice versa. Therefore, the chicken pituitary may function as an important source of TRH during early in ovo development at least until the moment hypothalamic control develops.

Localization of Progesterone Receptor in Brain and Pituitary of the Ring Dove: Influence of Breeding Cycle and Estrogen

An immunocytochemical method was used in male and female ring doves (Streptopelia risoria) to localize progesterone receptor immunoreactivity (PR-ir) in the brain and anterior pituitary gland in nonbreeding, incubating, brooding, and estrogen (E2)-treated nonbreeding birds. Progesterone receptor was found in four regions of the brain in males and females: the preoptic area (POA), nucleus preopticus paraventricularis magnocellularis (PPM), nucleus hypothalami lateralis (PLH), and the tuberal region (TR). Quantitative analysis demonstrated that the density of cell nuclei containing PR-ir in the POA, PPM, and PLH in brooding birds was significantly higher than in E2-treated doves or in birds at other stages of the reproductive cycle. The density of PR-containing cell nuclei in the TR of male ring doves was significantly higher on day 1 of incubation than in nonincubating males. In brooding birds, there was a significant decrease in PR-ir in the TR, particularly in the ventral region where nuclei containing PR-ir disappeared. In the anterior pituitary gland the density of cell nuclei containing PR-ir was higher in females than in males at the onset of incubation. E2treatment resulted in an increase in the density of PR-containing cell nuclei in both males and females. Brooding females had a lower concentration of PR-containing cell nuclei than did females at other stages of the breeding cycle. It is suggested that progesterone receptor in the POA mediates the expression of incubation behavior while progesterone receptor in the TR is involved in the control of neuroendocrine function. The source of estrogen which increases PR appears to be of central nervous origin in the male and may be predominantly peripheral in the female.

Autoradiographic localization of receptors for neuropeptide Y (NPY) in the brain of broiler and leghorn chickens ( Gallus domesticus)

Broiler and leghorn chickens show an extreme difference in ingestive and reproductive behavior. As neuropeptide Y (NPY) influences both behaviors the goal of this study was to elucidate the distribution, expression and affinity of NPY binding sites in broiler and leghorn chicken brain. By means of in vitro autoradiography, sections of chicken brains were incubated with 3H-NPY as tracer and NPY as displacer. Scatchard analysis revealed a curvilinear plot suggesting two subtypes of the NPY binding site in the chicken brain, a high affinity one ( K D = 2–4 nM) and one with a lower affinity ( K D = 18–24 nM). Binding sites for NPY are localized with high density in the different subdivisions of the neostriatum and the hyperstriatum, the cerebellum, the nucleus septalis lateralis and medialis, the nucleus ruber and the nucleus tractus solitarii. A lower density of NPY binding sites was found in the different subdivisions of the striatum, the nucleus mesencephalicus lateralis pars dorsalis, the paleostriatum, the archistriatum intermedium pars ventralis, the nucleus geniculatus lateralis, the nucleus taeniae, the locus ceruleus, the nucleus rotondus, the nucleus habenularis medialis, the nucleus dorsomedialis anterior (rostralis) thalami, the pituitary and the area of the hypothalamus with its nuclei such as the nucleus paraventricularis magnocellularis and the nucleus preopticus medialis. Comparison of the localization of NPY binding sites in the brains of broilers and leghorns showed no differences but the density of both receptor types is two to three times higher in broilers than in leghorns.

The localisation of LH-RH neurones in the diencephalon of the domestic hen.

Nerve fibers and perikarya containing LH-RH-like material were identified immunohistochemically in the diencephalon of the domestic hen using the peroxidase-anti-peroxidase technique. Perikarya were thinly scattered in bilateral bands close to the third ventricle extending from the nucleus praeopticus paraventricularis magnocellularis, passing in front of the anterior commissure into the septal area. In this latter area, the perikarya tended to spread out laterally. A few perikarya were seen in the anterior portion of the nucleus paraventricularis magnocellularis but were not found in the infundibular nuclear complex. Fibre tracts were seen running dorso-ventrally in the preoptic area apparently associated with the lamina terminalis. Fibres, possibly nerve terminals, were found in the lamina terminalis and in the external layers of the anterior and posterior divisions of the median eminence. A large number of fibres was seen distributed throughout the infundibular nuclear complex; scattered fibres were found close to the third ventricle in the anterior hypothalamus. Extrahypothalamic fibers were also observed to project from the septal area into other parts of the telencephalon.

A copulatory system in the hypothalamus and tegmentum of the domestic chick.

A tract in the chick is described that runs from the posterior nucleus paraventricularis magnocellularis (PVM) through the lateral hypothalamus to a small area of the anterior tegmentum, which is adjacent to the ventral tegmental area. Bilateral lesions of the posterior PVM or of the PVM tract or of its tegmental destination abolish the facilitation of copulation in male chicks by testosterone. The effect is specific in that the facilitation of attack is either unaffected or only slightly depressed by such lesions, while being itself specifically depressed by other hypothalamic lesions. No other hypothalamic tracts were found that were necessary for the facilitation of copulation. An equivalent copulatory system probably exists in the mammal, with a more diffuse distribution in the preoptic area but with similar connections back to the tegmentum.

The function of the preoptic, mammilaris lateralis and ruber nuclei in normal and sexually inactive male chickens

Male chickens were lesioned and cannulated at five weeks of age. Lesions were located in the mammilaris lateralis (ML) and Ruber (Ru) nuclei. Cannulas filled with testosterone propionate (TP) were positioned in the praeopticus paraventricularis magnocellularis (PPM) area of the hypothalamus. The mating behavior of lesioned birds was tested at maturity while mating behavior of cannulated birds was evaluated at eight weeks of age. Males hatched from eggs dipped in 2 g% TP were designated TP birds. The TP birds exhibited a marked decrease in their sexual behavior responses and lesioning did not after this effect. TP birds with cannulas in the PPM nuclei were stimulated to attempt to mate. These data indicate that TP birds failed to mate because of an interference in the development of the PPM nuclei. Bilateral lesions in the ML nuclei did not significantly influence sexual behavior while lesions in the Ru nuclei increased the sexual response. Therefore, the mammilaris region in the chicken's hypothalamus does not inhibit mating behavior while the Ru nucleus may be an inhibitory center for mating behavior in the chicken.

Testosterone concentration in the male chick brain: an autoradiographic survey.

Differential uptake of [(3)H]testosterone in male chick brain was found in periventricular areas of preoptic-hypothalamic continuum. Concentration of silver grains for all decapitation periods was especially high in the medial preoptic area, particularly the nucleus praeopticus paraventricularis magnocellularis. Distribution of testosterone-sensitive cells is in agreement with studies showing neuroanatomical control of reproductive behavior by the avian forebrain.

Effects of hypothalamic lesions on protein-bound 131iodine and thyroidal 131I uptake in the chicken

The hypothalamic site regulating thyroid-stimulating hormone (TSH) secretion was studied by measuring PB 131I and thyroidal uptake of 131I after production of lesions in the chicken diencephalon. Destruction of the area ventrocaudal to the anterior commissure, including the nucleus paraventricularis magnocellularis (PVM) and the area dorsocaudal to the optic chiasma, induced marked depression of PB 131I conversion ratio. In both cases, depression of PB 131I conversion ratio was accompanied by atrophy of the thyroid gland and thymus. Depression in PB 131I conversion ratio and 131I uptake was accompanied by the reduction in size and number of basophils in the cephalic lobe of the adenohypophysis. The results indicate that secretion of thyroid-stimulating hormone is regulated by a region of the anterior hypothalamus extending from the area ventrocaudal to the anterior commissure to the area dorsocaudal to the optic chiasma in the chicken.

Observations on the uptake of 35-sulfur by the hypothalamo-hypophysial system of the white-crowned sparrow (Zonotrichia leucophrys gambelii) following intraventricular injection of 35-S DL-cysteine.

By use of a stereotaxic instrument it has been consistently possible to introduce 35S DL-cysteine into the third ventricle of the White-crowned Sparrow, Zonotrichia leucophrys gambelii. Such injections are followed within six hours by a reproducible pattern of accumulation of the isotope in the hypothalamic nuclei around the third ventricle. The nucleus supraopticus, the nucleus paraventricularis magnocellularis, the lamina terminalis, and the area ependymalis vasculosa consistently showed the greatest accumulation of the isotope. In the supraoptic and paraventricular nuclei, conspicuous accumulation of the isotope was consistently observed in association with cells containing aldehyde-fuchsin positive material. The supraoptico-hypophysial tract, the pars nervosa, and the palisade layer of the zona externa of the median eminence showed pronounced accumulations of the isotope. These accumulations were, to a great extent, associated with aldehyde-fuchsin positive neurosecretory material.