Estradiol attenuates high glucose-induced endothelial nitrotyrosine: role for neuronal nitric oxide synthase

The Role of Epoxyeicosatrienoic Acids in Diabetes Mellitus-Induced Impaired Vascular Relaxation of Aortic Rings in Ovariectomized Sprague-Dawley Rats

AIM

The present study was aimed at determining if type 1 diabetes mellitus (DM) affects vascular function and at elucidating the mechanisms mediating vasorelaxation in both nonovariectomized and ovariectomized Sprague-Dawley (SD) rats.

MATERIALS AND METHODS

Eighty female SD rats were divided into four groups: nonovariectomized healthy (non-OVX-CTR) and diabetic (non-OVX-DM) rats and ovariectomized healthy (OVX-CTR) and diabetic (OVX-DM) rats. Bilateral ovariectomy was performed at the age of 5 weeks, and type 1 DM was induced by streptozotocin at the age of 6 weeks. At the age of 12 weeks, acetylcholine-induced relaxation (AChIR) was assessed in aortic rings in the absence/presence of L-NAME, Indomethacin, and MS-PPOH. Aortic tissue mRNA expression of eNOS, iNOS, COX-1, COX-2, thromboxane synthase 1 (TBXAS1), CYP4A1, CYP4A3, and CYP2J3, as well as plasma oxidative stress, was measured.

RESULTS

AChIR did not differ in non-OVX-DM rats compared to non-OVX-CTR ones. AChIR was significantly reduced in the OVX-DM group compared to the OVX-CTR group. MS-PPOH did not reduce AChIR in OVX-DM rats as it did in OVX-CTR ones. CYP4a3 mRNA expression in OVX-DM rats was significantly lower compared to that in the OVX-CTR group.

CONCLUSIONS

Female sex hormones may protect vasorelaxation in type 1 diabetic rats. Type 1 diabetes impairs vasorelaxation in response to ACh in ovariectomized rats (but not in nonovariectomized rats) by affecting vasorelaxation pathways mediated by EETs.

The impact of food structure on taste and digestibility

The current knowledge on how food structures relate to perception is discussed.

Dietary Vitamin D3 Restriction Exacerbates Disease Pathophysiology in the Spinal Cord of the G93A Mouse Model of Amyotrophic Lateral Sclerosis

Background

Dietary vitamin D₃ (D₃) restriction reduces paw grip endurance and motor performance in G93A mice, and increases inflammation and apoptosis in the quadríceps of females. ALS, a neuromuscular disease, causes progressive degeneration of motor neurons in the brain and spinal cord.

Objective

We analyzed the spinal cords of G93A mice following dietary D₃ restriction at 2.5% the adequate intake (AI) for oxidative damage (4-HNE, 3-NY), antioxidant enzymes (SOD2, catalase, GPx1), inflammation (TNF-α, IL-6, IL-10), apoptosis (bax/bcl-2 ratio, cleaved/pro-caspase 3 ratio), neurotrophic factor (GDNF) and neuron count (ChAT, SMI-36/SMI-32 ratio).

Methods

Beginning at age 25 d, 42 G93A mice were provided food ad libitum with either adequate (AI;1 IU D₃/g feed; 12 M, 11 F) or deficient (DEF; 0.025 IU D₃/g feed; 10 M, 9 F) D₃. At age 113 d, the spinal cords were analyzed for protein content. Differences were considered significant at P ≤ 0.10, since this was a pilot study.

Results

DEF mice had 16% higher 4-HNE (P = 0.056), 12% higher GPx1 (P = 0.057) and 23% higher Bax/Bcl2 ratio (P = 0.076) vs. AI. DEF females had 29% higher GPx1 (P = 0.001) and 22% higher IL-6 (P = 0.077) vs. AI females. DEF males had 23% higher 4-HNE (P = 0.066) and 18% lower SOD2 (P = 0.034) vs. AI males. DEF males had 27% lower SOD2 (P = 0.004), 17% lower GPx1 (P = 0.070), 29% lower IL-6 (P = 0.023) and 22% lower ChAT (P = 0.082) vs. DEF females.

Conclusion

D₃ deficiency exacerbates disease pathophysiology in the spinal cord of G93A mice, the exact mechanisms are sex-specific. This is in accord with our previous results in the quadriceps, as well as functional and disease outcomes.

Multi-targeted mechanisms underlying the endothelial protective effects of the diabetic-safe sweetener erythritol

Diabetes is characterized by hyperglycemia and development of vascular pathology. Endothelial cell dysfunction is a starting point for pathogenesis of vascular complications in diabetes. We previously showed the polyol erythritol to be a hydroxyl radical scavenger preventing endothelial cell dysfunction onset in diabetic rats. To unravel mechanisms, other than scavenging of radicals, by which erythritol mediates this protective effect, we evaluated effects of erythritol in endothelial cells exposed to normal (7 mM) and high glucose (30 mM) or diabetic stressors (e.g. SIN-1) using targeted and transcriptomic approaches. This study demonstrates that erythritol (i.e. under non-diabetic conditions) has minimal effects on endothelial cells. However, under hyperglycemic conditions erythritol protected endothelial cells against cell death induced by diabetic stressors (i.e. high glucose and peroxynitrite). Also a number of harmful effects caused by high glucose, e.g. increased nitric oxide release, are reversed. Additionally, total transcriptome analysis indicated that biological processes which are differentially regulated due to high glucose are corrected by erythritol. We conclude that erythritol protects endothelial cells during high glucose conditions via effects on multiple targets. Overall, these data indicate a therapeutically important endothelial protective effect of erythritol under hyperglycemic conditions.

Sex differences in renal responses to hyperglycemia, L-arginine, and L-NMMA in humans with uncomplicated type 1 diabetes

OBJECTIVE

Women exhibit exaggerated renal hemodynamic responses to hyperglycemia, which may promote kidney disease progression. Our aim was to determine if increased nitric oxide generation by l-arginine infusion would reverse this deleterious response to clamped hyperglycemia in women with type 1 diabetes mellitus.

RESEARCH DESIGN AND METHODS

Renal function, blood pressure, and plasma cyclic guanosine monophosphate (cGMP) were measured in 20 men and 15 women with type 1 diabetes mellitus during clamped euglycemia and clamped hyperglycemia. Renal function, blood pressure, and plasma cGMP responses to graded infusions of intravenous l-arginine and N(G)-monomethyl-l-arginine (l-NMMA) were measured during clamped hyperglycemia.

RESULTS

Subjects were young, normotensive, normoalbuminuric men and women who adhered to a high-sodium, moderate-protein diet. Plasma cGMP levels during euglycemia were generally lower in men compared with women, and systolic blood pressure (SBP) was higher in men. In response to hyperglycemia, cGMP levels did not change in men but did decline in women (Δ-1.10 ± 0.20 vs. Δ+0.05 ± 0.20 pmol/L, between-group effect of hyperglycemia on cGMP; P = 0.012). Hyperglycemia also was associated with an increase in SBP, glomerular filtration rate (GFR) (124 ± 6 to 143 ± 7 mL/min/1.73 m(2); P = 0.003) and filtration fraction (FF) in women, but these parameters did not change in men. In response to l-arginine during hyperglycemia, the increase in cGMP was exaggerated in women versus men and GFR and FF decreased in women only, back toward baseline values observed during clamped euglycemia. l-NMMA infusion did not exaggerate changes in hemodynamic function in response to hyperglycemia.

CONCLUSIONS

 l-Arginine reversed the renal hemodynamic effects of hyperglycemia in women, suggesting that nitric oxide is an important regulator of sex-dependent vascular responses to hyperglycemia in humans.