Alterations in the structural characteristics of rectus abdominis muscles caused by diabetes and pregnancy: A comparative study of the rat model and women

Abstract

Background and objective: In the present study, we compared the effect of diabetic pregnancy on the rectus abdominis muscle (RAM) in humans and rats. We hypothesized that our animal model could provide valuable information about alterations in the RAM of women with Gestational Diabetes (GDM).

Method: Newborns female rats (n = 10/group) were administered streptozotocin (100 mg/kg body weight) subcutaneously and were mated on reaching adulthood, to develop the mild hyperglycemic pregnant (MHP) rat model. At the end of pregnancy, the mothers were sacrificed, and the RAM tissue was collected. Pregnant women without GDM (non-GDM group; n = 10) and those diagnosed with GDM (GDM group; n = 8) and undergoing treatment were recruited, and RAM samples were obtained at C-section. The RAM architecture and the distribution of the fast and slow fibers and collagen were studied by immunohistochemistry.

Results: No statistically significant differences in the maternal and fetal characters were observed between the groups in both rats and women. However, significant changes in RAM architecture were observed. Diabetes in pregnancy increased the abundance of slow fibers and decreased fast fiber number and area in both rats and women. A decrease in collagen distribution was observed in GDM women; however, a similar change was not observed in the MHP rats.

Conclusion: Our results indicated that pregnancy- associated diabetes- induced similar structural adaptations in the RAM of women and rats with slight alterations in fiber type number and area. These findings suggest that the MHP rat model can be used for studying the effects of pregnancy-associated diabetes on the fiber structure of RAM.

Fig 1. Flowchart of participant recruitment strategy.

Fig 2

A: Oral Glucose Tolerance Test (OGTT) performed at 24–28 weeks for pregnant women and on the 17^th day of pregnancy for rats. B: The area under the curve of each group is expressed as the mean ± standard deviation. *p<0.05 shows a significant difference compared to the control group (t-test).

Fig 3. Micrographs showing slow and fast fibers in a transverse RAM section.

Non-GDM (slow 1, fast 2), GDM (slow 3, fast 4), non-MHP (slow 5, fast 6), and MHP (slow 7, fast 8). (A) The abundance of each fiber type is expressed as percentages, and (B) the area of each fiber type is expressed as mean ± SD. Differences in the abundance of each fiber type between the groups were determined using Poisson distribution. Differences in the fiber area between the groups were determined using the Student’s t-test. *p<0.05 shows a significant difference compared to the control group. Abbreviations: GDM, Gestational Diabetes, MHP, mild hyperglycemic pregnant.

Fig 4

Transverse RAM sections stained with picrosirius red showing striated muscle (yellow) and collagen (red). (1) Non-GDM, (2) GDM, (3) non-MHP, and (4) MHP. Differences in the collagen area between the groups were evaluated using the Student’s t-test. *p<0.05 shows a significant difference compared to the control group. Abbreviations: GDM, Gestational Diabetes, MHP, mild hyperglycemic pregnant; RAM, rectus abdominis muscle.