Effect of paricalcitol and enalapril on renal inflammation/oxidative stress in atherosclerosis

Combination Therapy with Enalapril and Paricalcitol Ameliorates Streptozotocin Diabetes-Induced Testicular Dysfunction in Rats via Mitigation of Inflammation, Apoptosis, and Oxidative Stress

BACKGROUND

As the impacts of diabetes-induced reproductive damage are now evident in young people, we are now in urgent need to devise new ways to protect and enhance the reproductive health of diabetic people. The present study aimed to evaluate the protective effects of enalapril (an ACE inhibitor) and paricalcitol (a vitamin D analog), individually or in combination, on streptozotocin (STZ)-diabetes-induced testicular dysfunction in rats and to identify the possible mechanisms for this protection.

MATERIAL AND METHODS

This study was carried out on 50 male Sprague-Dawley rats; 10 normal rats were allocated as a non-diabetic control group. A total of 40 rats developed diabetes after receiving a single dose of STZ; then, the diabetic rats were divided into four groups of equivalent numbers assigned as diabetic control, enalapril-treated, paricalcitol-treated, and combined enalapril-and-paricalcitol-treated groups. The effects of mono and combined therapy with paricalcitol and enalapril on testicular functions, sperm activity, glycemic state oxidative stress, and inflammatory parameters, as well as histopathological examinations, were assessed in comparison with the normal and diabetic control rats.

RESULTS

As a result of diabetes induction, epididymal sperm count, sperm motility, serum levels of testosterone, follicle-stimulating hormone (FSH) as well as luteinizing hormone (LH), and the antioxidant enzyme activities, were significantly decreased, while abnormal sperm (%), insulin resistance, nitric oxide (NO), malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were significantly increased, along with severe distortion of the testicular structure. Interestingly, treatment with paricalcitol and enalapril, either alone or in combination, significantly improved the sperm parameters, increased antioxidant enzyme activities in addition to serum levels of testosterone, FSH, and LH, reduced insulin resistance, IL-6, and TNF-α levels, and finally ameliorated the diabetes-induced testicular oxidative stress and histopathological damage, with somewhat superior effect for paricalcitol monotherapy and combined therapy with both drugs compared to monotherapy with enalapril alone.

CONCLUSIONS

Monotherapy with paricalcitol and its combination therapy with enalapril has a somewhat superior effect in improving diabetes-induced testicular dysfunction (most probably as a result of their hypoglycemic, antioxidant, anti-inflammatory, and anti-apoptotic properties) compared with monotherapy with enalapril alone in male rats, recommending a synergistic impact of both drugs.

Daily and seasonal mitochondrial protection: Unraveling common possible mechanisms involving vitamin D and melatonin

From an evolutionary point of view, vitamin D and melatonin appeared very early and share functions related to defense mechanisms. In the current clinical setting, vitamin D is exclusively associated with phosphocalcic metabolism. Meanwhile, melatonin has chronobiological effects and influences the sleep-wake cycle. Scientific evidence, however, has identified new actions of both molecules in different physiological and pathological settings. The biosynthetic pathways of vitamin D and melatonin are inversely related relative to sun exposure. A deficiency of these molecules has been associated with the pathogenesis of cardiovascular diseases, including arterial hypertension, neurodegenerative diseases, sleep disorders, kidney diseases, cancer, psychiatric disorders, bone diseases, metabolic syndrome, and diabetes, among others. During aging, the intake and cutaneous synthesis of vitamin D, as well as the endogenous synthesis of melatonin are remarkably depleted, therefore, producing a state characterized by an increase of oxidative stress, inflammation, and mitochondrial dysfunction. Both molecules are involved in the homeostatic functioning of the mitochondria. Given the presence of specific receptors in the organelle, the antagonism of the renin-angiotensin-aldosterone system (RAAS), the decrease of reactive species of oxygen (ROS), in conjunction with modifications in autophagy and apoptosis, anti-inflammatory properties inter alia, mitochondria emerge as the final common target for melatonin and vitamin D. The primary purpose of this review is to elucidate the common molecular mechanisms by which vitamin D and melatonin might share a synergistic effect in the protection of proper mitochondrial functioning.

The effect of vitamin D3 and paricalcitol on penicillin-induced epileptiform activity in rats

AIM

Epilepsy is a disease characterized by seizures which impair human life considerably. Vitamin D is of different systemic effects on metabolism and its deficiency is known to have a high prevalence among epilepsy patients. Paricalcitol, a vitamin D receptor agonist, has relatively fewer side effects. This study aimed to investigate the anticonvulsant effect of vitamin D₃ (cholecalciferol) and paricalcitol on penicillin-induced epileptiform activity.

METHOD

21 male Wistar rat weighing 180-240 g were used. After anesthetized by 1.25 g/kg urethane intraperitoneally (i.p.), rats were placed in the stereotaxic frame and tripolar electrodes were placed on the skull. The single microinjection of penicillin (2.5 μl, 500 IU, i.c.) into left sensorimotor cortex induced epileptiform activity. A single dose of 60.000 IU/kg (i.p.) vitamin D₃ was administered 14 days before intracortical penicillin (500 IU) injection. Paricalcitol (10 μg/kg, i.p.) was administered 30 min before intracortical penicillin (500 IU) administration and recorded for the following 180 min.

RESULTS

Vitamin D₃ pretreatment and paricalcitol diminished the frequency of epileptiform activity (p < 0.001) without changing the amplitude (p > 0.05) compared to the penicillin-injected group. Vitamin D₃ pretreatment and paricalcitol led to an important delay in the onset of penicillin-induced epileptiform activity (p < 0.001 and p < 0.05, respectively). Vitamin D₃ increased the latency of penicillin-induced epileptic activity compared to paricalcitol group (p < 0.001).

CONCLUSION

Results indicate that vitamin D₃ and paricalcitol decreased the frequency and increased the latency of the penicillin-induced epileptic activity. Vitamin D₃ was more effective than paricalcitol.

Heart Protection by Herb Formula BanXia BaiZhu TianMa Decoction in Spontaneously Hypertensive Rats

Modern research has shown that BanXia BaiZhu TianMa decoction (BBT) has the potential effect of lowering BP in vitro and in vivo. However, its therapeutic mechanism has not been clearly defined. The present study was designed to evaluate the protective effect of BBT on the heart by examining heart functioning and anti-inflammatory characteristics and to obtain scientific evidence for its further medical applications. BBT was extracted by decocting the herb extraction and analysed by HPLC. The left ventricular mass index (LVMI) was measured, and a histological examination of samples of the heart was performed. Inflammatory status was investigated by measuring tissue levels of interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor (TNF-α), inducible nitric oxide synthase (iNOS), and molecules of the nuclear factor κB (NF-κB) pathway. The BBT treatment significantly reversed the course of hypertension-derived heart damage. Meanwhile, the herb formula markedly reduced levels of IL-1, IL-6, TNF-α, and iNOS. In addition, the traditional compound suppressed the activity of the NF-κB pathway. The present study provides evidence of heart protection by BBT in SHRs. The action mechanisms may be partially attributable to the anti-inflammatory characteristic of the formula. Understanding the pharmacological action of BBT will benefit its impending use.

Effects of enalapril and paricalcitol treatment on diabetic nephropathy and renal expressions of TNF-α, p53, caspase-3 and Bcl-2 in STZ-induced diabetic rats

This study aimed to assess the renopreventive effect of enalapril and/or paricalcitol on streptozotocin (STZ) diabetes-induced nephropathy and to elucidate their mechanisms of action through investigation of the effects on renal oxidative stress, antioxidant defense system and expressions of TNF-α, p53, caspase-3, and Bcl-2. Diabetes mellitus was induced in fasting male Wistar rats by single intraperitoneal injection of STZ (45 mg /kg b.w.) dissolved in citrate buffer (pH 4.5). Ten days after STZ injection, the diabetic rats were treated with enalapril (25 mg/l of drinking water) and/or paricalcitol (8 μg/kg b.w. per os) dissolved in 5% DMSO daily for 4 weeks. The obtained data revealed that the treatment of diabetic Wistar rats with enalapril and/or paricalcitol led to significant decreases in the elevated serum urea, uric acid, creatinine, sodium and potassium levels; thereby reflecting the improvement of the impaired kidney function. The deteriorated kidney lipid peroxidation, GSH content and GST and catalase activities in diabetic rats were significantly ameliorated as a result of treatment with enalapril and/or paricalcitol. The elevated fasting and post-prandial serum glucose levels and the lowered serum insulin and C-peptide levels were also improved. The treatment with enalapril and paricalcitol in combination was the most potent in decreasing the elevated serum glucose levels. Moreover, the treatment of diabetic rats successfully prevented the diabetes-induced histopathological deleterious changes of kidney and islets of Langerhans of pancreas. In association, the immunohistochemically detected pro-inflammatory cytokine, TNF-α, and apoptotic mediators, p53 and caspase-3, were remarkably decreased in kidney of diabetic rats as a result of treatment while the expression of anti-apoptotic protein Bcl-2 was increased. Based on these findings, it can be concluded that enalapril and paricalcitol alone or in combination can prevent STZ diabetes-induced nephropathy through amelioration of the glycemic state and antioxidant defense system together with the suppression of oxidative stress, inflammation and apoptosis. However, the treatment of diabetic rats with enalapril and paricalcitol in combination has no further significant improvement effects on renal function and damage when compared with enalapril or paclitaxel treated diabetic groups.

Inhibitors of the renin-angiotensin system ameliorates clinical and pathological aspects of experimentally induced nephrotoxic serum nephritis

Introduction: Chronic kidney disease (CKD) is a global health concern, but the current treatments only slow down the progression. Thus an improved understanding of the pathogenesis and novel treatments of CKD are needed. The nephrotoxic nephritis (NTN) model has the potential to study the pathogenesis of CKD as it resembles human CKD. The classical treatments with angiotensin II receptor blocker (ARB) or the angiotensin-converting enzyme inhibitor (ACE I) have shown a clinical effect in CKD.

Methods: We characterized the disease development in the NTN model over 11 weeks by investigating functional and histopathological changes. We tested doses of 15 and 30 mg/kg/day enalapril and losartan in the NTN model in order to investigate the effect of inhibiting the renin-angiotensin-system (RAS).

Results: The NTN model displayed albuminuria peaking on days 6–7, mesangial expansion (ME), renal fibrosis, inflammation and iron accumulation peaking on day 42. However, albuminuria, ME, renal fibrosis and inflammation were still significantly present on day 77, suggesting that the NTN model is useful for studying both the acute and chronic disease phases. Enalapril and losartan significantly enhanced the glomerular filtration rate (GFR) and decreased albuminuria, ME, renal fibrosis and inflammation of NTN-induced kidney disease in mice.

Conclusions: This is the first study showing a comprehensive pathological description of the chronic features of the murine NTN model and that inhibiting the RAS pathway show a significant effect on functional and morphological parameters.

The potential therapeutic use of renin-angiotensin system inhibitors in the treatment of inflammatory diseases

Inflammation is a normal part of the immune response to injury or infection but its dysregulation promotes the development of inflammatory diseases, which cause considerable human suffering. Nonsteroidal anti-inflammatory agents are the most commonly prescribed agents for the treatment of inflammatory diseases, but they are accompanied by a broad range of side effects, including gastrointestinal and cardiovascular events. The renin-angiotensin system (RAS) is traditionally known for its role in blood pressure regulation. However, there is increasing evidence that RAS signaling is also involved in the inflammatory response associated with several disease states. Angiotensin II increases blood pressure by binding to angiotensin type 1 (AT₁ ) receptor, and direct renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors and AT₁ receptor blockers (ARBs) are clinically used as antihypertensive agents. Recent data suggest that these drugs also have anti-inflammatory effects. Therefore, this review summarizes these recent findings for the efficacy of two of the most widely used antihypertensive drug classes, ACE inhibitors and ARBs, to reduce or treat inflammatory diseases such as atherosclerosis, arthritis, steatohepatitis, colitis, pancreatitis, and nephritis.

Tail-Cuff Technique and Its Influence on Central Blood Pressure in the Mouse

BACKGROUND

Reliable measurement of blood pressure in conscious mice is essential in cardiovascular research. Telemetry, the "gold-standard" technique, is invasive and expensive and therefore tail-cuff, a noninvasive alternative, is widely used. However, tail-cuff requires handling and restraint during measurement, which may cause stress affecting blood pressure and undermining reliability of the results.

METHODS AND RESULTS

C57Bl/6J mice were implanted with radio-telemetry probes to investigate the effects of the steps of the tail-cuff technique on central blood pressure, heart rate, and temperature. This included comparison of handling techniques, operator's sex, habituation, and influence of hypertension induced by angiotensin II. Direct comparison of measurements obtained by telemetry and tail-cuff were made in the same mouse. The results revealed significant increases in central blood pressure, heart rate, and core body temperature from baseline following handling interventions without significant difference among the different handling technique, habituation, or sex of the investigator. Restraint induced the largest and sustained increase in cardiovascular parameters and temperature. The tail-cuff readings significantly underestimated those from simultaneous telemetry recordings; however, "nonsimultaneous" telemetry, obtained in undisturbed mice, were similar to tail-cuff readings obtained in undisturbed mice on the same day.

CONCLUSIONS

This study reveals that the tail-cuff technique underestimates the core blood pressure changes that occur simultaneously during the restraint and measurement phases. However, the measurements between the 2 techniques are similar when tail-cuff readings are compared with telemetry readings in the nondisturbed mice. The differences between the simultaneous recordings by the 2 techniques should be recognized by researchers.

Effect of paricalcitol on pancreatic oxidative stress, inflammatory markers, and glycemic status in diabetic rats

OBJECTIVES

This study is designed to explore the effect of paricalcitol (vitamin D receptor agonist) on pancreatic oxidative stress, inflammatory markers, and adiponectin and glycemic status in diabetic rats.

MATERIALS AND METHODS

Forty Sprague-Dawley male rats aged 10-12 weeks (150-250 g) were used in this study. Type 2 diabetes was developed by providing 4 weeks of high-fat-diet feeding before one shot of streptozotocin injection (40 mg/kg i.p.). Four study groups were designed as normal control rats, diabetic control vehicle-treated, diabetic paricalcitol-treated (0.8 μg/kg), and diabetic glibenclamide-treated (0.6 mg/kg) groups with 10 animals in each. After treatment of diabetic rats for 3 months, pancreatic inflammatory and oxidative stress markers, plasma adiponectin, glycemic status parameters, and histopathological pancreatic islet changes were evaluated.

RESULTS

Paricalcitol and glibenclamide treatment significantly (P < 0.05) decreased plasma glucose, insulin resistance, and pancreatic malondialdehyde and tumor necrosis factor-α levels. Moreover, they significantly (P < 0.05) increased plasma fasting insulin, C-peptide, adiponectin, pancreatic IL-2, catalase, superoxide dismutase, glutathione peroxidase, and reduced glutathione when contrasted with diabetic control rats. Furthermore, they prevented extensive histopathological damage in the pancreas of diabetic rats.

CONCLUSIONS

Paricalcitol reduced pancreatic oxidative stress and inflammatory markers, and improved glycemic status in diabetic rats.

Effect of Combination of Angiotensin-Converting Enzyme Inhibitors and Vitamin D Receptor Activators on Cardiac Oxidative Stress in Diabetic Rats

BACKGROUND

The principle mediator of diabetic myocardial injury is oxidative stress. The aim was to compare the effect of monotherapy with enalapril, angiotensin-converting enzyme inhibitor and paricalcitol (vitamin D receptor activator), to the combined therapy with both drugs on the cardiac oxidant-antioxidant balance in the type 2 diabetic rats.

MATERIALS AND METHODS

A total of 50 male Sprague-Dawley rats were divided into 5 groups, namely the normal control and diabetic, vehicle, enalapril, paricalcitol and paricalcitol and enalapril-treated groups. Enalapril was given at a dose of (25mg/L) in drinking water once daily and paricalcitol was given intraperitoneally (0.8μg/kg/3 × week) for 3 months. Glycemic status, cardiac oxidant-antioxidant parameters and histologic examination were determined.

RESULTS

Paricalcitol and combined treatment significantly (P < 0.01) reduced the level of fasting, postprandial blood glucose, homeostatic model assessment-insulin resistance, cardiac malondialdehyde and nitric oxide. Moreover, they significantly (P < 0.01) increased the levels of insulin and c-peptide compared to diabetic control rats. Combined treatment significantly (P < 0.01) raised the level of glutathione, glutathione S-transferase and catalase more than monotherapy.

CONCLUSION

The combination of angiotensin-converting enzyme inhibitors and vitamin D receptor activators has a superior effect on reducing cardiac oxidative stress by raising antioxidant activity than monotherapy in diabetic rats.