Pregnancy-blocking

Coopersmith C. and Lenington S. (1998). Pregnancy block in house mice (Mus domesticus) as a function of t-complex genotype examination of the mate choice and male infanticide hypotheses. J Comp Psychol 112, 82-91. 

Hoppe P. (1975). Genetic and endocrine studies of the pregnancy-blocking pheromones of mice. J Reprod Fertil 45, 109-115. 

Li C., Kaba H. and Seto K. (1994). Effective induction of pregnancy block by electrical-stimulation of the mouse accessory olfactory-bulb coincident with prolactin surges. Neurosci Lett 176, 5-8. 

Marchlewska-Koj A. (1981). Pregnancy block elicited by male urinary peptides in mice. J Reprod Fertil 61, 221-224. 

Peele, P., Salazar, I., Mimmack, M., Keveme, E. B. and Brennan, P. A. (2003) Low molecular weight constituents of male mouse urine mediate the pregnancy block effect and convey information about the identity of the mating male. Eur. J. Neurosci. 18, 622-8. 

Despite extensive investigation of pregnancy block since its discovery, a convincing explanation for its functional significance and evolutionary development has remained elusive. The postponement of reproduction inevitably impairs reproductive success, but in order to evolve the Bruce effect must offer an overall benefit. The costs and benefits may be very different for males and females. 

Female ability to control exposure to male scent at critical times may help to explain why similar pregnancy-blocking stimuli have produced conflicting results in different experiments. For example in one study manipulating male social status (Labov 1981a), females were housed directly below males, while a similar study (Huck 1982) housed females adjacent to males, separated by mesh. The pregnancy... 

Thus, rather than providing a reproductive benefit to males as traditionally assumed, the Bruce effect may have evolved solely to female advantage. Notably, this response also increases selective pressure on stud males to increase their investment in the territorial defence of nest sites that are preferred by females (Ims 1987). Females may improve their own reproductive success through threat of pregnancy block, compelling stud males to invest more heavily in nest defence. 

Male scent is typically used as the pregnancy-blocking stimulus during investigation of the Bruce effect. However experiments addressing the androgen-dependency... 

Brennan, PA. and Peele, P. (2003) Towards an understanding of the pregnancy-blocking urinary chemosignals of mice. Biochem. Soc. Trans. 31, 152-155. 

Bruce, H.M. (1961) Time Relations in Pregnancy-Block Induced in Mice by Strange Males, Jour-nal of Reproduction and Fertility. 2, 138-. ... 

Chipman, R.K. and Fox, K.A. (1966) Oestrus synchronization and pregnancy blocking in wild house mice (Mus musculus). J. Reprod. Fertil. 12, 233-236. 

Drickamer, L.C. (1989) Pregnancy block in wild stock house mice, Mus domesticus—olfactory preferences of females during gestation. Anim. Behav. 37,690-692. 

Huck, U.W. (1982) Pregnancy block in laboratory mice as a function of male social status. J. Reprod. Fertil. 66, 181-184. 

Huck, U.W. (1984) Infanticide and the evolution of pregnancy block in rodents. In G. Hausfater and S.B. Hrdy (Eds.), Infanticide comparative and evolutionary perspectives. Aldine, New York, pp. 349-365. 

Kaba, H., Rosser, A. and Keveme, B. (1989) Neural basis of olfactory memory in the context of pregnancy block. Neuroscience. 32,657-662. 

Labov, J.B. (1981b) Pregnancy blocking in rodents adaptive advantages for females. Am. Nat. 118,361-371. 

Olfaction is of primary importance for social recognition in mammals, including mice. Thus mice use odors to distinguish sex, social or reproductive status of conspecifics (Brennan and Zufall 2006 Brown 1979). In addition, odors have been shown to facilitate the display of sexual behavior (e.g. Thompson and Edwards 1972) and to induce neuroendocrine responses (e.g. pregnancy block in female mice Brennan and Keverne 1997). 

Becker, S.D. and Hurst, J.L. (2007) Pregnancy block from a female perspective. In J. Hurst, R. Beynon, C. Roberts, T. Wyatt (Eds.), Chemical Signals in Vertebrates 11. Springer Press, New York, pp. 127-136. 

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