Browsing by Subject "Paraventricular nucleus"

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    Genistein stimulates the hypothalamo-pituitary-adrenal axis in adult rats: morphological and hormonal study
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2012) Trifunović, Svetlana L.; Manojlović-Stojanoski, Milica; Ajdžanović, Vladimir Z.; Nestorović, Nataša; Ristić, Nataša; Medigović, Ivana; Milošević, Verica Lj.
    Genistein, the soy isoflavone structurally similar to estradiol, is widely consumed for putative beneficial health effects. However, there is a lack of data about the genisteins’ effects in adult males, especially its effects on the hipothalamo-pituitary-adrenal (HPA) axis. Therefore, the present study was carried out to investigate the effects of genistein on the HPA axis in orchidectomized adult rats, and to create a parallel with those of estradiol. Changes in the hypothalamic corticotrophin-releasing hormone (CRH) neurons and pituitary corticotrophs (ACTH cells) were evaluated stereologically, while corticosterone and ACTH levels were determined biochemically. Orchidectomy (Orx) provoked the enlargement (p<0.05) of: hypothalamic paraventricular nucleus volume (60%), percentage of CRH neurons (23%), percentage of activated CRH neurons (45%); pituitary weight (15%) and ACTH level (57%). In comparison with Orx, estradiol treatment provoked the enlargement (p<0.05) of: percentage of CRH neurons (28%), percentage of activated CRH neurons (2.7-fold), pituitary weight (131%) and volume (82%), ACTH level (69%), the serum (103%) and adrenal tissue (4.8 fold) level of corticosterone. Clearly, Orx has induced the increase in HPA axis activity, which even augments after estradiol treatment. Also, compared to Orx, genistein treatment provoked the enhancement (p<0.05) of: percentage of activated CRH neurons (2.3-fold), pituitary weight (28%) and volume (21%), total number of ACTH cells (22%) ACTH level (45%), the serum (2.6-fold) and adrenal tissue (2.8 fold) level of corticosterone. It can be concluded that an identical tendency, concerning the HPA axis parameters, follows estradiol and genistein administration to the orchidectomized adult rats
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    Prosomeric hypothalamic distribution of tyrosine hydroxylase positive cells in adolescent rats
    (Frontiers Media, 2022-05-06) Bilbao, María G.; Garrigos, Daniel; Martínez Morga, Marta; Toval, Ángel; Kutsenko Shchegolska, Yevheniy; Bautista, Rosario; Barreda, Alberto; Ribeiro do Couto, Bruno; Puelles López, Luis; Ferrán Bertone, José Luis; Anatomía Humana y Psicobiología
    Most of the studies on neurochemical mapping, connectivity, and physiology in the hypothalamic region were carried out in rats and under the columnar morphologic paradigm. According to the columnar model, the entire hypothalamic region lies ventrally within the diencephalon, which includes preoptic, anterior, tuberal, and mamillary anteroposterior regions, and sometimes identifying dorsal, intermediate, and ventral hypothalamic partitions. This model is weak in providing little or no experimentally corroborated causal explanation of such subdivisions. In contrast, the modern prosomeric model uses different axial assumptions based on the parallel courses of the brain floor, alar-basal boundary, and brain roof (all causally explained). This model also postulates that the hypothalamus and telencephalon jointly form the secondary prosencephalon, separately from and rostral to the diencephalon proper. The hypothalamus is divided into two neuromeric (transverse) parts called peduncular and terminal hypothalamus (PHy and THy). The classic anteroposterior (AP) divisions of the columnar hypothalamus are rather seen as dorsoventral subdivisions of the hypothalamic alar and basal plates. In this study, we offered a prosomeric immunohistochemical mapping in the rat of hypothalamic cells expressing tyrosine hydroxylase (TH), which is the enzyme that catalyzes the conversion of L-tyrosine to levodopa (L-DOPA) and a precursor of dopamine. This mapping was also combined with markers for diverse hypothalamic nuclei [agouti-related peptide (Agrp), arginine vasopressin (Avp), cocaine and amphetamine-regulated transcript (Cart), corticotropin releasing Hormone (Crh), melanin concentrating hormone (Mch), neuropeptide Y (Npy), oxytocin/neurophysin I (Oxt), proopiomelanocortin (Pomc), somatostatin (Sst), tyrosine hidroxilase (Th), and thyrotropin releasing hormone (Trh)]. TH-positive cells are particularly abundant within the periventricular stratum of the paraventricular and subparaventricular alar domains. In the tuberal region, most labeled cells are found in the acroterminal arcuate nucleus and in the terminal periventricular stratum. The dorsal retrotuberal region (PHy) contains the A13 cell group of TH-positive cells. In addition, some TH cells appear in the perimamillary and retromamillary regions. The prosomeric model proved useful for determining the precise location of TH-positive cells relative to possible origins of morphogenetic signals, thus aiding potential causal explanation of position-related specification of this hypothalamic cell type.
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    Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin
    (Murcia : F. Hernández, 1992) Sánchez, F.; González, R.; Carretero, J.; Rubio, M.; Riesco, J. M.; Blanco, E.; Juanes, J.A.; Vázquez, R.
    Using the peroxidase-antiperoxidase immunocytochernical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.
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    Vasopressinergic neurons and the associated blood vessels in the rat anterior hypothalamus, an immunohistochemical study
    (Murcia : F. Hernández, 1990) Ray, Prajnan K.; Roy Choudhury, S.
    The paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamic neurosecretory system have been extensively investigated by many workers. The functional aspects of vasopressin secretion (elaborated by the PVN and SON neurons) in relation to the vasculature of the anterior hypothalamus are also well documented. However, the available data concerning vasopressin (VP) functions are largely based on physiological studies. Corroborative morphological correlation with regard to this has received little attention. The present report elucidates the intricate anatomical relationships between the VP-neurons and the adjoining capillaries in the rat anterior hypothalamus. A peroxidase-antiperoxidase (PAP) immunocytochemical study, using a commercial VP antibody, was carried out for this purpose. The observations are interpreted from a functional standpoint. VP-immunostained elements, i.e. the somata and the processes (mainly dendrites), were localized (i) close to the wall, (ii) on the endothelium, and (iii) occasionally, in the lumen of the hypothalamic capillaries. The findings provide immunocytochemical evidence that the vasopressinergic elements are in direct relationship with the hypothalamic vasculature. This raises some interesting possibilities for the former to be involved in: (i) affecting the permeability of the blood-brain barrier for transport of various nutrient substances (important in aging and Alzheimer's disease), (ii) inducing an alteration in the water permeability of the brain vessels on which depends the precise adjustment of brain water content and of brain volume (fundamental to normal functioning of the brain), and (iii) serving as osmoreceptors of the blood flowing through the capillaries and thus providing a feedback mechanism for VP modulation.