Preliminary monosodium glutamate-induced changes in mammary gland receptors and gene expression, water channel, oxidative stress, and some lactogenic biomarkers in lactating rats

Changes induced by monosodium glutamate (MSG) can negatively impact milk production and secretion, among other adverse effects. This study aimed to investigate the effects of MSG consumption on receptor gene expression and quantification of hormones and receptors, as well as oxidative stress biomarkers and other lactogenic parameters in lactating animals. Twenty-four female Wistar rats, nine weeks of age, were randomly assigned to four groups, each containing six rats, at parturition. The rats in groups II, III, and IV were given varying doses of monosodium glutamate (MSG); while, group I was given distilled water and served as the control. The experimental period lasted two (2) weeks. The groups administered with MSG showed a significant decrease in mammary PRLR gene expression (p < 0.05), as well as a marked reduction (p < 0.05) in mammary PRLR, OXT receptor, AQP-3, brain antioxidant enzymes (SOD, GPx, and CAT), and pituitary SOD compared to the control group (p < 0.05). Furthermore, there was a significant increase (p < 0.05) in reactive oxygen species levels in the serum and mammary gland homogenates, erythrocyte osmotic fragility, and elevated (p < 0.05) brain and pituitary MDA levels in the MSG-administered groups compared to the control group. Daily milk yields were significantly decreased (p < 0.05) in the MSG-administered groups between days 10 and 14 of lactation. The findings of this study suggest that prolonged consumption of MSG could interfere with lactation-associated functions via increased ROS production, reduced antioxidants, decreased AQP-3, mammary prolactin and oxytocin receptors, and prolactin receptor mRNA in lactating Wistar rats.