Male-soiled bedding

Unlike control females, chemically naive females do not prefer the volatile components of male odors compared to female odors. When these females are allowed contact with the odors, however, they demonstrate robust preferences for the male odors. Critically, initially naive females that receive contact experience with male soiled bedding as adults display sexual odor preferences when subsequently... 

As suggested by Beauchamp s group, a female s unlearnt attraction to male-soiled bedding is probably reflecting the rewarding properties of sexual pheromones. To date, the only attempt to demonstrate this hypothesis rendered inconclusive... 

Table 25.1 Effects of dopaminergic drugs on preference for male-soiled bedding. 

Females receiving contact with an adult male were placed in a 36 x 30 x 18 cm cage containing an adult male (older than 90 days of age) and male-soiled bedding. Lepri and Vandenbergh (1986) reported uterine hypertrophy after 12—72 hours of contact with an... 

Figure 2. Mean 1 SE uterine mass (mg) of females exposed to clean or male-soiled bedding. Different letters indicate statistically significant differences between treatments. Sample sizes are shown within bars. Groups male bedding = females exposed to male-soiled bedding clean bedding = females exposed to clean bedding. Data are from Solomon et al. (1996).

Sexually differentiated responses to female-soiled bedding occur within the regions of the AOB only the rostral zone was -activated in males as opposed to that of females the caudal zone cells had no such differential activation VN-x removed the response (Dudley and Moss, 1999 Matsuoka et al., 1999). The number of Fos-ii cells was larger after exposure to females of ICR stain, than to BALB females. Male strain-differences gave equivalent amounts of rostral/caudal activity in females. It is probable that discrimination by females of between-strain chemosignals is related to the fine distinctions possible through the operation of cues related to influence of products from the MHC loci. 

Matsuoka M., Yokosuka M., Mori Y. and Ichikawa M. (1999). Specific expression pattern of Fos in the accessory olfactory bulb of male mice after exposure to soiled bedding of females. J Neurosci Res 35, 189-195. 

Yokosuka M., Matsuoka M., Ohtani-Kaneko R., Iigo M., et al. (1999). Female-soiled bedding induced Fos immunoreactivity in the ventral part of the premammillary nucleus (PMv) of the male mouse. Physiol Behav 68, 257-261. 

Mole rats of the superspecies Spalax ehrenbergi occur in four main chromosome forms 2n = 52, 54, 58, and 60. Females of two of these forms (52 and 58) were given choices between soiled bedding (or urine) from males of a homochromoso-mal or a heterochromosomal form. The females were estrous or diestrous. Only estrous females preferred soiled bedding and urine of homochromosomal males, measured in time spent near the odor samples. Diestrous females showed no preference (Nevo etal, 1976). 

Discrimination of species odors, and hy inference, reproductive isolation between species by means of odors, has been demonstrated for many species. Early examples are bank voles, Ckthrionomysglareolus (Godfrey, 1958), Peromyscus spp. (Moore, 1965 Doty, 1972),M sspp. (Bowers and Alexander, 1967), andger-bils (Dagg and Windsor, 1971). Male naked mole rats (superspecies Spalax ehren-hergi, Spalacidae) preferred odors from estrous females of their own to a different karyotype in a two-choice apparatus. The odors used were those of soiled bedding and urine from females (Nevo etah, 1976). 

Exposing young male prairie deer mice, Peromyscus maniculatus, to soiled bedding from adult male conspecifics retards the growth of their testes and seminal vesicles. Male, but not female, urine applied to the nose has the same effect. Removal of the olfactory lobes at the age of 3 weeks blocks this effect (Lawton, 1979). The reproductive development of male California voles, M. californicus, is suppressed hy chemical cues from the mother (Rissman etah, 1984). 

Rats ovulate when exposed to soiled bedding from males. The stimulus is nonvolatile, as a wire screen can eliminate this response. Vomeronasal organ occlusion reduces the response, implicating this pathway for priming pheromone reception in this species (Johns etal., 1978). Table 8.2 summarizes the role of the vomeronasal in priming effects in rodents. 

In outdoor enclosures treated with urine and soiled bedding from male mice, mouse populations grew to larger numbers than in water-treated control enclosures. Populations in enclosures treated with urine and soiled bedding from group-caged females, however, grew less than the water controls. Females... 

SOILED BEDDING FROM GROUP-HOUSED FEMALES EXERTS STRONG INFLUENCE ON MALE REPRODUCTIVE CONDITION... 

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