Synergistic protective effect of folic acid and vitamin B12 against nicotine-induced oxidative stress and apoptosis in pancreatic islets of the rat

Folic Acid Ameliorates Anxiety- and Depressive-Like Behavior Induced by Nicotine Withdrawal Through Restoration of Behavioral and Biochemical Alterations in Adolescent Male Rats

BACKGROUND

The present study aimed to assess the efficacy of folic acid (FA) on withdrawal following nicotine (Nic) administration in adolescent male rats.

AIMS AND METHODS

Adolescent male rats were divided into two groups: (1) vehicle and (2) Nic (Nic-2 mg/kg), and were under treatment from 21 to 42 days of age. After that, they continued the experiment without treatment and returned to a regular diet, except for one of those who received Nic. The rats were divided into four groups where they were treated with different doses of FA (5, 10, and 15 mg/kg) and bupropion (Bup) by oral gavage, and the final group included normal rats that received only FA (15 mg/kg) from 42 days of age for three weeks during which withdrawal occurred.

RESULTS

Results showed that adolescent Nic exposure exacerbated the behavioral indices of anxiety- and depression-like behaviors, while FA attenuated the effects of Nic withdrawal on anxiety and depression as well as Bup. In support, the biochemical results demonstrated a balance between oxidant and antioxidant mediators in addition to the increase and decrease of serotonin and monoamine oxidase (MAO) activity in cortical tissue. TNF-α as an inflammatory agent was decreased, whereas IL-10 as an anti-inflammatory parameter was increased.

CONCLUSIONS

The present findings suggest anxiety and depression caused by Nic withdrawal were attenuated by FA more likely through the reduction activity of MAO, the important enzyme responsible for serotonin metabolism along with balance between oxidant/antioxidant and pro-inflammatory/anti-inflammatory mediators. However, various mechanisms might be involved, which requires further investigation.

IMPLICATIONS

Nic withdrawal-induced depression and anxiety like behavior in rats followed by neuro-oxidative damage and neuro-inflammation. FA supplementation as well as Bup improved cognitive disorders induced by Nic withdrawal by increasing neuro-inflammation and neuro-oxidative damage.

Vitamin B12 reversed anxiety and depression induced by adolescent nicotine withdrawal through alteration the inflammatory, oxidative and serotoninergic profiles in male rats

BACKGROUND

The present study aims to assess the effect of vitamin B12 (Vit B12) on depression-like behavior caused by nicotine (Nic) withdrawal, which is more likely due to the anxiogenic effect of Nic in adolescent male rats, through assessing behavioral and biochemical analysis.

METHODS

Adolescent male rats were divided into vehicle (received normal saline), and experimental groups that received Nic (2 mg/kg, intraperitoneally (i.p.)) for three consecutive weeks and after that, the group that received normal saline was divided into two groups, one of which returned to a regular diet, and the second one received Vit B12 (1.5 mg/kg). The Nic group was divided into five groups, one of which received bupropion (Bup, 20 mg/kg), three of which received different doses of Vit B12 (0.5, 1, and 1.5 mg/kg), and the last one returned to a normal diet without treatment, which was considered as the withdrawal period.

RESULTS

Behavioral analysis showed that Nic withdrawal induced anxiety and depression. Vit B12 and Bup reduced anxiety and depression induced by Nic withdrawal. The biochemical analysis demonstrated the more activity of oxidative stress factors and pro-inflammatory cytokines in which Nic was administered, whereas both Vit B12 and Bup reversed the results and improved the activity of both antioxidant and anti-inflammatory parameters. Furthermore, both serum and cortical Vit B12 levels dramatically decreased in nicotine group, whereas treatment with both Vit B12 and Bup as desirable treatments corrected Vit B12 levels.

CONCLUSION

According to the present findings, the results revealed that Vit B12 is comparable with Bup in attenuation of Nic withdrawal symptoms. In addition, both Bup and Vit B12 improved the decreased serum and cortical levels of Vit B12, which caused by nicotine. Administration of Vit B12 in normal animals demonstrated better results in reducing antioxidant and anti-inflammatory parameters, which explores new hope to introduce Vit B12 as a novel antioxidant and anti-inflammatory agent to treat not only withdrawal, but also other diseases related to the prominent role of oxidative stress or inflammatory pathways, such as Alzheimer's disease.

The Effects of Smoking on the Diagnostic Characteristics of Metabolic Syndrome: A Review

Metabolic syndrome is a growing epidemic that increases the risk for cardiovascular disease, diabetes, stroke, and mortality. It is diagnosed by the presence of three or more of the following risk factors: 1) obesity, with an emphasis on central adiposity, 2) high blood pressure, 3) hyperglycemia, 4) dyslipidemia, with regard to reduced high-density lipoprotein concentrations, and 5) dyslipidemia, with regard to elevated triglycerides. Smoking is one lifestyle factor that can increase the risk for metabolic syndrome as it has been shown to exert negative effects on abdominal obesity, blood pressure, blood glucose concentrations, and blood lipid profiles. Smoking may also negatively affect other factors that influence glucose and lipid metabolism including lipoprotein lipase, adiponectin, peroxisome proliferator-activated receptors, and tumor necrosis factor-alpha. Some of these smoking-related outcomes may be reversed with smoking cessation, thus reducing the risk for metabolic disease; however, metabolic syndrome risk may initially increase post cessation, possibly due to weight gain. Therefore, these findings warrant the need for more research on the development and efficacy of smoking prevention and cessation programs.

Folate intake and incident chronic kidney disease: a 30-year follow-up study from young adulthood to midlife

BACKGROUND

The relation of long-term dietary folate intake with incident chronic kidney disease (CKD) remains uncertain.

OBJECTIVES

We aimed to investigate the association between dietary folate intake and incident CKD in a 30-y follow-up study from young adulthood to midlife.

METHODS

A total of 4038 American adults aged 18-30 y and without reduced estimated glomerular filtration rate (eGFR) were enrolled in 1985-1986 and monitored until 2015-2016 in the CARDIA (Coronary Artery Risk Development in Young Adults) study. Diet was assessed by a validated dietary history questionnaire at baseline, in 1992-1993, and in 2005-2006. The primary outcome was incident CKD, defined as an eGFR <60 mL · min-1 · 1.73 m-2 or a urinary albumin to creatinine ratio (ACR) ≥30 mg/g. The secondary outcomes included 1) incident decreased eGFR, defined as an eGFR <60 mL · min-1 · 1.73 m-2, and 2) incident albuminuria, defined as an ACR ≥30 mg/g.

RESULTS

During the follow-up, 642 (15.9%) participants developed CKD. Overall, there was a significant L-shaped relation of dietary folate with incident CKD after adjustment for potential confounders. Compared with the lowest quintile of total folate intake, the multivariable-adjusted HRs (95% CIs) in quintiles 2-5 for incident CKD were 0.69 (0.56, 0.85), 0.35 (0.27, 0.45), 0.34 (0.26, 0.45), and 0.39 (0.30, 0.51), respectively. Similar results were found for the secondary outcomes. Moreover, the L-shaped association was confirmed in a subset of the cohort (n = 1462) with serum folate measured at baseline, in 1992, and in 2000.

CONCLUSIONS

Higher folate intake in young adulthood was longitudinally associated with a lower incidence of CKD later in life. Additional studies are warranted to establish the causal inference.

Direct and Indirect Effects of Indoor Particulate Matter on Blood Indicators Related to Anemia

Exposure to indoor particulate matter (PM) is a potential risk factor that increases systemic inflammation and affects erythropoiesis. This study investigated the association between exposure to indoor PM and blood indicators related to anemia (BIRA) in housewives. Indoor PM and blood folate status are important factors in the risk of anemia. This was a housewife cohort study; we recruited 284 housewives in Seoul and Ulsan, Republic of Korea. Indoor exposure to PM2.5 and PM10 was measured by gravimetric analysis and sensors. We investigated the BIRA, such as hemoglobin (Hb), hematocrit, mean corpuscular volume (MCV), mean corpuscular Hb (MCH), and mean corpuscular Hb concentration (MCHC). Statistical analysis was performed by multiple linear regression model and mediation analysis. The association between BIRA and PM was assessed by multiple linear regression models fitted by mediation analyses. The increase in the level of indoor PM2.5 was associated with a decrease in MCV (Beta coefficient (B): −0.069, Standard error (SE): 0.022) and MCH (B: −0.019, SE: 0.009) in gravimetric measurements. The increase in the level of indoor PM2.5 was associated with a decrease in Hb (B: −0.024, SE: 0.011), hematocrit (B: −0.059, SE: 0.033), and MCV (B: −0.081, SE: 0.037) and MCH (B: −0.037, SE: 0.012) in sensor measurements (PM2.5-Lag10). Further, we identified a serum folate-mediated PM effect. The indoor PM exposure was significantly associated with decreased Hb, MCV, and MCH in housewives. Taken together, our data show that exposure to indoor PM is a risk factor for anemia in housewives. Blood folate concentration can be a mediating factor in the effect of indoor PM on BIRA. Therefore, folate intake should be recommended to prevent anemia in housewives. Moreover, indoor PM exposure should be managed.

Insulin Signal Transduction Perturbations in Insulin Resistance

Type 2 diabetes mellitus is a widespread medical condition, characterized by high blood glucose and inadequate insulin action, which leads to insulin resistance. Insulin resistance in insulin-responsive tissues precedes the onset of pancreatic β-cell dysfunction. Multiple molecular and pathophysiological mechanisms are involved in insulin resistance. Insulin resistance is a consequence of a complex combination of metabolic disorders, lipotoxicity, glucotoxicity, and inflammation. There is ample evidence linking different mechanistic approaches as the cause of insulin resistance, but no central mechanism is yet described as an underlying reason behind this condition. This review combines and interlinks the defects in the insulin signal transduction pathway of the insulin resistance state with special emphasis on the AGE-RAGE-NF-κB axis. Here, we describe important factors that play a crucial role in the pathogenesis of insulin resistance to provide directionality for the events. The interplay of inflammation and oxidative stress that leads to β-cell decline through the IAPP-RAGE induced β-cell toxicity is also addressed. Overall, by generating a comprehensive overview of the plethora of mechanisms involved in insulin resistance, we focus on the establishment of unifying mechanisms to provide new insights for the future interventions of type 2 diabetes mellitus.

Folic acid and vitamin B12 supplementation in subjects with type 2 diabetes mellitus: A multi-arm randomized controlled clinical trial

OBJECTIVE

This study was conducted to investigate and compare the effects of add-on folic acid and vitamin B12 supplementation on glycaemic control, insulin resistance and serum lipid profile in subjects with type 2 diabetes mellitus.

STUDY DESIGN & INTERVENTION

This study was a randomized, multi-arm, open-label clinical trial. 80 patients with type 2 diabetes and on stable oral antidiabetics were enrolled and 20 patients each were randomly allocated to one of the four groups - Group A: add-on Folic acid (5 mg/day); Group B: add-on Methylcobalamin (500 mcg/day); Group C: add-on Folic acid (5 mg/day) + Methylcobalamin (500 mcg/day) and Group D: Standard oral anti-diabetic drugs. The patients were followed up after 8 weeks.

RESULTS

HbA1c improved significantly in Groups B and C [median changes from baseline - 1.2 % (- 13 mmol/mol) and - 1.5 % (- 16 mmol/mol) respectively, p values 0.04 and 0.02 respectively] compared to Group D. Groups B and C also showed significant improvements in plasma insulin, insulin resistance and serum adiponectin compared to Group D. Serum homocysteine declined significantly in all three groups with add-on supplementation compared to standard treatment. No improvement in the lipid profile was noted in any of the groups.

CONCLUSIONS

Add-on supplementation with vitamin B12 improved glycaemic control and insulin resistance in patients with type 2 diabetes mellitus.

Protective efficacy of Tinospora sinensis against streptozotocin induced pancreatic islet cell injuries of diabetic rats and its correlation to its phytochemical profiles

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora sinensis Lour. (Merr.) belongs to the family Menispermaceae and its stem extract have been used traditionally in broad aspects of therapeutic remedies including debility, dyspepsia, fever, jaundice, ulcer, bronchitis, urinary disease, skin disease, liver disease and diabetes.

AIM OF THE STUDY

The aim of the study was to evaluate the protective effects of methanol extract of stem of Tinospora sinensis (METS) on streptozotocin induced pancreatic islet cell injuries of diabetic rats and its correlation to its phytochemical profiles.

MATERIALS AND METHODS

A high-performance liquid chromatography technique (HPLC) was used to identify and quantify the major phytochemicals present in the METS. Diabetic rats were administered with METS at a dose of (100, 200 and 400 mg/kg respectively orally) and standard drug Metformin (300 mg/kg) was given orally to group serving positive control. Effect of the METS on glucose homeostasis, oxidative stress, antioxidant status, histopathology of pancreas and also on intracellular reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, cell cycle of pancreatic islet cells were studied in diabetic rats.

RESULTS

The major phytochemicals identified and quantified by HPLC in the extract were berberine, caffeic acid, myricetin and ferulic acid. This result showed that methanol extract exhibited good antioxidant effect. The methanol extract of the plant prevented the diabetogenic effect of STZ and significantly lowered the fasting blood glucose level, glycated haemoglobin and increased insulin and C-peptide level in treated rats. METS reduced apoptosis of STZ treated islet cells by significantly decreasing pro-inflammatory cytokines (TNFα, IL6), intracellular ROS generation, lipid peroxidation, nitric oxide (NO) production and increasing mitochondrial membrane potential and sub-G₀ peak area, enzymatic and nonenzymatic antioxidants.

CONCLUSION

The results revealed that the methanol extract of the stem of the plant possesses protective effects against diabetes and associated complications.

Reduced serum concentrations of vitamin B12 and folate and elevated thyroid-stimulating hormone and homocysteine levels in first-trimester pregnant Saudi women with high A1C concentrations

Better understanding of the risk factors for diabetes can lead to proper prevention of this devastating metabolic abnormality. It is hypothesized that diabetes pathogenesis is linked to complex metabolic abnormalities involving homocysteine (HCY) pathways and affecting B₁₂, folate, and thyroid-stimulating hormone (TSH) concentrations. This study was conducted to determine the associations between serum concentrations of vitamin B₁₂, folate, TSH, and HCY in pregnant women with normal glycemic control, diabetes, or prediabetes. This cross-sectional study included 1159 healthy first-trimester pregnant women who were randomly selected from antenatal clinics in 2 hospitals and 21 health care centers across Al-Madinah, Saudi Arabia. Data collected included clinical history and blood sample analyses for serum folate, vitamin B₁₂, TSH, HCY, and glycated hemoglobin (A1C). Participants were classified with normal A1C (<5.7%), prediabetes (≥5.7 and <6.5%), or undiagnosed type 2 diabetes (≥6.5%). Results revealed that 79.5% of the participants had normal A1C levels, whereas 19.3% and 1.21% had A1C levels in prediabetic and diabetic ranges, respectively. Serum concentrations of vitamin B₁₂ and folate were lower in prediabetes subjects than in participants with normal A1C concentrations, whereas serum concentrations of TSH and HCY were significantly higher. There was a strong negative correlation among the concentrations of A1C, vitamin B_12, and folate, whereas positive correlations among A1C, TSH, and HCY were reported. Regression analysis identified TSH as having the strongest impact on A1C concentrations. These complex metabolic changes that occur at the prediabetic stage that involve TSH, HCY, folate, and vitamin B₁₂ might direct research on diabetes prevention.

Folic Acid and Vitamin B12 Administration in CKD, Why Not?

Patients affected by chronic kidney disease (CKD) or end-stage renal disease (ESRD) experience a huge cardiovascular risk and cardiovascular events represent the leading causes of death. Since traditional risk factors cannot fully explain such increased cardiovascular risk, interest in non-traditional risk factors, such as hyperhomocysteinemia and folic acid and vitamin B12 metabolism impairment, is growing. Although elevated homocysteine blood levels are often seen in patients with CKD and ESRD, whether hyperhomocysteinemia represents a reliable cardiovascular and mortality risk marker or a therapeutic target in this population is still unclear. In addition, folic acid and vitamin B12 could not only be mere cofactors in the homocysteine metabolism; they may have a direct action in determining tissue damage and cardiovascular risk. The purpose of this review was to highlight homocysteine, folic acid and vitamin B12 metabolism impairment in CKD and ESRD and to summarize available evidences on hyperhomocysteinemia, folic acid and vitamin B12 as cardiovascular risk markers, therapeutic target and risk factors for CKD progression.

Adequate or elevated dietary folate does not ameliorate the reduced antioxidant capacity induced by vitamin B12 deficiency in aged rats

Folate could have an antioxidant role but also may be detrimental under vitamin B₁₂ deficiency. The aim was to investigate the effect of different dietary folic acid (FA) levels, on oxidative stress in B₁₂ induced deficient aged rats. Thirty-five male aged Sprague-Dawley rats, were fed either a vitamin B₁₂ deficient (n = 27) or a control diet (n = 8) during eight weeks. Then, animals were divided into four groups: B₁₂ and FA deficient diet (DBDF), B₁₂ deficient diet and FA control diet (DBCF), B₁₂ deficient diet and FA supplemented diet (DBSF), and control diet (CBCF) for a 30 days period. Methionine metabolism and antioxidant status were evaluated. Both vitamins deficiencies elevated serum homocysteine (Hcy) (7.7 vs. 4.3 μmol/L, p < 0.05) and reduced S-adenosylmethionine hepatic content (283.7 vs. 581.9 μg/g protein, p < 0.05), the total antioxidant capacity (155.7 vs. 189.3 μmol/L, p < 0.05), glutathione (GSH) (120.5 vs. 419.9 μg/mg protein, p < 0.05) and oxidized glutathione (0.9 vs. 2.6 μg/mg protein, p < 0.05) compared to control. Activities of glutathione peroxidase and glutathione reductase enzymes or damage to macromolecules were unaffected. Adequate or elevated dietary FA in B₁₂ deficiency rats decreased Hcy (5.7 and 6.3 μmol/L, respectively) and increased total antioxidant capacity (189.8 and 192.6 μmol/L, respectively) to values similar to control group, whereas GSH concentration was significantly lower than control (209.1 and 208.0 μg/mg protein respectively, p < 0.05). In conclusion, in a vitamin B₁₂ deficiency status, adequate or elevated FA prevented impairment in one-carbon metabolism, but does not fully reverse the decrease in antioxidant capacity.

Effects of nicotine on rat adrenal gland: crosstalk between oxidative and inflammatory markers, and amelioration by melatonin

Although the risks of smoking are well known, the effects of exposure to nicotine on endocrine functions remain unclear. We investigated the deleterious effects of nicotine on the adrenal gland and the mechanisms of these changes in rats. The role of melatonin in ameliorating pathological changes also was investigated. We used 24 rats divided into four groups of six: group 1, control; group 2, nicotine treated; group 3, nicotine and melatonin treated; group 4, melatonin treated. We used histology; immunohistochemistry of inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF) and tyrosine hydroxylase (TH); measured oxidative and antioxidative markers, malondialdehyde (MDA) and glutathione (GSH); and performed real-time PCR for NF-κB 65, IL1-B and IL6. We also performed histomorphometric analysis. Indentation and lamellar separation of the adrenal capsule, vacuolated degenerated cells and lymphocytic infiltration were observed in group 2. Vacuolated cells and cells with pyknotic nuclei also were detected in the zona reticularis and medulla of the same group. We observed improved shape and cellular lining of the gland in groups 3 and 4. Widespread expression of iNOS, VEGF and TH, increased area percent collagen, decreased GSH (56%) and increased MDA, NF-κB, IL1-B and IL-6 were observed in group 2. All parameters were ameliorated in groups 3 and 4. The effects of nicotine on the adrenal gland can be attributed to oxidative and inflammatory stress; melatonin ameliorates these effects.

Targeting mitochondria with folic acid and vitamin B12 ameliorates nicotine mediated islet cell dysfunction

Nicotine, one of the well-known highly toxic components of cigarette smoke, causes a number of adverse health effects and diseases. Our previous study has shown that nicotine induces reactive oxygen species (ROS) in islet cell and disrupts islet cell mitochondrial membrane potential (ΔΨm). However, supplementation with folic acid and vitamin B12 were found effective against nicotine induced changes in pancreatic islet cells. But the toxicological effects and underlying mechanisms of nicotine-induced mitochondrial dysfunction is still unknown. In this study, nicotine exposure decreases mitochondrial enzymes (pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, aconitase, malate dehydrogenase) activities by increasing cytosolic Ca2+ level which may contribute to increased mitochondrial ROS production by raising its flow to mitochondria. This in turn produces malondialdehyde and nitric oxide (NO) with a concomitant decrease in the activities of antioxidative enzymes and glutathione levels leading to loss of ΔΨm. Simultaneously, nicotine induces pancreatic islet cell apoptosis by modulating ΔΨm via increased cytosolic Ca2+ level, altered Bcl-2, Bax, cytochrome c, caspase-9, PARP expressions which were prevented by the supplementation of folic acid and vitamin B12 . In conclusion, nicotine alters islet cell mitochondrial redox status, apoptotic machinery, and enzymes to cause disruption in the ΔΨm and supplementation of folic acid and vitamin B12 possibly blunted all these mitochondrial alterations. Therefore, this study may help to determine the pathophysiology of nicotine-mediated islet cell mitochondrial dysfunction.

Cigarette Smoking and Hyperglycaemia in Diabetic Patients

BACKGROUND:

The incidence rate of diabetes mellitus has increased throughout the year. Various studies indicate that smoking may affect glucose metabolism and cause hyperglycemia in diabetes mellitus. This study aimed to compare the blood glucose and HbA1c level in diabetic smoking patients and non-smoking diabetic patients.

METHODS:

This study used the cross-sectional approach. The study population consisted of 30 diabetic smoking patients and 30 non-smoking diabetic patients. The diabetes history and the smoking status of the study population obtained by questionnaire-based interview, the blood glucose and HbA1c level were measured by hexokinase and immunoturbidimetry method using cobas 6000 analyser module c501 (Roche Diagnostics, Switzerland).

RESULTS:

The result in this study showed the fasting blood glucose, postprandial blood glucose, and HbA1c were higher by 23.64 mg/dl (p = 0.325), 58.00 mg/dl (p = 0.016), 0.39% (p = 0.412) in smoking diabetic patients compared to non-smoking diabetic patients. After statistical analysis, there was a significant difference (p < 0.05) of postprandial glucose level between smokers group and non-smokers group, but the non-significant difference of fasting blood glucose and HbA1c

CONCLUSIONS:

This study concluded that there was a significant difference in postprandial glucose level between smokers group and non-smokers group but the non-significant difference of fasting blood glucose and HbA1c.

Folic acid delays development of atherosclerosis in low-density lipoprotein receptor-deficient mice

Many studies support the cardioprotective effects of folic acid (FA). We aimed to evaluate the utility of FA supplementation in preventing the development of atherosclerotic in low‐density lipoprotein receptor‐deficient (LDLR−/−) mice and to elucidate the molecular processes underlying this effect. LDLR−/− mice were randomly distributed into four groups: control group, HF group, HF + FA group and the HF + RAPA group. vascular smooth muscle cells (VSMCs) were divided into the following four groups: control group, PDGF group, PDGF + FA group and PDGF + FA + RAPA group. Blood lipid levels, oxidative stress and inflammatory cytokines were measured. Atherosclerosis severity was evaluated with oil red O staining. Haematoxylin and eosin (H&E) staining was used to assess atherosclerosis progression. Immunohistochemical staining was performed with antismooth muscle α‐actin (α‐SMA) antibodies and anti‐osteopontin (OPN) antibodies that demonstrate VSMC dedifferentiation. The protein expression of α‐SMA, OPN and mechanistic target of rapamycin (mTOR)/p70S6K signalling was detected by Western blot analysis. FA and rapamycin reduced serum levels of total cholesterol, triacylglycerol, LDL, inhibiting oxidative stress and the inflammatory response. Oil red O and H&E staining demonstrated that FA and rapamycin inhibited atherosclerosis. FA and rapamycin treatment inhibited VSMC dedifferentiation in vitro and in vivo, and FA and rapamycin attenuated the mTOR/p70S6K signalling pathway. Our findings suggest that FA attenuates atherosclerosis development and inhibits VSMC dedifferentiation in high‐fat‐fed LDLR−/− mice by reduced lipid levels and inhibiting oxidative stress and the inflammatory response through mTOR/p70S6K signalling pathway.

A prospective association between dietary folate intake and type 2 diabetes risk among Korean adults aged 40 years or older: the Korean Multi-Rural Communities Cohort (MRCohort) Study

It has not been well established whether dietary folate intake reduces the risk of diabetes development. We aimed to clarify the prospective association between dietary folate intake and type 2 diabetes (T2D) risk among 7333 Korean adults aged 40 years or older who were included in the Multi-Rural Communities Cohort. Dietary folate intake was estimated from all 106 food items listed on a FFQ, not including folate intake from supplements. Two different measurements of dietary folate intake were used: the baseline consumption and the average consumption from baseline until just before the end of follow-up. The association between folate intake and T2D risk was determined through a modified Poisson regression model with a robust error estimator controlling for potential confounders. For 29 745 person years, 319 cases of diabetes were ascertained. In multivariable analyses, dietary folate intake was inversely associated with risk of T2D for women, not for men. For women, the incidence rate ratio of diabetes in the third tertile compared with the first tertile was 0·57 (95 % CI 0·38-0·87, P for trend=0·0085) in the baseline consumption model and 0·64 (95 % CI 0·43-0·95, P for trend=0·0244) in the average consumption model. These inverse associations was found in both normal fasting blood glucose group and impaired fasting glucose group among women. Among non-users of multinutrients and vitamin supplements, the significant inverse association remained. Thus, higher dietary intake of folate is prospectively associated with lower risk of diabetes for women.

Nicotine suppresses apoptosis by regulating α7nAChR/Prx1 axis in oral precancerous lesions

Nicotine, a tumor promoter in tobacco, can increase Peroxiredoxin (Prx1) and nicotinic acetylcholine receptors (nAChRs) in oral squamous cell carcinoma (OSCC). In the present study, we investigate the effects of nicotine in oral precancerous lesions focusing on apoptosis and nAChR/Prx1 signaling. We detected expression of Prx1, α3nAChR, α7nAChR, phosphorylation of mitogen-activated protein kinases (MAPK) and apoptosis in dysplastic oral keratinocyte (DOK) cells as well as in 4-nitroquinoline 1-oxide (4NQO) or 4NQO + nicotine – induced oral precancerous lesions in Prx1 wild-type (Prx1^+/+) and Prx1 knockdown (Prx1^+/-) mice. In DOK cells, Prx1 knockdown and blocking α7nAChR activated apoptosis, and nicotine increased the expression of Prx1, α3nAChR and α7nAChR, and inhibited MAPK activation. Moreover, nicotine suppressed apoptosis depending on Prx1 and α7nAChR in DOK cells. In animal bioassay, nicotine and Prx1 promoted growth of 4NQO-induced precancerous lesions in mouse tongue. 4NQO plus nicotine suppressed MAPK activation in Prx1 wild-type mice but not in Prx1 knockdown mice. Our data demonstrate that nicotine inhibits cell apoptosis and promotes the growth of oral precancerous lesions via regulating α7nAChR/Prx1 during carcinogenesis of OSCC.

Effects of prenatal and lactation nicotine exposure on glucose homeostasis, lipogenesis and lipid metabolic profiles in mothers and offspring

There is increasing evidence suggesting that maternal nicotine (NIC) exposure alone can lead to many deleterious consequences in the fetus. In this study, we aimed to evaluate the effects of prenatal and lactation NIC exposure on glucose homeostasis, lipogenesis and lipid metabolism in mothers and pups. After maternal NIC exposure (from gestational day 9 to weaning), NIC mothers showed lower body weight, decreased parametrial white adipose tissue (pWAT) and inguinal WAT weights, lower homeostasis model assessment of beta cell function, higher serum total cholesterol (TC) and low-density lipoprotein cholesterol levels, higher Castelli index values, lower hepatic mRNA levels of sterol regulatory element binding protein-1c (SREBP1c), lipoprotein lipase, acetyl-CoA carboxylase, fatty acid synthase (FAS) and glucose transporters 4 (GLUT4), as well as lower SREBP1c, FAS, leptin and GLUT4 mRNA levels in pWAT. However, female NIC pups presented higher body weights and serum TC levels, and increased trends for high density lipoprotein-cholesterol and Castelli index I. Male NIC pups had higher body weight, serum TC levels and Castelli index I values, and lower glycemia levels. Additionally, hepatic and adipose FAS gene expression from the female NIC pups presented a decreasing trend, while the male NIC pups had lower hepatic FAS expression and higher adipose FAS expression. In conclusion, prenatal and lactation NIC exposure induced deleterious effects on the glucose homeostasis, lipogenesis and lipid metabolism in both mothers and pups, which may promote several important metabolic disorders in the progeny. Additionally, there are gender-specific effects on pups.