Project Summary
Long-lasting vulnerability to relapse is a major hurdle to achieving successful treatment outcomes in persons
with a substance use disorder. The glutamate receptor system is highly implicated in the development and
maintenance of functional and structural alterations driving a return to drug use. Increasing our understanding
of glutamatergic regulation of neurobiological alterations during drug use and withdrawal, we propose to
explore a new target for the development of therapeutic agents. Delta-type ionotropic glutamate receptors
(GluD) have been identified as regulators in the formation of synaptic connections, as they serve to regulate
the alignment and development of dendritic spines. A recent study has indicated that GluD1 receptor
function/expression plays a role in structural plasticity in a model of psychostimulant use. It is currently
unknown what role GluD1 plays in altering structural plasticity following chronic ethanol exposure or protracted
withdrawal. Using an ethanol exposure model this application seeks to identify the role GluD1 holds in the
regulation of dendritic spine density and morphology under ethanol exposure and after protracted withdrawal.
We will focus on the basolateral amygdala (BLA), a key region for ethanol action. We hypothesize that GluD1
dynamically controls chronic ethanol- and withdrawal-associated changes in spine morphology in the BLA. We
will test this hypothesis in one Specific Aim, comprised of three independent experiments. All experiments will
compare male and female rats. First, we will characterize dendritic spine morphology under control conditions,
ethanol exposure, and across various withdrawal time points (day 1, 21, 42), using iontophoretic dye injection
and confocal microscopy methods. We will also characterize GluD1 expression in surface membrane fractions
using a biotinylation procedure followed by western blot analysis at each experimental time point. Finally, we
will utilize dye injections and confocal microscopy paired with injection of a shRNA viral construct to knock
down GluD1 levels in the BLA prior to ethanol exposure. This experiment will identify the specific role GluD1
plays in dendritic spine expression and morphology across our treatment groups and sex. Together, these
studies will reveal the role of GluD1 in regulation of structural plasticity during ethanol exposure and
withdrawal. As such, GluD1 regulation of structural plasticity could contribute to well characterized functional
alterations of the glutamatergic receptor system during short term withdrawal. This would implicate GluD1 as a
key hub, capable of regulating functional and structural plasticity, making it a promising target for therapeutic
development. Long term objectives are to identify the overall impact of GluD1 regulation on both structural and
functional plasticity across additional brain regions impacted by drug taking and withdrawal.
