Microinjection of arginine-vasopressin into the periaqueductal gray stimulates flank marking in Syrian hamsters ( Mesocricetus auratus)

Abstract

Syrian hamsters can communicate using a distinctive form of scent marking called flank marking. Vasopressin-sensitive neurons within the medial preoptic-anterior hypothalamic continuum (MPOA-AH) play a critical role in the control of this form of olfactory communication. Extrahypothalamic regions may also mediate hamster flank marking. Since the MPOA-AH and the periaqueductal gray (PAG) are reciprocally connected, the present study investigated whether PAG neurons are involved n the control of flank marking. The first study found that microinjection of vasopressin, but not oxytocin or saline, into the PAG induced high levels of flank marking in male ( n = 8) and female ( n = 5) hamsters ( P < 0.01). The second study demonstrated that microinjection of vasopressin into the PAG stimulated flank marking in a dose-dependent manner in both male ( n = 7) and female ( n = 11) hamsters ( P < 0.01). These data suggest that vasopressin-responsive neurons within the periaqueductal gray participate in the control of hamster flank marking.