Ramasamy Raveendran

Blood sample collection in small laboratory animals

Collection of blood from small laboratory animals is necessary for a wide range of scientific research and there are a number of efficient methods available for that. It is important that blood sample collection from experimental animals should be least stressful because stress will affect the outcome of the study. Various regulatory agencies and guidelines have restricted the use of animals and the techniques used for blood collection in laboratory animals. This article deals with the approved blood collection techniques for laboratory animals like rodents, lagomorphs and nonrodents. Permission of the Institute Animal Ethics Committee has been obtained for the use of animals for demonstrating the techniques.

Measurement of invasive blood pressure in rats

Blood pressure (BP) is one of the vital parameters used to assess the cardiovascular functions of a mammal. BP is commonly recorded using invasive, noninvasive, and radio telemetry methods, but invasive blood pressure (IBP) recording is considered the gold standard. IBP provides a direct indication of the effect of the investigational products on the circulatory system. Recording the IBP in rodents is an essential part of the preliminary screening of any product to determine its effect on the cardiovascular system. The present article describes the measurement of the IBP in Wistar rats/Sprague Dawley rats.

Protocol for middle cerebral artery occlusion by an intraluminal suture method

Rupadevi M, Department of Pharmacology, Jawaharlal Institute of Postgraduate Medical Education andResearch, Pondicherry – 605 006, India. E-mail: rupadevim@gmail.comCopyright

Identification of natural inhibitors against angiotensin I converting enzyme for cardiac safety using induced fit docking and MM-GBSA studies.

Background: Cleistanthins A and B are isolated compounds from the leaves of Cleistanthus collinus Roxb (Euphorbiaceae). This plant is poisonous in nature which causes cardiovascular abnormalities such as hypotension, nonspecific ST-T changes and QTc prolongation. The biological activity predictions spectra of the compounds show the presence of antihypertensive, diuretic and antitumor activities. Objective: Objective of the present study was to determine the in silico molecular interaction of cleistanthins A and B with Angiotensin I- Converting Enzyme (ACE-I) using Induced Fit Docking (IFD) protocols. Materials and Methods: All the molecular modeling calculations like IFD docking, binding free energy calculation and ADME/Tox were carried out using Glide software (Schrödinger LLC 2009, USA) in CentOS EL-5 workstation. Results: The IFD complexes showed favorable docking score, glide energy, glide emodel, hydrogen bond and hydrophobic interactions between the active site residues of ACE-I and the compounds. Binding free energy was calculated for the IFD complexes using Prime MM-GBSA method. The conformational changes induced by the inhibitor at the active site of ACE-I were observed based on changes of the back bone Cα atoms and side-chain chi (x) angles. The various physicochemical properties were calculated for these compounds. Both cleistanthins A and B showed better docking score, glide energy and glide emodel when compared to captopril inhibitor. Conclusion: These compounds have successively satisfied all the in silico parameters and seem to be potent inhibitors of ACE-I and potential candidates for hypertension.

Effect of cleistanthin A and B on adrenergic and cholinergic receptors

Objective: The aim was to study the in vitro and in silico interactions of cleistanthin A and B on the adrenergic and cholinergic receptors using isolated animal tissues and bioinformatics tools. Materials and Methods: The alpha adrenergic receptor activities of cleistanthin A and B were studied in vitro using a guinea pig vas deferens preparation. The beta adrenergic receptor activities of cleistanthin A and B on an isolated rat heart were studied in vitro using a modified Langendorff apparatus. The effects of cleistanthin A and B on the nicotinic and muscarinic cholinergic receptors were studied in vitro using rabbit vas deferens and rabbit jejunum, respectively. All the drug responses were recorded using a data acquisition system through a variable force transducer. The receptor–ligand interactions of cleistanthin A and B with adrenergic and cholinergic receptor proteins were determined using the ArgusLab molecular modeling and drug docking program. Results: Cleistanthin A and B significantly inhibited the actions of the alpha adrenergic receptor and the nicotinic cholinergic receptor. Cleistanthin A and B shifted the dose–response curve to the right with an increased EC50 value of phenylephrine and acetylcholine. Both cleistanthin A and B did not have any significant effect on the beta adrenergic and muscarinic cholinergic receptors. Conclusion: Cleistanthin A and B block the alpha adrenergic and nicotinic cholinergic receptors, but these compounds do not interact at all with the beta adrenergic and muscarinic cholinergic receptors.

Sub-chronic toxicological evaluation of cleistanthin A and cleistanthin B from the leaves of Cleistanthus collinus (Roxb.)

Objective To investigate the toxicological effects of cleistanthin A and cleistanthin B using sub-chronic toxicity testing in rodents. Method Cleistanthins A and B were isolated from the leaves of Cleistanthus collinus. Both the compounds were administered orally for 90 days at the concentration of 12.5, 25 and 50 mg/kg, and the effects on blood pressure, biochemical parameters and histology were assessed. The dose for sub-chronic toxicology was determined by fixed dose method according to OECD guidelines. Result Sub-chronic toxicity study of cleistanthins A and B spanning over 90 days at the dose levels of 12.5, 25 and 50 mg/kg (once daily, per oral) revealed a significant dose dependant toxic effect in lungs. The compounds did not have any effect on the growth of the rats. The food and water intake of the animals were also not affected by both cleistanthins A and B. Both the compounds did not have any significant effect on liver and renal markers. The histopathological analysis of both cleistanthins A and B showed dose dependent morphological changes in the brain, heart, lung, liver and kidney. When compared to cleistanthin A, cleistanthin B had more toxic effect in Wistar rats. Both the compounds have produced a dose dependent increase of corpora amylacea in brain and induced acute tubular necrosis in kidneys. In addition, cleistanthin B caused spotty necrosis of liver in higher doses. Conclusion The present study concludes that both cleistanthin A and cleistanthin B exert severe toxic effects on lungs, brain, liver, heart and kidneys. They do not cause any significant pathological change in the reproductive system; neither do they induce neurodegenerative changes in brain. When compared to cleistanthin A, cleistanthin B is more toxic in rats.

Molecular docking and ex vivo pharmacological evaluation of constituents of the leaves of Cleistanthus collinus (Roxb.) (Euphorbiaceae).

Objective: To investigate the involvement of alpha adrenergic receptors in hypotension induced by cleistanthin A and cleistanthin B. Materials and Methods: Cleistanthins A and B were isolated from the leaves of Cleistanthus collinus using a column chromatographic method and purified. Structures were confirmed by spectroscopic analysis. The compounds were prepared for molecular docking studies using Ligprep 2.3 module and Induced Fit Docking was carried out against α-1 adrenergic receptors using Glide. The ex vivo experiments were carried out on male Wistar rats. Under anaesthesia, the femoral vein and carotid artery were cannulated for drug administration and for monitoring the blood pressure, respectively. The effect of epinephrine, norepinephrine, acetylcholine, histamine and dopamine were recorded before and after the administration of cleistanthin A or cleistanthin B. The molecular docking studies showed favorable molecular interactions, glide score, energy and emodel. Result: Cleistanthins A and B per se reduced the mean blood pressure and the effect was dose dependent. Both the compounds reduced the effect of epinephrine, norepinephrine and α-1 receptor activity of dopamine. Cleistanthin B significantly increased the duration of action of acetylcholine on mean blood pressure. Conclusion: The molecular docking and ex vivo studies conclude that cleistanthin A and cleistanthin B have significant α-1 adrenergic receptor antagonist effect on the peripheral vascular system.

Effects of Cleistanthins A and B on Blood Pressure and Electrocardiogram in Wistar Rats

We have studied the effects of cleistanthin A and cleistanthin B, phytoconstituents isolated from the leaves of Cleistanthus collinus Roxb. (Euphorbiaceae), on blood pressure, electrocardiogram, and barium chloride-induced arrhythmia in Wistar rats. The two compounds were isolated by column chromatography and their identity was confirmed spectroscopically. A healthy, male Wistar rat was used to record the invasive blood pressure and electrocardiograph. The antiarrhythmic effects of cleistanthins A and B were studied using the barium chloride model. Both cleistanthin A and cleistanthin B showed a dosedependent hypotensive effect. Both compounds reduced the mean blood pressure significantly although the dose required for the effect was higher in the case of cleistanthin B. In the electrocardiogram, cleistanthins A and B significantly altered the electrical activity of the heart, the changes were transient and of no further consequence. Intravenous injection of 64 μg or more of cleistanthins A and B caused a sudden respiratory depression without affecting the electrocardiogram. Cleistanthins A and B did not display any antiarrhythmic effect against barium chloride-induced arrhythmia. In conclusion, both cleistanthin A and cleistanthin B exert a hypotensive effect and have no antiarrhythmic effect against barium chloride-induced arrhythmia in Wistar rats

Diuretic Effects of Cleistanthin A and Cleistanthin B from the Leaves of Cleistanthus Collinus in Wistar Rats

To study the diuretic effects of cleistanthin A and cleistanthin B, phytoconstituents were isolated from the leaves of Cleistanthus collinus in Wistar rats. The in vivo diuretic effects of cleistanthins A and B were determined according to the Lipschitz test. Prior to the experiment, the animals were fasted for 5 h and placed individually in metabolic cages. Cleistanthins A and B (12.5, 25, and 50 mg/kg) and furosemide (5 mg/kg) were suspended in 0.5% w/v carboxymethyl cellulose and administered orally. The urine was collected up to 5 h after administration and subsequently up to 24 h after administration. The acidity and urine volume were measured immediately. The urinary sodium and potassium levels were determined using a flame photometer, and the chloride level was determined by argentometric titration. The diuretic index and diuretic activity were calculated mathematically. While cleistanthins A and B showed a diuretic index of more than one, the diuretic activity of these compounds was less than one, indicating inferior activity compared with furosemide. Both cleistanthin A and B produced a significant increase in the urine volume and alterations in urinary electrolyte levels. However, the effect of the compounds was not dose dependent. Cleistanthin A and cleistanthin B exert diuretic effects in male Wistar rats without affecting the urinary acidity.

Hypertension influences the exponential progression of inflammation and oxidative stress in streptozotocin-induced diabetic kidney

Objective: To investigate the association of hypertension coexisting with diabetes mellitus with oxidative stress and inflammation in the kidneys of streptozotocin (STZ)-induced diabetic rats. Materials and Methods: Male Wistar rats were used for the experiments. Blood glucose (BG), urea, blood pressure (BP), and heart rate (HR) were analyzed before and 48 h after STZ injection. Further, these parameters were monitored up to 3 months of diabetes induction. Subsequently, the inflammatory markers (C-reactive protein, tumor necrosis factor-alpha, and nitrate) and oxidative stress markers were estimated after 3 months of diabetes induction in the kidney homogenate. Histological analysis of renal tissue was also carried out. Results: Linear elevation of BG, urea, mean arterial pressure (MAP), and HR was observed up to 3 months of diabetes induction. In the same manner, inflammatory and oxidative stress markers were also found to be significantly increased. Notably, the histological analysis revealed the signs of nephropathy such as increased mesangial cell number, thickness of basement membrane, and renal artery. Inflammatory and oxidative stress markers positively correlated with elevated BP and BG, but the correlation was better with BP rather than BG. Conclusion: Hypertension has a strong implication in the increased oxidative stress and inflammation of diabetic kidney at the very early stage of diabetes mellitus.