Diabetes and Sexual Dysfunction / 임상당뇨병

Type 2 diabetes can produce various sexual dysfunctions in both men and women. Prevalence of sexual dysfunction is 25~75% in type 2 diabetes, which is three times that of the general population. As hyperglycemia persists, atherosclerosis progresses, and macrovascular and microvascular complications can occur. Autonomic neuropathy and hypogonadism are principal causes of various sexual dysfunctions such as erectile dysfunction, retrograde ejaculation, and premature ejaculation in males and loss of libido, vaginal dryness, anorgasmia, and dyspareunia in females. Although erectile dysfunction is reversible in early stages, it is more difficult to control as diabetes and associated autonomic dysfunction and microvascular complications progress. Sexual dysfunction can decrease quality of life in type 2 diabetes patients and is a marker of vascular dysfunction. Sexual dysfunction has prognostic value for cardiovascular events in type 2 diabetes. This illustrates the importance of sexual function evaluation in type 2 diabetes patients.

Serum Transferrin Predicts New-Onset Type 2 Diabetes in Koreans: A 4-Year Retrospective Longitudinal Study

Background@#It is well known that high serum ferritin, a marker of iron storage, predicts incident type 2 diabetes. Limited information is available on the association between transferrin, another marker of iron metabolism, and type 2 diabetes. Thus, we investigated the association between transferrin and incident type 2 diabetes. @*Methods@#Total 31,717 participants (mean age, 40.4±7.2 years) in a health screening program in 2005 were assessed via cross-sectional analysis. We included 30,699 subjects who underwent medical check-up in 2005 and 2009 and did not have type 2 diabetes at baseline in this retrospective longitudinal analysis. @*Results@#The serum transferrin level was higher in the type 2 diabetes group than in the non-type 2 diabetes group (58.32±7.74 μmol/L vs. 56.17±7.96 μmol/L, P<0.001). Transferrin correlated with fasting serum glucose and glycosylated hemoglobin in the correlational analysis (r=0.062, P<0.001 and r=0.077, P<0.001, respectively) after full adjustment for covariates. Transferrin was more closely related to homeostasis model assessment of insulin resistance than to homeostasis model assessment of β cell function (r=0.042, P<0.001 and r=–0.019, P=0.004, respectively) after full adjustment. Transferrin predicted incident type 2 diabetes in non-type 2 diabetic subjects in a multivariate linear regression analysis; the odds ratio (95% confidence interval [CI]) of the 3rd tertile compared to that in the 1st tertile of transferrin for incident diabetes was 1.319 (95% CI, 1.082 to 1.607) after full adjustment (P=0.006). @*Conclusion@#Transferrin is positively associated with incident type 2 diabetes in Koreans.

Pretreatment of Populus tomentiglandulosa protects hippocampal CA1 pyramidal neurons from ischemia-reperfusion injury in gerbils via increasing SODs expressions and maintaining BDNF and IGF-I expressions / 中国天然药物

To examine the effects of Populus tomentiglandulosa (PT) extract on the expressions of antioxidant enzymes and neurotrophic factors in the cornu ammonis 1 (CA1) region of the hippocampus at 5 min after inducing transient global cerebral ischemia (TGCI) in gerbils, TGCI was induced by occlusion of common carotid arteries for 5 min. Before ischemic surgery, 200 mg·kg PT extract was orally administrated once daily for 7 d. We performed neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B staining. Furthermore, we determined in situ production of superoxide anion radical, expression levels of SOD1 and SOD2 as antioxidant enzymes and brain-derived neurotrophic factor (BDNF) and insulin-like growth factor I (IGF-I) as neurotrophic factors. Pretreatment with 200 mg·kg PT extract prevented neuronal death (loss). Furthermore, pretreatment with 200 mg·kg PT extract significantly inhibited the production of superoxide anion radical, increased expressions of SODs and maintained expressions of BDNF and IGF-I. Such increased expressions of SODs were maintained in the neurons after IRI. In summary, pretreated PT extract can significantly increase levels of SODs and protect the neurons against TGCI, suggesting that PT can be a useful natural agent to protect against TGCI.

Extract Promotes Neurogenesis in the Hippocampal Dentate Gyrus of the Adult Mouse through Increasing Expressions of Brain-Derived Neurotrophic Factor and Tropomyosin-Related Kinase B / 中华医学杂志(英文版)

<p><b>Background</b>Glehnia littoralis has been used for traditional Asian medicine, which has diverse therapeutic activities. However, studies regarding neurogenic effects of G. littoralis have not yet been considered. Therefore, in this study, we examined effects of G. littoralis extract on cell proliferation, neuroblast differentiation, and the maturation of newborn neurons in the hippocampus of adult mice.</p><p><b>Methods</b>A total of 39 male ICR mice (12 weeks old) were randomly assigned to vehicle-treated and 100 and 200 mg/kg G. littoralis extract-treated groups (n = 13 in each group). Vehicle and G. littoralis extract were orally administrated for 28 days. To examine neurogenic effects of G. littoralis extract, we performed immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU, an indicator for cell proliferation) and doublecortin (DCX, an immature neuronal marker) and double immunofluorescence staining for BrdU and neuronal nuclear antigen (NeuN, a mature neuronal marker). In addition, we examined expressional changes of brain-derived neurotrophic factor (BDNF) and its major receptor tropomyosin-related kinase B (TrkB) using Western blotting analysis.</p><p><b>Results</b>Treatment with 200 mg/kg, not 100 mg/kg, significantly increased number of BrdU-immunoreactive () and DCX cells (48.0 ± 3.1 and 72.0 ± 3.8 cells/section, respectively) in the subgranular zone (SGZ) of the dentate gyrus (DG) and BrdU/NeuN cells (17.0 ± 1.5 cells/section) in the granule cell layer as well as in the SGZ. In addition, protein levels of BDNF and TrkB (about 232% and 244% of the vehicle-treated group, respectively) were significantly increased in the DG of the mice treated with 200 mg/kg of G. littoralis extract.</p><p><b>Conclusion</b>G. littoralis extract promots cell proliferation, neuroblast differentiation, and neuronal maturation in the hippocampal DG, and neurogenic effects might be closely related to increases of BDNF and TrkB proteins by G. littoralis extract treatment.</p>

PretreatedExtract Prevents Neuronal Death Following Transient Global Cerebral Ischemia through Increases of Superoxide Dismutase 1 and Brain-derived Neurotrophic Factor Expressions in the Gerbil Hippocampal Cornu Ammonis 1 Area / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Glehnia littoralis, as a traditional herbal medicine to heal various health ailments in East Asia, displays various therapeutic properties including antioxidant effects. However, neuroprotective effects of G. littoralis against cerebral ischemic insults have not yet been addressed. Therefore, in this study, we first examined its neuroprotective effects in the hippocampus using a gerbil model of transient global cerebral ischemia (TGCI).</p><p><b>METHODS</b>Gerbils were subjected to TGCI for 5 min. G. littoralis extract (GLE; 100 and 200 mg/kg) was administrated orally once daily for 7 days before ischemic surgery. Neuroprotection was examined by neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining. Gliosis was observed by immunohistochemistry for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1. For neuroprotective mechanisms, immunohistochemistry for superoxide dismutase (SOD) 1 and brain-derived neurotrophic factor (BDNF) was done.</p><p><b>RESULTS</b>Pretreatment with 200 mg/kg of GLE protected pyramidal neurons in the cornu ammonis 1 (CA1) area from ischemic insult area (F = 29.770, P < 0.05) and significantly inhibited activations of astrocytes (F = 22.959, P < 0.05) and microglia (F = 44.135, P < 0.05) in the ischemic CA1 area. In addition, pretreatment with GLE significantly increased expressions of SOD1 (F = 28.561, P < 0.05) and BDNF (F = 55.298, P < 0.05) in CA1 pyramidal neurons of the sham- and ischemia-operated groups.</p><p><b>CONCLUSIONS</b>Our findings indicate that pretreatment with GLE can protect neurons from ischemic insults, and we suggest that its neuroprotective mechanism may be closely associated with increases of SOD1 and BDNF expressions as well as attenuation of glial activation.</p>

Pre-treated Populus tomentiglandulosa extract inhibits neuronal loss and alleviates gliosis in the gerbil hippocampal CA1 area induced by transient global cerebral ischemia / 대한해부학회지

The genus Populus (poplar) belonging to the Salicaceae family has been used in traditional medicine, and its several species show various pharmacological properties including antioxidant and anti-inflammatory effects. No study regarding protective effects of Populus species against cerebral ischemia has been reported. Therefore, in the present study, we examined neuroprotective effects of ethanol extract from Populus tomentiglandulosa (Korea poplar) in the hippocampal cornu ammonis (CA1) area of gerbils subjected to 5 minutes of transient global cerebral ischemia. Pretreatment with 200 mg/kg of P. tomentiglandulosa extract effectively protected CA1 pyramidal neurons from transient global cerebral ischemia. In addition, glial fibrillary acidic protein immunoreactive astrocytes and ionized calcium binding adapter molecule 1 immunoreactive microglia were significantly diminished in the ischemic CA1 area by pretreatment with 200 mg/kg of P. tomentiglandulosa extract. Briefly, our results indicate that pretreatment with P. tomentiglandulosa extract protects neurons from transient cerebral ischemic injury and diminish cerebral ischemia-induced reactive gliosis in ischemic CA1 area. Based on these results, we suggest that P. tomentiglandulosa can be used as a potential candidate for prevention of ischemic injury.

Validation of a Newly Developed Equation for Estimating Serum Apolipoprotein B: Associations with Cardiovascular Disease Surrogate Markers in Koreans

PURPOSE: Many clinical guidelines recommend apolipoprotein B (apoB) measurement, particularly in subjects with metabolic syndrome or type 2 diabetes. Recently, we developed a new equation to estimate serum apoB (apoBE). We validated the clinical relevance of apoBE and compared the performance of the equation with conventional lipid measurements and direct measurement of apoB. MATERIALS AND METHODS: Study subjects were recruited from patients who visited the Health Screening Center at Kangbuk Samsung Hospital between January and December 2009 for routine medical examinations (n=78125). For analysis of coronary calcium score, we recruited study subjects from the same institution between January 2007 and December 2010 (n=16493). RESULTS: apoBE was significantly correlated with serum high-sensitivity C-reactive level {r=0.18 [95% confidence interval (CI), 0.18–0.19]} in partial correlation analysis adjusted for age, sex, and body mass index. apoBE was associated with a Framingham risk score indicating more than moderate risk (10-year risk ≥10%), the presence of microalbuminuria, and the presence of coronary artery calcium in multivariate logistic regression analysis. These associations were comparable to those of directly-measured serum apoB [odds ratio per 1 SD 3.02 (2.75–3.27) vs. 2.70 (2.42–3.02) for a Framingham risk score indicating more than moderate risk, 1.31 (1.21–1.41) vs. 1.35 (1.25–1.45) for the presence of microalbuminuria, and 1.33 (1.26–1.41) vs. 1.31 (1.23–1.38) for the presence of coronary calcium score respectively]. These findings were also consistently observed in subgroup analysis for subjects with type 2 diabetes. CONCLUSION: The associations between cardiovascular surrogate markers and apoBE were comparable to those of directly-measured apoB.

Insulin Secretory Capacity and Insulin Resistance in Korean Type 2 Diabetes Mellitus Patients

It is well known that many Korean patients with type 2 diabetes mellitus (T2DM) were non-obese and had decreased insulin secretion in past. However, during the past three decades, lifestyles in Korea have been westernized. As a result, the prevalence of obesity, the main cause of diabetes has increased. Thus, there is still a question as to whether the main pathophysiology of current Korean T2DM is insulin resistance or an insulin secretion defect. Because various anti-diabetes medications having different mechanisms of action are currently used as therapeutics, it is important to understand which of these factors is the main physiology in the development of diabetes in Koreans. In this review, we review changes in obesity prevalence, insulin resistance and insulin secretion defects in Korean T2DM during three decades.

C-Peptide-Based Index Is More Related to Incident Type 2 Diabetes in Non-Diabetic Subjects than Insulin-Based Index

BACKGROUND: Diabetes can be efficiently prevented by life style modification and medical therapy. So, identification for high risk subjects for incident type 2 diabetes is important. The aim of this study is to identify the best β-cell function index to identify high risk subjects in non-diabetic Koreans. METHODS: This is a retrospective longitudinal study. Total 140 non-diabetic subjects who underwent standard 2-hour 75 g oral glucose tolerance test from January 2007 to February 2007 at Kangbuk Samsung Hospital and followed up for more than 1 year were analyzed (mean follow-up, 54.9±16.4 months). The subjects were consist of subjects with normal glucose tolerance (n=44) and subjects with prediabetes (n=97) who were 20 years of age or older. Samples for insulin and C-peptide levels were obtained at 0 and 30 minutes at baseline. RESULTS: Thirty subjects out of 140 subjects (21.4%) developed type 2 diabetes. When insulin-based index and C-peptide-based index are compared between progressor and non-progressor to diabetes, all C-peptide-based indices were statistically different between two groups, but only insulinogenic index and disposition index among insulin-based index were statistically different. C-peptide-based index had higher value of area under receiver operating characteristic curve (AROC) value than that of insulin-based index. "C-peptidogenic" index had highest AROC value among indices (AROC, 0.850; 95% confidence interval, 0.761 to 0.915). C-peptidogenic index had significantly higher AROC than insulinogenic index (0.850 vs. 0.731 respectively; P=0.014). CONCLUSION: C-peptide-based index was more closely related to incident type 2 diabetes in non-diabetic subjects than insulin-based index.

Oenanthe Javanica Extract Protects Against Experimentally Induced Ischemic Neuronal Damage via its Antioxidant Effects / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Water dropwort (Oenanthe javanica) as a popular traditional medicine in Asia shows various biological properties including antioxidant activity. In this study, we firstly examined the neuroprotective effect of Oenanthe javanica extract (OJE) in the hippocampal cornus ammonis 1 region (CA1 region) of the gerbil subjected to transient cerebral ischemia.</p><p><b>METHODS</b>Gerbils were established by the occlusion of common carotid arteries for 5 min. The neuroprotective effect of OJE was estimated by cresyl violet staining. In addition, 4 antioxidants (copper, zinc superoxide dismutase [SOD], manganese SOD, catalase, and glutathione peroxidase) immunoreactivities were investigated by immunohistochemistry.</p><p><b>RESULTS</b>Pyramidal neurons in the CA1 region showed neuronal death at 5 days postischemia; at this point in time, all antioxidants immunoreactivities disappeared in CA1 pyramidal neurons and showed in many nonpyramidal cells. Treatment with 200 mg/kg, not 100 mg/kg, OJE protected CA1 pyramidal neurons from ischemic damage. In addition, 200 mg/kg OJE treatment increased or maintained antioxidants immunoreactivities. Especially, among the antioxidants, glutathione peroxidase immunoreactivity was effectively increased in the CA1 pyramidal neurons of the OJE-treated sham-operated and ischemia-operated groups.</p><p><b>CONCLUSION</b>Our present results indicate that treatment with OJE can protect neurons from transient ischemic damage and that the neuroprotective effect may be closely associated with increased or maintained intracellular antioxidant enzymes by OJE.</p>

Effect of Oenanthe Javanica Extract on Antioxidant Enzyme in the Rat Liver / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Oenanthe javanica (O. javanica) has been known to have high antioxidant properties via scavenging reactive oxygen species. We examined the effect of O. javanica extract (OJE) on antioxidant enzymes in the rat liver.</p><p><b>METHODS</b>We examined the effect of the OJE on copper, zinc-superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), catalase (CAT), and glutathione peroxidase (GPx) in the rat liver using immunohistochemistry and western blot analysis. Sprague-Dawley rats were randomly assigned to three groups; (1) normal diet fed group (normal-group), (2) diet containing ascorbic acid (AA)-fed group (AA-group) as a positive control, (3) diet containing OJE-fed group (OJE-group).</p><p><b>RESULTS</b>In this study, no histopathological finding in the rat liver was found in all the experimental groups. Numbers of SOD1, SOD2, CAT, and GPx immunoreactive cells and their protein levels were significantly increased in the AA-fed group compared with those in the normal-group. On the other hand, in the OJE-group, numbers of SOD1, SOD2, CAT, and GPx immunoreactive cells in the liver were significantly increased by about 190%, 478%, 685%, and 346%, respectively, compared with those in the AA-group. In addition, protein levels of SOD1, SOD2, CAT, and GPx in the OJE-group were also significantly much higher than those in the AA-group.</p><p><b>CONCLUSION</b>OJE significantly increased expressions of SOD1 and SOD2, CAT, and GPx in the liver cells of the rat, and these suggests that significant enhancements of endogenous enzymatic antioxidants by OJE might be a legitimate strategy for decreasing oxidative stresses in the liver.</p>

Oenanthe javanica extract increases immunoreactivities of antioxidant enzymes in the rat kidney / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Oenanthe javanica is an aquatic perennial herb originated from East Asia. Nowadays, the effects of Oenanthe javanica have been proven in various disease models. Studies regarding the antioxidant effect of Oenanthe javanica in the kidney are still unclear.</p><p><b>METHODS</b>This study was therefore performed to investigate the effect of the Oenanthe javanica extract (OJE) in the rat kidney using immunohistochemistry for antioxidant enzymes, copper, zinc-superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), catalase (CAT) and glutathione peroxidase (GPx). Sprague-Dawley rats were randomly assigned to three groups: (1) normal diet fed-group (normal-group), (2) diet containing ascorbic acid (AA)-fed group (AA-group) as a positive control, (3) diet containing OJE-fed group (OJE-group). AA and OJE were supplied during 28 days.</p><p><b>RESULTS</b>The side-effects were not observed in all the groups. Immunoreactivities of SOD1, SOD2, CAT and GPx were easily detected in the distal tubules of the kidney, and their immunoreactivities in the AA-and OJE-groups were increased to about 1.4-1.5 times and 2 times, respectively, compared with those in the normal-group.</p><p><b>CONCLUSION</b>OJE significantly increased expressions of SOD1 & 2, CAT and GPx immunoreactivities in the distal tubules of the rat kidney, and this finding suggests that significant enhancements of endogenous enzymatic antioxidants by OJE treatment may be a legitimate strategy for decreasing oxidative stresses in the kidney.</p>

Neuroprotection via maintenance or increase of antioxidants and neurotrophic factors in ischemic gerbil hippocampus treated with tanshinone I / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Danshen (Radix Salvia miltiorrhizae) has been used as a traditional medicine in Asia for treatment of various microcirculatory disturbance related diseases. Tanshinones are mainly hydrophobic active components, which have been isolated from Danshen and show various biological functions. In this study, we observed the neuroprotective effect of tanshinone I (TsI) against ischemic damage in the gerbil hippocampal CA1 region (CA1) after transient cerebral ischemia and examined its neuroprotective mechanism.</p><p><b>METHODS</b>The gerbils were divided into vehicle-treated-sham-group, vehicle-treated-ischemia-group, TsI-treated-sham-group, and TsI-treated-ischemia-group. TsI was administrated intraperitoneally three times (once a day for three days) before ischemia-reperfusion. The neuroprotective effect of TsI was examined using H&E staining, neuronal nuclei (NeuN) immunohistochemistry and Fluoro-Jade B staining. To investigate the neuroprotective mechanism of TsI after ischemia-reperfusion, immunohistochemical (IHC) and Western blotting analyses for Cu, Zn-superoxide dismutase (SOD1), Mn-superoxide dismutase (SOD2), brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-I (IGF-I) were performed.</p><p><b>RESULTS</b>Treatment with TsI protected pyramidal neurons from ischemia-induced neuronal death in the CA1 after ischemia-reperfusion. In addition, treatment with TsI maintained the levels of SOD1 and SOD2 as determined by IHC and Western blotting in the CA1 after ischemia-reperfusion compared with the vehicle-ischemia-group. In addition, treatment with TsI increased the levels of BDNF and IGF-I determined by IHC and Western blotting in the TsI-treated-sham-group compared with the vehicle-treated-sham-group, and their levels were maintained in the stratum pyramidale of the ischemic CA1 in the TsI-treated-ischemia-group.</p><p><b>CONCLUSION</b>Treatment with TsI protects pyramidal neurons of the CA1 from ischemic damage induced by transient cerebral ischemia via the maintenance of antioxidants and the increase of neurotrophic factors.</p>

Systemic administration of low dosage of tetanus toxin decreases cell proliferation and neuroblast differentiation in the mouse hippocampal dentate gyrus / 한국실험동물학회지

In the present study, we investigated the effect of Tetaus toxin (TeT) on cell proliferation and neuroblast differentiation using specific markers: 5-bromo-2-deoxyuridine (BrdU) as an exogenous marker for cell proliferation, Ki-67 as an endogenous marker for cell proliferation and doublecortin (DCX) as a marker for neuroblasts in the mouse hippocampal dentate gyrus (DG) after TeT treatment. Mice were intraperitoneally administered 2.5 and 10 ng/kg TeT and sacrificed 15 days after the treatment. In both the TeT-treated groups, no neuronal death occurred in any layers of the DG using neuronal nuclei (NeuN, a neuron nuclei maker) and Fluoro-Jade B (F-J B, a high-affinity fluorescent marker for the localization of neuronal degeneration). In addition, no significant change in glial activation in both the 2.5 and 10 ng/kg TeT-treated-groups was found by GFAP (a marker for astrocytes) and Iba-1 (a marker for microglia) immunohistochemistry. However, in the 2.5 ng/kg TeT-treated-group, the mean number of BrdU, Ki-67 and DCX immunoreactive cells, respectively, were apparently decreased compared to the control group, and the mean number of each in the 10 ng/kg TeT-treated-group was much more decreased. In addition, processes of DCX-immunoreactive cells, which projected into the molecular layer, were short compared to those in the control group. In brief, our present results show that low dosage (10 ng/kg) TeT treatment apparently decreased cell proliferation and neuroblast differentiation in the mouse hippocampal DG without distinct gliosis as well as any loss of adult neurons.

Neuroprotective effects of tanshinone I from Danshen extract in a mouse model of hypoxia-ischemia / 대한해부학회지

Hypoxia-ischemia leads to serious neuronal damage in some brain regions and is a strong risk factor for stroke. The aim of this study was to investigate the neuroprotective effect of tanshinone I (TsI) derived from Danshen (Radix Salvia miltiorrhiza root extract) against neuronal damage using a mouse model of cerebral hypoxia-ischemia. Brain infarction and neuronal damage were examined using 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin and eosin histochemistry, and Fluoro-Jade B histofluorescence. Pre-treatment with TsI (10 mg/kg) was associated with a significant reduction in infarct volume 1 day after hypoxia-ischemia was induced. In addition, TsI protected against hypoxia-ischemia-induced neuronal death in the ipsilateral region. Our present findings suggest that TsI has strong potential for neuroprotection against hypoxic-ischemic damage. These results may be used in research into new anti-stroke medications.

Syringaresinol causes vasorelaxation by elevating nitric oxide production through the phosphorylation and dimerization of endothelial nitric oxide synthase

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an important role in vascular functions, including vasorelaxation. We here investigated the pharmacological effect of the natural product syringaresinol on vascular relaxation and eNOS-mediated NO production as well as its underlying biochemical mechanism in endothelial cells. Treatment of aortic rings from wild type, but not eNOS-/- mice, with syringaresinol induced endothelium-dependent relaxation, which was abolished by addition of the NOS inhibitor NG-monomethyl-L-arginine. Treatment of human endothelial cells and mouse aortic rings with syringaresinol increased NO production, which was correlated with eNOS phosphorylation via the activation of Akt and AMP kinase (AMPK) as well as elevation of intracellular Ca2+ levels. A phospholipase C (PLC) inhibitor blocked the increases in intracellular Ca2+ levels, AMPK-dependent eNOS phosphorylation, and NO production, but not Akt activation, in syringaresinol-treated endothelial cells. Syringaresinol-induced AMPK activation was inhibited by co-treatment with PLC inhibitor, Ca2+ chelator, calmodulin antagonist, and CaMKKbeta siRNA. This compound also increased eNOS dimerization, which was inhibited by a PLC inhibitor and a Ca2+-chelator. The chemicals that inhibit eNOS phosphorylation and dimerization attenuated vasorelaxation and cGMP production. These results suggest that syringaresinol induces vasorelaxation by enhancing NO production in endothelial cells via two distinct mechanisms, phosphatidylinositol 3-kinase/Akt- and PLC/Ca2+/CaMKKbeta-dependent eNOS phosphorylation and Ca2+-dependent eNOS dimerization.