Rapid weight gain, at least in some women, is an expression of a neuroendocrine state characterized by reduced hypothalamic dopaminergic tone

A group of 17 consecutive regularly menstruating women who gained at least 5 kg the previous year (Group I) was compared with a control group of simil ar age, parity and social class (Group 2). Galactorrhea was observed in 6/1 7 women from group 1 and in 1/16 women from group 2 (chi(2) 4.571; p < .05) . Average morning prolactin levels were higher in group 1 (8.15 +/- 4.92 mu g/l) than in group 2 (5.29 +/- 2.48 mu g/l; p < .05). The two groups were similar in their morning thyroxin, triiodothyronine, TSH, estradiol, cortis ol, gastrin, cholecystokinin, somatostatin, oxytocin, insulin and IGF-I lev els. Leptin levels were significantly higher in group 1 than in group 2 (18 .85 +/- 10.63 mu g/l vs. 10.15 +/- 6.38 mu g/l; p < .02) but this differenc e could be attributed exclusively to the higher body mass index (BMI) of gr oup 1 (MANCOVA). Analysis of the distribution of basal prolactin levels in group I revealed a skewed distribution due to the presence of six outliers (Barnett and Lewis test associated with Mahalanobis distance) whose Values were higher than the highest value found in group 2. These outliers were he nceforth considered as subgroup la, and the remnant patients in group 1 as subgroup Ib. Besides the expected difference in basal prolactin levels betw een subgroups la and Ib (13.72 +/- 3.69 and 5.12 +/- 1.81 mu g/l, respectiv ely) and the higher frequency of galactorrhea in group la (4/6 vs. 2/11; p < .05) no other differences were observed in clinical or basal biochemical parameters. Following domperidone (10 mg, IV) the percentual increase in pr olactin (Delta Prl 20'/Prl 0') was significantly lower in group 1 than in g roup 2 (23.9 + 15.2 vs. 37.0 +/- 21.2, p < .05). In absolute values, the pr olactin rise in subgroup la (100.7 +/- 45.5 mu g/l) was significantly lower (p < .02) than that of subgroup Ib (157.3 +/- 50.3 mu g/l) and group 2 (15 2.7 +/- 34.5 mu g/l). Group I (and each one of its two sub-groups) also dif fered from group 2 in a higher incidence of meaningful life-events the year preceding the study. This study confirms previous observations that recent weight gain in women is preceded by important life-events and is associate d with galactorrhea and increased prolactin levels in a number of them. Bes ides, it provides evidence that the increased prolactin levels are due to r educed hypothalamic dopaminergic tone. (C) 1998 Elsevier Science Ltd. All r ights reserved.