Volume 91, Issue 3, March (2004), pp. 411-421 © The Author 2004
doi:10.1079/BJN20041049

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High leptin in pregnant mink (Mustela vison) may exert anorexigenic effects: a permissive factor for rapid increase in food intake during lactation

Anne-Helene Tauson¹, Mats Forsberg², André Chwalibog^1
1Department of Animal Science and Animal Health, The Royal Veterinary and Agricultural University, Bülowsvej 13, DK-1870 , Frederiksberg, C, Denmark
²Centre for Reproductive Biology in Uppsala, Department of Clinical Chemistry, Swedish University of Agricultural Sciences, Box 7038, S-750 07 , Uppsala, Sweden

 (Received 15 June 2003–Revised 9 October 2003–Accepted 23 October 2003)

The role for leptin in food intake regulation in the mink, a polytocous seasonal breeder with altricial young, was investigated in pregnant and lactating dams and data were related to quantitative energy metabolism measurements and plasma concentrations of other important metabolic hormones. A total of nine mink dams were measured in consecutive 1-week balance periods, each including a 22 h measurement of heat production by means of indirect calorimetry, and blood was sampled at weekly intervals throughout gestation and during lactation weeks 1–4. Intake of metabolisable energy (ME) was high and energy balance was positive until the first third of true gestation. During mid- and late gestation ME intake decreased (P<0·001) while heat production remained almost constant, resulting in negative energy balance and the loss of body weight. From late gestation until lactation week 4, ME intake increased by 3·5 times, but weight loss continued. Plasma concentrations of leptin were approximately doubled during the last two-thirds of true gestation (P<0·01), demonstrating a clear gestational hyperleptinaemia. Concentrations declined rapidly after parturition and then remained stable. Insulin was independent of leptin, with low concentrations coincident with hyperleptinaemia. Also, concentrations of thyroid hormones declined during gestation, probably reflecting the low food intake. Hyperleptinaemia concomitant with low ME intake, negative energy balance and mobilisation of body reserves suggested an anorexigenic effect of leptin in pregnant mink. This suppression of food intake in late gestation might be permissive for the rapid increase in food intake occurring after parturition.

Keywords:
Energy metabolism Substrate oxidation Thyroid hormones Insulin Insulin-like growth factor-1

Abbreviations:
BEFIMP, before implantation, CHO, carbohydrate, FT₄, free thyroxine, GEST1/3, first third of true gestation, GEST2/3, second third of true gestation, GEST3/3, last third of true gestation, HE, heat production, IGF-1, insulin-like growth factor-1, IMP, about the time of implantation, LACTW1, first week of lactation, LACTW2, second week of lactation, LACTW3, third week of lactation, LACTW4, fourth week of lactation, LW, live weight, ME, metabolisable energy, OXCHO, quantitative oxidation of CHO, OXF, quantitative oxidation of fat, OXP, quantitative oxidation of protein, RN, retained N, T₃, triiodothyronine, TT₃, total triiodothyronine, T₄, thyroxine, TT₄, total thyroxine, UN, urinary N