Development and Modification of Behavioral Responses to MHC and Other Odortypes

Monell Chemical Senses Center, Philadelphia PA

Investigators

Abstract

Body odor plays a prominent role in regulating social, sexual and endocrine responses of many species and specialized structures have evolved to produce and detect odorous signals. Individual recognition, often communicated through body odors, can be critical in mate choice, parental care, and inter-individual interactions. The goals of this project are to better understand how odors signify individuality and in what contexts individual signals modulate social behavior. The central idea underlying this project was articulated 25 years ago: Perhaps the same set of genes that code for individual identity in the immune system (i.e. those genes that insure rejection of foreign tissue and organ transplants) also provide an animal with a unique odor. These genes, termed Major Histocompatibility Complex (MHC) genes, form a linked set in most vertebrates and they include the most polymorphic of any known genes. They are also involved in coding for individuality of odor (providing each animal with what we have termed an odortype) as has been demonstrated in studies with mice, rats and humans. The current project explores three aspects of odortypes using the inbred domestic mouse as the model organism. First, studies conducted in the previous funding period documented the role of MHC odortypes in familial interactions. Maternal mice retrieve pups preferentially according to their MHC type and, reciprocally, pups are attracted to familial MHC odortypes. Studies in this project will investigate the roles of pre- and post-natal learning in modulating preference. Prior studies also demonstrated, for the first time in any species, that fetal odortypes are expressed in maternal odors and that the MHC type of the fetus may modulate adult male and female behavior. Studies described in the second part of the current proposal will investigate how experience with fetal odor influences subsequent behavior of the mother and the pup itself after birth. The third part of this project begins an exploration of a novel aspect of odor signaling between individual animals. Both male and female mice that are infected with mouse mammary tumor virus, a virus that causes mammary tumors in females following one or more pregnancies, develop a distinctive odor in the absence of tumors. Studies designed to explore the behavioral consequences of this observation will open a novel area of research. In sum, this multidisciplinary project links immunology, odors and olfaction, behavior, and disease to advance our understanding of the regulation of social behavior of mice and, by extension, other social mammals. It will also shed light on mechanisms underlying the maintenance of genetic diversity in MHC and other genes. This research program will continue to benefit from technical assistance provided through the Monell Chemical Senses Center's minority high school and college program. This program, which employs students from schools throughout the greater Philadelphia area including Camden, NJ, will provide training at Monell to over 40 students in the summer of 2001. It is funded by a major grant from the Annenberg Foundation as well as from other sources including institutional funds. We expect, as has been the case in the past years, two minority students per year from this program will work on this NSF project.