Insulin-like growth factor I in the pancreas of normal and diabetic adult rats.
Insulin-like growth factor I (IGF-I, somatomedin C) was mapped by immunocytochemistry in the pancreas of normal and experimentally influenced rats. The polyclonal IGF-I antiserum K 37 was characterized and demonstrated to be specific. In the exocrine pancreas some duct cells showed IGF-I immunoreactivity, other components being negative. The three main endocrine cell types in the islets of Langerhans were IGF-I immunoreactive, most strikingly the D cells. Hypophysectomy resulted in loss of IGF-I immunoreactivity in all three endocrine cell types, i.e. D, A and B cells, while the levels of somatostatin, glucagon and insulin, respectively, remained unchanged. Starvation seemed to increase and feeding to decrease the IGF-I immunoreactivity in the B cells. Cysteamine pre-treatment reduced the normally intense IGF-I and somatostatin immunoreactivities in the D cells. In rats made diabetic with alloxan or streptozotocin, the B cells were irreversibly damaged and lost both their insulin and IGF-I immunoreactivities, while the IGF-I immunoreactivity was increased in A cells; the D cells remained unchanged. The concentrations of IGF-I mRNA in the pancreas were almost equal in normal and alloxan diabetic rats as were the concentrations of extractable IGF-I. We conclude that IGF-I immunoreactive material can be demonstrated in adult animals in all endocrine islet cells, most prominently in the D cells. The expression of IGF-I immunoreactivity is in part under pituitary control. In the adult rat only one islet cell type synthesizes IGF-I immunoreactive material, i.e. the D cells, while, in contrast, the B cells are likely to be a major IGF-I source in fetal and neonatal islets.
Hansson
H A
HA
Department of Histology, University of Gothenburg, Sweden.
Edwall
D
D
Löwenadler
B
B
Norstedt
G
G
Paleus
S
S
Skottner
A
A
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007016:Hypophysectomy; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010179:Pancreas / Q000378:metabolism*; D012313:RNA; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000378:metabolism*
D013002:Somatomedins; D012313:RNA; D007334:Insulin-Like Growth Factor I