Estrogen Receptor Levels Higher in “Bad” Maternal Rats than in “Good” Maternal Rats

In mammalian species, parental care is critical for the survival as well as the mental and physical well-being of offspring (Dulac, 2014). This is particularly true in humans; researchers have long been interested in what the effects are of differences in parental upbringing, including the absence of parents (e.g., Cabrera et al., 2000) and differences in disciplinary parenting styles (e.g., Baumrind, 1967). Though tempting to think of all parents as “good” parents in both the human and animal worlds, that clearly is not the case; sadly, there are “bad” parents as well. For instance, cross-sectional studies in humans on parent-child relationships have shown that adverse and traumatic childhood experiences including neglect, abuse, or parental loss correlate to mood and anxiety disorders later in life (Bodensteiner, 2014). Moreover, such individuals have tendencies to form antisocial personalities and impulsive aggression. There are quantifiable physical effects of poor parenting as well - girls lacking proper parent-child relationships experience a variety of physiological and sociological changes vs. their “normal” counterparts, including ‘decreased age at menarche, earlier onset of sexual behavior, and increased number of sexual partners.’ These traits often have both physiological and psychological repercussions (Bodensteiner, 2014). In sum, early life experience, though relatively brief, are critical for molding the future of an individual’s success and overall fitness to survive the demands of life (Anacker, 2013). Thus, it is especially important to understand factors that can lead to lower levels of parental care (“bad” parenting) than expected from “good” or “average” parental care. These factors may be sociological, psychological, environmental, or genetic and their effects in humans are not trivial. For example, postpartum depression affects more than 10% of mothers in the United States, potentially resulting in poor care for offspring that then lead to negative consequences described earlier (Dulac, 2014). Given the complexity of human interactions and conditions, researchers can attempt to examine the factors that affect maternal behaviors in a model rat system - allowing us to control for more variables - in hopes of better understanding the factors that affect maternal behaviors in humans