Decreasing Insulin Sensitivity in Women Induces Alterations in LH Pulsatility.
Obesity is associated with neuroendocrine reproductive alterations and decreased fertility.



The objective of the study was to gain insight into the neuroendocrine mechanisms implicated in these alterations.



The effects on pulsatile LH secretion of 28 days of a hypercaloric diet were studied in lean and regularly cycling female volunteers. Approximately 50% extra calories (3 g sucrose/kg body weight per day and 1 g fat/kg body weight per day) were added to their individual daily requirements. Spontaneous and insulin-stimulated LH secretion was recorded on 2 different days, before and at the end of the caloric load.



The hypercaloric diet induced an average weight gain of 2.0 ± 0.3 kg (P < .05), corresponding to a body mass index increase of 0.7 ± 0.1 kg/m(2) (P < .05). A concomitant decrease of 11.6% ± 4.6% in whole-body insulin sensitivity was also observed (δ = -1.6 ± 0.7 mg/kg · min glucose; P < .05). The frequency of spontaneous and insulin-stimulated pulsatile LH secretion was increased by 17.9% ± 9.0% and 26.5% ± 9.0%, respectively (both P < .05). Spontaneous LH peak amplitude was decreased by 26.5% ± 9.0% (δ = -0.7 ± 0.36 U/L; P < .05), a change correlated with insulin sensitivity.



Short-term weight gain in normal female volunteers induces alterations of LH secretion reminiscent to those observed in obesity. A decrease in insulin sensitivity may constitute a mechanistic link between obesity and its associated neuroendocrine dysfunctions.
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
Magali
M
van Leckwyck
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
Weilin
W
Kong
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
Kathryn J
KJ
Burton
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
Francesca
F
Amati
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
Nathalie
N
Vionnet
Service of Endocrinology, Diabetology, and Metabolism (M.v.L., W.K., K.J.B., F.A., N.V., F.P.P.), Lausanne University Hospital, 1011 Lausanne, Switzerland; and Department of Physiology (F.A.), Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland.
François P
FP
Pralong
D000293:Adolescent; D000328:Adult; D004036:Diet, Atherogenic; D059305:Diet, High-Fat; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000097:blood / Q000209:etiology; D007333:Insulin Resistance / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D009765:Obesity / Q000097:blood / Q000150:complications; D055815:Young Adult
D007986:Luteinizing Hormone