L-glutamine ameliorates adipose-hepatic dysmetabolism in OC-treated female rats

Abstract

Adipose dysfunction and inflammation with or without hepatic defects underlie metabolic obesity. Glutamine (GLU) improves glucoregulation and metabolic indices but its effects on adipose function and hepatic lipid deposition in estrogen-progestin oral contraceptive (EPOC) users are unknown. Therefore, we hypothesized that GLUT supplementation would protect against adipose dysfunction and excess hepatic lipid influx and deposition in EPOC-treated animals by suppressing adenosine deaminase/xanthine oxidase (ADA/XO) activity and improving glucose-6-phosphate dehydrogenase (G6PD)-dependent antioxidant defense. Female Wistar rats weighing 150-180 g were allotted into control, GLUT, EPOC and EPOC + GLUT groups (six rats/group). The groups received vehicle (distilled water, p.o.), GLUT (1 g/kg), EPOC containing 1.0 µg ethinylestradiol plus 5.0 µg levonorgestrel and EPOC plus GLUT, respectively, daily for 8 weeks. Results showed that the administration of EPOC caused glucose dysregulation and increased triglyceride-glucose index and visceral adiposity, but the body weight and liver weight were not affected. However, EPOC significantly decreased adipose lipid, G6PD and glutathione and increased glycogen synthesis, ADA, XO, uric acid, lipid peroxidation, lactate production and gamma-glutamyl transferase activity (GGT). On the other hand, EPOC increased hepatic lipid, ADA, XO, uric acid, lipid peroxidation and lactate production and decreased glycogen synthesis, G6PD and glutathione. Nevertheless, supplementation with glutamine attenuated these alterations. Collectively, the present results indicate that EPOC causes metabolically induced obesity which is associated with adipose dysfunction and hepatic metabolic disturbance. The findings also suggest that glutamine confers metabo-protection with corresponding improvement in adipose and hepatic metabolic function by suppression of ADA/XO activity and enhancement of G6PD-dependent antioxidant defense.