Selective Ablation of RVLM-Projecting PVN Neurons
Abstract
The rostral ventrolateral medulla (RVLM) is a key brainstem region that maintains basal sympathetic vasomotor tone and serves as a major premotor output for sympathetic cardiovascular regulation. The paraventricular nucleus (PVN) directly controls the RVLM via descending neural projections. In subjects with PTSD and other chronic stress-related conditions, increased sympathetic drive involving forebrain–brainstem circuits contributes to hypertension and elevated cardiovascular risk. We aim to determine whether selective ablation of RVLM-projecting PVN neurons normalizes the stress-augmented sympathetic reflex responsiveness. To achieve this, we bilaterally injected Cre-dependent taCaspase3 viral vector (FLEX-taCasp3) into the PVN. We bilaterally injected a retrograde AAV expressing Cre-recombinase and the reporter gene tdTomato into the RVLM. The retrograde Cre-recombinase-expressing virus is transported to the cell bodies of neurons projecting to the RVLM and the PVN. When Cre-recombinase interacts with the FLEX-taCasp3 construct, it induces the recombination at loxP sites, resulting in the active expression of caspase-3. Activated caspase-3 triggers apoptosis, selectively killing RVLM-projecting PVN neurons. The cre-recombinase virus also carries the gene for the reporter protein tdTomato. To confirm selective targeting, control rats receiving FLEX-EGFP will exhibit co-expression of tdTomato and EGFP in the RVLM-projecting PVN neurons. In rats receiving FLEX-taCasp3tdTomato, labelling should be reduced or absent in the PVN due to Cre-induced apoptosis of RVLM-projecting neurons, while other retrogradely labelled neurons lacking taCasp3 are labelled. In a control experiment, we injected FLEX-taCasp3 into both right and left PVN, and the right and left amygdala; the right and left amygdala expressed tdTomato, while the left PVN was tdTomato-negative. These findings indicate successful retrograde targeting and elimination of RVLM-projecting PVN neurons expressing the Cre-dependent taCasp3 suicide construct. Given that the RVLM-projecting PVN neurons were selectively removed, these proof-of-concept data now allow us to perform neurophysiological experiments to test the role of the RVLM-projecting PVN and CeA neurons in the stress-augmented sympathetic reflex activity.
Start Time
15-4-2026 1:30 PM
End Time
15-4-2026 4:30 PM
Room Number
Culp Ballroom 316
Poster Number
8
Presentation Type
Poster
Presentation Subtype
Posters - Competitive
Presentation Category
Health
Student Type
Undergraduate Student
Faculty Mentor
Matthew Zahner
Selective Ablation of RVLM-Projecting PVN Neurons
Culp Ballroom 316
The rostral ventrolateral medulla (RVLM) is a key brainstem region that maintains basal sympathetic vasomotor tone and serves as a major premotor output for sympathetic cardiovascular regulation. The paraventricular nucleus (PVN) directly controls the RVLM via descending neural projections. In subjects with PTSD and other chronic stress-related conditions, increased sympathetic drive involving forebrain–brainstem circuits contributes to hypertension and elevated cardiovascular risk. We aim to determine whether selective ablation of RVLM-projecting PVN neurons normalizes the stress-augmented sympathetic reflex responsiveness. To achieve this, we bilaterally injected Cre-dependent taCaspase3 viral vector (FLEX-taCasp3) into the PVN. We bilaterally injected a retrograde AAV expressing Cre-recombinase and the reporter gene tdTomato into the RVLM. The retrograde Cre-recombinase-expressing virus is transported to the cell bodies of neurons projecting to the RVLM and the PVN. When Cre-recombinase interacts with the FLEX-taCasp3 construct, it induces the recombination at loxP sites, resulting in the active expression of caspase-3. Activated caspase-3 triggers apoptosis, selectively killing RVLM-projecting PVN neurons. The cre-recombinase virus also carries the gene for the reporter protein tdTomato. To confirm selective targeting, control rats receiving FLEX-EGFP will exhibit co-expression of tdTomato and EGFP in the RVLM-projecting PVN neurons. In rats receiving FLEX-taCasp3tdTomato, labelling should be reduced or absent in the PVN due to Cre-induced apoptosis of RVLM-projecting neurons, while other retrogradely labelled neurons lacking taCasp3 are labelled. In a control experiment, we injected FLEX-taCasp3 into both right and left PVN, and the right and left amygdala; the right and left amygdala expressed tdTomato, while the left PVN was tdTomato-negative. These findings indicate successful retrograde targeting and elimination of RVLM-projecting PVN neurons expressing the Cre-dependent taCasp3 suicide construct. Given that the RVLM-projecting PVN neurons were selectively removed, these proof-of-concept data now allow us to perform neurophysiological experiments to test the role of the RVLM-projecting PVN and CeA neurons in the stress-augmented sympathetic reflex activity.
