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Microanatomic features of pancreatic islets and immunolocalization of glucose transporters in tissues of llamas and alpacas

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  • 1 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.
  • | 2 Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.
  • | 3 Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

Abstract

Objective—To describe the microanatomic features of pancreatic islets and the immunohistochemical distribution of glucose transporter (GLUT) molecules in the pancreas and other tissues of New World camelids.

Animals—7 healthy adult New World camelids, 2 neonatal camelids with developmental skeletal abnormalities, and 2 BALB/c mice.

Procedure—Samples of pancreas, liver, skeletal muscle, mammary gland, brain, and adipose tissue were collected postmortem from camelids and mice. Pancreatic tissue sections from camelids were assessed microscopically. Sections of all tissues from camelids and mice (positive control specimens) were examined after staining with antibodies against GLUT-1, -2, -3, and -4 molecules.

Results—In camelids, pancreatic islets were prominent and lacked connective tissue capsules. Numerous individual endocrine-type cells were visible distant from the islets. Findings in neonatal and adult tissues were similar; however, the former appeared to have more non–islet-associated endocrine cells. Via immunostaining, GLUT-2 molecules were detected on pancreatic endocrine cells and hepatocytes in camelids, GLUT-1 molecules were detected on the capillary endothelium of the CNS, GLUT-3 molecules were detected throughout the gray matter, and GLUT-4 molecules were not detected in any camelid tissues. Staining characteristics of neonatal and adult tissues were similar.

Conclusions and Clinical Relevance—In New World camelids, microanatomic features of pancreatic islets are similar to those of other mammals. Data suggest that the poor glucose clearance and poor insulin response to hyperglycemia in adult camelids cannot be attributed to a lack of islet cells or lack of GLUT molecules on the outer membrane of those cells.

Abstract

Objective—To describe the microanatomic features of pancreatic islets and the immunohistochemical distribution of glucose transporter (GLUT) molecules in the pancreas and other tissues of New World camelids.

Animals—7 healthy adult New World camelids, 2 neonatal camelids with developmental skeletal abnormalities, and 2 BALB/c mice.

Procedure—Samples of pancreas, liver, skeletal muscle, mammary gland, brain, and adipose tissue were collected postmortem from camelids and mice. Pancreatic tissue sections from camelids were assessed microscopically. Sections of all tissues from camelids and mice (positive control specimens) were examined after staining with antibodies against GLUT-1, -2, -3, and -4 molecules.

Results—In camelids, pancreatic islets were prominent and lacked connective tissue capsules. Numerous individual endocrine-type cells were visible distant from the islets. Findings in neonatal and adult tissues were similar; however, the former appeared to have more non–islet-associated endocrine cells. Via immunostaining, GLUT-2 molecules were detected on pancreatic endocrine cells and hepatocytes in camelids, GLUT-1 molecules were detected on the capillary endothelium of the CNS, GLUT-3 molecules were detected throughout the gray matter, and GLUT-4 molecules were not detected in any camelid tissues. Staining characteristics of neonatal and adult tissues were similar.

Conclusions and Clinical Relevance—In New World camelids, microanatomic features of pancreatic islets are similar to those of other mammals. Data suggest that the poor glucose clearance and poor insulin response to hyperglycemia in adult camelids cannot be attributed to a lack of islet cells or lack of GLUT molecules on the outer membrane of those cells.

Contributor Notes

Funded by the Oregon Agricultural Experiment Station. Digital photographic equipment was supplied by the Cell and Tissue Analysis Facilities and Services Core, Environmental Health Sciences Center, Oregon State University.

Dr. Cebra.