Gut microbiota-derived propionate mediates the neuroprotective effect of osteocalcin in a mouse model of Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder with no absolute cure. The evidence of the involvement of gut microbiota in PD pathogenesis suggests the need to identify certain molecule(s) derived from the gut microbiota, which has the potential to manage PD. Osteocalcin (OCN), an osteoblast-secreted protein, has been shown to modulate brain function. Thus, it is of interest to investigate whether OCN could exert protective effect on PD and, if yes, whether the underlying mechanism lies in the subsequent changes in gut microbiota. RESULTS: The intraperitoneal injection of OCN can effectively ameliorate the motor deficits and dopaminergic neuronal loss in a 6-hydroxydopamine-induced PD mouse model. The further antibiotics treatment and fecal microbiota transplantation experiments confirmed that the gut microbiota was required for OCN-induced protection in PD mice. OCN elevated Bacteroidetes and depleted Firmicutes phyla in the gut microbiota of PD mice with elevated potential of microbial propionate production and was confirmed by fecal propionate levels. Two months of orally administered propionate successfully rescued motor deficits and dopaminergic neuronal loss in PD mice. Furthermore, AR420626, the agonist of FFAR3, which is the receptor of propionate, mimicked the neuroprotective effects of propionate and the ablation of enteric neurons blocked the prevention of dopaminergic neuronal loss by propionate in PD mice. CONCLUSIONS: Together, our results demonstrate that OCN ameliorates motor deficits and dopaminergic neuronal loss in PD mice, modulating gut microbiome and increasing propionate level might be an underlying mechanism responsible for the neuroprotective effects of OCN on PD, and the FFAR3, expressed in enteric nervous system, might be the main action site of propionate. Video abstract.

Association of bisphenol a exposure with circulating sex hormone concentrations in men and postmenopausal women.

A total of 1116 middle-aged and elderly men and 1442 postmenopausal women were recruited in this study. Whether bisphenol A exposure was associated with circulating sex hormone concentrations was studied. Univariate analysis revealed that the urinary bisphenol A concentration was negatively correlated with the serum levels of luteinizing hormone (ß=-0.061, P<0.0001) and follicle-stimulating hormone (ß=-0.086, P<0.0001) in men, and with the serum levels of follicle-stimulating hormone (ß=-0.037, P=0.018) and sex hormone-binding globulin (ß=-0.043, P=0.006) in women. However, no significant association was observed between the serum levels of urinary bisphenol A and circulating sex hormone after adjustment for the potential confounders.

[The effect of mannose-6-phosphate on adipocyte differentiation and its underlying molecular mechanism].

OBJECTIVE: Cathepsin K (CTSK) played an important role in adipocyte differentiation. The activation of CTSK needs to convey by mannose-6-phosphate receptors (M6PR) in osteoclasts. The aim of the present study was to identify the effects of mannose-6-phosphate (M6P) in adipocyte differentiation and its underlying molecular mechanism. METHODS: Oil red O staining, accumulation of cytoplasmic triglycerides and glycerine release were used to assess its effects on adipocyte differentiation in the 3T3-L1 cell line. The enzyme activity of CTSK was observed by laser confocal microscopy. The proliferation of 3T3-L1 preadipocytes was detected by MTT methods. mRNA expression of M6PR was determined by RT-PCR. RESULTS: M6P could prevent adipocyte differentiation in a dose-dependent manner as evidenced by absence of triglyceride accumulation and glycerol content. Statistical significance was showed when the concentrations of M6P were 5.0 mmol/L and 8.0 mmol/L respectively (P < 0.05). The mRNA expression of M6PR was detected during the whole process of adipocyte differentiation. With the increase of M6P concentration, enzyme activity of CTSK was inhibited in a concentration-dependent manner. MTT method showed that the absorbance at 570 nm of 3T3-L1 preadipocytes was 0.057 ± 0.091, increased about 62.9% at 10.0 mmol/L compared with the control group (P < 0.05). CONCLUSION: M6P inhibits the terminal differentiation of adipocyte, which may be associated with its effect of blocking CTSK activity by competitive binding with M6PR.

Identification of steroid biosynthetic defects in genotype-proven heterozygous individuals for 17alpha-hydroxylase/17,20-lyase deficiency.

OBJECTIVE: P450c17 deficiency (17alpha-hydroxylase/17,20-lyase deficiency, 17OHD) is a rare form of congenital adrenal hyperplasia caused by CYP17A1 gene mutations. The D487_F489 deletion in exon 8 and Y329fs in exon 6 are relatively frequent mutations of the CYP17A1 gene in China that completely abolish the enzyme activity of P450c17. However, little remains known about steroid biosynthetic functions in carriers with these mutations in a single allele of the CYP17A1 gene, who are assumed to have 50% P450c17 activity. We investigated adrenal steroidogenic function in genotype-proven heterozygotes carrying such mutations in the CYP17A1 gene in vivo. PATIENTS AND DESIGN: Eight patients and fourteen family members from five families with 17OHD were recruited. The mutations of the CYP17A1 gene in these individuals were screened by sequencing. The hormonal response to cosyntropin (ACTH) was evaluated in the 14 genotype-proven carriers and 45 age- and gender-matched normal controls. RESULTS: Fourteen carriers of the CYP17A1 mutation - seven with the D487_F489 deletion, six with Y329fs and one with H373L - were identified from the five families with 17OHD. Compared with normal controls, carriers showed lower basal and ACTH-stimulated cortisol levels but higher ACTH-stimulated corticosterone levels. The ratios of corticosterone to cortisol in the genotype-proven heterozygotes were higher than those of the normal controls at the baseline and after cosyntropin stimulation. Similarly, the progesterone levels and the ratios of progesterone to 17-hydroxyprogesterone in the male heterozygotes were also higher than those of the normal controls, both before and after ACTH stimulation. CONCLUSION: Genotype-proven carriers of the CYP17A1 mutation who lack apparent clinical symptoms exhibit decreased adrenal 17alpha-hydroxylase activity and altered adrenal gland reserve for steroid biosynthesis.

[Clinical and molecular genetic analysis for 7 patients from 5 pedigrees with 17a-hydroxylase/17, 20 lyase deficiency].

OBJECTIVE: To investigate the clinical and genetic characteristics of 7 patients from 5 families with 17a-hydroxylase/17,20 lyase deficiency (17OHD) and the CYP17A1 mutation in Chinese. METHODS: Clinical features and laboratory data were collected from 5 families with 17OHD. PCR direct sequencing was performed to screen the mutation of CYP17A1 gene of the patients. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and sequencing were performed to screen the mutations of CYP17A1 gene in 288 healthy individuals from Shandong province. RESULTS: Seven patients (5 of them were 46,XX; 2 were 46,XY) had typical clinical presentation of sexual infantilism, hypertension and hypokalemia. Hormone profile indicated decreased plasma cortisol and sex hormones, and elevated blood adrenocorticotrophic hormone (ACTH). TAC329AA and H373L in exon 6 and D487_F489del in exon 8 were identified from the patients. One heterozygote for D487_F489del was identified in 288 healthy controls. CONCLUSION: The TAC329AA and D487_F489del of the CYP17A1 gene were the most frequent mutations in Chinese with 17OHD.There might be certain frequency of heterozygotes for D487_F489del in Chinese population.

[The metabolic characteristics of isolated impaired fasting glucose and fasting hyperglycemia].

OBJECTIVE: To evaluate the metabolic characteristics of insulin secretion and insulin sensitivity in isolated impaired fasting glucose (iIFG) and isolated fasting hyperglycemia (IFH) and to clarify the factors responsible for the development of IFH. METHODS: Receiver operating characteristic curve (ROC) analysis was conducted in 1852 subjects. Three groups were classified according to a 75 g oral glucose tolerance test (OGTT): (1) normal glucose tolerance (NGT), n = 557; (2) iIFG, n = 221; (3) IFH, n = 81. The three groups were compared with insulin secretion (insulinogenic index) and insulin sensitivity (insulin sensitivity index). RESULTS: Using ROC analysis, the optimal cut point of fasting plasma glucose (FPG) related to diabetes diagnosis with OGTT was 6.695 mmol/L and the optimal cut point of FPG related to impaired glucose to lerance (IGT) diagnosis with OGTT was 5.590 mmol/L. From NGT to iIFG and IFH in these subjects, the insulinogenic index and insulin sensitivity index showed gradual decrease. CONCLUSION: Subjects with iIFG and IFH exhibit distinctly impaired early-phase insulin secretion and insulin sensitivity, indicating that both reduced insulin secretion and insulin resistance are the determinants of deterioration from NGT to iIFG and IFH.

Birth weight and risk of type 2 diabetes, abdominal obesity and hypertension among Chinese adults.

OBJECTIVE: To investigate the association between birth weight and risk of type 2 diabetes, abdominal obesity and hypertension among Chinese adults. RESEARCH METHODS AND PROCEDURES: Nine hundred and seventy-three individuals from a population-based cross-sectional survey for the prevalence of type 2 diabetes conducted in Shanghai in 2002 were enrolled and followed up to 2004 with yearly examination. Birth weight was classified into four categories: <2500, 2500-2999, 3000-3499 and >or=3500 g. RESULTS: In this study, there were 373 males and 600 females, with a mean age of 46.2+/-9.9 years. Fasting plasma glucose was higher in subjects with the lowest birth weight (<2500 g) compared with those with the highest birth weight. Waist circumference and systolic blood pressure showed U-shaped relationships with birth weight. Birth weight was found to be an independent risk factor for type 2 diabetes, abdominal obesity and hypertension. For type 2 diabetes, the crude odds ratio (95% confidence interval) was 3.17 (1.48-6.78) in the lowest birth weight category when compared with that in the highest birth weight category (>or=3500 g) and the ratio increased to 3.97 (1.71-9.22) after adjustment for related variables. The highest prevalence of type 2 diabetes (34.5%) was observed among those with the lowest birth weight and abdominal obesity. CONCLUSIONS: Birth weight is inversely associated with the risk of type 2 diabetes. Subjects with the lowest or the highest birth weight were associated with a high risk of developing abdominal obesity and hypertension. Low birth weight coupled with abdominal obesity is a strong predictor of type 2 diabetes.

Role and mechanism of rosiglitazone on the impairment of insulin secretion induced by free fatty acids on isolated rat islets.

BACKGROUND: Prolonged exposure of pancreatic beta-cells to fatty acids increases basal insulin secretion but inhibits glucose-stimulated insulin secretion. Rosiglitazone is a new antidiabetic agent of the thiazolidinediones. However, the relationship between thiazolidinediones and insulin secretion is highly controversial. The aim of this study is to explore the effect and mechanism of rosiglitazone on insulin secretion of islets under chronic exposure to free fatty acids (FFA). METHODS: Pancreatic islets were isolated from the pancreata of male Sprague-Dawley rats by the collagenase digestion and by the dextran gradient centrifugation method. The purified islets were cultured in the presence or absence of rosiglitazone and palmitate for 48 hours. The insulin secretion was measured by radioimmunoassay. The mRNA level of peroxisome proliferator-activated receptor gamma, uncoupling protein 2 (UCP-2) and insulin were determined by real-time polymerase chain reaction (PCR). The cell cytotoxicity assay was measured by cell counting kit-8. RESULTS: Islets exposed to elevated palmitate for 48 hours showed an increased basal and a decreased glucose-stimulated insulin secretion (P < 0.01). The mRNA level of UCP-2 was increased by 3.7 fold in the 0.5 mmol/L concentration of palmitate. When islets were cultured with palmitate (0.5 mmol/L) in the presence of rosiglitazone (1.0 micromol/L), both basal and glucose-stimulated insulin secretion reversed to a pattern of control islets (P < 0.05, P < 0.01). The addition of rosiglitazone in the culture medium decreased the mRNA level of UCP-2 by 2.2 fold, having a statistically significant difference (P < 0.05) as compared with islets cultured with palmitate alone. The cell viability was not affected. CONCLUSION: The protective effects of rosiglitazone on insulin secretion of isolated pancreatic islets under chronic exposure to palmitate might be mediated through the downregulation of UCP-2 expression.

[Clinical and molecular research in a case of familial Carney complex].

OBJECTIVE: A case of primary pigmented nodular adrenal disease (PPNAD) was first diagnosed in Ruijin Hospital, Shanghai, China and molecular genetic research was then carried on the proband and his family members. METHODS: History and laboratory tests were routinely taken. Liddle's test, adrenal CT and pituitary magnetic resonance imaging were also carried out. Complete family history was obtained and eight of the family members donated their blood for DNA extraction. Polymerase chain reaction was done on all the exons of PRKAR1A gene and the product of the reaction was sequenced with ABI 3700. The right adrenal of the patient was then resected, part of the tissue was preserved in liquid nitrogen for DNA/RNA extraction and the remaining sent to Department of Pathology. RESULTS: The patient presented an atypical appearance of Cushing's syndrome. His father had a typical history of cardiac myoma. Cortisone level could not be refrained in Liddle's test for the patient. Imaging examination presented a nodular adrenal and a full pituitary. A novel mutation of PRKAR1A-S147N was found in both the patient's and his father's gene. CONCLUSIONS: This is the first patient diagnosed as PPNAD based on his clinical manifestations, laboratory tests and imaging and pathological examinations. According to the history of his father and the results of molecular genetic analysis, the diagnosis of Carney complex can be established on this patient and his father. It is also the first time that this kind of point mutation was found in Chinese people.