The activity of ALT (units/l) in basal diet control (group 1) was 19.217±2.156, which was significantly (P<0.05) elevated in lead toxic control groups 6, 7, 12, 13, 14 and 15 at the end of 4th week. The activities of therapeutic control groups 2–5 were comparable to that of group 1 on 4th and 6th weeks. The groups 8–11 revealed a significant (P<0.05) increase in the activity of ALT at the end of 4th and 6th weeks as compared to group 1 and other therapeutic controls (groups 2–5) at respective time intervals. In groups 12–15, there was a significant (P<0.05) decrease in the activity at the end of 6th week as compared to groups 6 and 7 . The histological sections of the liver from the lead toxic control (group 6) showed moderate focal lymphoid aggregates , while group 11 showed mild central vein congestion and paracentral infiltration . The lesions were very mild or absent in treated groups 12 through 15 and plain controls.
Activity of ALT and CYP450 in different groups of broiler chicks
Liver of group 6 showing moderate focal lymphoid aggregates (H and E ×100)
Liver of group 11 showing mild central vein congestion and paracentral infiltration
The activity of ALT was determined to assess the degree of damage to liver as the levels of certain enzymes like ALT, aspartate transaminase (AST), gamma glutamyl transferase (GGT), etc., are elevated following hepatocellular injury.[14
] In this study, the activity of ALT was significantly elevated in the lead toxic control group, suggesting the hepatocellular insult following administration of lead. These results are further substantiated from the histopathological studies of liver, which revealed moderate focal lymphoid aggregates in lead toxic control. Treatment with PHF (stressroak), shilajith, amla and vit E + Se, following discontinuation of lead resulted in significant reduction in the activity of ALT. The hepatocellular injury due to lead could be attributed to the lead-induced generation of reactive oxygen species (ROS) or free radicals and the reversal of the findings following treatment could be attributed to the antioxidant and the hepatoprotective potential of the drugs in test. Alcoholic and aqueous extracts of the fruits of Emblica
have shown hepatoprotective properties in experiments in rats.[15
] Further, the treatment controls, which were not exposed to lead did not manifest any significant change in the activity of ALT, and also there were no significant lesions in the liver tissues. However, simultaneous supplementation of drugs in the test along with lead revealed a significant increase in ALT activity at different time intervals when compared to the plain control groups, though the values were significantly lower in comparison to pure lead toxic control groups 6 and 7. This finding suggests the prophylactic potential of these drugs to prevent lead-induced toxic manifestations, though there was no complete prevention of changes.
The CYP450 activity (nmol/mg microsomal protein) in basal diet control (group 1) was 0.2520±0.009, which was significantly (P<0.05) decreased in lead toxic control groups 6 and 7 at the end of 6th week. The activities of therapeutic control groups 2–5 revealed no significant difference in CYP450 activity as compared to group 1, while the groups 8–11 revealed a significant (P<0.05) decrease in the activity as compared to group 1, and groups 12-15 revealed a significant (P<0.05) increase in the activity as compared to group 6 at the end of 6th week .
The activity of Na+/K+-ATPase, Mg2+ATPase and Ca2+ATPase (mM of Pi liberated/mg protein) in basal diet control (group 1) was 2.5919±0.062, 1.8691±0.098, and 1.6609±0.081, respectively, which was significantly (P<0.05) decreased in lead toxic control groups 6 and 7 at the end of 6th week. The activities of therapeutic control groups 2-5 revealed no significant difference in the activity of ATPases as compared to group 1 at the end of 6th week. Groups 8-11 revealed a significant (P<0.05) decrease in the activity as compared to group 1 at the end of 6th week. Groups 12-15 revealed a significant (P<0.05) increase in the activity as compared to group 6 .
Activities of Na+/K+-ATPase, Mg2+ATPase and Ca2+ATPase in the liver of different groups of broiler chicks
In this study, significant reduction in the activities of Na+
ATPase and CYP450
in the liver of lead toxic control groups 6 and 7 may be attributed to the lipid proxidation by free radicals in lead treated groups, since these membrane-bound enzymes are SH group containing enzymes, which are lipid-dependent and their activity is likely to be altered with the change in the composition of membrane lipids.[6
] The treated groups revealed slight improvement in the membrane-bound enzymes though the activities were not exactly similar to those of controls. It has been reported that dietary lead alters fatty acid composition and membrane peroxidation in chick liver microsomes.[16
] These findings could be further substantiated from the results of the present study, wherein there was a significant increase in the activity of ALT (suggesting hepatocellular injury) and histopathological changes in liver in the toxic control group 6 as compared to the plain controls and treated groups.
In conclusion, the study enunciated that lead induces damage to the hepatocytes leading to elevation of ALT along with reduction in CYP and membrane ATPases. Supplementation of anti-stress agents is of use to reverse the hepatocytic damage caused by lead. Amongst the drugs in test, PHF (stressroak) was found to be superior owing to its synergistic antioxidant herbs, followed by shilajith, amla and vit E + Se in the given order.