Effects of maternal global nutrient restriction on fetal baboon hepatic insulin-like growth factor system genes and gene products

Abstract

Knowledge of altered maternal nutrition effects on growth-regulating systems is critical to understanding normal and abnormal fetal development. There are many reports of hepatic fetal IGF system responses to maternal nutrient restriction (MNR) during pregnancy in rodents and sheep but none in nonhuman primates. We determined effects of MNR on the fetal baboon hepatic IGF system. Social groups of female baboons were fed ad libitum, controls, or 70% controls (MNR) from 0.16 to 0.5 gestation and fetuses delivered by cesarean section. Fetal liver tissue was analyzed for IGF-I, IGF-II, and IGF binding protein (IGFBP)-3 mRNA by in situ hybridization and quantitative RT-PCR and protein by immunohistochemistry (IHC); IGF-I receptor, IGF-II receptor by quantitative RT-PCR and IHC and IGFBP-1 by in situ hybridization and IHC. MNR did not alter fetal body or liver weight. Fetal hepatic glycogen staining increased with MNR. MNR reduced fetal hepatic IGF-I and IGF-II and increased IGFBP-1 mRNA and decreased IGF-I, IGF-II, IGF-I receptor, and IGF-II receptor protein and increased protein for IGFBP-1 and IGFBP-3. MNR increased caspase-3, indicating apoptosis and decreased Akt staining, indicating decreased nutrient sensing. In conclusion, whereas fetal body and liver weights did not change in response to moderate MNR during the first half of baboon pregnancy, the major indices of function of the hepatic IGF system measured were all reduced.

Figure 1

ISH photomicrographs of liver at 90 d gestation from fetuses of mothers who were fed ad libitum (CTR): A, D, G, and J; MNR (fed 70% CTR diet from 30 to 90 d of gestation): B, E, H, and K; sense negative control: C, F, I, and L; IGF-I: A–C; IGF-II: D–F; IGFBP-1: G–I; and IGFBP-3: J–L in dark field. Bar (lower right) applies to all panels.

Figure 2

Immunohistochemistry for IGF-I (A–C) and IGF-II (D–F). Photomicrographs of liver at 90 d gestation from fetuses whose mothers were fed ad libitum (CTR; A and D), MNR (fed 70% CTR diet from 30 to 90 d of gestation; B and E); or negative control (C and F). Bar (right panel) applies to panels in that row.

Figure 3

Immunohistochemistry for IGF-1R (A–C) and IGF-IIR (D–F). Photomicrographs of liver at 90 d gestation from fetuses whose mothers were fed ad libitum (CTR; A and D) MNR (fed 70% CTR diet from 30 to 90 d gestation; B and E); or negative control (C and F). Bar (lower right) applies to all panels.

Figure 4

Immunohistochemistry for IGFBP-1 (A–C) and IGFBP-3 (D–F). Photomicrographs of liver at 90 d gestation from fetuses whose mothers were fed ad libitum (CTR; A and D); MNR (fed 70% CTR diet from 30 to 90 d gestation; B and E); or negative control (C and F). Bar (lower right) applies to all panels.

Figure 5

Photomicrographs of staining in liver sections from fetuses whose mothers were fed ad libitum (CTR; A, C, E, and G) or whose mothers were nutrient restricted (MNR; fed 70% CTR diet from 30 to 90 d gestation; B, D, F, and H). Immunostaining included: Ki67 (A and B); Caspase3 (C and D); AKT (E and F); and periodic acid Schiff staining for glycogen (G and H). Bar (right panel) applies to same-row panels.