Morphological study on the ovary of a PCOS mouse model: role of antioxidants

BACKGROUND: Oxidative and glycative stresses are involved in the pathogenesis of the polycystic ovary syndrome (PCOS), a complex metabolic disorder characterized by symptoms as hyperandrogenism, oligo-ovulation, and polycystic ovaries. This syndrome is usually associated with insulin resistance, metabolic disorders, and infertility. Antioxidants may be used to reduce detrimental PCOS symptoms; their consumption ameliorated ovarian function and morphology in PCOS patients, with a reduction of the oxidative stress. Among antioxidants, L-carnitine was selected as a possible complementary diet supplement due to its role as a cell metabolism regulator. L-carnitine is involved in fatty acid metabolism, in the regulation of glucose metabolism and sensing cellular energy level. Moreover, it protects mitochondrial metabolism and modulates the activities of ROS-producing enzymes. LC supplementation has been successfully employed in PCOS patients, who, as a consequence, showed improvements in hormonal and metabolic parameters, increased energy consumption, lipid and bodyweight reduction. Together with LC, the endogenous carnitine pool is formed by short-chain carnitine esters acetyl-Lcarnitine (ALC) and propionyl-L-carnitine (PLC). When exogenously administered, ALC and PLC have a higher bioavailability in comparison to LC. Therefore, by a morphological approach, we here evaluated the efficacy of LC-ALC formulation on PCOS ovarian physiology and underlying mechanisms. METHODS: 4 week-old CD1 mice were administered or not (controls) with dehydroepiandrosterone (DHEA) (6 mg/100 g body weight) for 20 consecutive days alone or with the carnitine formulation 1 (0.40 mg LC, 0.20 mg ALC, DHEA + C1) and the carnitine formulation 2 (0.40 mg LC, 0.20 mg ALC, 0.08 mg PLC, DHEA + C2). Part of the ovaries collected from the three groups was subjected to: 1) H&E staining for ovarian follicle classification and counting; 2) Heidenhain’s AZAN Trichrome Staining; 3) Immunofluorescence Analysis for BODIPY and 17 beta-hydroxysteroid dehydrogenase type 4 (17βHSD4), and 4) Immunohistochemical Analysis for MG-AGE and 4-HNE. RESULTS: Histologic examination of DHEA ovaries showed alterations in the collagen deposition, as seen by the fibrotic aspect of the ovarian cortex, respect to controls. DHEA + C1 ovaries were also fibrotic, while in DHEA + C2 the collagen deposition decreased. Follicular atresia decreased after carnitine administration. BODIPY immunostaining after DHEA administration was stronger than in controls, evidencing an increased lipid droplet accumulation. The number and size of lipid droplets decreased in DHEA + C1 and, more significantly, in DHEA + C2. Intense staining in the ovarian surface epithelium for 17β-HSD4 was also observed. MG-AGE staining increased in DHEA mice’s ovaries. Administration of carnitine formulation 2 but not 1 could prevent MGAGE accumulation, with levels similar to controls. CONCLUSIONS: These results represent an important contribution to better understand the possible protective effects of antioxidants as carnitines. Oral administration of acyl-L-carnitines alleviated ovarian dysfunctions associated with PCOS, and that coadministration of PLC provides a better activity, also due to antioxidant/glycative activity.