Manickam Kesavan

Oral nanoparticulate curcumin combating arsenic-induced oxidative damage in kidney and brain of rats:

Arsenic exposure through drinking water causes oxidative stress and tissue damage in the kidney and brain. Curcumin (CUR) is a good antioxidant with limited clinical application because of its hydrophobic nature and limited bioavailability, which can be overcome by the encapsulation of CUR with nanoparticles (NPs). The present study investigates the therapeutic efficacy of free CUR and NP-encapsulated CUR (CUR-NP) against sodium arsenite-induced renal and neuronal oxidative damage in rat. The CUR-NP prepared by emulsion technique and particle size ranged between 120 and 140 nm, with the mean particle size being 130.8 nm. Rats were divided into five groups (groups 1–5) with six animals in each group. Group 1 served as control. Group 2 rats were exposed to sodium arsenite (25 ppm) daily through drinking water for 42 days. Groups 3, 4, and 5 were treated with arsenic as in Group 2; however, these animals were also administered with empty NPs, CUR (100 mg/kg body weight), and CUR-NP (100 mg/kg), respectively, by oral gavage during the last 14 days of arsenic exposure. Arsenic exposure significantly increased serum urea nitrogen and creatinine levels. Arsenic increased lipid peroxidation (LPO), reduced glutathione content and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were depleted significantly in both kidney and brain. Treatment with free CUR and CUR-NP decreased the LPO and increased the enzymatic and nonenzymatic antioxidant system in kidney and brain. Histopathological examination showed that kidney and brain injury mediated by arsenic was ameliorated by treatment. However, the amelioration percentage indicates that CUR-NP had marked therapeutic effect on arsenic-induced oxidative damage in kidney and brain tissues.

Atorvastatin restores arsenic-induced vascular dysfunction in rats: Modulation of nitric oxide signaling and inflammatory mediators

We evaluated whether atorvastatin, an extensively prescribed statin for reducing the risks of cardiovascular diseases, can reduce the risk of arsenic-induced vascular dysfunction and inflammation in rats and whether the modulation could be linked to improvement in vascular NO signaling. Rats were exposed to sodium arsenite (100ppm) through drinking water for 90 consecutive days. Atorvastatin (10mg/kg bw, orally) was administered once daily during the last 30days of arsenic exposure. On the 91(st) day, blood was collected for measuring serum C-reactive protein. Thoracic aorta was isolated for assessing reactivity to phenylephrine, sodium nitroprusside and acetylcholine; evaluating eNOS and iNOS mRNA expression and measuring NO production, while abdominal aorta was used for ELISA of cytokines, chemokine and vascular cell adhesion molecules. Histopathology was done in aortic arches. Arsenic did not alter phenylephrine-elicited contraction. Atorvastatin inhibited Emax of phenylephrine, but it augmented the contractile response in aortic rings from arsenic-exposed animals. Sodium nitroprusside-induced relaxation was not altered with any treatment. However, arsenic reduced acetylcholine-induced relaxation and affected aortic eNOS at the levels of mRNA expression, protein concentration, phosphorylation and NO production. Further, it increased aortic iNOS mRNA expression, iNOS-derived NO synthesis, production of pro-inflammatory mediators (IL-1β, IL-6, MCP-1, VCAM, sICAM) and serum C-reactive protein and aortic vasculopathic lesions. Atorvastatin attenuated these arsenic-mediated functional, biochemical and structural alterations. Results show that atorvastatin has the potential to ameliorate arsenic-induced vascular dysfunction and inflammation by restoring endothelial function with improvement in NO signaling and attenuating production of pro-inflammatory mediators and cell adhesion molecules.

Immunomodulatory effects of nanocurcumin in arsenic-exposed rats

We evaluated whether the nanoformulation of curcumin could be more effective than free curcumin against arsenic-induced immune dysfunction in rats. Curcumin was encapsulated in polylactic-co-glycolic acid (PLGA). Nanocurcumin (CUR-NP) exhibited a spherical shape with the mean particle size of 130.8 nm. Rats were randomly divided into five groups of six each. Group I was kept as the control. In Group II, rats were exposed to sodium arsenite (25 ppm) daily through drinking water for 42 days. Groups III, IV and V were treated with arsenic as in Group II, however, they were administered with nanoparticle, curcumin (100 mg/kg bw) and CUR-NP (100 mg/kg bw), respectively, by oral gavage during the last 14 days of arsenic exposure. At term, serum and spleen were collected. Immune dysfunction was evaluated by assessing cellular and humoral immunities. Arsenic significantly decreased the splenic lymphocyte proliferation in response to the antigen -- Keyhole Limpet Hemocyanin (KLH) and mitogen -- concanavalin-A. Arsenic reduced both the delayed type hypersensitivity response and secondary antibody (IgG) response to KLH. It also reduced the lipopolysaccharide-stimulated nitric oxide production in splenic lymphocytes. Free curcumin and CUR-NP treatment significantly attenuated these arsenic-mediated effects. However, the magnitude of the effects indicates that CUR-NP has better ameliorative potential than free curcumin at the equivalent dose level.

Arsenic reduces the antipyretic activity of paracetamol in rats: Modulation of brain COX-2 activity and CB1 receptor expression

We examined whether subacute arsenic exposure can reduce paracetamol-mediated antipyretic activity by affecting COX pathway and cannabinoid CB1 receptor regulation. Rats were preexposed to elemental arsenic (4 ppm) as sodium arsenite through drinking water for 28 days. Next day pyrexia was induced with lipopolysaccharide and paracetamols (200 mg/kg, oral) antipyretic activity was assessed. The activities of COX-1 and COX-2, the levels of PGE₂, TNF-α and IL-1β and expression of CB₁ receptors were assessed in brain. Arsenic inhibited paracetamol-mediated antipyretic activity. COX-1 activity was not affected by any treatments. Paracetamol decreased COX-2 activity, levels of PGE₂, TNF-α and IL-1β and caused up-regulation of CB1 receptors. Arsenic caused opposite effects on these parameters. In the arsenic-preexposed rats, paracetamol-mediated effects were attenuated, while CB₁ receptor up-regulation was reversed to down-regulation. Results suggest that elevated COX-2 activity and reduced CB₁ expression could be involved in the arsenic-mediated attenuation of the antipyretic activity of paracetamol.

Candesartan ameliorates arsenic-induced hypertensive vascular remodeling by regularizing angiotensin II and TGF-beta signaling in rats.

Arsenic exposure can cause several cardiovascular diseases, including hypertension, atherosclerosis and microvascular disease. Earlier, we reported that arsenic-mediated enhancement of angiotensin II (AngII) signaling can impair vascular physiology. Here, we investigated whether the AT1 receptor (AT1R) blocker candesartan can ameliorate the arsenic-induced hypertensive vascular remodeling in rats and whether the amelioration could relate to attenuation in vascular AngII and TGF-β signaling. Rats were exposed to sodium arsenite (50ppm) through drinking water for 90 consecutive days. Candesartan (1mg/kg bw, orally) was administered once daily during the last 30days of arsenic exposure. Non-invasive blood pressure was recorded weekly in conscious rats, while AngII-induced change in mean arterial pressure in anaesthetized rats was measured by invasive method on the 91st day. On this day, blood was collected from other animals for measuring AngII level. Western blot of AT1, AT2 and TβRII receptors; ELISA of PTK, RasGAP, ERK-1/2, TGF-β and CTGF; immunohistochemistry of phosphorylated Smad3, Smad4 and collagen III, hydroxyproline/total collagen estimation, collagen deposition by Massons trichrome staining and histomorphometry were carried out in thoracic aorta. Arsenic increased non-invasive systolic, diastolic and mean arterial pressure. Further, AngII caused concentration-dependent incremental change in mean arterial pressure in the arsenic-exposed rats. Arsenic upregulated AT1 and TβRII receptor proteins; elevated the levels of PTK, ERK-1/2, TGF-β and CTGF, decreased RasGAP level and augmented the immunoreactivities of Smad3, Smad4 and collagen III. Arsenic also increased hydroxyproline/total collagen level, proliferation of collagen fibres and thickness of aortic wall and collagenous adventitia. Candesartan normalized blood pressure, regularized receptor expressions, MAP kinase and TGF-β signaling, restored collagen deposition and regressed aortic thickness. Our results demonstrate that candesartan can ameliorate the arsenic-mediated systemic hypertension and vascular remodeling in rats by regularizing the signaling pathways of AngII and TGF-β.

Arsenic decreases antinociceptive activity of paracetamol: Possible involvement of serotonergic and endocannabinoid receptors

We assessed whether repeated arsenic exposure can decrease paracetamol-mediated antinociception by modulating serotonergic and endocannabinoid pathways. Rats were preexposed to elemental arsenic (4ppm) as sodium arsenite through drinking water for 28 days. Next day paracetamols (400mg/kg, oral) antinociceptive activity was assessed through formalin-induced nociception. Serotonin content and gene expression of 5-HT1A, 5-HT2A and CB1 receptors were evaluated in brainstem and frontal cortex. Arsenic decreased paracetamol-mediated analgesia. Paracetamol, but not arsenic, increased serotonin content in these regions. Arsenic attenuated paracetamol-mediated increase in serotonin level. Paracetamol did not alter 5-HT1A expression, but caused down-regulation of 5-HT2A and up-regulation of CB1 receptors. Arsenic down-regulated these receptors. However, paracetamol-mediated down-regulation of 5-HT2A was more pronounced. Arsenic did not modify paracetamols effect on 5-HT1A expression, but reduced paracetamol-mediated down-regulation of 5-HT2A and reversed up-regulation of CB1 receptors. Results suggest arsenic reduced paracetamol-induced analgesia possibly by interfering with pronociceptive 5-HT2A and antinociceptive CB1 receptors.

Economic importance of ticks and their effective control strategies

Abstract Role of livestock in improvement of a countrys economy is inevitable. Livestock contributes a lions share in agricultural sector of developing countries. Several developing countries have adopted the use of exotic germplasm to improve the productivity of their native breeds, which has brought down the disease resistance. Among various problems hindering the growth and productivity of livestock, parasite related problem plays a major role. Tick and tick borne diseases are prevalent in 80% of the cattle population around the globe. They cause various worries to the farmers by transmitting major disease causing pathogens and jeopardize animal health leading to poor production. Ticks transmit various pathogenic agents like virus, bacteria, protozoa and other parasites as well. Many of them are dangerous for the livestock health and some are also zoonotic hence, need to be checked at the initial stages. Control of ticks is the major concern in the present situation as the use of anti-parasitic drugs has led to the current trend of resistance development. Search for an effective alternative method has begun; vaccination will be a better alternative and promising tool for protecting livestock from the tick infestations and thereby tick borne diseases.

Hypercholesterolemia impairs oxytocin-induced uterine contractility in late pregnant mouse

High cholesterol is known to negatively affect uterine contractility in ex vivo conditions. The aim of the present study was to reveal the effect of in vivo hypercholesterolemia on spontaneous and oxytocin-induced uterine contractility in late pregnant mouse uterus. Female Swiss albino mice were fed with high cholesterol (HC) diet (0.5% sodium cholate, 1.25% cholesterol and 15% fat) for 6 weeks and then throughout the gestation period after mating. On day 19 of gestation, serum cholesterol level was increased more than 3-fold while triglycerides level was reduced in HC diet-fed animals as compared to control animals fed with a standard diet. In tension experiments, neither the mean integral tension of spontaneous contractility nor the response to CaCl2 in high K+-depolarized tissues was altered, but the oxytocin-induced concentration-dependent contractile response in uterine strips was attenuated in hypercholesterolemic mice as compared to control. Similarly, hypercholesterolemia dampened concentration-dependent uterine contractions elicited by a GNAQ protein activator, Pasteurella multocida toxin. However, it had no effect on endogenous oxytocin level either in plasma or in uterine tissue. It also did not affect the prostaglandin release in oxytocin-stimulated tissues. Western blot data showed a significant increase in caveolin-1 and GRK6 proteins but decline in oxytocin receptor, GNAQ and RHOA protein expressions in hypercholesterolemic mouse uterus. The results of the present study suggest that hypercholesterolemia may attenuate the uterotonic action of oxytocin in late pregnancy by causing downregulation of oxytocin receptors and suppressing the signaling efficacy through GNAQ and RHOA proteins.

Nanocurcumin ameliorates Staphylococcus aureus-induced mastitis in mouse by suppressing NF‑κB signaling and inflammation

&NA; Mastitis is the inflammation of the mammary glands caused by bacteria. It causes severe economic loss to dairy industry. Curcumin, a polyphenol obtained from turmeric, has considerable anti‐inflammatory effect. Since it is rapidly eliminated from the body, its oral bioavailability is low. However, nanoformulation of curcumin significantly enhances its therapeutic efficiency by improving its oral bioavailability. We evaluated whether nanocurcumin could be more effective than normal curcumin against bovine Staphylococcus aureus mastitis in mouse model. Curcumin‐loaded PLGA nanoparticles (CUR‐NP) were prepared by solid‐in‐oil‐in‐water emulsion method. The mouse model of mastitis was induced by inoculation of a field strain of S. aureus (bovine mastitis isolate) on the 9th day of parturition through the duct of the mammary gland. CUR‐NP and curcumin were given orally for 7 days (day 2 to day 8 of parturition) prior to S. aureus inoculation. We determined the levels of inflammatory cytokines and the mRNA expression of NF‐&kgr;B. S. aureus infection increased the levels of tumor necrosis factor‐&agr;, interleukin‐1&bgr; and myeloperoxidase in mammary tissues and C‐reactive protein in serum. Both CUR‐NP and curcumin significantly attenuated the levels of these cytokines. However, comparatively, the ameliorative efficiency of CUR‐NP was better than normal curcumin. S. aureus infection‐induced NF‐&kgr;B mRNA expression was significantly reduced to the healthy control level by CUR‐NP. Our study demonstrates that the nanoformulation of curcumin can reduce pro‐inflammatory mediators in S. aureus‐infected mammary tissues by improving NF‐&kgr;B signaling. Besides, compared to normal curcumin, this nanoformulation appears to be a better alternative against murine mastitis.

DNA Tattooing – Pain Or Gain? -

Tattooing is one of a number of DNA delivery methods which results in an efficient expression of an introduced gene in the epidermal and dermal layers of the skin. The tattoo procedure causes minor mechanical injuries followed by hemorrhage, necrosis, inflammation and regeneration of the skin and thus non-specifically stimulates the immune system. DNA vaccines delivered by tattooing have been shown to induce higher specific humoral and cellular immune responses than intramuscularly injected DNA.