The pancreas of the naked mole-rat ( Heterocephalus glaber): an ultrastructural and immunocytochemical study of the endocrine component of thermoneutral and cold acclimated animals

• Published in: General and comparative endocrinology 2004-12, Vol.139 (3), p.206-214
• Main Authors: Kramer, Beverley, Buffenstein, Rochelle
• Format: Article
• Language: English
• Subjects: Acclimatization; Animals; Blood Glucose - metabolism; Cold acclimation; Cold Temperature; Endocrine Glands - metabolism; Endocrine Glands - ultrastructure; Iimmunocytochemistry; Immunohistochemistry; Islet cell distribution; Microscopy, Electron; Mole Rats - anatomy & histology; Mole Rats - metabolism; Naked mole-rat; Pancreas; Pancreas - metabolism; Pancreas - ultrastructure; Ultrastructure
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2004.09.006

Endocrine cell distribution within the islets of Langerhans may vary both between species and under different energetically demanding conditions such as cold acclimation. The naked mole-rat, Heterocephalus glaber, lacking an effective insulatory pelage, is effectively a poikilotherm, yet it shows a typical mammalian cold-acclimation response by substantially increasing food intake to meet higher energy requirements when housed at lower temperatures. The endocrine component of the pancreas of thermoneutral and cold-acclimated naked mole-rats was thus characterized using immunocytochemistry and ultrastructural analyses. Four distinct endocrine cells were identified: α (glucagon-producing), β (insulin-producing), δ (somatostatin-producing), and PP (pancreatic polypeptide-producing) cells. Distribution of these cells differed from that of other rodents, in that β cells formed the mantle while α cells formed the core of the islets. This distribution may contribute to the observed insulin insensitivity of this species, as indicated in abnormal responses to glucose tolerance tests. Insulin-producing cells, however, were more numerous than glucagon-producing cells. This ratio was unchanged with cold acclimation. Immunoreactivity of α and β cells was more intense in cold-acclimated than in thermoneutral animals, possibly indicative of a change in hormonal production in animals housed at a lower temperature.