RESUMO
The pituitary is a master endocrine gland that developed early in vertebrate evolution and therefore exists in all modern vertebrate classes. The last decade has transformed our view of this key organ. Traditionally, the pituitary has been viewed as a randomly organized collection of cells that respond to hypothalamic stimuli by secreting their content. However, recent studies have established that pituitary cells are organized in tightly wired large-scale networks that communicate with each other in both homo and heterotypic manners, allowing the gland to quickly adapt to changing physiological demands. These networks functionally decode and integrate the hypothalamic and systemic stimuli and serve to optimize the pituitary output into the generation of physiologically meaningful hormone pulses. The development of 3D imaging methods and transgenic models have allowed us to expand the research of functional pituitary networks into several vertebrate classes. Here we review the establishment of pituitary cell networks throughout vertebrate evolution and highlight the main perspectives and future directions needed to decipher the way by which pituitary networks serve to generate hormone pulses in vertebrates.
Assuntos
Sistema Hipotálamo-Hipofisário/citologia , Sistema Hipotálamo-Hipofisário/metabolismo , Redes e Vias Metabólicas/fisiologia , Hipófise/citologia , Hipófise/metabolismo , Animais , Células Endócrinas/metabolismo , Gonadotrofos/metabolismo , Humanos , Hipotálamo/citologia , Hipotálamo/metabolismo , Filogenia , VertebradosRESUMO
Endocrine cells (ECs) act as a luminal surveillance system responding to either the presence or absence of food in the gut through the secretion of peptide hormones. The aim of this study was to analyze the effects of feeding and fasting on the EC peptide-specific distribution along the intestine of Nile tilapia. We assessed the density of ECs producing gastrin (GAS), cholecystokinin-8 (CCK-8), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) in nine segments of the intestine using immunohistochemistry. Our results show that ECs immunoreactive to CCK-8, GAS, NPY, and CGRP can be found along all the intestinal segments sampled, from the midgut to hindgut, although differences in their distribution along the gut were observed. Regarding nutrient status, we found that the anterior segments of the midgut seem to be the main site responding to luminal changes in Nile tilapia. The NPY+ and CGRP+ EC densities increased in the fasted group, while the amount of CCK-8+ ECs were higher in the fed group. No effects of fasting or feeding were found in the GAS+ EC densities. Changes in ECs density were found only at the anterior segments of the intestine which may be due to the correlation between vagus nerve anatomy, EC location, and peptide turnover. Lastly, ECs may need to be considered an active cell subpopulation that may adapt and respond to different nutrient status as stimuli. Due to the complexity of the enteroendocrine system and its importance in fish nutrition, much remains to be elucidated and it deserves closer attention.
Assuntos
Ração Animal , Ciclídeos/fisiologia , Células Endócrinas/metabolismo , Privação de Alimentos , Intestinos/citologia , Hormônios Peptídicos/metabolismo , Animais , Regulação da Expressão Gênica , Intestinos/inervação , Hormônios Peptídicos/genéticaRESUMO
Generalized bone loss can be considered an extra-articular manifestation of rheumatoid arthritis (RA) that may lead to the occurrence of fractures, resulting in decreased quality of life and increased healthcare costs. The peptide ghrelin has demonstrated to positively affect osteoblasts in vitro and has anti-inflammatory actions, but the studies that correlate ghrelin plasma levels and RA have contradictory results. We aimed to evaluate the correlation between total ghrelin plasma levels, density of ghrelin-immunoreactive cells in the gastric mucosa, and bone mineral density (BMD) in twenty adult women with established RA with 6 months or more of symptoms (mean age of 52.70±11.40 years). Patients with RA presented higher ghrelin-immunoreactive cells density in gastric mucosa (P=0.008) compared with healthy females. There was a positive relationship between femoral neck BMD and gastric ghrelin cell density (P=0.007). However, these same patients presented a negative correlation between plasma ghrelin levels and total femoral BMD (P=0.03). The present results indicate that ghrelin may be involved in bone metabolism of patients with RA. However, the higher density of ghrelin-producing cells in the gastric mucosa of these patients does not seem to induce a corresponding elevation in the plasma levels of this peptide.
Assuntos
Artrite Reumatoide/metabolismo , Densidade Óssea , Células Endócrinas/citologia , Grelina/sangue , Adulto , Artrite Reumatoide/fisiopatologia , Índice de Massa Corporal , Densidade Óssea/fisiologia , Contagem de Células , Células Endócrinas/metabolismo , Feminino , Colo do Fêmur/anatomia & histologia , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Humanos , Pessoa de Meia-Idade , Células Parietais Gástricas/metabolismo , Células Parietais Gástricas/patologiaRESUMO
Generalized bone loss can be considered an extra-articular manifestation of rheumatoid arthritis (RA) that may lead to the occurrence of fractures, resulting in decreased quality of life and increased healthcare costs. The peptide ghrelin has demonstrated to positively affect osteoblasts in vitro and has anti-inflammatory actions, but the studies that correlate ghrelin plasma levels and RA have contradictory results. We aimed to evaluate the correlation between total ghrelin plasma levels, density of ghrelin-immunoreactive cells in the gastric mucosa, and bone mineral density (BMD) in twenty adult women with established RA with 6 months or more of symptoms (mean age of 52.70±11.40 years). Patients with RA presented higher ghrelin-immunoreactive cells density in gastric mucosa (P=0.008) compared with healthy females. There was a positive relationship between femoral neck BMD and gastric ghrelin cell density (P=0.007). However, these same patients presented a negative correlation between plasma ghrelin levels and total femoral BMD (P=0.03). The present results indicate that ghrelin may be involved in bone metabolism of patients with RA. However, the higher density of ghrelin-producing cells in the gastric mucosa of these patients does not seem to induce a corresponding elevation in the plasma levels of this peptide.
Assuntos
Humanos , Feminino , Adulto , Pessoa de Meia-Idade , Artrite Reumatoide/metabolismo , Densidade Óssea , Células Endócrinas/citologia , Grelina/sangue , Artrite Reumatoide/fisiopatologia , Índice de Massa Corporal , Densidade Óssea/fisiologia , Contagem de Células , Células Endócrinas/metabolismo , Colo do Fêmur/anatomia & histologia , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Células Parietais Gástricas/metabolismo , Células Parietais Gástricas/patologiaRESUMO
Endocrine cells secrete hormones through the mucosa of the gastrointestinal tract (GIT) and act on the overall regulation of digestive processes such as nutrient absorption, gut motility and intestinal blood flow. This study aimed to determine regional distribution and frequency of endocrine cells secretory of serotonin (5-HT), somatostatin (SST) and gastrin (GAS) in the GIT of a small-bodied widespread characin Astyanax bimaculatus using histological, histochemical and immunohistochemical techniques. Fragments of the stomach and gut fixed for 8h in Bouin liquid were subjected to histological processing and immunohistochemical routine. For the histological analyses, the technique of staining with hematoxylin and eosin (HE) was used, whereas for the histochemical analyses Gomori's trichrome, periodic acid+Schiff (PAS) and Alcian blue pH 2.5 (AB) were used to further immunohistochemical processing. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells; the glandular region (proximal and distal portions) has folds and pits, whereas the non-glandular region has pits only. The intestinal epithelium is simple with plain cylindrical grooved and goblet cells. The anterior region has thin folds with few goblet cells, and the posterior region with thick folds and many goblet cells. The regional distribution and frequency of endocrine cells varied across regions of the GIT with the stomach showing the highest amount of immunoreactive (IR) cells. Only the 5-HT was found in the stomach (epithelia and glands) and gut regions, with comparatively higher frequency in the stomach. SST-IR cells were found in the stomach (epithelia and gastric glands) with higher frequency in the glandular region, whereas GAS-IR were found in the gastric glands only. The stomach was the only organ to have all the three types of endocrine cells, indicating that this organ is the main site of digestion of food in this species.
Assuntos
Characidae/metabolismo , Células Endócrinas/metabolismo , Gastrinas/metabolismo , Trato Gastrointestinal/citologia , Trato Gastrointestinal/metabolismo , Serotonina/metabolismo , Somatostatina/metabolismo , Animais , Imuno-HistoquímicaRESUMO
The aim of this study was to identify and quantify the argyrophil, argentaffin and insulin-immunoreactive cells (IIC) in the small intestine of the opossum Didelphis aurita. Seven adult male specimens of opossums were investigated. The animals were captured, and their blood insulin levels were determined. After euthanasia, fragments of the small intestine were processed for light microscopy and transmission electron microscopy, and submitted to histochemistry and immunohistochemistry for identification of argyrophil and argentaffin endocrine cells, and IIC. Argyrophil and argentaffin cells were identified in the intestinal villi and Liberkühn crypts, whereas IIC were present exclusively in the crypts. Ultrastructure of the IIC revealed cytoplasmic granules of different sizes and electron densities. The numbers of IIC per mm(2) in the duodenum and jejunum were higher than in the ileum (p<0.05). The animals had low levels of blood insulin (2.8 ± 0.78 µIU/ml). There was no correlation between insulin levels and the number of IIC in the small intestine. The IIC presented secretory granules, elongated and variable morphology. It is believed that insulin secretion by the IIC may influence the proliferation of cells in the Liberkühn crypts, and local glucose homeostasis, primarily in animals with low serum insulin levels, such as the opossum.
Assuntos
Didelphis/metabolismo , Células Endócrinas/metabolismo , Células Endócrinas/ultraestrutura , Células Enterocromafins/metabolismo , Insulina/metabolismo , Intestino Delgado/metabolismo , Animais , Proliferação de Células , Grânulos Citoplasmáticos/ultraestrutura , Didelphis/imunologia , Células Endócrinas/citologia , Células Enterocromafins/citologia , Células Enterocromafins/ultraestrutura , Imuno-Histoquímica , Insulina/imunologia , Mucosa Intestinal/citologia , Mucosa Intestinal/ultraestrutura , Intestino Delgado/ultraestrutura , Masculino , Microscopia Eletrônica de Transmissão , Gambás/metabolismoRESUMO
The eSMT rat is a new spontaneous model of type 2 diabetes that develops a progressive diabetic syndrome with a stronger incidence in males than in females. We decide to investigate the progression of the pancreatic histopathological changes during the lifespan of the eSMT rat, especially those associated with islet cell populations. Besides that, some plasmatic parameters were evaluated in order to correlate them with the morphological findings. Male eSMT and Sprague-Dawley control rats were used. The results showed a dramatic decrease of the volume density (VD) of endocrine tissue in the eSMT rats without evidence of insulitis. Islets became fragmented structures with strong presence of interstitial fibrosis. Consequently, plasma insulin levels showed a significant decrease, while plasma glucose, cholesterol and triglyceride levels were increased. Normal rats showed no significant changes in the VD of endocrine tissue, except for the older animals, where the VD of ß-cell population was increased. Early derangements observed in islets, together with the progressive decrease of endocrine tissue and the metabolic disorders described, would be responsible for an irreversible pathologic condition which avoids the animal survival beyond about 18 months of age. However, there is still a need to investigate the causes of endocrine tissue decrease and its possible association with an inflammatory process that it could be associated with the development and progression of fibrosis.
Assuntos
Diabetes Mellitus Tipo 2/patologia , Células Secretoras de Insulina/patologia , Pâncreas/patologia , Fatores Etários , Animais , Glicemia/análise , Tamanho Celular , Colesterol/sangue , Diabetes Mellitus Tipo 2/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Células Endócrinas/metabolismo , Fibrose , Imuno-Histoquímica , Insulina/sangue , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Masculino , Pâncreas/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Triglicerídeos/sangueRESUMO
The purpose of this study was to analyze the esophageal morphology of Caiman latirostris using histochemicaland immunohistochemical techniques. The mucosae layer is composed of a pseudostratified columnarepithelium with goblet cells that occasionally form intra-epithelial glands. The goblet cells showed differentaffinity for the histochemical techniques. The lamina propria is composed of loose connective tissue with bloodvessels. The smooth muscle fibers that compose the muscularis mucosa are thick and form a clear demarcationbetween the mucosa layer and adjacent submucosa. There are no glands in the esophageal submucosa. Themuscle layer is composed a circular internal layer and a longitudinal external one. The adventitia layer iscomposed of loose connective tissue and blood vessels. The serotonin immunoreactive (IR) cells were notpreferentially distributed in any region of the epithelium, ranging from the base of the intra-epithelial gland tothe connection to the lumen. Somatostatina, glucagon and CCK IR cells were not detected.
Assuntos
Animais , Jacarés e Crocodilos , Células Endócrinas/metabolismo , Esôfago/anatomia & histologia , Mucinas/análise , Mucinas/metabolismo , RépteisRESUMO
The pars tuberalis (PT) is the only pituitary region in close contact with the medial-basal hypothalamus and bathed by cerebrospinal fluid (CSF). Although PT has long been recognized as an endocrine gland, certain aspects of its structure remain obscure. The present investigation has been designed to gain information concerning (1) the cellular organization of PT, (2) the PT/median eminence spatial relationship and (3) the exposure of various cell compartments of PT to CSF. Non-endocrine cells (S100-reactive) appear as the organizer of the PT architecture. The apical poles of these cells line large cistern-like cavities and the processes of these cells establish a close spatial relationship with PT-specific secretory cells, portal capillaries and tanycytes. The cisterns are also endowed with clusters of ciliated cells and with a highly electron-dense and PAS-reactive content. The unique spatial organization of endocrine and non-endocrine cells of the PT supports a functional relationship between both cell populations. PT endocrine cells display a hallmark of PT-specific cells, namely, the paranuclear spot, which is a complex structure involving the Golgi apparatus, a large pool of immature secretory granules and a centriole from which originates a single 9+0 cilium projecting to the intercellular channels. Horseradish peroxidase (HRP) injected into the CSF readily reaches the intercellular channels of PT and the inner channel of the single cilium and is incorporated by the endocytic machinery of the secretory cells. The PT endocrine cells, through their single 9+0 cilium, may act as sensors of the CSF. HRP also reaches the lumen of the cisterns, indicating that this PT compartment is also exposed to CSF. PT endocrine cells establish direct cell-to-cell contacts with hypothalamic beta(1) tanycytes, suggesting a second means of brain-PT communication.