RESUMEN
This study aimed at the assessment of the possible level of defence line of carnosine in chronic lead exposure. Evaluation of the possible relation of antioxidants and other functioning enzymes versus chronic lead exposure is also to be percussed. For this purpose, the study included two parts: Part [1]: was performed to deduce the correlation between the dose of carnosine and the different biochemical parameters measured in the studied tissues; Part [2]: was a long term study in which [56] male Wistar albino rats, divided into [6] groups, eight in each group: Group [1]: Negative control; Group [2]: Rats were treated with carnosine in a dose of 0.05 mg/g rat; Group [3]: Rats were treated with carnosine in a dose of 0.12 mg/ g rat; Group [4]: Comprised rats treated with lead acetate in a dose of [0.01 mg/g rat]; Group [5]: Included rats treated with lead [0.01 mg/g rat] and carnosine [0.05 mg/g rat]; Group [6]: Included rats treated with lead [0.01 mg/g rat] and carnosine [0.12 mg/g rat]. Treatment was performed daily for 6 days/ week for 5 months. The neural [brain] and visceral [heart, kidneys and liver] tissues were collected and different biochemical variables were determined; as well as a histological examination. In all the studied tissues, carnosine would only act as a free radical scavenger in the low dose only; and it could be used as an adjuvant in a low dose with chelating agents, since it cannot chelate lead in the brain tissue. Renal impairment was most probably a direct action of carnosine in a high dose on renal tissue, rather than being a result of lead intoxication. On the other hand, when carnosine was given in a small dose, it acted as a free radical scavenger. In the liver, carnosine in a small dose could not act as a chelator for lead, while in a high dose, it acts as a chelating agent. On the contrary, in a small dose, carnosine acts as a free radical scavenger but not in the high dose. Overall, carnosine cannot prevent the production of free radicals but can scavenge them only in a small dose