Buck odor production in the cornual gland of the male goat, Capra hircus– Validation with histoarchitecture, volatile and proteomic analysis

In many animals, glandular secretions or pheromones that possess biological moieties contain messages encoded by the intrinsic smell. In male goats, the cornual gland (a sebaceous gland), may synthesize and excrete relevant chemical components that are responsible for the ‘buck effect’. To test this, cornual glands from freshly-slaughtered male goats (N=6) were subjected to histoarchitecture analysis, to infer about the structural alignment, to the GC–MS analysis for volatile compounds and to SDS–PAGE for protein profiling followed by MALDI-TOF to characterize specific protein bands. The gland possesses sebum, vacuoles and hair follicles inferring its capability to synthesize and extrude the scent. We found 14 volatiles in GC–MS analysis, in which 1-octadecanol might be a putative pheromone of buck odor. We identified seven different proteins in SDS-PAGE. Two proteins, 28 and 33 kDa, were highly matched with DNA mismatch repair protein and Abietadiene synthase, respectively, as inferred from MALDI-TOF. Conclusively, the volatiles identified in the cornual gland suggest that the structural microelements of the gland may synthesize (sebum and vacuoles) and release the key volatiles through the hair follicles. The volatile(s) thus produced in male goats either solely or synergistically may confer the buck odor.

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.

Preputial gland activates olfactory receptor neurons in rat: Calcium imaging study using laser scanning confocal microscopy.

The rodent preputial gland is one of the major sources of odours and is reported to be involved in several behavioural activities. However, how the preputial gland initiates the olfactory response to manifest the effects is not known. Olfactory receptor neurons (ORNs) present in the olfactory epithelium are involved in the perception of odorant/pheromonal compounds. In the present study, the response of rat ORNs to preputial gland extract was evaluated by calcium imaging analysis. We found that some rat ORNs responded to the preputial gland extract by exhibiting an intracellular calcium response. By contrast, the ORNs did not respond at all to the foot pad extract (control). The results indicated that the substances contained in the preputial gland might interact with a type of receptor expressed in the female rat ORNs, suggested to manifest the behavioural responses, such as social and sexual interactions. This study provided the first evidence of activation of ORNs by the preputial gland extract.