Impact of pre-treatment with melatonin on hematological alterations and splenic lipid peroxidation in phenylhydrazine-induced acute hemolytic anemia in Wistar rats

Introduction Hemolytic anemias are characterized by the premature destruction of red blood cells, leading to redox imbalance in the organism. Under these conditions, organs such as the spleen may be particularly affected. Melatonin is known for its anti-inflammatory and antioxidant properties and has emerged as a promising therapeutic candidate. Thus, the present study investigated the impact of melatonin pretreatment in male Wistar rats subjected to phenylhydrazine-induced acute hemolytic anemia. Methods Twenty-eight male Wistar rats were randomly assigned to four experimental groups: control, anemic and untreated, non-anemic treated with melatonin, and anemic treated with melatonin. Hematological analyses were performed using whole blood samples, while spleen tissue was used for biochemical assessments of oxidative stress and morphometric analyses. Results The results showed a negative correlation between thiobarbituric acid-reactive substances and hemoglobin levels (r = −0.8406; p < 0.0001). Hemolysis also induced an antioxidant counterregulatory response, evidenced by increased thiol levels (p = 0.0005). Moreover, sulfhydryl levels were positively correlated with thiobarbituric acid-reactive substance levels (r = 0.8108; p < 0.0001). Nevertheless, melatonin did not restore hematological parameters in anemic animals and did not prevent the increase in splenic lipid peroxidation. Conclusion Splenic tissue exhibited an antioxidant response to oxidative damage induced by hemolysis, and lipid peroxidation was associated with the severity of anemia. However, under the conditions tested, melatonin was ineffective in attenuating oxidative stress or hematological alterations associated with acute hemolytic anemia.