Abstract
Seasonal variations in plasma contents of testosterone, 5α-dihydrotestosterone (5α-DHT) and other parameters related to the peripheral metabolism of testosterone have been determined in adult foxes and badgers, in natural climatic conditions.In both species, testosterone reaches peak levels in winter, but whereas the fox takes a sexual break beginning in spring (April), the badger has high concentrations of hormones until the summer. The mean annual concentration of testosterone is four times higher in the badger than in the fox; the annual mean value of 5α-dihydrotestosterone is identical in both species and levels of 5α-DHT are significantly higher during the breeding period.The annual cycle of testosterone peripheral metabolism in the fox is characterized by a decreased rate during summer and fall and an increased rate during winter (breeding period). In the badger, the metabolic clearance rate is high at the end of the fall and at the onset of the breeding period (October to January) and low during the peak reproduction period (February to April) and then increases as the period of sexual break approaches.The annual cycle of testosterone production rate is characterized in both species by a fall or prewinter increase; in the fox, this increase is followed by a decrease at the end of the winter, whereas the badger keeps pretty well the same rate of production until the summer.Seasonal variations of hormone peripheral metabolism are examined and discussed in relation to the fluctuations in testosterone levels and the hormone-specific protein linkage capacity.[Journal Translation]
Published Version
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