TY - JOUR
T1 - Modulation of leptin sensitivity by short photoperiod acclimation in the Djungarian hamster, Phodopus sungorus
AU - Klingenspor, M.
AU - Niggemann, H.
AU - Heldmaier, G.
N1 - Funding Information:
Acknowledgements We thank Amgen for supplying mouse recombinant leptin and Margery Nicolson at Amgen laboratories for the assay of hamster serum leptin. We are grateful to Andreas Ziegler for statistical advice (Institute for Medical Biometry and Epidemiology, Philipps-University Marburg). These studies were supported by a DFG grant (Kl 973/5–1) The experiments conducted comply with current German animal welfare legislation (Deutsches Tierschutzgesetz).
PY - 2000/2
Y1 - 2000/2
N2 - During seasonal acclimation, Djungarian hamsters spontaneously exhibit a reduction in food intake, body mass and body fat stores, which is externally cued by shortening of day length in autumn and controlled by a sliding set-point. We investigated the function of the leptin adipostatic feedback system in the photoperiodic control of seasonal acclimation. In response to mouse recombinant leptin injections for 10 days, long day photoperiod (LD) and short day photoperiod (SD)-acclimated hamsters decreased food intake and body mass. The reduction of body mass was due to the depletion of body fat, as revealed by carcass composition analysis. In SD hamsters, leptin caused a larger reduction of body fat mass than observed under LD conditions, whereas the anorectic effect was similar in both photoperiods. The serum leptin concentration was 9.3 ± 1.2 ng/ml in LD-acclimated hamsters and decreased significantly to 4.2 ± 0.8 ng/ml and 2.1 ± 0.6 ng/ml in hamsters exposed to SD for 66 days and 116 days, respectively (P < 0.001). A strong positive correlation between total body fat mass and serum leptin concentration was found (r(s) = 0.935, P < 0.0001, n = 70). Despite the anorectic action of exogenous leptin, higher endogenous leptin levels in LD hamsters were paralleled by higher food intake in LD hamsters as compared to SD hamsters. This paradoxical finding further supports the increased leptin sensitivity in SD hamsters as judged from leptin treatment experiments. We tested the functional significance of leptin for the controlled down-regulation of food intake and body mass induced by short photoperiod. Food restriction for 10 days during the transition phase decreased body mass below the desired sliding set-point, which was recovered in control hamsters following ad libitum refeeding. Treatment with mouse recombinant leptin during ad libitum refeeding inhibited the recovery of body mass and blunted the increase of food intake observed in controls, indicating that the sliding set-point utilizes leptin as a signal for the adjustment of the appropriate body mass level.
AB - During seasonal acclimation, Djungarian hamsters spontaneously exhibit a reduction in food intake, body mass and body fat stores, which is externally cued by shortening of day length in autumn and controlled by a sliding set-point. We investigated the function of the leptin adipostatic feedback system in the photoperiodic control of seasonal acclimation. In response to mouse recombinant leptin injections for 10 days, long day photoperiod (LD) and short day photoperiod (SD)-acclimated hamsters decreased food intake and body mass. The reduction of body mass was due to the depletion of body fat, as revealed by carcass composition analysis. In SD hamsters, leptin caused a larger reduction of body fat mass than observed under LD conditions, whereas the anorectic effect was similar in both photoperiods. The serum leptin concentration was 9.3 ± 1.2 ng/ml in LD-acclimated hamsters and decreased significantly to 4.2 ± 0.8 ng/ml and 2.1 ± 0.6 ng/ml in hamsters exposed to SD for 66 days and 116 days, respectively (P < 0.001). A strong positive correlation between total body fat mass and serum leptin concentration was found (r(s) = 0.935, P < 0.0001, n = 70). Despite the anorectic action of exogenous leptin, higher endogenous leptin levels in LD hamsters were paralleled by higher food intake in LD hamsters as compared to SD hamsters. This paradoxical finding further supports the increased leptin sensitivity in SD hamsters as judged from leptin treatment experiments. We tested the functional significance of leptin for the controlled down-regulation of food intake and body mass induced by short photoperiod. Food restriction for 10 days during the transition phase decreased body mass below the desired sliding set-point, which was recovered in control hamsters following ad libitum refeeding. Treatment with mouse recombinant leptin during ad libitum refeeding inhibited the recovery of body mass and blunted the increase of food intake observed in controls, indicating that the sliding set-point utilizes leptin as a signal for the adjustment of the appropriate body mass level.
KW - Adipose tissue
KW - Body weight
KW - Energy expenditure
KW - Melatonin
KW - Sliding set-point
UR - http://www.scopus.com/inward/record.url?scp=0034041759&partnerID=8YFLogxK
U2 - 10.1007/s003600050005
DO - 10.1007/s003600050005
M3 - Article
C2 - 10707323
AN - SCOPUS:0034041759
SN - 0174-1578
VL - 170
SP - 37
EP - 43
JO - Journal of Comparative Physiology - B Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology - B Biochemical, Systemic, and Environmental Physiology
IS - 1
ER -