Role of adiponectin receptors, AdipoR1 and AdipoR2, in the steroidogenesis of the human granulosa tumor cell line, KGN.

BACKGROUND: Adiponectin is involved in the regulation of energy homeostasis and more recently in the reproductive functions. We have previously shown that adiponectin receptors (AdipoR1 and AdipoR2) are expressed in human granulosa cells. However, it remains to be investigated whether both AdipoR1 and AdipoR2 or only one of these receptors serve as the major receptor(s) for adiponectin in human granulosa cells. METHODS: The RNA interference (RNAi) technology was used to specifically knockdown the expression of either AdipoR1 or AdipoR2. Progesterone and estradiol levels in the conditioned media were measured by radioimmunoassay, and determination of cell proliferation by tritiated thymidine incorporation. The levels of adiponectin receptors and proteins involved in the steroidogenesis and in the signalling pathways were examined by western blot. RESULTS: We generated AdipoR1 (R1) and AdipoR2 (R2) knockdown KGN cell lines. R1 cells were apoptotic and had increased expression levels of cleaved caspase 3 and decreased levels of BAD phosphorylation and PCNA as compared with control or parental KGN cells. R2 cells had similar morphology to control or KGN cells. However, they produced less progesterone and estradiol and expressed lower levels of StAR protein in response to FSH or IGF-1 stimulation compared with control cells. Furthermore, the increase of MAPK ERK1/2 phosphorylation in response to human recombinant adiponectin and FSH was lower in R2 than control cells. CONCLUSIONS: In the human granulosa KGN cell-line, AdipoR1 seems to be involved in the cell survival whereas AdipoR2, through MAPK ERK1/2 activation, may be implicated in the regulation of steroid production.

[Role of the fatty acids in ovarian functions: involvement of peroxisome proliferator-activated receptors (PPAR) and adipokines]. / Rôle des acides gras sur les fonctions ovariennes : implications des Peroxisome Proliferator-Activated Receptors (PPAR) et des adipocytokines.

The impact of nutrition and energy reserves on the reproductive functions is known for a very long time. However, the metabolic factors involved in the interactions between nutrition and reproduction are still poorly understood. These factors may be hormones or nutrients (glucose, protein and fatty acids). However, it remains to determine whether these factors act directly or indirectly on the reproductive tissues. In this issue, we briefly summarize the impact of fatty acids on the development of ovarian follicles, oocyte and embryo. We then discuss the current hypotheses about the mechanisms of action of these fatty acids on the ovarian functions. We describe more particularly the role of some receptors of fatty acids, Peroxisome Proliferator-Activated Receptors (PPAR) and Liver X Receptors (LXR) and two adipokines, leptin and adiponectin on ovarian cells.

[Elastosonography of thyroid lesions]. / Elastographie ultrasonore des lésions thyroïdiennes.

UNLABELLED: While ultrasound is the imaging modality of choice for diagnosis of thyroid lesions, characterization remains limited and tissue diagnosis frequently is required for management. The availability of additional tools such as elastography may improve lesion characterization and direct management. MATERIALS AND METHODS: A total of 96 patients (11 males and 85 females; 58+/-24 years) referred for fine needle aspiration (FNA) of mainly solid thyroid nodules 9-32 mm in diameter underwent conventional US and elastosonography. Results on elastography were correlated with histological results from FNA and classified as follows: suspected malignant lesion, suspected benign lesion, suspicious, indeterminate. RESULTS: The nodules were classified as follows: 95 nodules were soft (classes I and II) and 13 nodules were hard (classes III and IV). No cancers were detected in class and II lesions and 6 cancers were detected in class III and IV lesions. FNA provided insufficient cellular material for diagnosis in 5 class I-II nodules and 2 class III-IV nodules. CONCLUSION: Real-time elastosonography may be a useful adjunct to conventional US in the evaluation and characterization of thyroid nodules allowing identification of patients at high risk of malignancy for whom tissue diagnosis and/or close follow-up is required.

The effect of AMP-activated kinase activation on gonadotrophin-releasing hormone secretion in GT1-7 cells and its potential role in hypothalamic regulation of the oestrous cyclicity in rats.

Hypothalamic AMP-activated kinase (AMPK) is a key regulator of food intake in mammals. Its role in reproduction at the central level and, more precisely, in gonadotrophin-releasing hormone (GnRH) release has never been investigated. We showed that each subunit of AMPK is present in immortalised GnRH neurones (GT1-7 cells). Treatment with 5-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR) and metformin, two activators of AMPK, increased dose-dependent and time-dependent phosphorylation of AMPKalpha atThr172 in GT1-7 cells. Phosphorylation of acetyl-coenzyme A carboxylase at ser79 also increased. Treatment with AICAR (5 mM) or metformin (5 mM) for 4 h inhibited GnRH release in the presence or absence of GnRH (10(-8) M). Specific AMPK inhibitor compound C completely eliminated the effects of AICAR or metformin on GnRH release. Finally, we determined the central effects of AICAR in vivo on food intake and oestrous cyclicity. Ten-week-old female rats received a 50 microg AICAR or a saline i.c.v. injection. We detected increased AMPK and acetyl-CoA carboxylase phosphorylation, specifically in the hypothalamus, 30 min after AICAR injection. Food intake was significantly higher (P < 0.05) in animals treated with AICAR than in animals injected with saline, 24 h after injection. This effect was abolished after 1 week. Moreover, during the 4 weeks following injection, the interval between two oestrous stages was significantly lower in the AICAR group than in the saline group. Our findings suggest that AMPK activation may act directly at the hypothalamic level to affect fertility by modulating GnRH release and oestrous cyclicity.

Five-year predictive factors of type 2 diabetes in men with impaired fasting glucose.

AIM: The outcome of 743 French men (age 20-60) with impaired fasting glucose (IFG) [blood glucose 6.1-6.9 mmol/l] at T1 was evaluated 5 years later, at T2. METHODS: Personal and family medical history, smoking, nutritional habits, physical activity, blood pressure, body mass index (BMI) and waist girth, fasting biological data were collected at T1 and T2. Predictive factors for developing diabetes were compared between those who returned to normal fasting glucose and those who had diabetes, before and after adjustment for age, BMI, glucose and triglyceride (TG) levels. RESULTS: At T2, 44%, 39%, 17% were classified as normal fasting plasma glucose (FPG), IFG or diabetic, respectively. Odd ratios for diabetes were 4.2 for men with a family history of diabetes (FHD), 3.4 if BMI > or = 25 kg/m(2), 2.9 if waist girth > or = 90 cm, 2.8 if TG > or = 2 mmol/l and 1.9 if no daily dairy products were eaten. Still significant after adjustment for age, BMI, glucose and TG levels were: FHD (P=0.001), no daily dairy products (P=0.001), high alcohol intake (P=0.02) and low physical activity (P = 0.02). CONCLUSION: No daily dairy products, high alcohol intake and low physical activity were independent predictive factors of a 5-year onset of diabetes after adjusting for BMI, FHD, triglyceride and glucose levels at baseline. For a better prevention of diabetes, these findings give clues for behaviour modifications as soon as IFG is detected.

Apolipoprotein E genotype and plasma lipid levels in Caucasian diabetic patients.

OBJECTIVE: Apo E polymorphism has been shown to affect lipid profiles in non-diabetic and diabetic populations. We evaluated the relationship between Apo E phenotype and fasting lipid plasma levels in type 2 diabetes patients. METHODS: Two hundred and ten French type 2 diabetic patients (115 men and 95 women) without any lipid lowering drugs were studied. Fasting lipids were measured by usual methods and Apo E genotype was established for each patient: PCR was followed by digestion of the amplification product with restriction enzymes and separation of the fragments by polyacrylamide gel. RESULTS: Genotypes epsilon3/epsilon3, epsilon2/epsilon3 and epsilon3/epsilon4, epsilon2/epsilon2 and epsilon2/epsilon4 were found in 68.1%, 14.8%, 15.7%, 1.0% and 0.5%, respectively. No patient had the epsilon4/epsilon4 genotype. Lipid plasma levels were compared between E3 group (epsilon3/epsilon3) as a reference and E2 (epsilon2/epsilon2 or epsilon2/epsilon3) or E4 (epsilon3/epsilon4 or epsilon2/epsilon4). Total cholesterol, LDL cholesterol and Apo B levels were lower in the E2 group. Total cholesterol, LDL cholesterol and Apo B levels were higher in the E4 group. HDL cholesterol levels were increased in the E4 group, as only previously observed in Japanese populations. CONCLUSION: These results agree with those already reported in diabetic patients of several western European countries. E4 allele carriers have a greater cardio-vascular risk and this could be partially explained by the metabolic variation in lipid metabolism induced by E4 with higher LDL cholesterol and Apo B levels. These results observed in French diabetic subjects without any lipid-lowering drugs may be used as a reference for other studies performed in France.