Increased circadian prolactin release is blunted after body weight loss in obese premenopausal women

• Published in: American journal of physiology: endocrinology and metabolism 2006-02, Vol.53 (2), p.E218
• Main Authors: KOK, Petra, ROELFSEMA, Ferdinand, LANGENDONK, Janneke G, DE WIT, Caroline C, FRÖLICH, Marijke, BURGGRAAF, Jacobus, EDO MEINDERS, A, PIJI, Hanno
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Chronobiology; Circadian rhythm; Fundamental and applied biological sciences. Psychology; Hormones; Medical sciences; Menstruation; Metabolic diseases; Obesity; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Women
• ISSN: 0193-1849; 1522-1555

We recently showed that prolactin (PRL) release is considerably enhanced in obese women in proportion to the size of their visceral fat mass. PRL release is inhibited by dopamine 2 receptor (D2R) activation, and dietary restriction/weight loss are associated with increased dopaminergic signaling in animals. Therefore, we hypothesized that enhanced PRL release in obese humans would be reversed by weight loss. To evaluate this postulate, we measured 24-h plasma PRL concentrations at 10-min intervals in 11 obese premenopausal women (BMI 33.3 plus or minus 0.7 kg/m2) before and after weight loss (50% reduction of overweight/15% absolute weight loss, using a very low-calorie diet) in the follicular phase of their menstrual cycle. The 24-h PRL concentration profiles were analyzed by a peak detection program (Cluster) and a wave form-independent deconvolution technique (Pulse). Spontaneous 24-h PRL secretion was significantly reduced in obese women [mean daily release, before 128 plus or minus 24 vs. after weight loss 110 plus or minus 17 g/liter distribution volume (Vdl) 1 x 24 h, P = 0.05]. Body weight loss particularly blunted PRL secretory burst mass (Pulse area, before 230 plus or minus 28 vs. after weight loss 221 plus or minus 31 g/Vdl 1 x 24 h, P = 0.03), whereas burst frequency was unaffected (no. of pulses, before 11 plus or minus 1 vs. after weight loss 12 plus or minus 1 n/24 h, P = 0.69). Thus elevated PRL secretion rate in obese women is significantly reduced after loss of 50% of overweight. We speculate that amelioration of deficit D2R-mediated neurotransmission and/or diminutions of circulating leptin/estrogen levels might be involved in the physiology of this phenomenon.[PUBLICATION ABSTRACT]