Date on Master's Thesis/Doctoral Dissertation

8-2019

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Anatomical Sciences and Neurobiology

Degree Program

Anatomical Sciences and Neurobiology, PhD

Committee Chair

Hubscher, Charles

Committee Co-Chair (if applicable)

Harkema, Susan

Committee Member

Harkema, Susan

Committee Member

Kumar, Ashok

Committee Member

Ovechkin, Alexander V.

Committee Member

Magnuson, David

Committee Member

Petruska, Jeffrey

Author's Keywords

sexual function; spinal cord injuy; activity-based training; erectile function; telemetry; ex copula sexual reflex

Abstract

Spinal cord injury (SCI) causes severe neurological impairment with widespread motor, autonomic and sensory deficits, leading to a substantial quality of life impairment. The number of individuals with SCI increases by approximately 12,500 annually, and over 80% of individuals with SCI are males. SCI individuals rate sexual function as a top priority quality of life issue, and men with SCI likely suffer from sexual dysfunction, such as erectile and ejaculatory dysfunction, as well as infertility. Regardless of the high status of importance of sexual function, limited numbers of experimental studies in SCI animal models have focused on sexual function after SCI. Interestingly, human clinical research participants with SCI undergoing daily locomotor treadmill training have reported changes in sexual function. To advance targeted recovery of sexual function after SCI, a better understanding of the post-injury neural circuitry is necessary. The objective of this project was to determine the effect of activity-based training (ABT) on sexual function in a rat model of SCI and examine the effects of a contusion SCI on sexual function using improved quantifiable measures. Two well-established measures of sexual function were used to determine the effects of ABT on sexual function after SCI: the penile dorsiflexion reflex (PDFR) and bulbospongiosus electromyography. The second and third studies focused on determining the effect of a clinically relevant contusion injury of varying severities using kinematic analysis of the PDFR and real-time intracavernosal pressure recordings from the penis of rats undergoing mating behavior testing. ABT was shown to positively affect sexual function after SCI, where task-specific stepping and/or hindlimb loading impacts the local spinal cord circuitry responsible for sexual function. ABT may strengthen the residual fibers crossing the lesion epicenter, providing better coordination of supraspinal influences on the spinal cord sexual circuitry. Sexual function after SCI was determined to be correlated with the percent of white matter spared (a measure of injury severity), further supporting the disruption of spinobulbospinal coordination as the cause of sexual dysfunction after SCI. Kinematic analysis of the penile dorsiflexion reflex and telemetric recording of intracavernosal pressure may provide improved quantifiable measures for examining sexual function after SCI.

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