Porter, Caleb

The Role of BDNF Expression In Chronic Ethanol Usage

Faculty Mentor: Scott Steffensen, Neuroscience

Introduction

It has been observed that chronic exposure to drugs of abuse, particularly opiates,
increases brain-derived neurotrophic factor (BDNF) levels in ventral tegmental area (VTA)
neurons. In particular, BDNF expression is dramatically increased during drug withdrawal,
which would suggest a direct connection between the aversive state of withdrawal and BDNFinduced
neuronal plasticity. The purpose of this project was to evaluate the relationship between
brain-derived neurotrophic factor (BDNF) expression, which is dramatically increased within the
ventral tegmental area (VTA) during drug abuse, and alcohol withdrawal symptoms.

Methodology

Through the use of an alcohol vapor chamber system, we successfully enabled
automation of chronic intermittent ethanol (CIE) exposure. The alcohol vapor chamber system
has a breathalyzer that facilitated regulation of the level of blood alcohol within the mice. Mice
were anesthetized with isofluorane and decapitated. Brains were sectioned in high Mg2+, low
Ca2+, ice-cold artificial cerebrospinal fluid (ACSF). After taking tissue punches of the VTA
from horizontal brain slices, slices were frozen until ready for use. We then quantified levels of
endogenous mature BDNF and pro-BDNF through an enzyme-linked immunosorbent assay
(ELISA). Throughout the process protein expression was observed at multiple time points of
withdrawal after CIE exposure.

Results

During the winter semester of 2016 I worked closely with Lauren, one of Dr. Steffensen’s
lab assistants in preparing our project to collect the necessary data and attempt to run an ELISA
that would properly evaluate specific BDNF receptors. Throughout our project I learned how to
properly create ACSF, prepare tissue samples and carry out the procedures to successfully run an
ELISA. Lauren and I recreated the previous results in Dr. Steffensen’s lab, which correlated an
increase in BDNF with CIE exposure. However, we struggled to find a specific receptor that was
linked to CIE exposure and withdrawal symptoms. I worked with Dr. Steffensen’s lab
throughout the spring, however, after running a few different ELISAs our research continued to
struggle in finding a specific receptor associated with the increase in BDNF. We were hindered
due to the lack of development of quality BDNF receptor ELISAs and our research stalled as a
result of this problem. At the conclusion of the spring semester, I left on a study abroad to
London and was unable to continue working with Dr. Steffensen’s lab. Although the project did
not lead to any significant findings in terms of which specific receptor correlated with the
increase in BDNF expression, we did further confirm the association between BDNF and
withdrawal symptoms. This implies the need for further research regarding the understanding of
the various underlying mechanisms which contribute to the release of BDNF during withdrawal
symptoms.

Discussion

By better understanding which receptors help to incite increased BDNF expression within the VTA, it could become theoretically possible to target these specific kinase receptors and aid in the regulation of BDNF expression to minimize the aversive effects of withdrawal on the brain. Further research is needed in order to find the underlying mechanisms that lead to BDNF release into the VTA. Specifically, through the development of more effective assays that can properly evaluate the involvement of specific BDNF receptors, a greater understanding of the role of BDNF in withdrawal could be achieved.