EXPRESSION OF INSULIN, GLUCAGON, SOMATOSTATIN, AND PANCREATIC POLYPEPTIDE IN THE PANCREAS OF THE EURASIAN MOORHEN (Gallinula chloropus)

Abstract

The pancreas is a complex gland that possesses both endocrine and exo-crine functions. The present study investigated the gross anatomy, histochemical fea-tures, and immunohistochemical expression of insulin, glucagon, somatostatin, and pancreatic polypeptide in the pancreas of the Eurasian moorhen. Grossly, the pancreas consisted of three duodenal lobes and unpaired splenic and gastric lobes. The pancre-atic capsule appeared thin with no distinct lobulation pattern. Three islet types were observed namely alpha, beta, and mixed types. The alpha-type islets formed mainly of glucagon- and somatostatin-expressing cells. The beta-type islets appeared relatively smaller than the two other islet types and formed predominately of insulin-expressing cells with a limited number of other endocrine cells. The mixed islets were formed by almost equal proportions of insulin-, glucagon- and somatostatin-expressing cells. A higher number of alpha-type islets was observed in the splenic lobe than in other pan-creatic lobes. Unlike other pancreatic endocrine cells which appeared oval or triangular in shape, somatostatin-expressing cells appeared with irregular outlines with cytoplas-mic processes contacting each other’s forming a meshwork within the islet. The results of this study revealed species-specific features of the endocrine and exocrine pancreas in the Eurasian moorhen and could suggest pancreatic functional differences depend-ing on feeding habits. Izražanje insulina, glukagona, somatostatina in pankreatičnega polipeptida v trebušni slinavki evrazijskega zelenonoge tukalice (Gallinula chloropus) Izvleček: Trebušna slinavka je kompleksna žleza z endokrino in eksokrino funkcijo. V tej študiji smo preučevali splošno anatomijo, histokemične značilnosti in imunohistokemično izražanje inzulina, glukagona, somatostatina in pankreas-nega polipeptida v trebušni slinavki evrazijske zelenonoge tukalice. Makroskopsko je bila trebušna slinavka sestavljena iz treh dvanajstnikovih režnjev ter neparnih vraničnega in želodčnega režnja. Kapsula trebušne slinavke je bila tanka, brez izrazitega vzorca lobulacije. Opazni so bili trije tipi otočkov - alfa, beta in mešani. Otočki tipa alfa so bili sestavljeni predvsem iz celic, ki so izražale glukagon in somatostatin. Otočki tipa beta so bili relativno manjši od drugih dveh tipov otočkov in sestavljeni pretežno iz celic, ki so izražale inzulin ter omejenega števila drugih endokrinih celic. Mešani tipi otočkov so bili sestavljeni iz enakega deleža celic, ki izražajo inzulin, glukagon in somatostatin. V vraničnem režnju je bilo opazno več otočkov tipa alfa kot v drugih režnjih trebušne slinavke. V primerjavi z drugimi endokrinimi celicami trebušne slinavke, ki so bile ovalne ali trikotne oblike, so bile celice, ki izražajo somatostatin, nepravilnih obrisov s citoplazems-kimi izrastki, ki so se stikali med seboj in tvorili mrežo znotraj otočka. Rezultati te študije so razkrili vrstno specifične značilnosti endokrine in eksokrine trebušne slinavke pri evrazijski zelenonogi tukalici in bi lahko nakazovali funkcionalne razlike v delovanju trebušne slinavke glede na prehranjevalne navade. Ključne besede: trebušna slinavka; otoček; inzulin; glukagon; somatostatin; polipeptid; sladkorna bolezen