Welcome back to the fifth installment of “Dissertation Diaries.” This week, we will be highlighting Chantal Aaron, a fifth-year Ph.D. student in The Elizabeth Byrne Lab at the Tufts Graduate School of Biomedical Sciences.
Originally from Jamaica, Aaron moved to the United States to attend Ferrum College in Virginia, where she obtained her bachelor’s degree. There she met a biology professor who introduced her to basic neuroscience research and encouraged her to pursue further education in this field.
After her undergraduate studies, Aaron moved to Massachusetts and spent a year working in a drug lab, analyzing samples and testing drugs. Eventually, she did a post-baccalaureate program at Boston University to gain more experience in neuroscience. During her time there, she worked with the rhesus monkey brain, studying memory and the effects of aging.
Currently, Aaron is in the Byrne Lab, which revolves around opioids and transgenerational epigenetic effects. More specifically, her work revolves around the long-term behavioral effects of prenatal opioid exposure on offspring.
The opioid epidemic emerged in the ’90s when Purdue Pharma began marketing the drug OxyContin. Investigations and legal battles have since revealed that, despite their knowledge of the drug’s addiction potential, they invested a huge amount of money and resources into the drug’s promotion. This marketing campaign contributed to the current opioid epidemic as the drug was overprescribed and millions of people have since developed opioid-use disorders.
In the lab, Aaron uses a rat model to study the prenatal effects in female rats. They are exposed to oxycodone, an opioid, using a method called intravenous self-administration.
“There is [an] active and inactive lever, and they actually learn to voluntarily intake [oxycodone],” Aaron said. Animals cannot be classified as having an ‘addiction,’ but this method is one way of monitoring addiction-like phenotypes.
The animals learned to press the active lever three weeks prior to pregnancy and, as the pregnancy progressed, they pressed the lever significantly more, nearly doubling their oxycodone intake throughout the course of the pregnancy.
One of the consequences of oxycodone intake during pregnancy that has risen is litter size. While a healthy litter size in rats is typically 10 to 14 pups, Aaron mentioned, “With the [oxycodone] moms, their litters will sometimes be 5 pups. … We will see lower body weights in the offspring.”
As the offspring age, they go through a similar process as their mothers, but with intravenous administration of sucrose pellets instead of oxycodone. “The male offspring — they have a higher motivation. So they learn to press quicker or significantly different than the control male groups,” Aaron said of the observed results.
The rodent offspring are tested during adolescence and adulthood due to great development and reorganization in the brain. Similarly, during this time period, humans have a developing prefrontal cortex and experience synaptic growth; this time period is also when risky behaviors are typically observed.
Aaron performs many western blots, which are brain punches of certain regions, to study protein expression and certain receptors linked to enhanced reward motivation. To look at gene expression, she also utilizes polymerase chain reaction, a technique that amplifies numerous copies of a specific segment of DNA to allow them to be studied in greater detail.
These experiments can be used to better understand the molecular impacts of substance abuse in humans.
Neonatal opioid withdrawal syndrome consists of the short-term impacts infants experience due to being exposed to drugs via the placenta during embryonic development. When born, they are actively going through withdrawal from drugs, leading to seizures and irritable crying.
Studies have also shown that oxycodone reduces white matter in the brain, impacting cognitive abilities and motor skills. The brain has different lobes, and myelin allows for insulation as well as easy transmission of information to different regions. White matter is the myelination that occurs.
After years as a doctoral candidate, Aaron shares that behavioral research, especially when working with animals, can be very intense because it can involve being at the lab seven days a week during parts of the experiment. She also mentioned how the overall process is repetitive, as troubleshooting an experiment can take months.
Aaron also mentioned the emotional burden of behavioral research. “When you work with animals, you want to make sure that their well-being is taken care of, so that can be challenging emotionally,” she said.
Inspired by mentors who “significantly chartered or directed the flow of [her] life,” Aaron hopes to work in academia, such as in a small liberal arts college like the one she went to.
Finally, she shared a piece of advice for undergraduate students interested in research or working toward a Ph.D.: “If you really want to study a certain thing or work on a certain thing, try to network and never give up.” Finding a mentor can be a pivotal point in the process, as their guidance can help you figure out the process, just as Aaron’s mentors influenced her journey to where she is now.
