Retrograde Infection of Spinal Sympathetic Preganglionic Neurons for Chemogenetic Stimulation to Improve the Recovery of Cardiovascular Function after Spinal Cord Injury
Abstract
Traumatic spinal cord injury (SCI) can have devastating physiological effects. Early intervention, like physical therapy, is crucial in recovery. However, people with SCI often suffer from orthostatic hypotension where they become dizzy when assuming an upright posture. During orthostatic hypotension brainstem activity that regulates blood pressure is unable to stimulate spinal sympathetic preganglionic neurons (SPNs) and blood pools to the lower extremities. Spinal electrical stimulation significantly attenuates orthostatic hypotension. However, the molecular mechanisms responsible for these improvements are not well known. For example, it is unknown if it activates SPNs directly or indirectly by stimulation of propriospinal networks that synapse on the SPNs. This is important because a better understanding of the neuroplasticity after SCI will provide better-targeted therapeutics allowing those with SCI to fully participate in rehabilitation. In this study we used gene therapy and state-of-the-art chemogenetics to create a rat model where we can provide focal stimulation of SPNs to study spinal neuroplasticity. To do this we used a novel approach to deliver a retrograde viral vector (pAAV-hSyn-DIO-hM3D(Gq)-mCherry) containing Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to infect spinal SPNs by injecting into the adrenal gland. To limit the expression of the DREADDs to only SPNs, we created a colony of transgenic Long Evans ChAT::Cre rats that express the cre recombinase enzyme driven by the Choline Acetyl Transferase (ChAT) promoter. Control rats were infected with a retrograde virus expressing enhanced green florescent reporter protein. Here we show immunofluorescent evidence of viral infection by the reporter gene mCherry or EGFP (control) co-labelled for ChAT. Our next step is to activate the DREADDs with clozapine N-oxide in the drinking water and measure blood pressure using noninvasive radiotelemetry. With this novel gene delivery approach to study neuroplasticity, we can develop more effective therapies that to restore cardiovascular function after SCI.
Start Time
16-4-2025 9:00 AM
End Time
16-4-2025 11:30 AM
Presentation Type
Poster
Presentation Category
Health
Student Type
Undergraduate Student
Faculty Mentor
Matthew Zahner
Faculty Department
Biomedical Health Sciences
Retrograde Infection of Spinal Sympathetic Preganglionic Neurons for Chemogenetic Stimulation to Improve the Recovery of Cardiovascular Function after Spinal Cord Injury
Traumatic spinal cord injury (SCI) can have devastating physiological effects. Early intervention, like physical therapy, is crucial in recovery. However, people with SCI often suffer from orthostatic hypotension where they become dizzy when assuming an upright posture. During orthostatic hypotension brainstem activity that regulates blood pressure is unable to stimulate spinal sympathetic preganglionic neurons (SPNs) and blood pools to the lower extremities. Spinal electrical stimulation significantly attenuates orthostatic hypotension. However, the molecular mechanisms responsible for these improvements are not well known. For example, it is unknown if it activates SPNs directly or indirectly by stimulation of propriospinal networks that synapse on the SPNs. This is important because a better understanding of the neuroplasticity after SCI will provide better-targeted therapeutics allowing those with SCI to fully participate in rehabilitation. In this study we used gene therapy and state-of-the-art chemogenetics to create a rat model where we can provide focal stimulation of SPNs to study spinal neuroplasticity. To do this we used a novel approach to deliver a retrograde viral vector (pAAV-hSyn-DIO-hM3D(Gq)-mCherry) containing Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to infect spinal SPNs by injecting into the adrenal gland. To limit the expression of the DREADDs to only SPNs, we created a colony of transgenic Long Evans ChAT::Cre rats that express the cre recombinase enzyme driven by the Choline Acetyl Transferase (ChAT) promoter. Control rats were infected with a retrograde virus expressing enhanced green florescent reporter protein. Here we show immunofluorescent evidence of viral infection by the reporter gene mCherry or EGFP (control) co-labelled for ChAT. Our next step is to activate the DREADDs with clozapine N-oxide in the drinking water and measure blood pressure using noninvasive radiotelemetry. With this novel gene delivery approach to study neuroplasticity, we can develop more effective therapies that to restore cardiovascular function after SCI.