Streptozotocin as a tool for induction of rat models of diabetes: a practical guide

Linalool exerts antioxidant activity in a rat model of diabetes by increasing catalase activity without antihyperglycemic effect

Diabetes mellitus (DM) is a prevalent metabolic disorder often accompanied by oxidative stress, which contributes to various diabetic complications. Investigating the antioxidant activity of linalool (LIN) is crucial as it may offer a natural therapeutic approach to mitigate oxidative damage in DM. The aim of the present study was to investigate the antioxidant activity of LIN in a DM rat model. A total of 40 male Wistar albino rats (age, 8 weeks; weight, 250-300 g) were used. CONTROL and DM groups were administered physiological saline solution by oral gavage for 21 days. In rats in the DM + LIN and LIN groups, 100 mg/kg LIN was administered intragastrically after streptozotocin injection (n=10 per group). In the first (48 h after STZ injection), second (1 week later), third (2 weeks later), and fourth (3 weeks later) blood glucose measurements, a statistically significant increase was found in the blood glucose values of the DM and DM + LIN groups compared with those of the CONTROL group. During the 21-day experimental period, there was no reduction in blood glucose levels of the DM + LIN group. Consequently, no discernible anti-hyperglycemic effect of LIN was observed. Catalase enzyme activity, superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) levels and glutathione (GSH) levels were measured spectrophotometrically. All assays were conducted according to the protocols provided in the respective kits. The results were analyzed to assess the oxidative status and antioxidant capacity in the experimental groups. Catalase (CAT) activity was decreased in the DM group compared with that in the CONTROL group in both the serum and liver. However, LIN administration restored CAT activity in the DM + LIN group to the level of the CONTROL group. In the liver, the DM + LIN-treated group showed a notable reduction in malondialdehyde (MDA) levels compared with those in the DM group. In conclusion, the present results suggest that the antioxidant properties of LIN may have a regulatory effect on the oxidative status in diabetes-affected systems, potentially offering therapeutic benefits in managing oxidative stress associated with diabetes.

Effects of Sevoflurane and Fullerenol C60 on the Heart and Lung in Lower-Extremity Ischemia-Reperfusion Injury in Streptozotocin-Induced Diabetes Mice

Background and Objectives: Lower-extremity ischemia-reperfusion injury can induce distant organ ischemia, and patients with diabetes are particularly susceptible to ischemia-reperfusion injury. Sevoflurane, a widely used halogenated inhalation anesthetic, and fullerenol C60, a potent antioxidant, were investigated for their effects on heart and lung tissues in lower-extremity ischemia-reperfusion injury in streptozotocin (STZ)-induced diabetic mice. Materials and Methods: A total of 41 mice were divided into six groups: control (n = 6), diabetes-control (n = 7), diabetes-ischemia (n = 7), diabetes-ischemia-fullerenol C60 (n = 7), diabetes-ischemia-sevoflurane (n = 7), and diabetes-ischemia-fullerenol C60-sevoflurane (n = 7). Diabetes was induced in mice using a single intraperitoneal dose of 55 mg/kg STZ in all groups except for the control group. Mice in the control and diabetes-control groups underwent midline laparotomy and were sacrificed after 120 min. The DIR group underwent 120 min of lower-extremity ischemia followed by 120 min of reperfusion. In the DIR-F group, mice received 100 μg/kg fullerenol C60 intraperitoneally 30 min before IR. In the DIR-S group, sevoflurane and oxygen were administered during the IR procedure. In the DIR-FS group, fullerenol C60 and sevoflurane were administered. Biochemical and histological evaluations were performed on collected heart and lung tissues. Results: Histological examination of heart tissues showed significantly higher necrosis, polymorphonuclear leukocyte infiltration, edema, and total damage scores in the DIR group compared to controls. These effects were attenuated in fullerenol-treated groups. Lung tissue examination revealed more alveolar wall edema, hemorrhage, vascular congestion, polymorphonuclear leukocyte infiltration, and higher total damage scores in the DIR group compared to controls, with reduced injury parameters in the fullerenol-treated groups. Biochemical analyses indicated significantly higher total oxidative stress, oxidative stress index, and paraoxonase-1 levels in the DIR group compared to the control and diabetic groups. These levels were lower in the fullerenol-treated groups. Conclusions: Distant organ damage in the lung and heart tissues due to lower-extremity ischemia-reperfusion injury can be significantly reduced by fullerenol C60.

The potential of Myrmecodia pendans in preventing complications of diabetes mellitus as an antidiabetic and antihyperlipidemic agent

Background

Hyperglycemia in diabetes mellitus (DM) can lead to dyslipidemia, which is a risk factor for macrovascular complications such as heart disease and stroke. Aside from administering antidiabetic medications, DM treatment can also be achieved through the use of natural components, such as Myrmecodia pendans, commonly known as the ant nest plant (ANP).

Aim

This study aimed to investigate the impact of administering the ANP on the lipid profile of Wistar rats.

Methods

A group of 20 rats was divided into two categories: 6 rats served as healthy controls (H), while the remaining 14 rats were subjected to a high-lipid diet and streptozotocin to generate a model of type 2 diabetes mellitus (T2DM). The diabetic rats were divided into two groups: the DM group consisted of rats that did not receive any treatment, while the ANP group was administered the herb orally.

Results

The results revealed significant variations in triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels among the three groups (p < 0.05). The post hoc test revealed disparities in triglyceride and LDL between those in the DM group and the ANP group (p < 0.05).

Conclusion

Myrmecodia pendans demonstrated the ability to decrease triglyceride and LDL, while increasing HDL levels in rats with T2DM.

Effects of empagliflozin on gonadal functions of hyperglycemic male wistar rats

Empagliflozin (EMPA) showed antiapoptotic, oxidative and anti-inflammatory potential effect. EMPA attenuates the inflammation and oxidative stress biomarkers in patients with heart failure while significantly decreases the malondialdehyde (a lipid peroxidation marker) levels in the plasma of diabetic patients. The present study examined the effects of moderate hyperglycemia on reproductive function. Sixty male Wister rats ‎ were divided and randomly allocated into four groups of 15 animals each‎‎. Diabetes was induced by a single intraperitoneal injection of a prepared solution containing STZ diluted in 0.1 M sodium citrate buffer (pH 4.5) at a dosage of 40 mg/kg body weight in selected in groups II and III for seven days before starting the treatment with EMPA. The current study revealed that EMPA for eight weeks prevented testicular high glucose-induced oxidative stress markers such as penile nitric oxide (NO), glutathione peroxidase (GPX) and total anti-oxidant capacity (TAC) in STZ-induced hyperglycemia in a rat model. In addition, EMPA ameliorated the high levels of endogenous Interleukin-6 (IL-6) present in gonads in response to an acute inflammatory found in the hyperglycemic STZ-induced rats. The present study further suggested the protective effects of EMPA and how it has a beneficial role and can effectively attenuate hyperglycemia-induced testicular oxidative damage and inflammatory markers as well as androgen dependent testicular enzymes activity as a protective role against the consequences of hyperglycemia and male sub-infertility.

Functional candesartan loaded lipid nanoparticles for the control of diabetes-associated stroke: In vitro and in vivo studies

Diabetes mellitus is a metabolic disease that raises the odds of developing stroke. Candesartan has been used to prevent stroke due to its inhibitory effects on blood pressure, angiogenesis, oxidative damage, and apoptosis. However, oral candesartan has very limited bioavailability and efficacy due to its weak solubility and slow release. The study aimed to develop a nasal formulation of candesartan-loaded liposomes containing ethanol and propylene glycol (CLEP) to improve candesartan's delivery, release, permeation, and efficacy as a potential diabetes-associated stroke treatment. Using design expert software, different CLEP formulations were prepared and evaluated in vitro to identify the optimum formulation, which. The selected optimum formulation composed of 3.3% phospholipid, 10% ethanol, and 15% propylene glycol significantly increased the release and permeation of candesartan relative to free candesartan by a factor of 1.52 and 1.47, respectively. The optimum formulation significantly reduced the infarction after stroke in rats; decreased flexion, spontaneous motor activity, and time spent in the target quadrant by 70%, 64.71%, and 92.31%, respectively, and enhanced grip strength by a ratio of 2.3. Therefore, nasal administration of the CLEP formulation could be a potential diabetes-associated stroke treatment.

Quercetin prevents kidney against diabetes mellitus (type 1) in rats by inhibiting TGF-β/apelin gene expression

BACKGROUND

One of the main causes of diabetic nephropathy is oxidative stress induced by hyperglycemia. Apelin inhibits insulin secretion. Besides, renal expression of TGF-β is increased in diabetes mellitus (DM). The preventive effect of quercetin (Q) against renal functional disorders and tissue damage developed by DM in rats was assessed.

METHODS

Forty male Wistar rats were grouped into normal control (NC), normal + quercetin (NQ: quercetin, 50 mg/kg/day by gavage), diabetic control (DC: streptozotocin, 65 mg/kg, i.p.), diabetic + quercetin pretreatment (D + Qpre), and diabetic + quercetin post-treatment (D + Qpost). All samples (24-hour urine, plasma, pancreatic, and renal tissues) were obtained at the terminal of the experiment.

RESULTS

Compared to NC and NQ groups, DM ended in elevated plasma and glucose levels, decreased plasma insulin level, kidney dysfunction, augmented levels of malondialdehyde, decreased level of reduced glutathione, reduced enzymatic activities of superoxide dismutase and catalase, elevated gene expression levels of apelin and TGF-β, also renal and pancreatic histological damages. Quercetin administration diminished entire the changes. However, the measure of improvement in the D + Qpre group was higher than that of the D + Qpost group.

CONCLUSION

Quercetin prevents renal dysfunction induced by DM, which might be related to the diminution of lipid peroxidation, strengthening of antioxidant systems, and prevention of the apelin/ TGF-β signaling pathway.

The effects of ecdysterone and enalapril on nitric oxide synthesis and the markers of oxidative stress in streptozotocin-induced diabetes in rats: a comparative study

Cardiovascular functions in diabetes greatly depend on constitutive NOS (cNOS) activity. A comparative study of the effects of a steroid hormone ecdysterone and enalapril, an ACE inhibitor widely used to treat cardiac disorders on cNOS, inducible NOS (iNOS), xanthine oxidoreductase (XOR) activity, RNS, ROS, and lipid peroxidation in heart tissue in experimental diabetes was conducted. The rat model of diabetes was established by streptozotocin injection. NOS activity, NO2-, NO3-, uric acid, nitrosothiols, hydroperoxide, superoxide, and diene conjugate formation were studied spectrophotomerically. In diabetes, cNOS downregulation correlated with a dramatic fall of NO2- production and ~4.5-fold elevation of nitrosothiols, which agreed with a steep rise of iNOS activity, while NO3- remained close to control. Dramatic activation of XOR was observed, which correlated with the elevation of both superoxide production and nitrate reductase activity and resulted in strong lipid peroxidation. Ecdysterone and enalapril differently affected RNS metabolism. Ecdysterone moderately restored cNOS but strongly suppressed iNOS, which resulted in the reduction of NO3-, but full restoration of NO2- production. Enalapril better restored cNOS but less effectively suppressed iNOS, which promoted NO3- formation. Both drugs similarly inhibited XOR, which equally alleviated oxidative stress and lipid peroxidation. The synergistic action of iNOS and XOR was a plausible explanation for strong lipid peroxidation, abolished by the inhibition of iNOS and XOR by ecdysterone or enalapril. Complementary effects of ecdysterone and enalapril on cNOS, iNOS, and RNS are a promising basis for their combined use in the treatment of cardiovascular disorders caused by cNOS dysfunction in diabetes.

Identifying the stability of housekeeping genes to be used for the quantitative real-time PCR normalization in retinal tissue of streptozotocin-induced diabetic rats

AIM

To investigate the stability of the seven housekeeping genes: beta-actin (ActB), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 18s ribosomal unit 5 (18s), cyclophilin A (CycA), hypoxanthine-guanine phosphoribosyl transferase (HPRT), ribosomal protein large P0 (36B4) and terminal uridylyl transferase 1 (U6) in the diabetic retinal tissue of rat model.

METHODS

The expression of these seven genes in rat retinal tissues was determined using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) in two groups; normal control rats and streptozotocin-induced diabetic rats. The stability analysis of gene expression was investigated using geNorm, NormFinder, BestKeeper, and comparative delta-Ct (ΔCt) algorithms.

RESULTS

The 36B4 gene was stably expressed in the retinal tissues of normal control animals; however, it was less stable in diabetic retinas. The 18s gene was expressed consistently in both normal control and diabetic rats' retinal tissue. That this gene was the best reference for data normalisation in RT-qPCR studies that used the retinal tissue of streptozotocin-induced diabetic rats. Furthermore, there was no ideal gene stably expressed for use in all experimental settings.

CONCLUSION

Identifying relevant genes is a need for achieving RT-qPCR validity and reliability and must be appropriately achieved based on a specific experimental setting.

Topical naltrexone increases aquaporin 5 production in the lacrimal gland and restores tear production in diabetic rats

Diabetes mellitus is a prevalent disease that is often accompanied by ocular surface abnormalities including delayed epithelial wound healing and decreased corneal sensitivity. The impact of diabetes on the lacrimal functional unit (LFU) and the structures responsible for maintaining tear homeostasis, is not completely known. It has been shown that the Opioid Growth Factor Receptor (OGFr), and its ligand, Opioid Growth Factor (OGF), is dysregulated in the ocular surface of diabetic rats leading to overproduction of the inhibitory growth peptide OGF. The opioid antagonist naltrexone hydrochloride (NTX) blocks the OGF-OGFr pathway, and complete blockade following systemic or topical treatment with NTX restores the rate of re-epithelialization of corneal epithelial wounds, normalizes corneal sensitivity, and reverses dry eye in diabetic animal models. These effects occur rapidly and within days of initiating treatment. The present study was designed to understand mechanisms related to the fast reversal (<5 days) of dry eye by NTX in type 1 diabetes (T1D) by investigating dysregulation of the LFU. The approach involved examination of the morphology of the LFU before and after NTX treatment. Male and female adult Sprague-Dawley rats were rendered hyperglycemic with streptozotocin, and after 6 weeks rats were considered to be a T1D model. Rats received topical NTX twice daily to one eye for 10 days. During the period of treatment, tear production and corneal sensitivity were recorded. On day 11, animals were euthanized and orbital tissues including conjunctiva, eyelids, and lacrimal glands, were removed and processed for histologic examination including immunohistochemistry. Male and female T1D rats had significantly decreased tear production and corneal insensitivity, significantly decreased number and size of lacrimal gland acini, decreased expression of aquaporin-5 (AQP5) protein and decreased goblet cell size. Thus, 10 days of NTX treatment restored tear production and corneal sensitivity to normal values, increased AQP5 expression, and restored the surface area of goblet cells to normal. NTX had no effect on the number of lacrimal gland acini or the number of conjunctival goblet cells. In summary, blockade of the OGF-OGFr pathway with NTX reversed corneal and lacrimal gland complications and restored some components of tear homeostasis confirming the efficacy of topical NTX as a treatment for ocular defects in diabetes.

Therapeutic potential of orally applied KB-R7943 in streptozotocin-induced neuropathy in rats

Both peripheral neuropathy and depression can be viewed as neurodegeneration's consequences of diabetes, at least in part coexisting with or resulting from sodium-calcium dysbalance. This study aims to assess the therapeutic potential of the orally applied reverse-mode inhibitor of the sodium-calcium exchanger (NCX) KB-R7943 in the streptozotocin (STZ) diabetes model in rats. A pilot pharmacokinetic (PK) study with high-performance liquid chromatography with high-resolution tandem mass spectrometric detection revealed higher drug exposure (AUC), lower volume of distribution (Vd) and clearance (Cl), and faster decline of the plasma concentration (ƛ) in rats with diabetes vs. controls. Brain and heart accumulation and urinary excretion of the unmetabolized KB-R7943 at least 24 h were also demonstrated in all rats. However, heart and hippocampus KB-R7943 penetration (AUCtissue/AUCplasma) was higher in controls vs. diabetic rats. The development of thermal, mechanical, and chemical-induced allodynia was assessed with the Cold plate test (CPT), Randall-Stiletto (R-S) test, and 0.5% formalin test (FT). Amitriptyline 10 mg/kg, KB-R7943 5 mg/kg, or 10 mg/kg p.o once daily was applied from the 28th to the 49th day. The body weight, coat status, CPT, R-S, and FT were evaluated on days (-5), 0, and 42. On day 41, a forced swim test and 24-h spontaneous physical activities were assessed. The chronic treatment effects were calculated as % of the maximum. A dose-depended amelioration of neuropathic and depression-like effects was demonstrated. The oral application of KB-R7943 for potentially treating neurodegenerative consequences of diabetes merits further studies. The brain, heart, and kidneys are essential contributors to the PKs of this drug, and their safety involvement needs to be further characterized.

Nephroprotective effect of cranberry (Vaccinium oxycoccos) in streptozocin-induced diabetic nephropathy in mice

OBJECTIVES

Diabetic nephropathy is a chief reason of mortality particularly in individuals with renal dysfunction. The current research was aimed to assess the nephroprotective portion of Vaccinium oxycoccos toward mice diabetic nephropathy induced by streptozotocin (STZ). V. oxycoccos was purchased and used for hydroalcoholic extraction.

METHODS

Sixty male mice were subjected to STZ-intraperitoneal injection (45 mg/kg). After diabetes induction, mice were divided into five groups of diabetic control (received only STZ), non-diabetic control (received only citrate buffer), two V. oxycoccos treatment (received V. oxycoccos extract (200 and 400 mg/kg) oral daily by gavage), and metformin treatment (received metformin (500 mg/kg) oral daily by gavage). Glucose and weight of mice were checked weekly.

RESULTS

After 28 days, the effect of V. oxycoccos extract on serum and urine parameters were assessed. STZ caused significant decreased in the mice body weight. Mice treated with the V. oxycoccos (400 mg/kg) harbored the lowest weight loss at day 28 (70.2±1.38 g). STZ caused significant increase in the mice FBS. Mice treated with the V. oxycoccos (400 mg/kg) harbored the lowest FBS at day 28 (189.2±1.20 mg/dL). Treatment of mice with V. oxycoccos (400 mg/kg) caused the lowest increase in the levels of cholesterol, HbA1c and triglycerides compared to the diabetic control mice. Compared to the diabetic control group, mice treated with V. oxycoccos (400 mg/kg) had the highest HDL, insulin, SOD, and GSH (p<0.05). The lowest serum BUN, CR, and UR were found in mice treated with V. oxycoccos (400 mg/kg). Anti-inflammatory effects of V. oxycoccos (400 mg/kg) was shown by the lowest TNF-α, IL-6, and TGF-β1 concentration in mice treated with V. oxycoccos (400 mg/kg).

CONCLUSIONS

The current study disclosed that treatment with V. oxycoccos resulted in substantial development in the serum and urine parameters and also antioxidant and anti-inflammatory response of STZ-induced diabetic mice.

Myocardial infarct size is reduced by nitrite and nitrate administration: a systematic review and meta-analysis of animal studies

Ischemic heart disease (IHD) is the leading cause of mortality worldwide and can be complicated by myocardial infarction (MI), leading to cardiac failure. Inorganic nitrite and nitrate, which release nitric oxide (NO), can protect the heart against myocardial injury. This animal systematic review and meta-analysis aims to assess whether the administration of nitrite/nitrate decreases myocardial infarct size. We systematically searched PubMed, Scopus, and Web of Science databases until October 2023; 15 eligible animal studies (35 study arms for in-vivo and 10 for in-vitro studies) published between 1989 and 2023 were included. In-vivo studies were conducted on rats, mice, cats, and dogs, and in-vitro studies on rats and mice with an overall exposure of 0.03 to 12713 mg/kg to nitrate/nitrite administrated before, after, or during ischemia mainly by intravenous single bolus or by oral over 270 days. All in-vitro studies used nitrite/nitrate before ischemia, with the concentration ranging between 0.34 to 201 μM. MI was induced by occlusion of the left anterior diagonal or left circumflex arteries in in-vitro studies and by isoproterenol in in-vivo studies. Infarct size was measured by direct staining of the sliced heart sections. In in-vivo studies, nitrite (overall effect size (ES)=-17.0 %, 95 % confidence interval (CI)=-21.3, -12.8, P<0.001) and nitrate (overall ES= -9.6 %, 95 % CI=-15.7, -3.4, P=0.002) reduced myocardial infarct size. In in-vitro studies, nitrite (overall ES=-15.8 %, 95 % CI=-25.5, -6.2, P=0.001) reduced the infarct size. Sensitivity analysis showed that the overall effect of nitrite on myocardial infarct size was unaffected by doses or health conditions in in-vivo and in-vitro studies. In conclusion, our meta-analysis showed that nitrite/nitrate administration can effectively reduce myocardial infarct size. However, these results should be approached with caution because of the limitations of animal studies and the existing high heterogeneity.

Structural changes in testes of Streptozotocin induced diabetic rats and possible protective effect of royal jelly: light and electron microscopic study

Diabetes mellitus (DM) is one of the most common metabolic diseases causing damage in many organs in the body including the testes. Royal Jelly (RJ) is one of the honey bee products that has antioxidant, anti-inflammatory and antidiabetic properties. This study was performed to evaluate the changes in the microscopic structure of the testes in Streptozotocin (STZ)-induced diabetic rats, and the possible protective role of RJ. 60 adult male albino rats were divided into three groups. Group I Control group, Group II STZ group, and Group III STZ+RJ group. Group II received a single dose of STZ (50 mg/kg) by intraperitoneal injection. Group III received a single dose of STZ as in the second group then received RJ orally by intragastric tube in dose of (100 mg/kg/day) for 4 weeks after confirmation of diabetes. Light and electron microscopic studies were performed. Group II revealed marked structural changes affecting seminiferous tubules with sever reduction in germinal epithelium and loss of mature spermatozoa in their lumina. The interstitial tissue revealed degenerated Leydig cells and congested blood vessels. Mallory trichrome stained section of group II revealed marked increase in the amount of collagen fibers. Group III revealed highly preserved testicular architecture almost near to that appeared in the control group except few tubules that were damaged. In conclusion, RJ protected the testicular structure from the damaging effect of diabetic oxidative stress through its antioxidant effect thus preserving male fertility.

Long-term effects of warm water immersion on kidney tissue damage in diabetic rats

Objectives

This study aimed to investigate the effects of Warm Water Immersion (WWI) on inflammation, kidney function, and kidney tissue damage in rats with diabetes mellitus (DM).

Materials and Methods

Forty male rats were divided into four groups: Healthy Control (HC), Diabetic Control (DC), Diabetic Rats treated with WWI (DW), and Healthy Rats treated with WWI (HW). Daily 15-minute WWI sessions at 43 °C were administered for eight weeks. Various parameters including lipids, fasting blood sugar (FBS), HbA1C, insulin, advanced glycation end products (AGEs), HSP70, glomerular filtration rate (GFR), urinary albumin excretion, creatinine, blood urea nitrogen (BUN), oxidative stress, anti-oxidant parameters, and gene expression of RAGE, VEGF, and TGFß1 were assessed. Histological examination of kidney tissue was also conducted.

Results

Significant reductions in FBS, AGEs, glutathione, superoxide dismutase (SOD), and nitric oxide (NO) levels were observed in the DW group compared to DC. Expression of RAGE, VEGF, and TGFß1 genes decreased in DW. Triglycerides, total cholesterol, and LDL cholesterol were lower in DW. Insulin, HDL cholesterol, catalase, total anti-oxidant capacity (TAC), and tissue HSP70 were higher in DW. Histological assessment revealed reduced kidney damage in DW compared to DC.

Conclusion

WWI for eight weeks shows promise in mitigating diabetic nephropathy in rats, suggesting its potential as a non-invasive adjunctive therapy for managing diabetes complications.

Dissolving sodium hydrosulfide in drinking water is not a good source of hydrogen sulfide for animal studies

Hydrogen sulfide (H2S) has many physiological and pathological roles in the human body. Sodium hydrosulfide (NaHS) is widely used as a pharmacological tool for assessing H2S effects in biological experiments. Although H2S loss from NaHS solution is a matter of minutes, some animal studies use NaHS in solution as an H2S-donating compound in drinking water. This study addresses whether 30 μM NaHS in drinking water prepared in rat/mouse water bottles remains stable for at least 12-24 h, as presumed by some authors. NaHS solutions (30 μM) were prepared in drinking water and immediately transferred to rat/mice water bottles. Samples were obtained from the tip of water bottles and from inside of the bottles at 0, 1, 2, 3, 4, 5, 6, 12, and 24 h for sulfide measurement using the methylene blue method. Furthermore, NaHS (30 μM) was administered to male and female rats for two weeks, and serum sulfide concentrations were measured every other day in the first week and at the end of the second week. NaHS solution was unstable in the samples obtained from the tip of water bottles; it declined by 72% and 75% after 12 and 24 h, respectively. In the samples obtained from the inside of the water bottles, the decline in the NaHS was not significant until 2 h; however, it decreased by 47% and 72% after 12 and 24 h, respectively. NaHS administration did not affect serum sulfide levels in male and female rats. In conclusion, NaHS solution prepared in drinking water can not be used for H2S donation as the solution is unstable. This route of administration exposes animals to variable and lower-than-expected amounts of NaHS.

Altered sialin mRNA gene expression in type 2 diabetic male Wistar rats: implications for nitric oxide deficiency

Nitrate therapy has been suggested to boost nitric oxide (NO) levels in type 2 diabetes (T2D); however, little is known about nitrate transport across the membranes. This study aimed to assess changes in the mRNA expression of sialin, as a nitrate transporter, in the main tissues of rats with T2D. Rats were divided into two groups (n = 6/group): Control and T2D. A high-fat diet combined with a low dose of streptozotocin (STZ, 30 mg/kg) was used to induce T2D. At month 6, samples from the main tissues of rats were used to measure the mRNA expression of sialin and levels of NO metabolites. Rats with T2D had lower nitrate levels in the soleus muscle (66%), lung (48%), kidney (43%), aorta (30%), adrenal gland (58%), epididymal adipose tissue (eAT) (61%), and heart (37%) and had lower nitrite levels in the pancreas (47%), kidney (42%), aorta (33%), liver (28%), eAT (34%), and heart (32%). The order of sialin gene expression in control rats was: soleus muscle > kidney > pancreas > lung > liver > adrenal gland > brain > eAT > intestine > stomach > aorta > heart. Compared to controls, rats with T2D had higher sialin mRNA expressions in the stomach (2.1), eAT (2.0), adrenal gland (1.7), liver (8.9), and soleus muscle (3.4), and lower sialin expression in the intestine (0.56), pancreas (0.42), and kidney (0.44), all P values < 0.05. These findings indicate altered sialin mRNA expression in the main tissues of male T2D rats and may have implications for future NO-based treatment of T2D.