Ajai K. Srivastav

Parathyroid hormone 1 (1–34) acts on the scales and involves calcium metabolism in goldfish

The effect of fugu parathyroid hormone 1 (fugu PTH1) on osteoblasts and osteoclasts in teleosts was examined with an assay system using teleost scale and the following markers: alkaline phosphatase (ALP) for osteoblasts and tartrate-resistant acid phosphatase (TRAP) for osteoclasts. Synthetic fugu PTH1 (1-34) (100pg/ml-10ng/ml) significantly increased ALP activity at 6h of incubation. High-dose (10ng/ml) fugu PTH1 significantly increased ALP activity even after 18h of incubation. In the case of TRAP activity, fugu PTH1 did not change at 6h of incubation, but fugu PTH1 (100pg/ml-10ng/ml) significantly increased TRAP activity at 18h. Similar results were obtained for human PTH (1-34), but there was an even greater response with fugu PTH1 than with human PTH. In vitro, we demonstrated that both the receptor activator of the NF-κB ligand in osteoblasts and the receptor activator NF-κB mRNA expression in osteoclasts increased significantly by fugu PTH1 treatment. In an in vivo experiment, fugu PTH1 induced hypercalcemia resulted from the increase of both osteoblastic and osteoclastic activities in the scale as well as the decrease of scale calcium contents after fugu PTH1 injection. In addition, an in vitro experiment with intramuscular autotransplanted scale indicated that the ratio of multinucleated osteoclasts/mononucleated osteoclasts in PTH-treated scales was significantly higher than that in the control scales. Thus, we concluded that PTH acts on osteoblasts and osteoclasts in the scales and regulates calcium metabolism in goldfish.

Effects of chlorpyrifos on the kidney of freshwater catfish,Heteropneustes fossilis

The toxicity of pesticides to non-target organisms has been reported to be of great concern, but their use can not be denied for economic reasons. In many countries, restrictions have been imposed on the use of organochlorine pesticides. This has shifted the use patterns away from the organochlorine toward organophosphate pesticides. Though several studies have reported the effects of organophosphorus pesticides on aquatic organisms but they are mostly restricted to mortality studies. Kumar and Pant (1984) have stated that histopathological studies are useful to evaluate the pollution potential of pesticides since trace levels of pesticides, which do not cause animal mortality over a given period, are capable of producing considerable organal damage.

Therapeutic potential of N-acetyl cysteine with antioxidants (Zn and Se) supplementation against dimethylmercury toxicity in male albino rats

Mercury (Hg) is currently one of the most prevalent pollutants in the environment. Many studies have examined its effects on the health of both humans and animals. Experimental studies have shown that sulfur-containing nutrients play an important role as detoxification and protecting cell against the detrimental properties of mercury. The present study was undertaken to elucidate the toxicity induced by dimethylmercury in male rats through the activities of transaminases, alkaline phosphatase, lactate dehydrogenase in serum and oxidative damage as acetyl cholinesterase activity in different regions of brain and lipid peroxidation, reduced glutathione content, mean DNA damage in liver, kidney and brain of rats given dimethylmercury (10 mg/kg, p.o., once only) along with combination therapy of N-acetyl cysteine (2 mM/kg, i.p.), zinc (2 mM/kg, p.o.) and selenium (0.5 mg/kg, p.o.) for 3 days. In the dimethylmercury group, activities of transaminases, alkaline phosphatase, lactate dehydrogenase in serum, level of lipid peroxidation, mean DNA damage and mercury ion concentration were significantly higher whereas reduced glutathione content and the activity of acetyl cholinesterase were significantly lower compared to controls (P≤0.05). Combined treatment of zinc and selenium with N-acetyl cysteine to dimethylmercury-exposed rats showed a substantial reduction in the levels of DMM-induced oxidative damage and comet tail length. In conclusion, the results of this study support that the supplementation of zinc and selenium with N-acetyl cysteine can improve the DMM induced blood and tissue biochemical oxidative stress and molecular alterations by recoupment in mean DNA damage.

Monohydroxylated polycyclic aromatic hydrocarbons inhibit both osteoclastic and osteoblastic activities in teleost scales

AIMS We previously demonstrated that monohydroxylated polycyclic aromatic hydrocarbons (OHPAHs) bound to a human estrogen receptor (ER) by a yeast two-hybrid assay, but polycyclic aromatic hydrocarbons did not have a binding activity. Therefore, the direct effect of 3-hydroxybenz[a]anthracene (3-OHBaA) and 4-hydroxybenz[a]anthracene (4-OHBaA) on osteoclasts and osteoblasts in teleosts was examined. As a negative control, 1-hydroxypyrene (1-OHPy), which has no binding activity to human ER, was used. MAIN METHODS The effect of OHPAHs on osteoclasts and osteoblasts was examined by an assay system using teleost scale as each marker: tartrate-resistant acid phosphatase for osteoclasts and alkaline phosphatase for osteoblasts. Changes in cathepsin K (an osteoclastic marker) and insulin-like growth factor-I (IGF-I) (an osteoblastic marker) mRNA expressions in 4-OHBaA-treated goldfish scales were examined by using a reverse transcription-polymerase chain reaction. KEY FINDINGS In both goldfish (a freshwater teleost) and wrasse (a marine teleost), the osteoclastic activity in the scales was significantly suppressed by 3-OHBaA and 4-OHBaA, although 1-OHPy did not affect the osteoclastic activity. In reference to osteoblasts, the osteoblastic activity decreased with both 3-OHBaA and 4-OHBaA and did not change with the 1-OHPy treatment. However, 17beta-estradiol (E(2)) significantly increased both the osteoclastic and osteoblastic activities in the scales of both goldfish and wrasse. The mRNA expressions of both cathepsin K and IGF-I decreased in the 4-OHBaA-treated scales but increased in the E(2)-treated scales. SIGNIFICANCE The current data are the first to demonstrate that 3-OHBaA and 4-OHBaA inhibited both osteoclasts and osteoblasts and disrupted the bone metabolism in teleosts.

N-acetyl cysteine and selenium protects mercuric chloride-induced oxidative stress and antioxidant defense system in liver and kidney of rats: A histopathological approach

Mercury exposure is second-most common cause of metal poisoning which is quite stable and biotransformed to highly toxic metabolites thus eliciting biochemical alterations and oxidative stress. The aim of present study describes the protective effect of selenium either alone or in combination with N-acetyl cysteine (NAC) against acute mercuric chloride poisoning. The experiment was carried out in male albino Sprague Dawley rats (n=30) which was divided into five groups. Group 1 served as control. Groups 2-5 were administered mercuric chloride (HgCl2: 12mol/kg, i.p.) once only, group 2 served as experimental control. Animals of groups 3, 4 and 5 were received N-acetyl cysteine (NAC: 0.6mg/kg, i.p.) and selenium (Se: 0.5mg/kg, p.o.) and NAC with Se in combination. Acute HgCl2 toxicity caused significant rise in serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, albumin, bilirubin, γ-glutamyl transpeptidase, cholesterol, triglycerides, protein, urea, creatinine, uric acid and blood urea nitrogen content. Animals also showed significantly higher mercury content in liver and kidney, significant rise in lipid peroxidation level with concomitant decrease in reduced glutathione content and the antioxidant enzyme activities of superoxide dismutase and catalase after HgCl2 exposure. Results of the present investigation clearly showed that combination therapy with NAC+Se provide maximum protection against mercury toxicity than monotherapy (alone treated groups) by preventing oxidative degradation of biological membrane from metal mediated free radical attacks.

Nephrotoxicity induced by long-term oral administration of different doses of chlorpyrifos

Wistar rats (male) were divided into 3 groups — group A (GA) served as control, group B (GB) were daily administered chlorpyrifos (Anu Products Ltd., India) orally at a dose of 5 mg/kg b wt. and animals in group C (GC) received daily an oral administration of chlorpyrifos at a dose of 10 mg/kg b wt. Rats were sacrificed on 1st, 2nd, 4th, 6th and 8th week after initiation of the experiment. Kidneys were extirpated and fixed in aqueous Bouin’s solution. The tissues thus fixed were routinely processed for histological studies. The present study showed that the histopathological changes were caused in kidney of rats by chlorpyrifos administration. The changes noticed were mainly the shrinkage of glomerulus at initial stage of treatment, the tubular dilation, the glomerular hypercellularity, hypertrophy of tubular epithelium, degeneration of glomerulus and renal tubules, deposition of eosin-positive substances in the glomerulus and renal tubules and infiltration of leucocytes. A decrease in the body weight gain was observed in chlorpyrifos-treated rats. However, variable intensities of these changes were noticed depending upon the doses and duration of the treatment.

Effects of deltamethrin on serum calcium and corpuscles of Stannius of freshwater catfish, Heteropneustes fossilis.

Catfish, Heteropneustes fossilis, were subjected to deltamethrin for short-term (96 h; 1.49 μg L−1) and long-term (28 days; 0.37 μg L−1) durations. The effects of deltamethrin exposure were evaluated on the corpuscles of Stannius (CS) of the fish, as it has been reported recently that stanniocalcin homologs are present in fish as well as in tetrapods, including human beings. Moreover, in addition to their role in mineral homeostasis, stanniocalcin proteins also play a significant role in metabolism, reproduction, and development. Serum calcium levels of deltamethrin-treated fish decreased from 48 to 96 h in the short-term, and from day 7 to day 28 in the long-term experiment. The aldehyde fuchsin-positive (AF-positive) cells of CS of deltamethrin-treated fish exhibited increased granules after 72 and 96 h. No change was noticed in the nuclear volume of AF-positive cells. The AF-negative cells of CS depicted an increased nuclear volume after 96 h of deltamethrin treatment. The AF-positive cells of CS of long-term deltamethrin-treated fish exhibited increased granulation after 21 and 28 days. The nuclear volume of these cells depicted a progressive decrease from 14 days until the end of the experiment. The nuclear volume of AF-negative cells exhibited an increase at 21 and 28 days.

Dose-dependent vitamin D3 and 1,25-dihydroxyvitamin D3-induced hypercalcemia and hyperphosphatemia in male catfish Clarias batrachus

Abstract 1. 1. Vitamin D 3 (5000 i.u. and 100 i.u./100 g body wt) and 1,25-dihydroxycholecalciferol (0.5 unit, 5 units and 500 units/100 g body wt) were administered daily to the male catfish, Clarias batrachus for 17 days. The serum calcium and inorganic phosphate levels were measured colorimetrically. 2. 2. The serum calcium level increased significantly in all the treated groups and is dose-dependent. 3. 3. The serum inorganic phosphate was elevated in the treated groups (except in the group where only 100 units vitamin D 3 /100 g body wt was administered). 4. 4. This is the first report of the 1,25-dihydroxyvitamin D 3 -induced hypercalcemia in fish.

Prostaglandin E2 Increases Both Osteoblastic and Osteoclastic Activity in the Scales and Participates in Calcium Metabolism in Goldfish

Using our original in vitro assay system with goldfish scales, we examined the direct effect of prostaglandin E2 (PGE2) on osteoclasts and osteoblasts in teleosts. In this assay system, we measured the activity of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as respective indicators of each activity in osteoblasts and osteoclasts. ALP activity in scales significantly increased following treatment at high concentration of PGE2 (10-7 and 10-6 M) over 6 hrs of incubation. At 18 hrs of incubation, ALP activity also significantly increased in the PGE2 (10-9 to 10-6 M)-treated scale. In the case of osteoclasts, TRAP activity tended to increase at 6 hrs of incubation, and then significantly increased at 18 hrs of incubation by PGE2(10-7 to 10-6 M) treatment. At 18 hrs of incubation, the mRNA expression of osteoclastic markers (TRAP and cathepsin K) and receptor activator of the NF-&kgr;B ligand (RANKL), an activating factor of osteoclasts expressed in osteoblasts, increased in PGE2 treated-scales. Thus, PGE2 acts on osteoblasts, and then increases the osteoclastic activity in the scales of goldfish as it does in the bone of mammals. In an in vivo experiment, plasma calcium levels and scale TRAP and ALP activities in the PGE2-injencted goldfish increased significantly. We conclude that, in teleosts, PGE2 activates both osteoblasts and osteoclasts and participates in calcium metabolism.

Histological alterations in the prolactin cells of a teleost, Heteropneustes fossilis, after exposure to cypermethrin

Freshwater fish Heteropneustes fossilis (H. fossilis) were subjected to 5.76 μg/L (80% of 96 h LC50) and 1.44 μg/L (20% of 96 h LC50) of cypermethrin for short‐term (96 h) and long‐term (28 days) duration, respectively. Plasma calcium of H. fossilis exposed for short term (96 h) to cypermethrin exhibited no change at 24 h. The levels indicate a decrease in plasma calcium at 48 h. This response persists till the close of experiment (96 h). No change has been noticed throughout the experiment in the histological structure and nuclear volume of prolactin cells of short‐term cypermethrin treated fish. Long‐term exposure of cypermethrin to fish provoked hypocalcemia. The prolactin cells remain unchanged till 7 days following cypermethrin treatment. After 14 days, the nuclear volume exhibits an increase and the cells exhibit degranulation. These changes increase progressively 21 days onwards. Also, few degenerating cells are discerned after 28 days.