Response of male mice to odours of female mice in different stages of oestrous cycle: self-grooming behaviour and the effect of castration.

The behavioural assays were carried out in a Y-maze wherein intact, castrated and testosterone-treated male mice were exposed to oestrus and non-oestrus urine samples. The intact male mice investigated more frequently and spent more time in the Y-maze arm with oestrus urine than in that with non-oestrus urine. In contrast, the castrated mice were not attracted to oestrus urine, whereas testosterone-treated mice showed preference for oestrus urine. The rate of self-grooming was higher in intact males in case of exposure to oestrus urine while the rate was lower with respect to non-oestrus urine. However, castrated mice exhibited less self-grooming behaviour which was partially restored by testosterone treatment. The results suggest that self-grooming behaviour is an indicator of detection and discrimination of oestrus by males, and supports the androgen role in male chemosensory ability to discriminate between oestrus and non-oestrus female odours.