Browsing by Subject "Pituitary"

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    Abnormal periodic acidSchiff (PAS)-positive substance in the islets of Langerhans, pituitaries and adrenal glands of 139H scrapie-infected hamsters
    (Murcia : F. Hernández, 1999) Ye, X.; Scallet, A.; Carp, R.I.
    Previous studies showed that the 139H strain of scrapie injected intra-cerebrally in hamsters caused obesity, and extensive histopathological changes in islets of Langerhans and pituitaries. In the current study, we report that an abnormal granular substance, which stained positively with periodic acid-Schiff (PASpositive substance; PPS), was found in the islets of Langerhans, pituitaries, adrenal glands, in the lumens of blood vessel cores (BVCs) and in blood vessels in 139Hinfected hamsters, but not in either 263K-infected or control hamsters. This substance was found in the endocrine organs, forming grape-like or plaque-like structures, which were small, round to ovoid, and homogenous measuring up to 7pm in diameter and usually grouped in clusters. PPS was not found in the brains of control or scrapie-infected hamsters. Using immunostaining for amyloid protein (PrP, 13A4), as well as Congo red and thioflavin-S stains, no evidence was found of amyloid plaque formation in the islets of Langerhans, the adrenal glands, or the pituitaries of 139H- or 263K-infected hamsters. PPS might relate to the pathological changes in the endocrine organs in 139H-infected hamsters.
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    Histopathology of the pituitary gland in neonatal little (lit) mutant mice
    (Murcia : F. Hernández, 1992) Wilson, D.B.; Wyatt, D.P.
    The pituitary gland in the little (lit) mutant mouse was analyzed with respect to the cytoarchitecture of the pars distalis and the volumetric density of imrnunoreactive growth hormone (GH) cell granules in neonatal litllit and normal C57BL mice. At 8 days postnatally the volume of GH granules/total tissue was significantly less in the IiUlit pars distalis, and the cells were loosely arranged, as compared with the normal pars distalis. In newborn mice a statistically significant difference could not be detected between normal and IiVIit mice with respect to the volumetric density of GH granules; however, differences occurred in the cytoarchitectural organization of the pars distalis. These differences included prominent vascular channels and well-defined cords and clusters of cells in the normal newborn mice, in contrast to indistinct vascular elements and a more diffuse arrangement of cells in livlit.
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    In vitro effects of estradiol on pituitary GH-immunoreactive cells
    (Murcia : F. Hernández, 1997) Carretero, J.; Rubio, M.; Sanchez, F.; Pereña, J.; Estévez, F.I.; Vázquez, G.; Pérez, R.M.; Vazquez, R.
    In order to determine whether estradiol modulates the proliferation and activity of somatotrophic cells in vitro, a study of GH-immunoreactive cells was carried out in pituitary monolayer cultures obtained from male adult rats treated with ~ o - ~esMtrad iol for 3 hours. Cellular activity was evaluated in a morphometric study of GH-immunoreactive cells. The proliferation rate was determined by double immunostaining for GH and PCNA (proliferating cellular nuclear antigen). The results were compared to those obtained from control dishes. Estradiol was seen to increase the cellular (p<0.05), nuclear (pc0.01) and cytoplasmic areas (pc0.05). Estradiol decreased the percentage of proliferating GH-immunroeactive cells (pc0.05) and the numerical density of somatotrophs (pc0.05) when al1 cells present in the dishes were considered. However, when only GH-immunoreactive cells were considered, estradiol increased the proliferation rate of these cells (pc0.05). Overall, our results suggest that, in vitro, estradiol stimulates the cellular activity and proliferation of GH-immunoreactive cells in the rat.
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    Involvement of neuropeptides in the regulation of growth, structure and function of the adrenal cortex
    (Murcia : F. Hernández, 1993) Malendowicz, L.K.
    Current data on the influence of neuropeptides on the growth, structure and function of cells comprising the hypothalamo-pituitaq-adrenal axis were presented and discussed. The action of vasopressin, oxytocin, neurotensin, bombesin, neuropeptide Y, substance P and VTP have been evaluated. The hypothesis has been introduced that in vivo effect of some neuropeptides on the structure and function of the adrenal cortex is mediated by vasopressin.
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    lmmunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe
    (Murcia : F. Hernández, 1991) Carbajo, S.; Carbajo-Pérez, E.; Hernández, J.L.; Vázquez, R.; Carvajal, J.C.
    An immunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe (IL) has been carried out. Paraffinembedded sections, in which cysts were identifiable, were treated either with anti-serotonin or anti-S-100 protein sera. S-100-positive cells were intermingled with glandular cells surrounding the cyst lumen. These S-100- positive cells sent slender cytoplasmic processes as if to cover the apical surface of neighbouring cells. Rarely were 5-HT-immunopositive cells seen in the cyst epithelial lining. Most cells of the marginal layer of the IL were found reactive either to an S-100 or a-5-HT serum. The presence of an epithelial lining positive to S-100 protein sera is in keeping with the notion that cysts in the IL might form as evaginations of the epithelial lining of the pituitary cleft. The lack of correspondence between 5-HT-positive cells in the marginal layer and the cyst lining is controversial. A peculiar spatial relationship of 5-HT cells with the vascular network of the IL is suggested.
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    Neonatal treatment with monosodium glutamate MSG structure of the TSH-immunoreactive pituitary cells
    (Murcia : F. Hernández, 2000) Miskowiak, B.; Partyka, M.
    Glutamic acid represents the most abundant stimulatory neurotransmitter in the central nervous system. Monosodium glutamate (MSC), subcutaneously administered to newborn rats in the perinatal period, induces lesions in 80 to 90% of the neurocytes of arcuate nuclei in the hypothalamus. These nuclei are the site of production of numerous stimulatory and inhibitory hormones including growth hormone releasing hormone (GHRH). The present studies were performed on male Wistar strain rats, subcutaneously injected on days 2, 4, 6, 8, and 10 of postnatal life with MSC at a dose of 4 mglg body weight. Eighteen-month-old rats were additionally treated with Ambinon. When the animals reached the ages of 6 or 12 months, their body weight, body length and weight of pituitary were determined. On parafrin sections, using imrnunohistochemical techniques, TSHimmunoreactive cells were detected and characterised by computerised image analysis. The results were subjected to statistical analysis using Student's t test. The rats which were perinatally treated with MSC and examined after 6 or 12 months of life were obese and shorter than control rats by 7% and 10% respectively. They also exhibited a reduction in the weight of the pituitary of 30% and 40% respectively in the two age groups. The proportion of TSH-immunoreactive cells in the pituitary remained unchanged and amounted to 4.5% in the 6-month-old and 5.4% in the 12-month-old rats respectively. The number of TSH-positive cells per mm 2 area remained unchanged. The area and circumference of the cells in the 12-month-old rats were reduced by 22% and 18%, respectively. Perinatal injury to hypophyseal arcuate nuclei induced by monosodium glutamate injection, was not associated with any significant alterations in pituitary structure, as defined by the proportion of pituitary volume occupied by TSH-immunoreactive cells.
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    Neuromedins and their involvement in the regulation of growth, structure and function of the adrenal cortex
    (Murcia : F. Hernández, 1994) Malendowicz, L.K.; Markowska, A.
    Current data on the synthesis and the mechanism of action of neuromedins on adrenal cortex are presented. The localization of these biologicallyactive peptides in all components of the hypothalamopituitary- adrenal axis as well as their action on the adrenal cortex both in vivo and in vitro suggest their involvement in the regulation of growth, structure and function of the adrenal cortex. Neuromedins may exert both direct and indirect effect on the adrenal cortex. Direct effect is proven by the stimulation of glucocorticoid synthesis by adrenocortical cells in culture (NMK, NML) while indirect effects may be mediated by ACTH, vasopressin (aldosterone secretagogue effect) and angiotensin (prompt proliferative response) or by substances of medullary origin. The last mechanism of action is well documented for NMU.
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    Neuropeptide Y-related peptides and hypothalamo-pituitary-adrenal axis function
    (Murcia : F. Hernández, 1996) Malendowicz, L.K.; Markowska, A.; Zabel, M.
    Current data on the localization of neuropeptide Y-related peptides in the hypothalamo-pituitaryadrenal gland (HPA) axis as well as the effects of these peptides on the function of cells comprising HPA axis are presented and discussed. The action of neuropeptide Y. peptide YY, and pancreatic polypeptide on HPA axis are evaluated. Moreover, we report the presence of pancreatic polypeptide immunoreactivity in subset of chromaffin cells in the medulla of rat adrenal gland.
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    PTTG and cancer
    (Murcia : F. Hernández, 2003) Hamid, T.; Kakar, S.S.
    Pituitary tumor transforming gene (pttg) is a recently isolated oncogene that is expressed in most of the tumors. Overexpression of pttg results in an increase in cell proliferation, induces cell transformation in vitro, and promotes tumor formation in nude mice. The gene encodes a protein of 202 amino acids with no significant homology with other known proteins. The protein is a multi domain consisting of a transactivation domain, domain required for ubiquitin-mediated proteolysis and a DNA binding domain. pttg protein is bestowed with a multitude of functions and seems to be involved in most of the important mechanisms of cell proliferation, differentiation and signaling. Given the number of processes that are involved in the manifestation of cancer, it thus becomes mandatory to study the role of this potent oncogene in relation to the processes of cell survival, death and functioning.
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    Serotonin immunoreactivity in the intermediate lobe of the rat pituitary
    (Murcia : F. Hernández, 1991) Carvajal, J.C.; Carbajo, S.; Carbajo-Pérez, E.; Castro, S.; Rodríguez, J.
    Immunocytochemical staining for serotonin (5-HT) in paraffin-embedded sections of rat pituitary resulted in the localization of reactive nerve fibres and cell bodies in the intermediate lobe. Immunostaining was also found in the anterior and posterior lobes. Labelled nerve fibres appear to enter the intermediate lobe from the neural lobe through the interlobular spaces. These fibres are relatively scarce and lightly stained. Neuroglandular contacts were identified between varicose nerve endings containing serotonin and immunoreactive perykarion. It is not clear whether intermediate lobe cells produced 5-HT themselves or, alternatively, these cells take in 5-HT from serotoninergic nerve terminals.