Immunocytochemical detection of glucagon and insulin cells in endocrine pancreas and cyclic disparity of plasma glucose in the turtle Melanochelys trijuga.

The present investigation was carried out to know the seasonal variation in plasma glucose,insulin and glucagon cells during the reproductive cycle of untreated Melanochelys trijuga. Pancreatic endocrine cells were immunochemically localized.Insulin-immunoreactive (IR) cells occurred in groups of 3-20 and were in close apposition, while glucagon-IR cells were distributed individually between the exocrine pancreas or formed anastomosing cords where cells were not intimately attached. Whenever both IR cell types were present together forming an islet,insulin-IR cells formed clusters in the centre with glucagon-IR cells being scattered at the periphery. Glucagon-IR cells seemed to be secretory throughout the pancreas during the reproductive cycle,while insulin-IR cells were found to be pulsating in their secretion. Mean size of the islet was 1.306, 0.184 and 2.558 mm in the regenerative, reproductive and regressive periods,respectively. In general,insulin-IR cells measured 5.18 (mu)m and glucagon-IR cells 5.22 (mu)m in their longest axis. Invariably, glucagon-IR cells were more in number than insulin-IR cells. The fasting plasma glucose level was 69.97 mg% during the regenerative period, which increased to 97.96 mg% during the reproductive period,and reached a peak value of 113.52 mg% in the regressive period.

An immunohistochemical study of the gastrointestinal endocrine cells in the ddY mice

The distributions and frequencies of some endocrine cells in the gastrointestinal (GI) tract of ddY mice were studied with immunohistochemical method using 7 types of antisera against bovine chromogranin (BCG), serotonin, gastrin, cholecystokinin (CCK)-8, somatostatin, glucagon and human pancreatic polypeptide (HPP). All of 7 types of immunoreactive (IR) cells were identified. Most of IR cells in the intestinal portion were generally spherical or spindle in shape (open typed cell) while cells showing round in shape (close typed cell) were found in the intestinal gland and stomach regions occasionally. Their relative frequencies were varied according to each portion of GI tract. BCG-IR cells were demonstrated throughout whole GI tract except for the cecum and they were most predominant in the fundus and pylorus. Serotonin-IR cells were detected throughout whole GI tract and they were most predominant cell types in this species of mice. Gastrin-IR cells were restricted to the pylorus and CCK-8-IR cells were demonstrated in the pylorus, duodenum and jejunum with numerous frequencies in the pylorus. Somatostatin-IR cells were detected throughout whole GI tract except for the cecum and rectum and they showed more numerous frequencies in the stomach regions. In addition, glucagon-IR cells were restricted to the fundus, duodenum and jejunum with rare frequencies, and HPP-IR cells were restricted to the rectum only with rare frequency. In conclusion, some strain-dependent unique distributional patterns of gastrointestinal endocrine cells were found in GI tract of ddY mice.

An immunohistochemical study on the pancreatic islets cells of the Mongolian gerbils, Meriones unguiculatus

In order to study the regional distribution and relative frequency of the immunoreactive endocrine cells in the pancreatic islets of the Mongolian gerbil, pancreatic sections of Meriones unguiculatus were immunostained using an immunohistochemical (PAP) method with four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). The pancreatic islets were subdivided into three portions (central region, mantle zone and peripheral region) according to their composition of immunoreactive cells. Spherical to spindle shaped insulin, glucagon, somatostatin and PP-immunoreactive cells were observed in this study. Insulin-immunoreactive cells were present in the central regions with high frequency, and a few of these cells were also demonstrated in the mantle zones. Glucagon-immunoreactive cells were mainly restricted to the mantle zones. However, rare examples were found in the peripheral regions. As for the glucagon-immunoreactive cells, somatostatin-immunoreactive cells were detected in the mantle zones and peripheral regions with moderate and rare frequencies, respectively. PP-immunoreactive cells were found in the mantle zones and peripheral regions with rare and moderate frequencies, respectively. In the mantle and the peripheral regions, cytoplasmic process of glucagon-, somatostatin- and PP-immunoreactive cells were intermingled. In conclusion, the regional distribution of endocrine cells in the pancreatic islets of Mongolian gerbil was found to be similar to that of other mammals, especially other rodents, except for the topographical different distribution of somatostatin which differs that of other rodents.

Immunohistochemical localization of eight phospholipase C isozymes in pancreatic islets of the mouse

The possible involvement of phospholipase C (PLC) in the regulation of insulin secretion is not clearly understood and neither its isozymes expressed nor cellular localization in the pancreatic islets is known. By using specific monoclonal antibodies, we have investigated the expression and localization of eight different PLC isozymes, beta1, beta2, beta3, beta4, gamma1, gamma2, delta1, and delta2, in the pancreatic islets of adult mice. Immunohistochemical analysis carried out on paraffin embedded sections showed a distinct pattern of expression for each of the PLC isozymes. In the central part of the islets containing beta cells, a high level of beta4 and moderate levels of beta3 and gamma1 were expressed, whereas PLC-beta1 and -gamma1 were abundantly expressed in the exocrine pancreas. These results demonstrated the heterogeneity in expression of the phospholipase C isozymes in pancreatic islets. It is conceivable that these isozymes are coupled to different receptors and perform selective tasks in the regulation of insulin secretion for glucose homeostasis.

Comparative study of endocrine cells in the principal pancreatic islets of two teleosts, Silurus asotus (Siluridae) and Siniperca scherzeri (Centropomidae)

The regional distribution and relative frequency of some endocrine cells in the principal pancreatic islets of two teleosts, Silurus asotus Linne (Siluridae) and Siniperca scherzeri Steindachner (Centropomidae), which have similar feeding habits, were observed using specific antisera against insulin, glucagon, somatostatin and bovine pancreatic polypeptide (bovine PP) using the peroxidase antiperoxidase (PAP) method. Spherical to spindle shaped cells were demonstrated in the principal pancreatic islets in both species of teleost fishes. However, they were not detected in the exocrine portions nor the pancreatic ducts. Insulin-immunoreactive cells were located in the central regions of the principal pancreatic islets at high frequency in both species. Glucagonimmunoreactive cells were restricted to the peripheral regions of the principal pancreatic islets in both species. They formed a mantle zone in the peripheral regions of Silurus asotus with moderate frequency, and occupied a narrower mantle zone in Siniperca scherzeri with moderate frequency. In addition, glucagonimmunoreactive cell cores were also found in the peripheral zone of some principal pancreatic islets of Siniperca scherzeri. Somatostatin-immunoreactive cells were dispersed in the central zone of the principal pancreatic islets of Silurus asotus with moderate frequency, but were located in the peripheral regions with low frequency in Siniperca scherzeri. Bovine PPimmunoreactive cells were found in the peripheral region and the mantle zone of the principal pancreatic islets with low and rare frequency, respectively in both species. In conclusion, the regional distribution and relative frequency of endocrine cells in the principal pancreatic islets of Silurus asotus showed general patterns similar to those of other teleostean fishes. But, some speciesdependent distributional patterns and/or relative frequencies, particularly in glucagon-, somatostatin- and bovine PP-immunoreactive cells, were detected in the principal pancreatic islets of Siniperca scherzeri

Experimental pancreas transplantation the consequences of the portocaval shunt on the blood glucose, plasma insulin and glucagon

A proposiçäo foi realizada, no período pós-operatório imediato, em 40 ratos Wistar, distribuidos por sorteio em dois grupos: grupo NC, vinte ratos correspondentes ao grupo controle, näo diabético, submetidos a operaçäo simulada e o grupo PT, 20 ratos correspondentes ao grupo diabético que recebeu transplante de pâncreas heterotópico de ratos Wistar normais. Durante sete dias, antes do transplante, e 1, 3 6, 12, 24, 48, 72, 96 horas após, determinava-se a glicose sanguínea, a insulina plasmática e o glucagon. Estes parâmetros eram obtidos também no grupo NC. Diabetes mellitus experimental era induzida pela administraçäo intravenosa de aloxana. O grupo PT era imunosuprimido com ciclosporina A. O grupo NC apresentou níveis normais de glicose sanguínea, de insulina plasmática e de glucagon, durante todo o experimento. Foi encontrada nítida hiperinsulinemia no sangue venoso periférico do grupo PT. A insulina plasmática era significantemente maior no grupo PT comparada ao grupo NC começando 72 horas após o transplante. O glucagon plasmático, elevado no período pré-transplante, näo se alterou após o transplante. Apesar da hiperinsulinemia e hiperglucagonemia, os níveis de glicose sanguínea eram elevados 6 horas após o transplante e mantiveram-se normais após este período. Considerando-se os níveis de glicose sanguínea 12 horas pós-transplante, näo houve diferença estatisticamente significante entre os grupos PT e NC, até o sacrifício