Hepatocyte ballooning and steatosis in early and late gestation without liver malfunction: Effects of low protein/high carbohydrate diet

Abstract

Pregnancy is a challenging metabolic and physiological condition. The aim of this study was to include a second demanding situation as a low protein/high carbohydrate diet (LPHCD) to characterize the histological and functional responses of the maternal liver. It is unknown how the maternal liver responds during early and late pregnancy to LPHCD intake. We explored early pregnancy (3 and 8 gestational age, G) and late pregnancy (15 and 20 G). The results indicated that pregnant rats under control diet showed an evident presence of ballooned hepatocytes, lipid vesicles and edema at late pregnancy (15G); in contrast, pregnant rats under LPHCD showed similar pattern of histological modification but at early pregnancy (3G). Unexpectedly, the serum biomarkers didn't display functional alterations in either group, despite of the evident histological changes no liver malfunction was detected. We conclude that pregnant rats fed with control diet and experimental LPHCD, are subjected to metabolic and physiological conditions that impact the histopathological condition of the maternal liver. Control diet promoted the histological modifications during late pregnancy whereas LPCHCD advanced the onset of these changes. Further experiments are needed to explore the biochemical mechanisms that underlie these histological modifications. Our results are also an example of the resilience associated with the pregnancy: since no functional hepatic alterations accompanied the histopathological changes, another conclusion is that no evident pathological condition was detected in this nutritional protocol.

Fig 1. Morphometric liver characteristics in non-pregnant (n = 10) and pregnant rats (n = 48) at different stages of pregnancy.

Gray bars correspond to the low protein/high carbohydrate diet (LPHCD) group; black bars correspond to the control group (CNP, CP). Shows proportion in arbitrary units (A.U.). A) Body weight, B) Liver/Body weight ratio, C) Adipose/body weight ratio. Data are shown as mean±standard error; and *P<0.05. **P<0.01, ***P<0.0001.

Fig 2. Liver histology by hematoxylin and eosin (H&E) in non-pregnant (n = 10) and pregnant rats (n = 48) at different stages of pregnancy.

Pathological evaluation of the liver. Gray bars correspond to the low protein/high carbohydrate diet (LPHCD) group; black bars correspond to the control group (CNP, CP). Shows proportion in arbitrary units (A.U.). A) Ballooned hepatocytes item, B) Fat microvesicles item, C) Fat macrovesicles item, D) Vacuoles item, E) Edema item, F) Inflammation item. Data are shown as mean±standard error; and *P<0.05. **P<0.01, ***P<0.0001.

Fig 3. Liver histology by hematoxylin and eosin (H&E) in non-pregnant rats.

A. Liver biopsy of control non pregnant rat (CNP). Accumulation of fat micro vesicles (MIV) was ts.observed in the cytoplasm. No damage in central vein (CV) and sinusoids (SI), normal hepatocytes (H), and trabeculae were observed. Ballooned hepatocytes (BH) were detected. B. Liver biopsy of non-pregnant rats fed with experimental diet (LPHCD). Diffuse accumulation of fat micro vesicles (MIV) and macrovesicles (MAV) were observed in the cytoplasm. Ballooning degeneration (BH) was also noticed.

Fig 4. Liver histology in early pregnant rats (hematoxylin-eosin).

A. Liver biopsy of pregnant rat on the control diet group, at the third day of gestation (3G). Accumulation of fat microvesicles (MIV) were observed in the cytoplasm. No damage in central vein (CV) and sinusoids (SI), normal hepatocytes (H), and trabeculae were reported. Ballooned hepatocytes (BH) were also observed. B. Liver biopsy of pregnant rat on the low protein diet group, at the third day of gestation (3G). Diffuse accumulation of fat microvesicles (MIV) and macrovesicles (MAV) were observed in the cytoplasm. Several hepatocytes showing ballooning degeneration (BH) were also observed.

Fig 5. Liver histology in late pregnant rats (hematoxylin-eosin).

A. Liver biopsy of pregnant rat on the control diet group, at twentieth day of gestation (20G). Diffuse accumulation of fat microvesicles (MIV) and macrovesicles (MAV) were largely observed in the cytoplasm (steatosis). Ballooned hepatocytes (BH) were also observed. B. Liver biopsy of pregnant rat on the low protein diet group, at twentieth day of gestation (20G). No accumulation of fat microvesicles were observed, normal hepatocytes were observed, nevertheless, it is observed notable sinusoidal (SI) dilatation.

Fig 6. Biomarkers in serum of non-pregnant (NP) (n = 10) and pregnant rats (n = 48) at different stages of pregnancy.

Gray bars correspond to the low protein/high carbohydrate diet (LPHCD) group; black bars correspond to the control group (CNP, CP). Albumin (A), Urea (B), Uric acid (C), Glutamic oxaloacetic transaminase (GOT) (D), Glutamic pyruvic transaminase (GPT) (E), Triacylglycerides (F), Cholesterol (G), Insulin (H), Glucose (I). Data are shown as mean±standard error; and *P<0.05. **P<0.01, ***P<0.0001.