A possible role of insulin-like growth factor-II C-peptide in regulating the function of steroidogenic cells in adult frog adrenal glands

Castillo S. S.

ACTA HISTOCHEMICA, vol.110, no.6, pp.451-461, 2008 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 110 Issue: 6
  • Publication Date: 2008
  • Doi Number: 10.1016/j.acthis.2007.12.008
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.451-461
  • Istanbul University Affiliated: No


The sole structural determinant for the differential ability of the insulin-like growth factors (IGF-I and IGF-II) to induce autophosphorylation of specific insulin receptor (IR) tyrosine residues and activate downstream signaling molecules is the C domain. The IR is structurally related to the type I insulin-like growth factor receptor (IGF-IR). This study aimed to identify the presence of IGF receptors by which the IGF-II C-peptide could mediate its effects in the frog (Rana ridibunda) adrenal glands and to observe whether injection of IGF-II C-peptide affects the function of adrenal steroidogenic cells using light and transmission electron microscopy and by the evaluation of the immunoreactivity of steroidogenic acute regulatory protein (StAR). After IGF-II C-peptide injection, there was a reduction of StAR protein immunoreactivity levels, an accumulation of large Lipid droplets in close contact with each other, and an induction of proliferation of the steroidogenic cells. These results indicate a possible rote of IGF-II C-peptide in steroidogenic cell function and in induction of steroidogenesis. The detection in this study of IGF-I receptor (IGF-IR) immunoreactivity in frog adrenal glands also indicates that the metabolic and mitogenic effects of IGF-II C-peptide in these glands may occur via the IGF-IR. (c) 2008 Elsevier GmbH. All rights reserved.