Antiosteoporotic effect of Hydrilla verticillata against lead induced damage in bone samples of edible fish Labeo rohita - an FTIR approach

Hepatotoxic effect of lead and hepatoprotective effect of Hydrilla verticillata on hepatic transcriptional and physiological response in edible fish Labeo rohita

Lead tops the list of developmental toxicants released by industry into the environment according to Commission for Environmental Corporation. Hydrilla verticillata is an aquatic weed and rich source of variable nutrients and chemical constituents like saponins, vitamins, minerals, antioxidants, amino acids, detoxifying agents, etc. This weed is used in a beneficial way to detoxify lead in fish model. The fish were treated with sublethal concentration of lead to induce liver damage and fed with supplementary feed containing 20% of hydrilla dry powder. The present work revealed that lead accumulation is highly toxic to liver. Lead toxicity increased the expressions of cytochrome P450 1 A (CYP1A) and cytochrome P450 3 A (CYP3A) when compared to control. The metal binding stress proteins, heat shock proteins (Hsp60 & Hsp70) and metallothionein were also upregulated due to lead toxicity. Lead intoxicated fish exhibited reduced δ-aminolevulinic acid dehydratase activity in the blood, leading to reduced red blood cell count and changes in cell morphology. The lead toxicity also decreases the level of liver marker enzymes alanine transaminase, aspartate transaminase in serum. In hydrilla supplemented protective group, there was amelioration of these changes. Administration of supplementary feed to the lead intoxicated protective group significantly decreased the expressions of CYP1A, CYP3A, Hsp60, Hsp70 and metallothionein genes. The red blood cell count in lead intoxicated fish was maintained almost normal due to the protective action of Hydrilla verticillata in the diet. The observed increase in the enzymes, which further confirmed the protective effect of Hydrilla verticillata against lead induced toxicity.

Chronic effects of lead on metamorphosis, development of thyroid gland, and skeletal ossification in Bufo gargarizans

We examined the Pb²⁺ exposure on tadpoles of Bufo gargarizans from Gosner stage 26-42. Mortality, growth and development, time to metamorphosis, size, and skeletal ossification at metamorphic climax of Bufo gargarizans were examined. Also, histological characteristics of thyroid glands in tadpoles at Gosner stage 33, 38, and 42 as well as transcript levels of thyroid hormone-related genes in the hind-limb, tail, and liver of tadpoles at metamorphic climax were examined. Pb²⁺ exposure induced mortality in a concentration-dependent manner in Bufo gargarizans larvae. The significant increase in growth and development, percent metamorphosis, size at metamorphic climax, and skeletal ossification were observed at 50 μg Pb²⁺ L^-1; however, exposure to 1000 μg Pb²⁺ L^-1 resulted in the opposite effects in tadpoles. In addition, histological alterations of thyroid gland, such as follicular cell hyperplasia and colloid depletion could be found in 50-1000 μg Pb²⁺ L^-1 treatments. Furthermore, Pb²⁺ exposure at 1000 μg L^-1 resulted in significantly decreased transcript levels of Dio2, TRα and TRβ, and increased transcript levels of Dio3. In contrast, 50 μg Pb²⁺ L^-1 significantly upregulated the mRNA levels of Dio2, TRα, and TRβ, but it reduced the Dio3 expression. These results suggested that Pb²⁺ might disrupt TH homeostasis in tadpoles by histological alterations of thyroid gland and disturb the transcript levels of Dio2, Dio3, TRα, and TRβ, leading to altered growth and development, as well as percent metamorphosis and skeletal ossification. Further studies are needed to elucidate the underlying mechanisms of low-dose stimulation and high-dose inhibition effects.