[Seasonal peculiarities of female hormonal response of females to conspecific chemical signals of the male in two species of the genus Phodopus].

Changes in diestrous female blood plasma progesterone, estradiol, and cortisol in response to odors of urine and midventral gland secretion (MVGS) of conspecific males during different seasons have been studied in the desert hamster (Phodopus roborowskii and Djungarian hamster (Phodopus sungorus). In desert hamster females, a statistically significant (p < or = 0.05) increase in the plasma hormonal level was observed: for progesterone in response to conspecific male MGVS in all seasons except winter, and to conspecific male urine in spring and summer; for cortisol in response to male MVGS and urine in all seasons except spring; and for estradiol in response to male MGVS in autumn. Djungarian hamster females demonstrated a statistically significant increase in the plasma progesterone level in response to conspecific male MVGS and urine in winter and summer, and no response to the estradiol and cortisol level for both odors in all seasons.

[Seasonal changes of steroid levels in blood plasma of three Phodopus species (Mammalia, Cricetinae)].

Seasonal change of the base plasma level of testosterone and cortisol in males and progesterone, estradiol, and cortisol levels in females were analyzed in three Phodopus species: Ph. campbelli (Campbell's dwarf hamster), Ph. sungorus (Russian dwarf hamster), and Ph. roborovskii (Roborovski's dwarf hamster). Our results showed a significant difference in the seasonal plasma level of testosterone and cortisol in males and cortisol in females of all Phodopus species, though the rhythms of breeding activity were similar. The results are discussed in the context of adaptive differences between hormonal patterns of evolutionarily young species (Campbell's dwarf hamster and Russian dwarf hamster) and the evolutionarily old Roborovski's dwarf hamster, the phylogenic position of which is currently under discussion.