The expression of some behaviors, like reproductive behaviors, depends on appropriate exposure to sex hormones during development and in adulthood. Two main questions emerge from this observation that guide Jordan’s research: which cells among thousands do sex hormones directly affect to trigger changes in behavior, and what are the molecular pathways involved. Most studies to date use a neuromuscular model system (the SNB) in rodents that is both profoundly sensitive to gonadal androgens and sexually dimorphic. Unlike most other neuromuscular systems in rodents, the SNB system requires gonadal androgens for its survival and growth. Recent work includes characterizing the expression of androgen receptors and steroid receptor coregulators, examining the role of NMDA receptors and neurotrophic factors in androgen-regulated neural plasticity and assessing the cellular basis of hormone-dependent sexual dimorphisms in the brain, including analyses of brain neurons and glia. Development of a new transgenic mouse model has led to studying a motoneuron disease known as spinal bulbar muscular atrophy or Kennedy’s disease, a slowly progressing neuromuscular disease that affects men and involves the androgen receptor. Studying this disease model is a major focus of ongoing work in the lab.
Jordan’s research is now directed toward three main goals:
1. understanding the mechanisms by which androgens keep certain motoneurons alive and healthy
2. understanding the mechanisms by which androgens under certain circumstances can trigger the demise and, ultimately, the death of motoneurons
3. understanding the role of glia in steroid effects on brain and behavior
Methodologies. Ongoing studies use approaches at the behavioral, cellular and molecular levels of analyses in addition to genetic mouse models that alter the expression of genes of interest in a cell specific and time-dependent manner using cre/lox technology and transgenesis. Some methods routinely used in the lab include tests of motor competence (such as rotarod, open field, paw print analysis, grip strength test), cellular methods such as immunocytochemistry, tract tracing, stereology, confocal microscopy, and molecular techniques such as quantitative PCR, in situ hybridization, Westerns and gene transfection.
Models. Several rodent models are used in the lab, including rodents carrying spontaneous mutations in the androgen receptor gene and several lines of genetically engineered mice, including transgenic, knock-in, and conditional knock out models.
Please feel free to contact Dr. Jordan if you have any questions about her research. She runs a lab jointly with Marc Breedlove. To learn more about their research visit their website.