RESUMO
The interaction of Toxoplasma gondii with the gastrointestinal tract of its host is highly regulated. Once ingested, the parasite crosses the epithelium without altering the permeability of the intestinal barrier. Nevertheless, many studies report alterations ranging from structural to functional damage in cells and tissues that make up the wall of the small and large intestine. Although the immune response to the parasite has been extensively studied, the role of serotonin (5-HT) in toxoplasmosis is poorly understood. Here we investigate the distribution of cells expressing 5-HT and its effects on cells and tissues of the jejunal wall of rats after 2, 3, or 7 days of T. gondii infection. KEY RESULTS: Our results show that transposition of the jejunal epithelium by T. gondii leads to ruptures in the basement membrane and activation of the immune system, as confirmed by the decrease in laminin immunostaining and the increase in the number of mast cells, respectively. CONCLUSIONS AND INFERENCES: We showed an increase in the number of enterochromaffin cells and mast cells expressing 5-HT in the jejunal wall. We also observed that the percentage of serotonergic mast cells increased in the total population. Thus, we can suggest that oral infection by T. gondii oocysts preferentially activates non-neuronal cells expressing 5-HT. Together, these results may explain both the changes in the extracellular matrix and the morphology of the enteric ganglia.
Assuntos
Células Enterocromafins , Jejuno , Oocistos/metabolismo , Serotonina/biossíntese , Toxoplasma/metabolismo , Toxoplasmose/metabolismo , Doença Aguda , Animais , Células Enterocromafins/metabolismo , Células Enterocromafins/parasitologia , Jejuno/metabolismo , Jejuno/parasitologia , Masculino , Ratos , Ratos WistarRESUMO
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
A partir da síntese da serotonina, em 1951, iniciou-se a investigaçäo farmacológica dos receptores serotoninérgicos. A estimulaçäo dos mais variados tipos de receptores gera múltiplas respostas funcionais verificadas em nível de sistema nervoso central, terminaçöes nervosas serotoninérgicos em nível metabólico e fisiopatológico
Assuntos
Humanos , Animais , Ratos , Técnicas In Vitro , Receptores de Serotonina/efeitos dos fármacos , Receptores de Serotonina/metabolismo , Receptores de Serotonina/fisiologia , Serotonina/metabolismo , Células Enterocromafins/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Núcleos da Rafe , Núcleos da Rafe/metabolismo , Antagonistas da Serotonina/farmacocinética , Antagonistas da Serotonina/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Serotonina/farmacologia , VasoconstriçãoRESUMO
In this work we have demonstrated the influence of a short chain fatty acid (acetate) on the number of enterochromaffin (EC) cells containing serotonin (5HT), at two different pH (pH 6.9 absorptive stimuli, and pH 2.9 secretory stimuli), infused into the colon during one hour. The number of EC cells decrease significatively, specially in the cecum with a solution of low pH (2.9). The action of piprenzepine in preventing this reduction demonstrated that was partly mediated by a cholinergic receptor mechanism. On the other hand, a decrease on the release of 5HT to the lumen was a observed under the influence of pirenzepine. We conclude that the short chain fatty acid acetate, at a low pH induces the release of serotonin through a cholinergic mechanisms indicated by the inhibition observed with antimuscarinic drug.
Assuntos
Colo/metabolismo , Ácidos Graxos Voláteis/farmacologia , Pirenzepina/farmacologia , Serotonina/metabolismo , Acetatos/farmacologia , Ácido Acético , Animais , Ceco/citologia , Ceco/efeitos dos fármacos , Ceco/metabolismo , Colo/citologia , Colo/efeitos dos fármacos , Células Enterocromafins/efeitos dos fármacos , Células Enterocromafins/metabolismo , Concentração de Íons de Hidrogênio , Infusões Intravenosas , Mucosa Intestinal/citologia , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
En este trabajo hemos la influencia de un ácido graso de cadena corta (acetato) sobre el número de células enterocromafines (EC) conteniendo serotonina (5HT) a dos diferentes pH (pH 6.9, estímulo absortivo y pH 2.9 estímulo secretor) infundido durante una hora en el colon. El número de células EC disminuye significativament con una solución infundida a pH 2.9, especialmente en el ciego. La acción de la pirencepina en prevenir esta reducción demuestra que el mecanismo se efectúa parcialmente a través de receptores colinérgicos. Por parte, se observa una disminución de la liberación de 5HT, a través de un mecanismo colinérgico, como lo indica la inhibición observada con la droga antimuscarínica (AU)
Assuntos
Animais , Masculino , Ratos , Pirenzepina/farmacologia , Colo/citologia , Serotonina/metabolismo , Ácidos Graxos Voláteis/farmacologia , Colo/efeitos dos fármacos , Colo/metabolismo , Acetatos/farmacologia , Células Enterocromafins/efeitos dos fármacos , Células Enterocromafins/metabolismo , Ceco/citologia , Ceco/efeitos dos fármacos , Ceco/metabolismo , Mucosa Intestinal/citologia , Infusões Intravenosas , Concentração de Íons de Hidrogênio , Ratos Sprague-DawleyRESUMO
The possibility that VIP (Vasoactive intestinal peptide) could influence the enterochromaffin (EC) cell secretion of serotonin (5HT) and the action of VIP on the mast cell population of lamina propria were investigated in Wistar rat colon infused with a short chain fatty acid solution (sodium acetate), during a 1 h period. Under the action of an intravenous injection of synthetic porcine VIP, 14 micrograms/kg/h), the number of EC cells diminished significantly in the cecum and left colon, when compared to non-injected animals, both infused with a sodium acetate solution. At the same time, the number of mucosal mast cells in the crypts and lamina propria decreased significantly in the cecum. The postulate we put forward is that these VIP-induced changes are exerted through the stimulation of 5HT released from EC cells not only under normal physiological conditions but probably also under pathological conditions.