Effectiveness of niacin supplementation for patients with type 2 diabetes: A meta-analysis of randomized controlled trials.

BACKGROUND: Lipid profiles and glycemic control play a critical role in subsequent atherosclerotic cardiovascular disease for patients with type 2 diabetes mellitus (T2DM). This study aimed to evaluate the effectiveness of niacin supplementation on lipid profiles and glycemic control for patients with T2DM. METHODS: The PubMed, Embase, and the Cochrane Library databases were searched to identify randomized controlled trials (RCTs) that investigated the effects of niacin supplementation for patients with T2DM throughout December 2019. The weighted mean differences (WMDs) with 95% confidence intervals (CIs) were applied to calculate the pooled effect estimates using a random-effects model. RESULTS: Eight RCTs comprised a total of 2110 patients with T2DM who were selected for final quantitative analysis. The patients' niacin supplementation was associated with lower levels of total cholesterol (WMD, -0.28; 95% CI, -0.44 to -0.12; P = .001), triglyceride (WMD, -0.37; 95% CI, -0.52 to -0.21; P < .001), and low-density lipoprotein (WMD, -0.42; 95% CI, -0.50 to -0.34; P < .001). Moreover, the level of high-density lipoprotein was significantly increased when niacin supplementation (WMD, 0.33; 95% CI, 0.21 to 0.44; P < .001) was provided. However, niacin supplementation produced no significant effects on plasma glucose (WMD, 0.18; 95% CI, -0.14 to 0.50; P = .275) and hemoglobin A1c (HbA1c) levels (WMD, 0.39; 95% CI, -0.15 to 0.94; P = .158). CONCLUSIONS: This study found that niacin supplementation could improve lipid profiles without affecting the glycemic levels for patients with T2DM. Additional large-scale RCTs should be conducted to evaluate the long-term effectiveness of niacin supplementation.

Effect of Schisandra chinensis on interleukins, glucose metabolism, and pituitary-adrenal and gonadal axis in rats under strenuous swimming exercise.

OBJECTIVE: To investigate the effect of Chinese medicine (CM) Schisandra chinensis on interleukin (IL), glucose metabolism, and pituitary-adrenal and gonadal axis of rats after strenuous navigation and exercise. METHODS: A total of 45 Sprague-Dawley rats were randomized into the quiet control group, the stress group, and the CM group (15 in each group). The CM group received 2.5 g/kg of Schisandra chinensis twice per day for one week before modeling. Except the quiet controls, rats were trained using the Bedford mode for 10 days. On the 11th day, they performed 3 h of stressful experimental navigation and 3 h of strenuous treadmill exercise. The levels of serum testosterone (T), cortisol (CORT), luteinizing hormone (LH), IL-1, IL-2, and IL-6 were tested by radioimmunoassay and enzyme-linked immunosorbent assay, respectively. The adrenal cortex ultrastructure was observed using electron microscopy. RESULTS: Compared with the quiet control group, after navigation and strenuous exercise, blood glucose was increased, and T level was decreased in the stress group (both P<0.01). The blood glucose, CORT, IL-1 and IL-2 levels were significantly reduced in the CM group (P<0.05 or P<0.01) as compared with the stress group. Electron microscopy revealed that the rats in the CM group had a smaller decrease in adrenal intracellular lipid droplets and higher levels of apoptosis than those in the stress group. CONCLUSIONS: Schisandra chinensis can reduce serum CORT and blood glucose levels in stressed rats. It appears to protect the cell structure of the adrenal cortex, and offset the negative effects of psychological stress and strenuous exercise related to immune dysfunction. Schisandra chinensis plays a regulatory role in immune function, and can decrease the influence of stress in rats.

[Salidroside protects the hypothalamic-pituitary-gonad axis of male rats undergoing negative psychological stress in experimental navigation and intensive exercise].

OBJECTIVE: To study the effects of salidroside on the function and ultramicro-pathological change of the hypothalamic-pituitary-gonadal (HPG) axis of male rats in experimental navigation and intensive exercise. METHODS: Six-week SD rats were randomized into 3 groups: non-stress control (NC, n = 10), training control (TC, n = 12) and salidroside treatment (ST, n = 12) group. Blood samples were collected from the NC rats that did not receive any stimulus after a 7-day intragastric administration of saline. The TC rats underwent a 10-day running training with increasing load on the treadmill followed by a 7-day intragastric administration of saline. The ST rats were subjected to the same process of running training as the TC group and received intragastric administration of salidroside. Then blood samples were immediately obtained and the levels of testosterone (T), corticosterone (CORT), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH) and gonadotropin-releasing hormone (GnRH) measured by radioimmunoassay. The testis histopathology was observed by HE staining, and the ultrastructural changes of the pituitaries and testes investigated by electron microscopy. RESULTS: The serum T level was significantly lower in the TC than in the NC group, but showed no significant difference between the ST and NC groups. HE staining revealed no significant difference in testis histopathology among the 3 groups. Ultramicro-pathology showed that the secretory granules of the pituitary cells were significantly reduced in the TC rats compared with the NC ones; the number of the granules significantly increased in the ST group compared with the TC rats; and mitochondrial swelling, increase of electron density and decrease/disappearance of mitochondrial cristae were observed in the Leydig cells of the TC rats. But no significant differences were found in the testicular cells between the ST and NC groups. CONCLUSION: Negative psychological stress and intensive exercise can significantly suppress the function of the HPG axis in rats. Salidroside therapy has protective effect on the HPG axis.

[Effects of schisandra on the function of the pituitary-adrenal cortex, gonadal axis and carbohydrate metabolism in rats undergoing experimental chronic psychological stress, navigation and strenuous exercise].

OBJECTIVE: To investigate the effects of schisandra on the function of the pituitary-adrenal cortex, gonadal axis and carbohydrate metabolism in male rats undergoing experimental chronic psychological stress, navigation and strenuous exercise. METHODS: Thirty-four SD rats were randomly allocated into a non-stress group (Group A), a stress control group (Group B) and a schisandra group (Group C). The latter two groups received 10 days of Benford's high-intensity training, followed by 3 hours of wearing floating with psychological stress and another 3 hours of running at the speed of 26.7 m/min. Then blood samples were immediately obtained for the measurement of the levels of testosterone (T), corticosterone (CORT), luteinizing hormone (LH) and blood glucose (Glu). Meanwhile the adrenal gland was excised and its cortex ultrastructure observed under the electron microscope. RESULTS: The Glu level was increased while the T level decreased significantly in Group B as compared with Group A. The CORT level remained unchanged in Group B. Both the Glu and CORT levels were significantly reduced in Group C in comparison with B. However, no significant differences were found in serum LH levels among the three groups. And electron microscopy revealed a reduction of lipid droplets and apoptosis of the adrenal cortex cells in Group B as compared with C. CONCLUSION: Schisandra can reduce the levels of CORT and Glu and protect the structure of the adrenal cortex.

[Expressions of NOS isoforms in the cavernous tissues of diabetic rat models].

OBJECTIVE: To investigate the mechanism of diabetic erectile dysfunction (ED) and find new methods for its treatment by detecting the changes in nitric oxide synthase (NOS) isoforms and erectile function of diabetic rats and observing the effects of insulin and alpha-lipoic acid (LA) on it. METHODS: Fifty male Sprague-Dawley rats were divided into Groups A (normal control, n=10), B (non-intervention diabetes mellitus, n=13), C (insulin intervention diabetes mellitus, n=12), and D (insulin + LA intervention, n=15). And the diabetic models were made by intraperitoneal injection of streptozocin (STZ). Eight weeks later, the erectile function of the rats was assessed following apomorphine injection and the contents of NOS isoforms in the erectile tissues measured by immunohistochemical staining. RESULTS: All the rats of Group A showed a normal erectile function (100%). In comparison, those in Groups B, C and D exhibited a significantly decreased rate, 28.6% in Group B, 62.5% in Group C and 80.9% in Group D. The numbers of positive nNOS fibers and eNOS in the penile tissues per visual field were 86.7 and 9.6 in Group A, but only 36.5 and 3.3 in Group B, 52.7 and 5.7 in Group C, and 71.4 and 7.4 in Group D (P < 0.05). However, the expression of iNOS was significantly lower in Group A (6.9) than in Groups B (43.6), C (36.2) and D (19.3) (P < 0.05). Compared with Groups B and C, the erectile function and the expressions of nNOS and eNOS were markedly increased, while the expression of iNOS significantly decreased in Group D (P < 0.05). CONCLUSION: Diabetes mellitus severely affects penile erectile function and the expressions of NOS isoforms in the cavernous tissues, for which hyperglycemia is mainly responsible. LA is proved obviously efficacious for diabetic ED, which might be related to its antioxidant effect.

[Experimental navigation and deuteroexhaustive exercise suppress the function of the hypothalamic-pituitary-testicle axis in rats].

OBJECTIVE: To study the effects of experimental navigation and deuteroexhaustive exercise on the serum levels of testosterone (T), corticosterone (CORT), luteinizing hormone (LH) and follicle stimulating hormone (FSH). METHODS: Thirty-six male SD rats were randomly divided into an experimental navigation group (Group A), which underwent 180 min wearing floating with psychological stress, a deuteroexhaustive exercise group (Group B), which were subjected to 120 min intensive running on the treadmill after the accomplishment of the same procedure as Group A, and a control group (Group C). Blood samples were obtained at the end of the experiment to determine the T, CORT, LH and FSH of the rats. RESULTS: Compared with Group C, serum T was statistically decreased in Group A and B (P < 0.05), while CORT was increased slightly in Group A and significantly in Group B (P < 0.05). A statistically lower level of serum LH was observed in Group B (P < 0.05), but no significant differences were found in serum FSH among the three groups. CONCLUSION: Stresses of experimental navigation and intensive exercise suppress the function of the hypothalamic-pituitary-testicle axis in rats.

[Inhibitory effects of reduced glutathione sodium on renal nuclear factor-kappaB expression in rats with diabetes of different stages].

OBJECTIVE: To investigate the relation between diabetic nephropathy and nuclear factor-kappaB (NF-kappaB) expression, and observe the effect of reduced glutathione sodium (GSH) on NF-kappaB activation and in prevention of diabetic nephropathy. METHODS: Seventy male Sprague-Dawley rats weighing 200-/+25 g were randomized into control group (10 rats) and diabetic group (60 rats, subgrouped into 1 month, 3 months, 6 months and their corresponding intervention subgroups, each consisting of 10 rats). The rats in the 6 diabetic groups were subjected to intraperitoneal injection of streptozotocin, and those in the control group received injection with 0.1 mmol/L citric acid buffer solution of the same volume. The diabetic models were affirmed upon a fasting blood glucose >or=16.5 mmol/L 3 days after the injection. The intervention groups were injected intraperitoneally with GSH (10 mg/100 g) once daily. Fasting blood glucose and body weight were measured every week. The rats were executed at the end of 1, 3, and 6 months respectively and the nucleoproteins were extracted from the renal specimen. NF-kappaB was measured using electrophoretic mobility shift assay (EMSA) after labeling with isotope probe, and the gray scale of the electrophoretic bands was analyzed. RESULTS: EMSA optical density analysis of electrophoretic bands showed that NF-kappaB expression increased in each diabetic groups in comparison with the control group (P<0.05), and NF-kappaB level rose proportionally with the disease course of 1 month, 3 months and 6 months. The activity of NF-kappaB decreased in the intervention groups as compared with the corresponding untreated groups (P<0.05). CONCLUSION: The activation of NF-kappaB plays a role in the onset and development of diabetes. NF-kappaB inhibition and containment of inflammation might be one of the mechanisms of GSH treatment for diabetes.

Angiotensin II receptor blocker provides pancreatic beta-cell protection independent of blood pressure lowering in diabetic db/db mice.

AIM: Several epidemiological studies have suggested that treatment with angiotensin II type 1 receptor blocker provided a risk reduction of developing type 2 diabetes. The aim of this study was to investigate whether and how chronic candesartan treatment can attenuate the deleterious influence of the hyperactive local intra-islet renin-angiotensin system in the diabetes state. METHODS: Eight-week-old db/db mice were randomized to candesartan 1 mg/kg, candesartan 10 mg/kg, manidipine 10 mg/kg, or placebo via gavage for 6 weeks. Their age-matched nondiabetic littermates db/m mice were treated with placebo and acted as nondiabetic controls. After 6 weeks' treatment, an intraperitoneal glucose tolerance test, immunohistochemical staining of oxidative stress markers, insulin, CD31, azan staining and an electron microscopy observation were performed. RESULTS: Chronic candesartan treatment provided an improvement of glucose tolerance, and greatly rescued islet beta-cell mass. Candesartan treatment also notably decreased staining intensity of oxidative stress markers, as well as attenuating intra-islet fibrosis and improving blood supply in the islet. In the electron microscopy observation, candesartan-treated animals exhibited improved granulation and less remarkable endoplasmic reticulum and Golgi bodies; furthermore, candesartan treatment greatly relieved the swelling of mitochondria to nearly normal. Both the benefits of reducing oxidative stress and ultrastructure protection were in a dose-dependent and blood pressure-independent manner. CONCLUSION: After diabetes was initiated, candesartan treatment could not reverse the state of diabetes, but it effectively improved glucose tolerance and protected beta-cell function by attenuating oxidative stress, islet fibrosis, sparsity of blood supply and ultrastructure disruption in a dose-dependent and blood pressure-independent manner.

[Immunosuppressive therapies in patients with Graves' ophthalmopathy].

OBJECTIVE: To compare the efficacy and tolerability of 4 immunosuppressants in treating Graves' ophthalmopathy (GO). METHODS: Seventy-five untreated GO patients were enrolled in this study. The diagnosis of GO was based on the presence of the typical clinical features and exclusion of possible cranial/orbital diseases. In group A, 31 patients were randomly assigned to receive either prednisone (n = 16, treatment completed in 13 cases with doses of 40 mg, 20 mg and 10 mg per day for 4 weeks) or tripterygium wilfordii multiglycoside (TW, n = 15, 30 - 60 mg per day); in group B, 23 adults were randomized to receive cyclosporin A (CsA, n = 11, 5 - 6 mg per kilogram of body weight per day) or mycophenolate mofetil (MMF, n = 12, 16 - 18 mg per kilogram of body weight per day) therapy. The remaining 21 patients (control group) were given only anti-thyroid drugs and levo-thyroxine. The disease severity and therapeutic response were quantitatively assessed according to the Ophthalmopathy Index Scoring System from Given-Wilson (1989) with sensible modification. Improvement or progression of ophthalmopathy was defined if the difference, either increase or decrease, of the score, reached 3 or more in the ophthalmopathy index. If this did not occur, a lack of response was indicated. RESULTS: After 12 weeks, 7 of the 13 treated with prednisone improved and the remaining 6 lacked response. In the TW group, 10 of the 15 responded to the therapy; 5 had no change. There was no significant difference in clinical response between the above 2 groups (P > 0.05). Five CsA-treated and 11 MMF-treated patients responded to the therapy (45% vs 92%; P < 0.05). It seems that MMF is more effective than CsA in the treatment of GO, although a significant decrease (P < 0.01) in the mean score of the CsA group has also been shown at the end of the course. Four of the controls improved, 5 (24%) showed worsening of ophthalmopathy, and the remaining 12 (57%) had no significant change. In the prednisone group, 3 gained body weight by more than 5%, and 2 developed impaired glucose tolerance. These two and one of the three weight gaining patients ceased the therapy. CONCLUSIONS: New immunosuppressant MMF may be more effective than CsA in the treatment of Graves' ophthalmopathy. TW may be equally effective as and perhaps better tolerable than prednisone in the immunotherapy of Graves' ophthalmopathy.