Princy Quadros Mennella
Assistant Professor Department of Biological Sciences
Member of INBRE Research Committee
Delaware State University
1200 N. Dupont Highway
Dover, DE 19901
Phone: (302) 857-6842
Fax: (302) 857-6512
Ph.D. Neuroscience and Behavior, University of Massachusetts, Amherst, MA, 2004
B.S. Psychology, University of Richmond, Richmond, VA, 1998
Broadly, my lab investigates the contributions that steroid hormones, such as progesterone, make to the development of the brain using rodents as our model organism. There are many areas of the developing brain that are sensitive to progesterone, as evident by the expression of progesterone receptors in these structures. My lab focuses on three different brain areas: arcuate nucleus of the hypothalamus; substantia nigra, pars compacta; and the lower rhombic lip. We use these brain areas to better understand the ways in which progesterone receptors may be contributing to basic neurodevelopmental processes such as apoptosis, neurogenesis, migration, phenotypic differentiation and sexual differentiation.
The arcuate nucleus is an integral contributor to the estrous cycle as well as lactation (milk production). We have observed a sex difference in progesterone receptor expression during development, where males express higher levels of this receptor compared to females. We have documented that this sex difference is produced by exposure to testosterone in males and the absence of this hormone in females. The sex difference in progesterone receptor expression results in males experiencing greater effects of progesterone during development than females. We are currently exploring the contributions that progesterone receptors in the developing arcuate nucleus are making toward producing the sexually dimorphic characteristics of this structure.
The adult substantia nigra, pars compacta, is critical for proper voluntary motor function. Ninety percent of cells in the cells in the substantia nigra contain dopamine and it is the loss of these cells that result in Parkinson’s disease. The developing rat substantia nigra expresses progesterone receptors transiently; the adult substantia nigra lacks progesterone receptors. This suggests that progesterone receptors in this structure have a developmentally specific function. Using high resolution histochemical procedures, transgenic mice and behavioral assays, we are currently assessing the contributions of progesterone receptors in the substantia nigra toward the development of this structure.
Lastly, our lab is investigating the functional role of progesterone receptors in neurogenesis using the lower rhombic lip. The lower rhombic lip is a developmentally transient structure. Its primary function is to provide new neurons for the brainstem. We have observed progesterone receptors in this structure 5 days prior to birth and 7 days after birth, for a total of 12 days. Previous literature suggests that neurogenesis, the birth of new brain cells, terminates 4 days before birth. Using a thymidine analog, current experiments are examining the presence of neurogenesis in the postnatal lower rhombic lip as well as the extent to which progesterone receptors might be contributing to this process.