Kidneys; Hyperprolactinemia; Morphology; Melatonin

The increase in prolactin levels causes a pathological condition called hyperprolactinemia. This condition is associated with many diseases, including chronic kidney disease (CKD), which represents the most common syndrome of pituitary hypersecretion in both men and women. On the other hand, melatonin has shown potential to prevent hepatotoxicity and nephrotoxicity, due to its role in eliminating free radicals. Based on this, the aim of this study was to analyze the kidney morphology of rats induced to hyperprolactinemia and treated with melatonin. The study used 48 male rats, divided into two treatment periods: 30 and 60 days, each treatment group was subdivided into three groups: Control, DOMP (rats induced to hyperprolactinemia) and DOMP+MEL (rats induced to hyperprolactinemia and treated with melatonin). The melatonin treatment was 200μg/100g, subcutaneously (SC). Hyperprolactinemia was induced with a dose of 4mg/kg of domperidone, SC. The results of the renal histomorphometric analysis of the control and treated animals for the 30-day period showed that there was no significant difference in the following variables: glomerular area, glomerular capsule area, subcapsular area, glomerular diameter, renal weight and rat weight. However, significant differences were observed between the control and DOMP+MEL groups in the somatic renal index variable. In the histopathological findings, animals treated with DOMP showed greater glomerular damage compared to the other groups, with the greatest damage observed in the group treated for 30 days. Additionally, the DOMP group was the only group to present hemorrhage in the renal parenchyma. All groups presented congested vessels, with the highest incidence observed in the treated groups. The treated groups also presented renal tubular edema. Among the damages affecting the renal tissue, tubular necrosis and glomerular atrophy were also observed. Based on the previous results obtained, it can be concluded that hyperprolactinemia causes damage to the renal parenchyma, and melatonin can act to reduce these damages, and consequently promote tissue regeneration.