Exposure to ethinylestradiol during prenatal development and postnatal supplementation with testosterone causes morphophysiological alterations in the prostate of male and female adult gerbils

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cellular changes in the prostatic stroma of glucocorticoid-treated rats

Glucocorticoid hormones (GCs) have been widely used for the treatment of prostate cancer because of their inhibitory property against tumour growth. However, their mechanism of action in the prostate has received little attention. Excess GCs can lead to peripheral insulin resistance resulting in hyperglycaemia and hyperinsulinaemia. Insulin plays an important role as a cellular stimulant and high levels are related to low levels of androgens. Our objective has been to describe the effects of insulin resistance induced by dexamethasone treatment on the morphology of rat ventral prostate. Mate adult Wistar rats received daily intraperitoneal injections of dexamethasone or saline for five consecutive days after which the rats were killed and the ventral prostate was removed, weighed and prepared for conventional and transmission electron microscopy (TEM). Dexamethasone treatment resulted in atrophy and decreased proliferative activity of prostatic epithelial cells. TEM analysis revealed changes in the epithelium-stroma interface, with some interruptions in the basement membrane. Fibroblasts showed a secretory phenotype with dilated endoplasmic reticulum. Smooth muscle cells exhibited a contractile pattern with 50% atrophy, an irregular membrane and twisted nuclei. Mitochondrial alterations, such as enlarged size and high electron density in the mitochondrial matrix, were also detected in smooth muscle cells. Insulin resistance induced by dexamethasone is thus associated with epithelial atrophy similar to that described for diabetic rats. However, GCs are responsible for morphological changes in the stromal cell population suggesting the activation of fibroblasts and atrophy of the smooth muscle cells.

Differential distribution of some extracellular matrix fibers in an experimentally denervated rat megaileum

Absence of enteric neurons is associated with thickening of the intestinal muscularis externa in Chagas' disease. The thickening is due to hyperplasia and hypertrophy of the smooth muscle cells and increased extracellular matrix components. The influence of the nervous system on the structure of the smooth muscle cells and its associated matrix has been poorly investigated. An experimental model of denervation of the ileum in rats was performed by application of the surfactant agent benzalkonium chloride that selectively destroys the myenteric plexus. Three months later, ileal tissue samples were obtained and studied by histochemistry and transmission electron microsocopy. Sham operated rats were used as controls. The diameter of collagen fibrils was evaluated in electron micrographs. The histopathological analysis showed thickening of the muscular layer. The thin and weakly arranged collagen and reticulin fibers surrounding the smooth muscle cells, observed in control cases by Picrosirius polarization (PSP) stain method, corresponded to a population of loosely packed thin collagen fibrils of uniform diameters (mean = 29.16 nm) at the ultrastructural level. In contrast, the thick and strongly birefringent fibers around the muscle cells, observed in the treated group, stained by PSP, corresponded to densely packed thicker fibrils with large variation in diameter (mean = 39.41 nm). Comparison of the data demonstrated statistically significant difference between the groups suggesting that the replacement of loosely arranged reticulin fibers by fibrous tissue (with typical collagen fiber), may alter the biomechanical function resulting in impairment of muscular contraction. (c) 2007 Elsevier Ltd. All rights reserved.

Short-term stromal alterations in the rat ventral prostate following alloxan-induced diabetes and the influence of insulin replacement

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Oestrogen supplementation following castration promotes stromal remodelling and histopathological alterations in the Mongolian gerbil ventral prostate

The effect of oestradiol on the intact and castrated adult gerbil prostate was evaluated by focussing on stromal and epithelial disorders, and hormonal receptor immunoreactivity. The experimental animals were studied by histological, histochemical and immunohistochemical techniques, morphometric-stereological analysis and transmission electron microscopy. Epithelial alterations in the oestradiol-treated animals were frequent, with an increase in epithelial cell height, areas of intense dysplasia and hyperplasia and formation of prostatic intraepithelial neoplasia (PIN). Another aspect that did not depend on the presence of testosterone was the arrangement of the fibrillar and non-fibrillar elements of the extracellular matrix among smooth muscle cells (SMC), suggesting a possible role of these cells in rearrangement and synthesis of these components, after oestrogenic treatment. In the castrated animals, an accumulation of extracellular matrix elements under the epithelium was evident, while in the intact animals the same compounds were dispersed and scarce. In the groups of intact and castrated animals, SMC and fibroblasts exhibited a secretory phenotype, which was accentuated after oestradiol administration. There was an increase of the immunoreactivity to alpha-oestrogen and androgen receptors in hyperplastic areas compared to normal epithelium, revealing the involvement of these steroid receptors in the hyperplasia and PIN development.

Localized matrix metalloproteinase (MMP)-2 and MMP-9 activity in the rat ventral prostate during the first week of postnatal development

The initial events in prostatic morphogenesis involve cell proliferation, epithelial canalization and outgrowth toward the stroma. We have hypothesized that stromal rearrangement takes place at the sites of epithelial growth and branching and that this rearrangement involves the action of gelatinases matrix metalloproteinase (MMP)-2 and MMP-9. Thus, the purpose of the present study was to characterize structural aspects of epithelial growth during the first week of postnatal development of the rat ventral prostate and to investigate the expression, localization and activity of MMP-2 and MMP-9 during this period by histological, ultrastructural and immunocytochemical analysis, in addition to gel zymography, in situ zymography and Western blotting. An increasing complexity of prostatic architeture was observed within the first postnatal week. Concurrently, the stroma became more organized and some cells differentiated into smooth muscle cells. Reticulin fibers appeared in a basket-like arrangement around both growing tips and epithelial sprouts, associated with a fainter staining for laminin. MMP-2 and MMP-9 activities were detected. MMP-2/MMP-9 expression decreased during the first week. Developing epithelial cords showed strong and difuse gelatinolytic activity. This activity coincided with the distribution of MMP-2 as determined by immunocytochemistry. on the other hand, MMP-9 was rather concentrated at the epithelial tips. These results suggest that gelatinolytic activity (with contribution of both MMP-2 and MMP-9) in the epithelium and at the epithelium-stroma interface are at least in part responsible for the tissue remodeling that allows epithelial growth and its projection into the surrounding stroma.

Diabetes induces stromal remodelling and increase in chondroitin sulphate proteoglycans of the rat ventral prostate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reduction of insulin signalling pathway IRS-1/IRS-2/AKT/mTOR and decrease of epithelial cell proliferation in the prostate of glucocorticoid-treated rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Long-term inhibition of 5-alpha reductase and aromatase changes the cellular and extracellular compartments in gerbil ventral prostate at different postnatal ages

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

High fat-induced obesity associated with insulin-resistance increases FGF-2 content and causes stromal hyperplasia in rat ventral prostate

Obesity affects sex hormone secretion, which can negatively influence prostatic structure, homeostasis, and disease. This investigation aimed to evaluate the repercussions of obesity induced by a high-fat diet on the rat prostate, with or without treatment with the aromatase inhibitor, Letrozole. Adult Wistar rats were fed a high-fat diet (20% saturated fat, O) for 15 weeks to induce obesity or received a balanced diet (4% fat, C). Then, a group of C and O rats were daily treated with Letrozole (1 mg/kg b.w. per day) for 2 weeks (CL and OL, respectively). Subsequently, ventral prostate was processed for analysis by transmission electron microscopy, immunohistochemistry, and Western blotting. Obesity decreased 70% of the testosterone plasma level. The prostate showed epithelial atrophy and dilated acini in the intermediate portion and epithelial wrinkling in the distal tips. The relative frequency of smooth muscle alpha-actin in the O group increased by 67%. Ultrastructurally, epithelial cells in obese animals presented altered secretory organelles, lipid droplets, and thicker subjacent fibromuscular layer. Letrozole treatment caused a partial restoration of the prostatic changes caused by obesity. Obesity increased the prostatic content of fibroblast growth factor-2 (FGF-2) by 150%, and Letrozole treatment increased this protein even more in the control and obese groups. This investigation shows that obesity provokes structural and ultrastructural changes in the epithelium of rat prostate; these changes might affect gland homeostasis and physiology. The epithelial and smooth muscle cell hyperplasia and increased FGF-2 expression observed in this experimental model of obesity/insulin-resistance might explain the high frequency of benign prostatic hyperplasia in insulin-resistant men.

Arterial diffuse intimal thickening associated with enzootic calcinosis of sheep

Foram feitos estudos morfométrico, imunoistoquímico e ultra-estrutural do espessamento intimal difuso (DIT) das artérias de 7 ovinos com sinais clínicos de calcinose enzoótica espontânea causada pela ingestão da planta Nierembergia veitchii. As lesões caracterizavam-se por deposição de sais de cálcio na média como placas e estrias que, com frequência faziam saliência para a luz, criando rugosidades e irregularidades da íntima. Não foram observadas calcificações na artéria pulmonar e no sistema venoso. Microscopicamente, as calcificações das artérias restringiam-se quase que exclusivamente à média. Na imunoistoquimica, foi verificada a-actina nas células da média e nas do espessamento intimal. Receptores para 1,25(OH)2D3 foram evidenciados nos núcleos das células musculares da média, da íntima e das células endoteliais. As análises morfométricas em microscopia ótica revelaram, nas artérias, DIT irregularmente distribuido sem relação com a intensidade dos processos de calcificação subjacente nem com a espessura da média remanescente. A morfometria das alterações ultra-estruturais das células musculares lisas da média e da íntima espessada, mostrou que nessas últimas foi verificado aumento de até 318% na fração volumétrica das organelas de síntese em detrimento dos elementos contráteis, quando comparados com os valores das células da média. Essas modificações indicam a transformação das células musculares lisas de um tipo contrátil para células de tipo sintético. Entre essses dois extremos foram evidenciadas diversas formas intermediárias. Foram observadas evidências histológicas e ultra-estruturais da transformação e migração de células da média através das fenestras da lâmina elástica interna, para a íntima, onde proliferam e formam o DIT. Foi concluído que o DIT é um componente constante nas lesões arterioscleróticas nas calcinoses dos ovinos induzidas pela planta N. veitchii e que as células predominantes são células musculares lisas provenientes de predecessoras da média. Foi constatado que o DIT só excepcionalmente apresenta calcificação, vascularização, presença de células espumosas e fendas de colesterol. Não foram vistas áreas de necrose. Sugere-se que o fator indutor das alterações arteriais é o 1,25(OH)2D3 contido em N. veitchii.

Effect of amitraz and xylazine on some physiological variables of horses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Macrophage activation by Paepalanthus spp. extracts

Macrófagos são conhecidos por exercerem uma importante função de mecanismo de defesa quando estas células são estimuladas com produtos naturais e produtos bacterianos (dentre outros). Uma variedade de citocinas e compostos químicos são liberados para induzir sistema de defesa fundamental. Entre outros peróxido de hidrogênio (H2O2) tem sido identificado como moléculas tendo multifunções. Entretanto está bem estabelecido que (H2O2) está envolvido em inúmeros processos fisiológicos, como por exemplo, neurotransmissão, relaxamento da musculatura lisa ou regulação imune. Para a determinação de peróxido de hidrogênio (H2O2) em macrófago peritoneal em camundongos, determinou-se a ação imunomodulatória de extratos (etanólico e etanólico 70%) obtidos de quatro espécies do gênero Paepalanthus (Eriocaulaceae) na concentração de 10 mg/mL. Os estratos etanólicos 70 % de capítulos de P. Hilairei, P. robustus, P. vellozioides e P. speciocus apresentaram maior liberação de (H2O2) do que os outros extratos etanólicos.

STRUCTURE OF THE RETE TESTIS OF THE CAT (FELIS-DOMESTICA, L)

The rete testis of the cat consists of 3 parts: a septal or interlobular part; a mediastinal part and a tunical part. The septal part contains the septal or transitory tubuli recti and the tubuli recti. The transitory tubules are formed as a confluence of the seminiferous tubules at the apex of the testicular lobules and the tubuli recti. The mediastinal rete is formed of long, straight channels which increase in size and become more irregular and anastomotic below the tunica albuginea at the cranial extremity of the testis. The end is characterized as the tunical part of the rete testis and communicates with the extratesticular rete testis. The channels all parts of the rete are lined by simple cuboidal or columnar epithelium. These epithelial channels are supported by a connective tissue containing smooth muscle cells. The framework tissue of the rete is more conspicuous at the cranial extremity of the testis, with a mio-connective matrix organization.

Synthesis and pharmacological properties of TOAC-labeled angiotensin and bradykinin analogs

Angiotensin II (AngII) and bradykinin (BK) derivatives containing the TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) spin label were synthesized by solid phase methodology. Ammonium hydroxide (pH 10, 50degreesC, 1 h) was the best means for reverting nitroxide protonation occurring during peptide cleavage. EPR spectra yielded rotational correlation times for internally labeled analogs that were nearly twice as large as those of N-terminally labeled analogs. Except for TOAC(1)-AngII and TOAC(0)-BK, which showed high intrinsic activities, other derivatives were inactive in smooth muscle preparations. These active paramagnetic analogs may be useful for conformational studies in solution and in the presence of model and biological membranes. (C) 2002 Elsevier B.V. All rights reserved.