Autoradiographic analysis of 125I-insulin-like growth factor II internalization into pancreatic acini.
The internalization and intracellular distribution of 125I-insulin-like growth factor II (125I-IGF II) in mouse isolated pancreatic acini was studied by electron microscope autoradiography. 125I-IGF II was rapidly internalized; after 30 min over 70% of silver grains derived from the bound hormone were localized over the interior of the cells. The grain distribution from 125I-IGF II differed significantly from both a random grain distribution and that derived from bound 125I-insulin. The majority of intracellular 125I-IGF II grains were over the endoplasmic reticulum and Golgi; the Golgi showed the highest density of intracellular grains. Pretreatment of acini with 10 nM cholecystokinin octapeptide (CCK 8) reduced both the amount of acinar-associated IGF II and the density of intracellular 125I-IGF II grains. Moreover, CCK 8 altered the relative distribution of grains from 125I-IGF II between organelles. These studies indicate, therefore, that 125I-IGF II is internalized by pancreatic acini, and that this internalization is regulated by CCK 8.
D000818:Animals; D001345:Autoradiography; D002462:Cell Membrane / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D012844:Sincalide / Q000494:pharmacology; D013002:Somatomedins / Q000378:metabolism*
D007328:Insulin; D013002:Somatomedins; D007335:Insulin-Like Growth Factor II; D012844:Sincalide