Transformation of the stress response into motor behavior by the external globus pallidus

Project: Research project

Project Details

Description

TASKS:
Task 1. To determine the cellular connectivity of PVN inputs to GPe neurons
The majority of neurons in the PVN are glutamatergic, including CRF neurons. To examine the synaptic connectivity between the PVN and the GPe, cre­dependent ChR2­eYFP encoding adeno­associated virus (AAV) will be injected into the PVN of CRF­cre mice 3–5 week prior to ex vivo electrophysiological recordings. Identified PV+ GPe neurons and Npas1+ GPe neurons in ex vivo slices will be voltage clamped with a cesium methanesulphonate internal solution at –70 mV. PVN inputs will be optogenetically activated using blue light delivered to the GPe. The glutamatergic nature of the synaptic responses will be confirmed by their sensitivity to AMPA and NMDA receptor blockers, NBQX and CPP. AMPA­NMDA, paired­pulse, and kinetic properties of synaptic responses will be measured as additional biophysical signatures of the PVN input. A subset of mice will be perfused fixed to examine the expression of vesicular glutamate transporter (vGluT2) in ChR2­eYFP labelled axons using confocal immunofluorescence analysis.

Task 2. To determine the cellular connectivity of CeA inputs to GPe neurons
CRF neurons in the CeA are GABAergic. To examine the synaptic connectivity between the CeA and the GPe, cre­dependent ChR2­eYFP encoding AAV will be injected into the CeA of CRF­cre mice 3–5 weeks prior to ex vivo electrophysiological recordings. Identified PV+ GPe neurons and Npas1+ GPe neurons in ex vivo slices will be voltage clamped with a cesium chloride internal solution at –70 mV. CeA inputs will be optogenetically activated using blue light delivered to the GPe. The GABAergic nature of the synaptic responses will be confirmed by their sensitivity to GABAA receptor blockers, SR95531. Paired­pulse and kinetic properties of synaptic responses will be measured as additional biophysical signatures of the CeA input. A subset of mice will be perfused fixed to examine the expression of vesicular GABA transporter (vGAT) in ChR2­eYFP labelled axons using confocal immunofluorescence analysis.

Task 3. To determine the effects of CRF on intrinsic properties of GPe neurons
To examine CRF release, PVN or CeA inputs will be targeted using approaches similar to those outlined in Task 1–2. In the presence of fast synaptic blockers (i.e. NBQX, CPP, and SR95531), CRF release will be optogenetically evoked using a train of light pulses at 20 Hz in ex vivo slices. The cellular impact on identified GPe neurons will be first examined by monitoring the autonomous activity of identified PV+ GPe neurons and Npas1+ GPe neurons in cell­attached configuration. In addition, intrinsic excitability of PV+ GPe neurons and Npas1+ GPe neurons will be characterized using a series of current steps in whole­cell current clamp configuration. The number of action potential evoked with current injections will be used as an outcome measure. Biophysical and pharmacological properties of CRF­responsive conductances will be determined in voltage­clamp. Effects of exogenously applied CRF on GPe neurons will be compared to optogenetically evoked

responses. Lastly, the effects of CRFR1 antagonist (R121919) on (both endogenous and exogenous) CRF­induced changes in firing and membrane properties will be examined.

Task 4. To determine the effects of CRF on synaptic inputs to GPe neurons
To investigate if CRF effects major synaptic inputs to GPe neurons, GABAergic inputs from the dStr or the glutamatergic inputs from the STN will be examined. In ex vivo slices, dStr inputs and STN inputs will be activated using op
StatusActive
Effective start/end date6/5/173/31/22

Funding

  • University of Texas Health Science Center at Houston (0012774A//5R01MH112768-03)
  • National Institute of Mental Health (0012774A//5R01MH112768-03)

Fingerprint

Explore the research topics touched on by this project. These labels are generated based on the underlying awards/grants. Together they form a unique fingerprint.