Hormonal and Environmental Influences on Maternal Behavior

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These experiments are designed to explore the exact routes by which hormones have their effects on behavior. We know that the hormones associated with reproduction have profound effects on the behavior of humans and other animals. Dr. Schneider will work with steroid hormones that are produced during pregnancy and have measurable effects on the maternal behavior of the female during pregnancy and after the birth of her offspring. Dr. Schneider will use house mice for this project because during pregnancy the female typically increases the size of her nest in preparation for the birth of her offspring. This increase in nesting behavior can be mimicked in a nonpregnant female by injecting her with the pregnancy steroid, progesterone. Dr. Schneider believes that progesterone changes the mother's behavior by way of brain mechanisms that are also involved in the regulation of body temperature. (House mice give birth all year round, even during cold winters, and their young are born without the ability to maintain their own body temperature.) To unravel the connection between the regulation of body temperature and the control of maternal behavior, Dr. Schneider will (1) measure nesting, maternal care, and body temperature in mice that have progesterone implants in very precise brain areas to show where there may be overlap among the brain mechanisms controlling maternal behavior and temperature regulation, and (2) test the effects of a variety of steroids in these brain sites to see if the same ones influence both maternal nesting and body temperature. Dr. Schneider will also measure the levels of steroids in the blood to find out if the action of progesterone on the brain changes the secretion of naturally occurring steroids from the ovaries or adrenal glands. Dr. Schneider's research will help to show how hormones prepare the mother for the birth and care of her offspring. More generally, these studies may provide a better understanding of the mechanisms by which steroid hormones (commonly prescribed for a variety of reasons: birth control, infertility, menopause, allergies) produce their primary and side effects on human behavior and physiology.