Identification of penile inputs to the rat gracile nucleus

Cothron, Kyle J.; Massey, James M.; Onifer, Stephen M.; Hubscher, Charles H.

doi:10.1152/ajpregu.00656.2007

Cited by 6 publications

(5 citation statements)

References 61 publications

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“…The MRF is located in the brainstem. It is essential for governing some of the most basic functions of higher organisms, including somatic motor and cardiovascular control, pain modulation, and sleep/consciousness [61–63]. Neurons in the MRF receive a vast array of inputs from somatic sensory neurons of the external genitalia and visceral autonomic input from lower urinary and gastrointestinal tracts [62].…”

Section: Supraspinal Sexual Centersmentioning

confidence: 99%

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The Role of Genital Nerve Afferents in the Physiology of the Sexual Response and Pelvic Floor Function

Tajkarimi

Burnett

2011

The Journal of Sexual Medicine

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Introduction Our understanding of genital and pelvic floor physiology is rapidly expanding. Penile erection is a neurovascular event controlled by spinal autonomic centers, the activity of which is dependent on input from supraspinal centers and the genitalia. Genital afferent stimulation excites spinal autonomic nuclei and supraspinal sexual centers of both genders. Aim To present a detailed understanding of the functional importance of genital afferent neuroanatomy and neurophysiology. Methods English-written articles of diverse disciplines from 1980 to 2010 that contained information on genital anatomy, pudendal/dorsal/perineal/cavernous nerves, vibratory stimulation, reflexogenic erection, peripheral/central nervous system-mediated erectile and micturition pathways, and sexual arousal in animals and humans were reviewed. Main Outcome Measures Analysis of supporting evidence for the role of genital afferents in the physiology of erectile response and pelvic floor function. Results Basic science and clinical studies support the concept that pudendal nerve circuitry serves an essential purpose for sexual behavior, erectile function, penile rigidity, ejaculation, and micturition. Males and females share a comparable pattern of genital afferent neuroanatomy and neurophysiology, and sexual and micturition reflexes are similar in both genders. Pudendal nerve branches communicate with the cavernous nerves and are nitric oxide synthase positive. Genital afferents activate multiple spinal reflexes that modulate erection and micturition. Genital sensory information is transmitted to supraspinal centers important for sexual function. Conclusions There is expanding support for the critical role of genital afferent neurophysiology in the mechanisms of erectile function and micturition. Genital afferent stimulation is a safe and natural modality that can be harnessed to amplify autonomic and somatic activity within the penis, female genitalia, spinal cord, and higher centers via established neurological principles. Such physiological adaptive processes may be beneficial in improving sexual response, erectile function, and micturition in many disease states, including in men after radical pelvic surgery. Well-designed and -executed studies in each specific population are needed to authenticate such prospects.

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Section: Supraspinal Sexual Centersmentioning

confidence: 99%

“…In a study by Kaddumi et al. electrophysiologic recordings were used to investigate MRF's responses to pelvic input [63]. Mechanical and electrical stimulation of rat pelvic organs was performed.…”

Section: Supraspinal Sexual Centersmentioning

confidence: 99%

The Role of Genital Nerve Afferents in the Physiology of the Sexual Response and Pelvic Floor Function

Tajkarimi

Burnett

2011

The Journal of Sexual Medicine

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“…In addition, responses remain not only for pinching the penis but for distension of the urinary bladder and descending colon as well. The low threshold penile input to MRF that is lost is likely to be conveyed, either directly or indirectly, via the nucleus gracilis in the caudal medulla, which receives primary afferent inputs from the DNP (Cothron et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Select spinal lesions reveal multiple ascending pathways in the rat conveying input from the male genitalia

Hubscher

Reed

Kaddumi

et al. 2010

The Journal of Physiology

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The specific white matter location of all the spinal pathways conveying penile input to the rostral medulla is not known. Our previous studies using rats demonstrated the loss of low but not high threshold penile inputs to medullary reticular formation (MRF) neurons after acute and chronic dorsal column (DC) lesions of the T8 spinal cord and loss of all penile inputs after lesioning the dorsal three-fifths of the cord. In the present study, select T8 lesions were made and terminal electrophysiological recordings were performed 45-60 days later in a limited portion of the nucleus reticularis gigantocellularis (Gi) and Gi pars alpha. Lesions included subtotal dorsal hemisections that spared only the lateral half of the dorsal portion of the lateral funiculus on one side, dorsal and over-dorsal hemisections, and subtotal transections that spared predominantly just the ventromedial white matter. Electrophysiological data for 448 single unit recordings obtained from 32 urethane-anaesthetized rats, when analysed in groups based upon histological lesion reconstructions, revealed (1) ascending bilateral projections in the dorsal, dorsolateral and ventrolateral white matter of the spinal cord conveying information from the male external genitalia to MRF, and (2) ascending bilateral projections in the ventrolateral white matter conveying information from the pelvic visceral organs (bladder, descending colon, urethra) to MRF. Multiple spinal pathways from the penis to the MRF may correspond to different functions, including those processing affective/pleasure/motivational, nociception, and mating-specific (such as for erection and ejaculation) inputs.

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“…The experimenter was blinded to the type of implant. A modification of our previously published protocol was used (Cothron et al, 2008). Each slide contained five 30 μm sections, which were at least 120 μm apart.…”

Section: Methodsmentioning

confidence: 99%

Estradiol Treatment Prevents Injury Induced Enhancement in Spinal Cord Dynorphin Expression

Gupta¹,

Hubscher²

2012

Front. Physio.

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Administration of the ovarian steroid estradiol in male and female animals has been shown to have neuromodulatory and neuroprotective effects in a variety of experimental models. In the present study, spinal tissues from dermatomes just above (T5–T7, at level) a severe chronic spinal cord injury (SCI) at T8 were analyzed for expression levels of prodynorphin (PRDN) and phospho-(serine 369) κ-opioid receptor (KOR-P) in 17 β estradiol (EB)- and placebo-treated adult male rats. Dynorphin was targeted since (1) it has previously been shown to be elevated post-SCI, (2) intrathecal injection of dynorphin produces several of the same adverse effects seen with a SCI, and (3) its increased expression is known to occur in a variety of different experimental models of central neuropathic pain. A significant elevation of extracellular levels of both PRDN and KOR-P in the placebo-treated SCI group relative to uninjured surgical sham controls was found in spinal tissues above the injury level, indicating increased dynorphin levels. Importantly, the EB-treated SCI group did not show elevations of PRDN levels at 6 weeks post-injury. Immunohistochemical analysis of at level tissues revealed that EB treatment significantly prevented a post-SCI increase in expression of PRDN puncta co-labeling synapsin I, a nerve terminal marker. The dynorphin-containing terminals co-labeled vesicular glutamate receptor-2 (a marker of glutamatergic terminals), a finding consistent with a non-opioid basis for the adverse effects of dynorphin. These results support a beneficial role for EB treatment post-SCI through a reduction in excessive spinal cord levels of dynorphin. Studies manipulating the timing of the EB treatment post-injury along with specific functional assessments will address whether the beneficial effects are due to EB’s potential neuromodulatory or neuroprotective action.

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Identification of penile inputs to the rat gracile nucleus

Cited by 6 publications

References 61 publications

The Role of Genital Nerve Afferents in the Physiology of the Sexual Response and Pelvic Floor Function

The Role of Genital Nerve Afferents in the Physiology of the Sexual Response and Pelvic Floor Function

Select spinal lesions reveal multiple ascending pathways in the rat conveying input from the male genitalia

Estradiol Treatment Prevents Injury Induced Enhancement in Spinal Cord Dynorphin Expression

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