Abstract:

Lead is an industrially significant heavy metal used in explosives, manufacturing paints, batteries, pottery, and other various essential products of daily life. The marine environments and ecosystems are degraded by the constant discharge of heavy metals. Currently, the toxic effects of heavy metals on aquatic organisms are attracting widespread interest, especially in studies linked with industrial contamination. Lead nitrate does not have a role in the human body. So the present experiment is designed to study the toxicological consequences of lead nitrate on enzymological changes in the muscle and gill of zebrafish. In the present experiment, test fish (Danio rerio) were procured and, after acclimatization, categorized into six groups: one control group and two treated groups. Every 24 hours, tissues were extracted from fish taken out of the aquarium to examine the enzyme activity of glycolysis and the Kreb’s cycle. The rate of oxidative metabolism decreases due to the toxic stress of lead nitrate in zebrafish. Enzyme activity decreases in the muscle and gill as the concentration of lead nitrate increases. Compared to the muscle, the gill enzyme function is affected due to lead nitrate. Due to toxic stress, the rate of oxidative metabolism slows down in zebrafish, which results in a decrease in the enzymatic activity, such as LDH and SDH. Lead nitrate binds to enzymes, inhibits their function, and alters the structure of enzymes. Due to modifications in the mitochondrial membrane function, the amount of LDH decreases. Lead disrupts carbohydrate metabolism in zebrafish. Lead nitrate affects the water quality and changes physicochemical properties, such as pH, salinity, bicarbonate, and bicarbonate. Slight increase in water pH with positive correlation. Increase in the salinity of water and dissolved oxygen with positive correlation. Bicarbonates in the water decrease with a negative correlation. The result clearly indicates that zebrafish exposed to lead nitrate affect not only zebrafish but also the physicochemical properties of water. Toxic heavy metals alter the activity of enzymes and cause severe harm to various tissues. Therefore, long-term exposure to heavy metals with high concentrations of lead nitrate severely affects the health conditions of fish.