Hi everyone. Thank you so much for stopping by my poster today. >> My name is Katie Zimmerman and today I'm going to be presenting my senior thesis research which is titled preventative effects of valproic acid on outcomes associated with Caregiver maltreatment. Our experiences in early life are incredibly important in shaping our development because our brains are changing so rapidly during this time, these experiences are particularly impactful on our future behavior. >> One particularly interesting type of early life experience is early life adversity, which can have detrimental and long-lasting effects on the brain. >> And this project, we are focused on caregiver maltreatment, one type of early life adversity that includes less nurturing care and more abusive or neglectful behaviors by a parent or caregiver. >> Previous research has shown that there is a strong link between maltreatment and adverse behavioral outcomes. >> Victims of maltreatment are more likely to have a high-end responsivity to stress, reduce cognitive performance, and impaired social development. Further exposure to maltreatment has also been associated with increased risk of developing psychological disorders such as depression and anxiety. >> Research in our lab is specifically focused on the link between maltreatment in early life and the changes that occur in our brain. >> As a result of this, we know that early life stress can have lasting impacts on our brain and that these exposures can lead to adverse behavior or outcomes. >> However, what we don't know is exactly how these changes occur in our brain. One suggested mechanism for how these changes occur is epigenetics. >> Epigenetic modifications can either increase or decrease expression of a certain gene, but do not alter the underlying DNA sequence itself. >> These modifications are highly susceptible to environmental influences and depending on the situation, can have either beneficial or detrimental effects on gene expression. >> Now, there are multiple types of epigenetic modifications, but I will first focus on DNA methylation, which is represented and figure one in the introduction section of my poster. >> This involves the addition of a methyl group to a cytosine, which alters the chromatin structure, leading to changes in gene expression. Lower methylation levels mean that this chromatin structure is more open and available for transcription, which leads to increased expression of the gene. In contrast, higher methylation levels result in tighter chromatin structure, which leads to decreased expression of the gene. >> Aberrant patterns of DNA methylation have been implicated in many psychological disorders, including depression, schizophrenia, and PTSD. >> Further, DNA methylation has been studied as a potential mechanism for how adverse experiences >> Early life influence future behavioral outcomes. >> Another type of epigenetic mechanism is histone modifications, which includes histone acetylation and deacetylation. >> These processes are represented in figure two in the introduction section of my poster. >> Histone acetylation as a process when an acetyl group is added to a histone tail by a histone acetyltransferase. This results in a more open chromatin structure and increase gene expression. >> The opposite process can also occur with histone deacetylation. When an acetyl group is removed from a histone tail by histone deacetylation or DAC, resulting in condensed chromatin and decrease gene expression. Now there are certain drugs that target these epigenetic processes. And the focus of this study was on a particular drug called valproic acid, which is a histone deacetylation inhibitor. >> This drug prevents Ajax from removing acetyl groups, leading to a more open chromatin structure and increase gene expression. Previous studies have shown that treatment with H HDAC inhibitors has led to positive behavioral effects. >> Vpa, mainly a fax molecular pathways responsible for synaptic plasticity and neuronal survival, making this drug and important focus for our developmental epigenetics research. >> Now, while many genes can be affected by early life adversity, one gene of focus in our lab is brain-derived neurotrophic factor, or BDNF. >> Bdnf plays an important role and neurogenesis and neuroplasticity and expression of this gene is incredibly susceptible to environmental influences. >> Previous work and our lab has established that exposure to maltreatment during the first seven days of life leads to increased DNA methylation at BDNF exon nine in the prefrontal cortex. >> Further, a recent study in our lab has shown that sodium butyrate, an eight shock inhibitor, was able to prevent these maltreatment induce changes in methylation, BDNF, exon nine in the prefrontal cortex, indicating that each shack inhibition can be successful at preventing negative outcomes associated with early life stress. Other studies have also shown that this exposure to maltreatment and infancy can affect behavioral outcomes as well. >> Specifically, studies have found that the quality of care a female pop, perceives an infancy influences the quality of care that she as a mother, will give her own offspring. So building upon all of these previous findings, the first aim of this project was focused on determining a dose of VPA that could effectively prevent maltreatment, induce changes in DNA methylation. Once an effective dose was determined. The second aim of this project was focus. It focused on examining the long-term effects of this dose of VPA using caregiving behavior in adulthood as an outcome measure. >> So to do this, we used a modified version of the scarcity adversity paradigm developed by our lab, represented in figure three in the methods section of my poster. >> In this design, our maltreatment dam is placed in an environment with limited nesting material, an inadequate habituation time. This induces stress and the dam and causes her to exhibit more aversive behaviors towards her pups. >> Just stepping on, actively avoiding or rough handling in contrast are normal care. >> Dam is left in her home environment with adequate nesting material. She will exhibit more nurturing behaviors towards her pups, such as nursing, licking, and grooming, and hovering. >> So each letter was essentially split in half with each pump assigned to either the normal care or maltreatment condition. >> And each pump is then exposed to their respective caregiving conditions for 30 minutes per day. During postnatal days one to seven. And concurrent with this, pups were also assigned either a two hundred, four hundred or 600 milligram per kilogram dose, VPA, or ceiling vehicle, which was administered intraperitoneal E. >> And then after our seventies of testing, brains were extracted and we isolated the prefrontal cortex tissue. >> We then extracted DNA, purified it, and bisulfite treated it to convert unmethylated cytosines two-year. >> So while leaving the methylated cytosines unaffected after this treatment, we used methylation specific PCR to quantify methylation at BDNF exon nine and to quantify global methylation are extracted. >> Dna was run through and Elisa calorimetric assay. >> So to see which dose a VPA was successfully able to prevent maltreatment, induce changes in DNA methylation. >> We quantified the methylation levels at BDNF exon nine in the prefrontal cortex. So these results are represented in figure four of the first half of the results section of my poster. And this figure shows a comparison of the DNA methylation levels for each drug dose across the normal care and maltreatment conditions, we found that there were no significant differences in methylation levels between drug conditions, indicating that VPA was not effective at preventing an increase in DNA methylation. However, we did see that pumps in the maltreatment condition had significantly higher levels of DNA methylation compared to pumps in the normal care condition. So importantly, this replicates previous findings from our lab using our scarcity adversity paradigm, indicating that exposure to maltreatment early in life can lead to increased levels of BDNF exon nine methylation. So then to assess if EPA was able to change methylation states genome-wide. >> We assess global methylation levels across the whole prefrontal cortex. >> And this data is represented in figure five. >> This graph shows a comparison of the global methylation levels for each drug dose across the normal care and maltreatment conditions. >> And here we see a main effect of drug. >> And in post hoc analysis, we found that pumps receiving a 400 milligram per kilogram dose, a VPA in the normal care condition had significantly lower global methylation levels compared to pups receiving saline in the normal care condition >> And further pumps receiving a 400 milligram per kilogram dose of VPA. >> And the maltreatment condition had marginally lower global methylation levels compared to pups receiving saline in the maltreatment condition. >> So from these findings, we were able to conclude that a 400 milligram per kilogram dose, a VPA, was effective in lowering global methylation in the prefrontal cortex. >> So given this, we were able to move on to aim two of our study in which we wanted to explore the long-term effects of VPA. >> So now we are specifically asking the question, does our chosen 400 milligram per kilogram dose of EPA affect future caregiving behavior? >> And to investigate this, we repeated are behavioral paradigm with pups assigned to the one of two caregiving conditions, maltreatment or normal care and pumps. >> We're additionally assigned to either a dose of sailing vehicle or 400 milligram per kilogram MVPA. >> And this was administered daily before exposure to the caregiving condition during postnatal days one to seven. >> And we then allow these animals to reach adulthood, bred them and observed and quantified their caregiving behavior towards their own offspring on postnatal day is 147. And this experimental timeline is shown in figure six in the second half of the result section of my poster. And then if we look at Figure seven, This shows the occurrences of aversive caregiving behavior exhibited by dams who received sailing or 400 milligram per kilogram VPA in infancy. And it further compares dams who had a history of maltreatment in infancy and those who had a history of normal care in infancy. >> And here we see that ***** who received 400 milligram per kilogram of VPA and infancy exhibited a greater amount of aversive behaviors compared to those who received sailing vehicle in both normal care and maltreatment conditions. >> Now this is quite an interesting finding and suggest perhaps that there is an optimal level of global methylation in the brain. >> And that a reduction in global methylation can lead to adverse consequences such as increase aversive caregiving behavior, like we see here. >> Now, further, a recent study from our lab that was very similar in design to this study investigated the effects of a different drug, said Bulara, and on maltreatment induced DNA methylation. >> And findings from that study showed that's Abdul Arne was able to normalize caregiving behavior and dams with history of maltreatment, BUT disturbed caregiving behavior and dams with no history of maltreatment. So taken together with the findings of this study, highlights the complicated relationship between epigenetic changes and behavior outcomes, but does indicate that epigenetic changes do indeed have a functional consequence. >> So in summary, throughout this project, we found that VPA was unsuccessful at preventing maltreatment induced DNA methylation at BDNF exon nine across all doses. However, we did find that a 400 milligram per kilogram dose of VPA was able to successfully lower global methylation across the prefrontal cortex. Treatment with a 200 or 600 milligram per kilogram dose of EPA was not able to lower global methylation across the prefrontal cortex, suggesting a specific therapeutic window for dosage of the drug. >> Lastly, we found that treatment with VPA and infancy leads to increased incidence of aversive caregiving behavior in adulthood. >> Independent of whether a dam was exposed to maltreatment in infancy or not, indicating that this relationship between epigenetic changes and behavioral outcomes is not always unidirectional and may be quite complicated. >> So ask for future work. We collected prefrontal cortex tissues from the dams and pumps that were part of our long-term experimentation. >> So we're hoping to analyze their BDNF exon nine and global methylation levels to further understand what is happening here molecularly. >> And then based on these findings, this may prompt further exploration of how VPA affects behavior such as social interaction and fear conditioning. >> And finally, investigating non-pharmacological interventions such as exercise or environmental enrichment in the context of early life stress could help inform future prevention strategies. >> So taken together, the findings from this study indicate that BPA is indeed able to alter the epigenome and influence behavior or outcomes. But more research is needed to better understand the exact mechanisms of this drug. However, insight from this study does bring us closer to understanding how early life experiences affect the epigenome and how changes and both can impact behavioral outcomes. So that is the end of my presentation. >> Thank you so much for listening and for stopping by my poster today.
Zimmerman-Collins-Roth--2020-PosterPresentation
From Tamara Medina May 19, 2020
12 plays
12
0 comments
0
You unliked the media.