# Exploring the antioxidant potential of prolactin

## TL;DR

This study shows that high prolactin levels boost antioxidant defenses and reduce oxidative stress, suggesting prolactin is a key antioxidant hormone.

## Contribution

The study reveals a novel role of prolactin as an endogenous antioxidant, linking it to thiol-disulfide homeostasis and maternal-infant antioxidant defense.

## Key findings

- Hyperprolactinemia increases total antioxidant and thiol levels while decreasing oxidants and oxidative stress.
- Prolactin correlates positively with antioxidant markers and negatively with oxidative stress indicators.
- Elevated prolactin during pregnancy and lactation may support fetal development through antioxidant defense.

## Abstract

Prolactin (PRL) is primarily recognized for its role in lactation, yet its antioxidant function remains incompletely elucidated. The purpose of the present study was to examine the antioxidative role of prolactin.

Seventy female volunteers were equally divided into hyperprolactinemia and control groups in this case–control study. Total antioxidant status (TAS), total oxidant status (TOS), native thiol (NT), total thiol (TT), prolactin, thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) analyses were performed using the serum samples with the relevant kits based on the colorimetric or spectrophotometric methods. In addition, oxidative stress index (OSI), disulfide (DS), and the percent ratios of disulfide/native thiol (DS/NT), disulfide/total thiol (DS/TT), and native thiol/total thiol (NT/TT) were also determined.

TAS, NT, and TT concentrations and NT/TT percent ratio were found to be higher in patients than in the control group (p < 0.05). OSI and TOS levels, along with DS/NT and DS/TT percent ratios, were significantly lower in the hyperprolactinemia group than in the control group (p < 0.001 for all). FT4 was also lower in the hyperprolactinemia group (p < 0.05). Prolactin demonstrated a statistically significant positive correlation with TAS, NT, TT, and NT/TT and a significant negative correlation with TOS, OSI, and FT4 (p < 0.05). The TOS exhibits a statistically significant negative regression with prolactin, while NT has a statistically significant positive regression (p = 0.002 for both).

Hyperprolactinemia elevated total antioxidant and thiol levels while suppressing total oxidants, oxidative stress, and disulfide/thiol ratios. These findings indicate that prolactin plays a pivotal role in maintaining thiol–disulfide homeostasis and oxidative balance, functioning as a crucial endogenous antioxidant hormone. Moreover, the elevated prolactin levels during gestation and lactation may reflect its essential contribution to maternal–infant antioxidant defense, thereby supporting optimal fetal development.

Graphical abstract illustrating hyperprolactinemia. On the left, increased markers include Total Antioxidant Status, Native Thiol, Total Thiol, and Native Thiol/Total Thiol Ratio. On the right, decreased markers include Total Oxidant Status (TOS), Oxidative Stress Index (OSI), Disulfide/Native Thiol Ratio, and Disulfide/Total Thiol Ratio. Arrows indicate the direction of change.