SGER: PROGESTERONE AND SEXUAL DIFFERENTIATION OF BRAIN AND BEHAVIOR

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

In most adult mammals, the ability to demonstrate effective patterns of reproductive physiology and behavior is the result of exposure during fetal life to hormones such as estradiol and testosterone produced by the fetus' developing gonads. However, the mammalian fetus is also exposed to another hormone, progesterone, which is produced by the maternal ovaries and the placenta during pregnancy. The effects of this exposure are unclear at this time, but recent evidence suggests that progesterone may actually masculinize the brain and later impact behavioral responses. Marsupial mammals offer a unique opportunity to directly explore the effects of progesterone on fetal development. Because marsupial mammals are very premature at birth compared to other mammals, much of their early development takes place outside the body of the mother, in an environment that is relatively free of progesterone. Therefore, marsupials are particularly useful for the study of reproductive development. With this animal model the effects of progesterone can be tightly controlled and directly measured, in the absence of maternal hormonal influences. Gray short tailed opossums (Monodelphis domestica), small, gerbil-sized laboratory marsupials, will be used here to characterize the effects of progesterone on the development of masculine and feminine characteristics and behavior in mammals. Opossums will be exposed to different amounts of progesterone soon after birth. When they are adults their behavior will be observed and hormone levels in their blood will be measured. It is expected that early exposure to progesterone will decrease feminine hormonal and behavioral traits in adult animals. Progesterone has wide effects on reproductive processes and brain function. It is already known that progesterone maintains pregnancy, activates reproductive and parental behavior and affects learning and memory. The new researchin this project will further extend our understanding of the role of this important hormone as it impacts reproductive development. This project will also provide a wide range of unique training opportunities for undergraduate and graduate students with Dr. Harder at the Ohio State University (OSU) and with Dr. Fadem at the University of Medicine and Dentistry of New Jersey (UMDNJ).