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Twenty-four-hour Variation of Plasma Leptin Concentration and Pulsatile Leptin Secretion in Cattle

  • Kawakita, Y. (Department of Animal Nutrition, National Institute of Animal Industry) ;
  • Abe, H. (Department of Animal Nutrition, National Institute of Animal Industry) ;
  • Hodate, K. (Department of Animal Nutrition, National Institute of Animal Industry)
  • Received : 2001.02.05
  • Accepted : 2001.05.07
  • Published : 2001.09.01

Abstract

We conducted this study to investigate 24 h leptin profiles and to ascertain whether leptin secretion occurs in a pulsatile manner in cattle. Plasma leptin concentrations were measured every 10 min for 24 h in five Holstein steers aged 10 months. Simultaneously, feeding behavior was recorded every 5 min during this experiment. In two of the five cattle, leptin showed diurnal rhythmicity, which could be described by a cosine, with peaks between 15:00 and 16:00 and nadirs at around midnight. Pulsatile leptin release was quantified by model-free Cluster analysis. Plasma leptin showed a pulsatile pattern in all cattle, with an average number of pulses at 15 peaks/24 h. The daily number of pulses was not related to total time spent eating, ruminating or chewing. However, when divided into six 4 h time intervals, time spent ruminating was positively related with pulse number (p=0.05) in cattle showing no diurnal plasma leptin variation. These results suggest that cattle may have unique diurnal variation and pulsatile patterns of plasma leptin, differing from those of monogastric animals.

Keywords

Leptin;Circadian Rhythm;Cattle