Effects of chronic caffeine administration on blood glucose levels and on glucose tolerance in healthy and diabetic rats

Effect of sakuranin on carbohydrate-metabolizing enzyme activity modifications in streptozotocin-nicotinamide-induced diabetic wistar rats

This study is to assess the glucose lowering activity of sakuranin in diabetes induced rats by streptozotocin (STZ) and nicotinamide (NA). Diabetic rats were treated sakuranin for 45 days (20, 40, 80 mg/kg) by orally. Sakuranin (80 mg/kg body weight) was normalized the changes of abnormal blood glucose plasma glucose and plasma insulin levels. Hence, we have continued the further research with this active dose of 80 mg/kg sakuranin. The plasma glucose and glycosylated hemoglobin (HbA₁c) reduced and insulin, glycogen and hemoglobin levels increased by Sakuranin administration in diabetic rats. Additionally, hexokinase and glucose-6-phophate dehydrogenase activities increased and glucose-6-phosphatase and fructose-1,6-bisphosphatase activities decreased in diabetic condition while administration of treated compound. In this observed result signified that sakuranin may have potential role of diabetic condition rats by evidenced with reducing glucose and increasing insulin and also protect the carbohydrate metabolic changes.

Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes

Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.

Beneficial Impact of Semicarbazide-Sensitive Amine Oxidase Inhibition on the Potential Cytotoxicity of Creatine Supplementation in Type 2 Diabetes Mellitus

Creatine supplementation of the population with type 2 diabetes mellitus (T2DM) combined with an exercise program is known to be a possible therapy adjuvant with hypoglycemic effects. However, excessive administration of creatine leads to the production of methylamine which is deaminated by the enzyme semicarbazide-sensitive amine oxidase (SSAO) and as a result, cytotoxic compounds are produced. SSAO activity and reaction products are increased in the serum of T2DM patients. Creatine supplementation by diabetics will further augment the activity of SSAO. The current review aims to find a feasible way to ameliorate T2DM for patients who exercise and desire to consume creatine. Several natural agents present in food which are involved in the regulation of SSAO activity directly or indirectly are reviewed. Particularly, zinc-α2-glycoprotein (ZAG), zinc (Zn), copper (Cu), histamine/histidine, caffeine, iron (Fe), and vitamin D are discussed. Inhibiting SSAO activity by natural agents might reduce the potential adverse effects of creatine metabolism in population of T2DM.

Investigation of the effect of coffee on body weight, serum glucose, uric acid and lipid profile levels in male albino Wistar rats feeding on high-fructose diet

Coffee is one of the most commonly consumed beverages in the worldwide and is assumed to have protective effects against metabolic syndrome. The present study was aimed at investigating the effect of coffee on body weight, serum glucose, uric acid and lipid profile levels in male albino Wistar rats feeding on high fructose diet. A post-test experimental study was conducted on a total of 30 (9–10 weeks old) male albino Wistar rats. The rats were divided into 6 groups: group I (normal control)-fed on standard chow and plain tap water only; group II (fructose control)-fed on standard chow and 20% of fructose solution; group III–VI (treatment groups)-fed on standard chow, 20% of fructose solution and treated with 71, 142, 213 and 284 mg/kg body weight/day of coffee respectively for six weeks. At the end, body weight, serum glucose, uric acid and lipid profile levels were investigated. Data was entered and cleared by epi-data software version 3.1 and analyzed by one way ANOVA followed by Tukey post hoc multiple comparison tests using SPSS V. 23.00. Statistical significance was considered at p < 0.05. The results showed that body weight, fasting serum glucose and uric acid levels significantly lowered in rats treated with 213 (p = 0.047; 0.049; 0.026) and 284 (p = 0.035; 0.029; 0.010) mg/kg body weight/day of coffee compared to fructose control group. Fasting serum triglycide (TG) and low density lipoprotein (LDL-C) levels showed significant reduction in rats treated with 284 mg/kg body weight/day of coffee as compared to fructose control group (p = 0.031; 0.046) respectively. In conclusion, treating rats with coffee decreased body weight, fasting serum glucose, uric acid, TC, TG and LDL-C, and increased HDL-C in a dose dependent manner in rats feeding on high fructose diet, suggesting that coffee consumption may be helpful in ameliorating metabolic syndrome.

Caffeine Improves Hormonal and Lactate Homeostasis in Diabetic Rats

Introduction:

Lactate Minimum Test (LMT) identifies a sustainable exercise intensity, in which an equilibrium is observed between production and clearance of blood lactate and the hormone influence during this physiological moment.

Objective:

The present study aimed to identify the levels of LM and hormones after caffeine consumption and exercise Stress Test (ST) in diabetic rats.

Methods:

This study was composed of 24 animals, of 60 days, allocated into four groups: Control, Diabetic, Caffeine, and Diabetes+Caffeine. The Diabetes model was induced by intraperitoneal administration of 120 mg/kg of alloxan. On the test day, 6 mg/kg of caffeine were administrated 30 minutes before the exercise Stress Test (ST) protocol. During the ST animals underwent a Stress Test (ST), in which they performed forced swimming (until exhaustion) tie to loads of 13% Body’s Weight (BW). The incremental phase of LM began with an initial load of 4% Body’s Weight (BW) and increased 0.5% every 5 min. Lactate concentration was measured 5, 7 and 9 min (mmol/L) after ST. The Incremental Progressive Test (IPT) involved swimming with loads of 4.0, 4.5, 5.0, 5.5, 6.0, and 7.0% of BW, for 5min with each. Blood samples were collected by a caudal puncture to subsequent lactate and hormone assay.

Results:

Performance time and lactate concentration of hyperlactatemia test, as well as Lactate Minimum (LM) and Lactate (LAC) concentration after the progressive test presented a significant difference when comparing the levels of the control group with caffeine and diabetic group (p<0.05).

Conclusion:

It is suggested that caffeine improves lactate clearance and hormonal steady state condition of diabetic animals after hyperlactacidemia and physical exercise maintenance.

The Comparative Effect of Nopal and Mucilage in Metabolic Parameters in Rats with a High-Fructose Diet

Nopal is used in Mexico as both food and traditional medicine for metabolic diseases. Our aim was to analyze the effect of the chronic administration of mucilage fiber extracted from nopal (Opuntia ficus indica; 500 mg/kg body weight per day) on male Wistar rats on a high-fructose diet (HFD). After which three groups were administered one of the following for 30 days: whole-fresh nopal mixed in water, mucilage, and control. Metabolic and hemodynamic parameters (triglycerides, cholesterol, fasting glucose, oral glucose tolerance test, blood pressure, and abdominal circumference) were determined. Rats administered nopal and mucilage had lower levels of triglycerides and diastolic arterial pressure than control, but only nopal had significant differences. Furthermore, systolic and diastolic pressure were higher in the control group. Thus, whole nopal and mucilage improve metabolic parameters in rats fed a HFD.

Comparative effects of energy restriction and resveratrol intake on glycemic control improvement

Resveratrol (RSV) has been proposed as an energy restriction mimetic. This study aimed to compare the effects of RSV and energy restriction on insulin resistance induced by an obesogenic diet. Any additive effect of both treatments was also analyzed. Rats were fed a high-fat high-sucrose diet for 6 weeks. They were then distributed in four experimental groups which were either fed a standard control diet (C), or treated with RSV (30 mg/kg/d), or submitted to energy restriction (R, 15%), or treated with RSV and submitted to energy restriction (RR). A glucose tolerance test was performed, and serum glucose, insulin, fructosamine, adiponectin, and leptin concentrations determined. Muscle triacylglycerol content and protein expression of insulin receptor (IRβ), protein kinase B (Akt), Akt substrate of 160 kDa (AS160) and glucose transporter 4 (GLUT-4) were measured. In RSV rats, fructosamine concentrations were reduced, HOMA-IR remained unchanged, but glucose tolerance was improved, without changes in phosphorylation of IRβ, Akt, and AS160 or in GLUT-4 protein expression. Rats under energy restriction showed an improvement in all the markers related to glycemic control, as well as increased phosphorylation of AS160 and protein expression of GLUT-4. In rats from RR group the results were similar to R group, with the exception of IRβ and Akt phosphorylation, which were increased. In conclusion, mild energy restriction is more efficient than intake of RSV within a standard balanced diet, and acts by means of a different mechanism from that of RSV. No additive effects between RSV and energy restriction were observed. © 2017 BioFactors, 43(3):371-378, 2017.

Caffeine intake decreases oxidative stress and inflammatory biomarkers in experimental liver diseases induced by thioacetamide: Biochemical and histological study

Liver disease remains a significant global health problem. Increased caffeine consumption has been associated with a lower prevalence of chronic liver disease. This study aimed to investigate the modifying effects of caffeine on liver injury induced by thioacetamide (TAA) administration in male rats and the possible underlying mechanisms. Forty adult male rats were equally classified into four groups: control group, received only tap water; caffeine-treated group, received caffeine (37.5 mg/kg per day); TAA-treated group, received intraperitoneal (i.p.) TAA (200 mg/kg b.w.) twice a week; and caffeine + TAA-treated group, received combined TAA and caffeine in the same previous doses. After eight weeks of treatment, blood samples were collected for biochemical analysis and liver specimens were prepared for histological and immunohistochemical studies and for assessment of oxidative stress. TAA induced liver toxicity with elevated liver enzymes and histological alterations, fatty changes, apoptosis, and fibrosis evidenced by increased immunohistochemical reaction to matrix metalloproteinase-9 (MMP-9) and collagen type IV in hepatocytes. Also, the levels of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in serum were significantly elevated. Co-treatment with caffeine and TAA restored normal liver structure and function. Caffeine provided an anti-fibrogenic, anti-inflammatory, and antioxidant effect that was associated with recovery of hepatic histological and functional alterations from TAA-induced hepatotoxicity.

CHRONIC CAFFEINE'S EFFECTS ON BEHAVIOURAL CHANGES IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

Context

Memory deficits, anxiety and depression are often associated with diabetes, worsening diabetic patients' prognosis. Caffeine, a worldwide used psychoactive substance, is a candidate for improving these conditions.

Objective

The aim of this study was to assess the behaviour in streptozotocin-induced diabetic Wistar rats and to evaluate the behavioural effects of caffeine administration.

Materials and methods

Diabetes was induced by a single intraperitoneal injection of 50 mg/kg BW streptozotocin (n=10), while control rats received the vehicle (n=9). After six weeks, behavioural tests for anxiety, memory and depression were performed: elevated plus maze (EPM) test, novel object recognition (NOR) test and forced swimming test (FST), respectively. The tests were repeated after further 2 weeks of continuous caffeine administration (20 mg/kg BW/day in drinking water).

Results

Diabetic rats manifested a high anxiety level, showed by a reduced exploratory activity compared to control rats (p<0.05) and long-term memory impairment, spending more time near the old object in NOR test. Caffeine administered for 2 weeks did not modify glycemic values in either group, and attenuated the behavioural changes observed in the EPM test. Also, in NOR test for long-term memory, caffeine administration induced an increased time spent with the novel object than with the old one in both groups.

Conclusions

Our data suggest that chronic caffeine administration has an anxiolytic effect in diabetic rats and improves long-term memory in both diabetic and control rats.