Urine and urine-derived compounds induce c-fos mRNA expression in accessory olfactory bulb

Soiled bedding from male mice induced c-fos mRNA expression in the accessory olfactory bulb (AOB) and main olfactory bulb (MOB) of female mice. The increase observed in the AOB, but not the MOB, was dependent on the presence of the vomeronasal organ (VNO). Male urine alone also increased c-fos mRNA expression in the AOB. The urine-derived compounds dehydro-exo-brevicomin (DHB) and sec-butyl-dihydrothiazole (SBT) in combination with major urinary protein (MUP) induced significantly greater c-fos mRNA expression in the AOB than in the MOB. The results indicate that compounds derived from male urine are detected at the AOB and suggest that specific urinary compounds play an important role in AOB-mediated reproductive events.