The neural mechanisms involved in the control/coordination of urogenital functions is poorly understood, making restoration of function following traumatic spinal cord injury a difficult task. In humans, spinal cord injury occurs predominantly in young males, compromises sexual function, and leaves most patients infertile because of an inability to ejaculate. Moreover, bladder voiding dysfunction is common due to bladder-sphincter dyssynergia. Incoordination of perineal motoneuron circuits, resulting from spinal cord injury-induced changes in non-locomotor segmental reflex circuits involved in male reproductive function and micturition, likely contributes to these complications. Since normal ejaculation and micturition require both an intact segmental reflex arc and brainstem integration, we have, in recent years, developed and characterized an in vivo brainstem-spinal cord electrophysiological animal model to study the neurological causes of sexual dysfunction following severe midthoracic spinal cord injury. Our previous studies with this model have shown that chronic bilateral lesions of the dorsal 3/5 of T8 spinal cord is correlated with (i) impaired bladder/sexual reflexes, (ii) changes in lumbosacral neural circuits mediating perineal muscle function and (iii) loss of ascending and descending connections between the distal urogenital tract and the medullary reticular formation (ii/iii - as determined in terminal electrophysiological experiments). The overall aim of the proposed research is to use this spino-bulbo-spinal model to address important questions regarding the neural control/coordination of smooth and striated muscles subserving sexual and bladder functions in male rats following chronic spinal cord injury. A unique benefit of our model lies in our ability to focus on the integration of information from multiple pelvic viscera. The knowledge gained from these basic scientific experiments will more specifically ascertain the spinal cord regions and the specific neural circuitry which should be targeted for therapeutic interventions designed to improve the control/coordination of sexual, bladder and bowel functions following chronic spinal cord injury. Parallel electrophysiological, behavioral and neuroanatomical studies are proposed.
