Increased Prolactin is an Adaptive Response to Protect Against Metabolic Disorders in Obesity

Objective Prolactin (PRL) is a polypeptide hormone named for its crucial role in lactation. Recently, PRL has been recognized as a metabolic hormone that regulates energy metabolism. The current study aimed to investigate the relationship between circulating PRL and metabolic alterations in overweight/obese patients and the effect of weight loss through bariatric surgery on circulating PRL. Methods A total of 448 overweight/obese patients aged between 18 and 40 years and 120 age- and sex-matched healthy controls with normal weight were enrolled. Among all participants, 156 obese patients underwent bariatric surgery. Results Circulating PRL levels were significantly increased in the overweight (15.27 ± 9.58 μg/L) and obese (17.75 ± 9.15 μg/L) groups compared with the normal weight (13.57 ± 9.03 μg/L) group. Multiple regression analyses demonstrated that the adipose tissue insulin resistance (adipo-IR) level was an independent predictor for PRL (β = −0.451, P < .01). Despite comparable anthropometric parameters, the overweight/obese patients with a higher PRL tertile had decreased levels of triglycerides, nonesterified fatty acids, homeostasis model assessment of insulin resistance, and adipo-IR compared with the patients in the moderate and lower PRL tertiles. Serum PRL levels were significantly decreased following the alleviation of metabolic parameters after bariatric surgery (from 17.12 ± 8.27 to 13.00 ± 5.78 μg/L, P < .05), and the decrease in PRL levels was significantly greater in the lower adipo-IR group than in the higher adipo-IR group (P < .01). Conclusion An increased serum PRL level might be an adaptive response for protecting against metabolic disorders in obesity.