Beneficial effects of walnut (Juglans regia L.) oil-derived polyunsaturated fatty acid prevents a prooxidant status and hyperlipidemia in pregnant rats with diabetes

Abstract

Background: Gestational diabetes mellitus has a long-term effect on pregnant women. Walnut (Juglans regia L.) oil-derived polyunsaturated fatty acid (PUFA) possesses multifarious pharmacological activities. This study investigated the beneficial effects of walnut oil-derived PUFA on glucose metabolism, pregnancy outcomes, oxidative stress, and lipid metabolism in gestational diabetes mellitus.

Methods: The GDM rat model was generated by intraperitoneal injection of streptozotocin (40 mg/kg) on gestational day (GD) 6, GD7 and GD8. The differences between groups were estimated using one-way ANOVA followed by the Tukey's multiple comparison test for post-hoc analysis.

Results: The results indicated that PUFA could mitigate GDM in pregnant diabetic rats, as embodied by the decrease of fasting blood glucose and the increase of plasma insulin and hepatic glycogen levels. Also, PUFA could suppress oxidative stress in pregnant diabetic rats, as reflected by the decrease of malondialdehyde content, an increase of superoxide dismutase, catalase and gutathione peroxidase activities. PUFA could also mitigate the abnormal changes of lipid profiles in plasma and hepatic tissue. Moreover, the relative mRNA expression of sterol regulatory element-binding transcription factor-1, stearoyl-CoA desaturase-1, fatty acid synthase, and acetyl-coenzyme A carboxylase, was suppressed by PUFA in pregnant diabetic rats.

Conclusions: These results suggested that PUFA supplementation during pregnancy is beneficial in preventing diabetic complications in pregnant rats.

Keywords: Dyslipidemia; Gestational diabetes; Oxidative stress; Walnut oil-derived PUFA.

Fig. 1

Walnut oil-derived PUFA alleviates gestational diabetes symptoms in GDM rats. Maternal body weight (a), blood glucose levels (b) and insulin levels (c) were measured on gestation day (GD) 0, 9, and 18 in different groups. Homeostatic model assessment of insulin resistant (HOMA-IR) indexes in different groups (D). Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 2

Walnut oil-derived PUFA effectively improves glucose and insulin tolerance in pregnant rats with diabetes. Oral glucose tolerance test (OGTT) and intraperitoneal insulin tolerance test (IPTT) were carried out on gestation day (GD) 17. Effect of PUFA on glucose tolerance (a, b) and insulin tolerance (c, d) on GD 17 in pregnant rats with diabetes. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 3

Effect of walnut oil-derived PUFA on the levels of Hb (a), HbA1c (b), and liver glycogen (c) in pregnant rats with diabetes. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 4

Walnut oil-derived PUFA effectively improves the fetal growth restriction caused by GDM. Fetal body weights (a) and placental weights (b) were recorded in pregnant rats. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^*P < 0.05 (vs the GDM group)

Fig. 5

Walnut oil-derived PUFA alleviates oxidative stress in GDM. Hepatic SOD (a), hepatic GSH-Px (b), hepatic CAT (c), hepatic MDA (d) were measured in GD 18. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 6

Walnut oil-derived PUFA alleviates lipid metabolism in GDM. Plasma TC levels (a), plasma TG levels (b), plasma LDL-C levels (c), plasma HDL-C levels (d), hepatic TC levels (e) and hepatic TG levels (f) were measured in GD 18. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 7

Effect of walnut oil-derived PUFA on the mRNA expression of SREBP-1 and its target genes in pregnant rats. The mRNA expression of SREBP-1 (a), SCD-1 (b), ACC (c) and FAS (d) were examined. Data are expressed as the mean ± SD (n = 8/group). ^#P < 0.01 (vs the PC group), ^**P < 0.01 (vs the GDM group), ^*P < 0.05 (vs the GDM group)

Fig. 8

The graphic abstract of the present study. Abbreviations: polyunsaturated fatty acid (PUFA); gestational diabetes mellitus (GDM); gestational day (GD); malondialdehyde (MDA); superoxide dismutase (SOD); catalase (CAT); gutathione peroxidase (GSH-Px); sterol regulatory element-binding transcription factor-1 (SREBP-1); stearoyl-CoA desaturase-1 (SCD-1); streptozotocin (STZ); fatty acid synthase (FAS); and acetyl coenzyme A carboxylase (ACC)