Siberian hamster (Phodopus sungorus) volatile compound profiles vary seasonally in relation to aggression and hormonal status between the sexes

Chemical communication in the Siberian hamster (Phodopus sungorus) involves cues from urine, feces, as well as the ventral gland and supplemental sacculi glands. There are 48 constituent compounds in the ventral gland secretion of male Siberian hamsters, including constituents with typical steroidal mass spectra that remain unidentified. Such steroidal compounds present in reproductively active males suggests that the volatile profile in the ventral gland and other modes of chemical communication can vary seasonally and in relation to hormonal status. Seasonally breeding species exhibit many physiological and behavioral changes that occur during the transition from non-breeding to breeding condition. In the Siberian hamster, a long day breeder, these physiological changes are mediated by sex steroid hormones in response to photoperiod (i.e. elevated testosterone during breeding season, compared to basal testosterone during non breeding season), and aggressiveness increases significantly during the non-breeding season. In this study, we examined whether Siberian hamster ventral gland secretions contained information about sex and season and whether such volatile profiles changed in response to a same-sex aggressive encounter. In males, we also examined urine volatile profiles. Further, we determined if such individual volatile profiles varied in relation to testosterone, elucidating the relationship between variation in steroid hormone levels and concentrations of volatile compounds. The present study supports the hypothesis that volatile profiles change seasonally and in relation to hormonal status and same-sex aggressive encounters.