In Utero Dexamethasone Exposure Exacerbates Hepatic Steatosis in Rats That Consume Fructose During Adulthood

Abstract

Distinct environmental insults might interact with fructose consumption and contribute to the development of metabolic disorders. To address whether in utero glucocorticoid exposure and fructose intake modulate metabolic responses, adult female Wistar rats were exposed to dexamethasone (DEX) during pregnancy, and the offspring were administered fructose at a later time. Briefly, dams received DEX during the third period of pregnancy, while control dams remained untreated. Offspring born to control and DEX-treated mothers were defined as CTL-off and DEX-off, respectively, while untreated animals were designated CTL-off-CTL and DEX-off-CTL. CLT-off and DEX-off treated with 10% fructose in the drinking water for 8 weeks are referred to as CTL-off-FRU and DEX-off-FRU. We found that fructose promoted glucose intolerance and whole-body gluconeogenesis in both CTL-off-FRU and DEX-off-FRU animals. On the other hand, hepatic lipid accumulation was significantly stimulated in DEX-off-FRU rats when compared to the CTL-off-FRU group. The DEX-off-FRU group also displayed impaired very-low-density lipoprotein (VLDL) production and reduced hepatic expression of apoB, mttp, and sec22b. DEX-off-FRU has lower hepatic levels of autophagy markers. Taken together, our results support the unprecedented notion that in utero glucocorticoid exposure exacerbates hepatic steatosis caused by fructose consumption later in life.

Keywords: DOHaD; fructose; glucocorticoids; hepatic steatosis; pregnancy.

Figure 1

Effects of fructose on glucose homeostasis in rats exposed to dexamethasone (DEX) in utero. CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU groups were fasted and subjected to either a glucose tolerance test (GTT) (A) or pyruvate tolerance test (PTT) (B) The areas under the curves were calculated above each individual baseline. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 6–8. Area Under the Curve (AUC); Control (CTL); Fructose (FRU).

Figure 2

Effects of fructose on the relative fat pad weights and hepatic triglyceride contents in rats exposed to DEX in utero. (A) Mesenteric, (B) epididymal, and (C) retroperitoneal fat pads of the CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU groups were excised and expressed relative to body weight. (D) Fragments of liver were subjected to lipid extraction and subsequent triglyceride determination (D). The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 10–12.

Figure 3

Effects of fructose on the hepatic activity of glycolysis enzymes and levels of glycogen and lactate in rats exposed to DEX in utero. (A) Glycogen content of liver fragments from the CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU groups; (B–D) phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) activities, respectively; and (E) lactate determinations. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 10–12.

Figure 3

Effects of fructose on the hepatic activity of glycolysis enzymes and levels of glycogen and lactate in rats exposed to DEX in utero. (A) Glycogen content of liver fragments from the CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU groups; (B–D) phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) activities, respectively; and (E) lactate determinations. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 10–12.

Figure 4

Effects of fructose on hepatic enzyme activities associated with nonesterified fatty acids (NEFA) levels in rats exposed to DEX in utero. The activities of (A) citrate synthase (CS), (B) glucose 6-phosphate dehydrogenase (G6PDH), and (C) carnitine palmitoyltransferase (CPT1) were measured in fragments of liver from the CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU groups. (D) Expression of fasn and acca in liver fragments, as determined by qPCR. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 10–12.

Figure 5

Effects of fructose on parameters related to very-low-density lipoprotein (VLDL) production in rats exposed to DEX in utero. (A) Total cholesterol and (B) triglyceride (TG) liver content. (C) Hepatic gene expression of sec22b, mttp, and apoB, as determined by qPCR. (D) VLDL production in CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU rats injected with tyloxapol. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 6–8.

Figure 5

Effects of fructose on parameters related to very-low-density lipoprotein (VLDL) production in rats exposed to DEX in utero. (A) Total cholesterol and (B) triglyceride (TG) liver content. (C) Hepatic gene expression of sec22b, mttp, and apoB, as determined by qPCR. (D) VLDL production in CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU rats injected with tyloxapol. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 6–8.

Figure 6

Effects of fructose on autophagy markers in rats exposed to DEX in utero. (A) Summary of beclin 1, p62, and LC3B expression in CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU rats, as determined by Western blots. (B) Immunoblots were normalized using Ponceau-stained membranes. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 6–8.

Figure 6

Effects of fructose on autophagy markers in rats exposed to DEX in utero. (A) Summary of beclin 1, p62, and LC3B expression in CTL-off-CTL, DEX-off-CTL, CTL-off-FRU, and DEX-off-FRU rats, as determined by Western blots. (B) Immunoblots were normalized using Ponceau-stained membranes. The results are presented as the mean ± SE. Means with different superscript minuscule letters are significantly different. The p values are provided in Section 3. N = 6–8.