Explore the vast range of titles available.

Neurogenic bladder dysfunction causes urological complications and reduces the quality of life in persons with spinal cord injury (SCI). Glutamatergic signaling via AMPA receptors is fundamentally important to the neural circuits controlling bladder voiding. Ampakines are positive allosteric modulators of AMPA receptors that can enhance the function of glutamatergic neural circuits after SCI. We hypothesized that ampakines can acutely stimulate bladder voiding that has been impaired due to thoracic contusion SCI. Adult female Sprague–Dawley rats received a unilateral contusion of the T9 spinal cord (n = 10). Bladder function (cystometry) and coordination with the external urethral sphincter (EUS) were assessed 5 d post-SCI under urethane anesthesia. Data were compared to responses in spinal-intact rats (n = 8). The ‘low-impact’ ampakine CX1739 (5, 10, or 15 mg/kg) or vehicle (2-hydroxypropyl-beta-cyclodextrin [HPCD]) was administered intravenously. The HPCD vehicle had no discernible impact on voiding. In contrast, following CX1739, the pressure threshold for inducing bladder contraction, voided volume, and the interval between bladder contractions were significantly reduced. These responses occurred in a dose-dependent manner. We conclude that modulating AMPA receptor function using ampakines can rapidly improve bladder-voiding capability at subacute time points following contusion SCI. These results may provide a new and translatable method for therapeutic targeting of bladder dysfunction acutely after SCI.

Impaired respiratory motor output contributes to morbidity and mortality in many neurodegenerative diseases and neurologic injuries. We investigated if expressing designer receptors exclusively activated by designer drugs (DREADDs) in the mid-cervical spinal cord could effectively stimulate phrenic motor output to increase diaphragm activation. Two primary questions were addressed: (1) does effective DREADD-mediated diaphragm activation require focal expression in phrenic motoneurons (vs. non-specific mid-cervical expression), and (2) can this method produce a sustained increase in inspiratory tidal volume? Wild-type (C57Bl/6) and ChAT-Cre mice received bilateral intraspinal (C4) injections of an adeno-associated virus (AAV) encoding the hM3D(Gq) excitatory DREADD. In wild-type mice, this produced non-specific DREADD expression throughout the mid-cervical ventral horn. In ChAT-Cre mice, a Cre-dependent viral construct was used to drive neuronal DREADD expression in the C4 ventral horns, targeting phrenic motoneurons. Diaphragm electromyograms (EMG) were recorded in isoflurane-anesthetized spontaneously breathing mice at 4–9 weeks post-AAV delivery. The DREADD ligand JHU37160 (J60) caused a bilateral, sustained (>1 hr) increase in inspiratory EMG bursting in both groups; the relative increase was greater in ChAT-Cre mice. Additional experiments in ChAT-Cre rats were conducted to determine if spinal DREADD activation could increase inspiratory tidal volume during spontaneous breathing, assessed using whole-body plethysmography without anesthesia. Three to four months after intraspinal (C4) injection of AAV driving Cre-dependent hM3D(Gq) expression, intravenous J60 resulted in a sustained (>30 min) increase in tidal volume. Subsequently, phrenic nerve recordings performed under urethane anesthesia confirmed that J60 evoked a >200% increase in inspiratory output. We conclude that targeting mid-cervical spinal DREADD expression to the phrenic motoneuron pool enables ligand-induced, sustained increases in phrenic motor output and tidal volume. Further development of this technology may enable application to clinical conditions associated with impaired diaphragm activation and hypoventilation.

Impaired diaphragm activation is common in many neuromuscular diseases. We hypothesized that expressing photoreceptors in diaphragm myofibers would enable light stimulation to evoke functional diaphragm activity, similar to endogenous bursts. In a mouse model, adeno-associated virus (AAV) encoding channelrhodopsin-2 (AAV9-CAG-ChR2-mVenus, 6.12 × 10 11 vg dose) was delivered to the diaphragm using a minimally invasive method of microinjection to the intrapleural space. At 8–18 weeks following AAV injection, mice were anesthetized and studied during spontaneous breathing. We first showed that diaphragm electromyographic (EMG) potentials could be evoked with brief presentations of light, using a 473 nm high intensity LED. Evoked potential amplitude increased with intensity or duration of the light pulse. We next showed that in a paralyzed diaphragm, trains of light pulses evoked diaphragm EMG activity which resembled endogenous bursting, and this was sufficient to generate respiratory airflow. Light-evoked diaphragm EMG bursts showed no diminution after up to one hour of stimulation. Histological evaluation confirmed transgene expression in diaphragm myofibers. We conclude that intrapleural delivery of AAV9 can drive expression of ChR2 in the diaphragm and subsequent photostimulation can evoke graded compound diaphragm EMG activity similar to endogenous inspiratory bursting.

Dysfunction and/or reduced activity in the tongue muscles contributes to conditions such as dysphagia, dysarthria, and sleep disordered breathing. Current treatments are often inadequate, and the tongue is a readily accessible target for therapeutic gene delivery. In this regard, gene therapy specifically targeting the tongue motor system offers two general strategies for treating lingual disorders. First, correcting tongue myofiber and/or hypoglossal (XII) motoneuron pathology in genetic neuromuscular disorders may be readily achieved by intralingual delivery of viral vectors. The retrograde movement of viral vectors such as adeno-associated virus (AAV) enables targeted distribution to XII motoneurons via intralingual viral delivery. Second, conditions with impaired or reduced tongue muscle activation can potentially be treated using viral-driven chemo- or optogenetic approaches to activate or inhibit XII motoneurons and/or tongue myofibers. Further considerations that are highly relevant to lingual gene therapy include (1) the diversity of the motoneurons which control the tongue, (2) the patterns of XII nerve branching, and (3) the complexity of tongue muscle anatomy and biomechanics. Preclinical studies show considerable promise for lingual directed gene therapy in neuromuscular disease, but the potential of such approaches is largely untapped.

The spiny mouse (Acomys species) has emerged as an exciting research organism due to its remarkable ability to undergo scarless regeneration of skin wounds and ear punches. Excitingly, Acomys species demonstrate scar-free healing in a wide-range of tissues beyond the skin. In this perspective article, we discuss published findings from a variety of tissues to highlight how this emerging research organism could shed light on numerous clinically relevant human diseases. We also discuss the challenges of working with this emerging research organism and suggest strategies for future Acomys-inspired research.

Neurogenic bladder dysfunction causes urological complications and reduces the quality of life in persons with spinal cord injury (SCI). Glutamatergic signaling via AMPA receptors is fundamentally important to the neural circuits controlling bladder voiding. Ampakines are positive allosteric modulators of AMPA receptors that can enhance the function of glutamatergic neural circuits after SCI. We hypothesized that ampakines can acutely stimulate bladder voiding that has been impaired due to thoracic contusion SCI. Adult female Sprague–Dawley rats received a unilateral contusion of the T9 spinal cord (n = 10). Bladder function (cystometry) and coordination with the external urethral sphincter (EUS) were assessed 5 d post-SCI under urethane anesthesia. Data were compared to responses in spinal-intact rats (n = 8). The ‘low-impact’ ampakine CX1739 (5, 10, or 15 mg/kg) or vehicle (2-hydroxypropyl-beta-cyclodextrin [HPCD]) was administered intravenously. The HPCD vehicle had no discernible impact on voiding. In contrast, following CX1739, the pressure threshold for inducing bladder contraction, voided volume, and the interval between bladder contractions were significantly reduced. These responses occurred in a dose-dependent manner. We conclude that modulating AMPA receptor function using ampakines can rapidly improve bladder-voiding capability at subacute time points following contusion SCI. These results may provide a new and translatable method for therapeutic targeting of bladder dysfunction acutely after SCI.

Impaired respiratory motor output contributes to morbidity and mortality in many neurodegenerative diseases and neurologic injuries. We investigated if expressing designer receptors exclusively activated by designer drugs (DREADDs) in the mid-cervical spinal cord could effectively stimulate phrenic motor output to increase diaphragm activation. Two primary questions were addressed: (1) does effective DREADD-mediated diaphragm activation require focal expression in phrenic motoneurons (vs. non-specific mid-cervical expression), and (2) can this method produce a sustained increase in inspiratory tidal volume? Wild-type (C57Bl/6) and ChAT-Cre mice received bilateral intraspinal (C4) injections of an adeno-associated virus (AAV) encoding the hM3D(Gq) excitatory DREADD. In wild-type mice, this produced non-specific DREADD expression throughout the mid-cervical ventral horn. In ChAT-Cre mice, a Cre-dependent viral construct was used to drive neuronal DREADD expression in the C4 ventral horns, targeting phrenic motoneurons. Diaphragm electromyograms (EMG) were recorded in isoflurane-anesthetized spontaneously breathing mice at 4–9 weeks post-AAV delivery. The DREADD ligand JHU37160 (J60) caused a bilateral, sustained (>1 hr) increase in inspiratory EMG bursting in both groups; the relative increase was greater in ChAT-Cre mice. Additional experiments in ChAT-Cre rats were conducted to determine if spinal DREADD activation could increase inspiratory tidal volume during spontaneous breathing, assessed using whole-body plethysmography without anesthesia. Three to four months after intraspinal (C4) injection of AAV driving Cre-dependent hM3D(Gq) expression, intravenous J60 resulted in a sustained (>30 min) increase in tidal volume. Subsequently, phrenic nerve recordings performed under urethane anesthesia confirmed that J60 evoked a >200% increase in inspiratory output. We conclude that targeting mid-cervical spinal DREADD expression to the phrenic motoneuron pool enables ligand-induced, sustained increases in phrenic motor output and tidal volume. Further development of this technology may enable application to clinical conditions associated with impaired diaphragm activation and hypoventilation.

Study design Experimental Animal Study. Objective To continue validating an antibody which targets an epitope of neurofilament light chain (NF-L) only available during neurodegeneration and to utilize the antibody to describe the pattern of axonal degeneration 10 days post-unilateral C4 contusion in the rat. Setting University of Florida laboratory in Gainesville, USA. Methods Sprague Dawley rats received either a unilateral 150kdyne C4 contusion (n = 4 females, n = 5 males) or a laminectomy control surgery (n = 2 females, n = 3 males). Ten days following SCI or laminectomy, spinal cords and brainstems were processed for immunohistochemistry. Serial spinal cord and brainstem cross-sections were stained with the degeneration-specific NF-L antibody (MCA-6H63) and dual labeled with either an antibody against the C-terminus portion of NF-L (NF-L-Ct), to label healthy axons, or an antibody against amyloid precursor protein (APP), considered the current “gold standard” for identifying axonal injury. The pattern of ongoing axonal degeneration was assessed. Results Spinal cord and brainstem cross-sections from injured rats had punctate MCA-6H63 positive fibers with a pathological appearance, loss of anti-NF-L-Ct colabeling, and frequent colocalization with APP. Immunopositive fibers were abundant rostral and caudal to the lesion in white matter tracts that would be disrupted by the unilateral C4 contusion. This pattern of staining was not observed in control tissue. Conclusions The MCA-6H63 antibody labels degenerating axons following SCI and offers a tool to quantify axonal degeneration.

Nearly 17,000 new cases of spinal cord injuries (SCI) are diagnosed in the USA each year. Majority of these injuries involve the cervical spinal cord and result in significant impairment of ventilatory-related diaphragm activity. Subsequently, some of these patients are unable to maintain adequate ventilation and become dependent on mechanical ventilation, a situation associated with significant morbidity and mortality. We previously showed that trans-diaphragmatic pressures generated by the diaphragm during ventilatory (breathing) behaviors require the recruitment of only smaller phrenic motor neurons comprising fatigue resistant slow (type S) and fast (type FR) motor units. In contrast, higher force airway clearance behaviors of the diaphragm require recruitment of larger phrenic motor neurons comprising more fatigable fast motor units (type FInt and FF). Thus, fundamental size-dependent differences are expected in the neuroplasticity underlying recovery after SCI. Most cervical SCIs are incomplete, involving partial disruption of descending pre-motor excitatory drive from the medulla to the phrenic motor neuron pool, thereby causing complete or partial diaphragm paralysis. In recent studies, we found that unilateral C2 spinal hemisection (C2SH) impairs ipsilateral ventilatory-related diaphragm EMG activity which requires recruitment of smaller phrenic motor neurons, but there is little impact of C2SH on higher force airway clearance behaviors, which require recruitment of larger phrenic motor neurons. Accordingly, for smaller phrenic motor neurons, spared contralateral descending glutamatergic input provides an extant substrate for neuroplasticity and recovery of ventilatory behaviors. In this thesis, we examined density of glutamatergic terminals at phrenic motor neurons in a size dependent fashion and changes in presynaptic glutamatergic terminal density at phrenic motor neurons of varying size after C2SH. We previously found that glutamatergic NMDA receptor mRNA expression in phrenic motor neurons increases after C2SH. In studies presented in this thesis, we characterized expression of glutamatergic receptor type mRNA across phrenic motor neurons of varying sizes and quantified subsequent changes in glutamatergic receptor type mRNA expression after C2SH. Key findings of this thesis indicate size dependent differences in pre-synaptic glutamatergic innervation and post-synaptic glutamatergic receptor expression in phrenic motor neurons, such that, small phrenic motor neurons have a higher density of glutamatergic inputs and receptor expression compared to large phrenic motor neurons. Immediately following C2SH (by 3 days), there was absence of ipsilateral diaphragm EMG activity during eupnea. Following C2SH (by 3 and 7 days), there was a pronounced reduction in NMDAR mRNA expression in smaller phrenic motor neurons as well as a substantial reduction in glutamatergic synaptic input, but no change in AMPAR mRNA expression in small phrenic motor neurons. In contrast, AMPAR and NMDAR mRNA expression and glutamatergic synaptic input in larger phrenic motor neurons was unaffected. These results indicate a more pronounced impact of C2SH on smaller phrenic motor neurons. Subsequently by 21 days post-C2SH, we observed a marked increase in NMDAR mRNA expression in smaller phrenic motor neurons. These results are consistent with the involvement of glutamatergic synaptic transmission in the spontaneous recovery of ipsilateral diaphragm EMG activity after C2SH and highlight the heterogeneity in motor and cellular response within a muscle and motor neuron pool respectively following trauma.

Neurogenic bladder dysfunction causes urological complications and reduces the quality of life in persons with spinal cord injury (SCI). Glutamatergic signaling via AMPA receptors is fundamentally important to the neural circuits controlling bladder voiding. Ampakines are positive allosteric modulators of AMPA receptors that can enhance the function of glutamatergic neural circuits after SCI. We hypothesized that ampakines can acutely stimulate bladder voiding that has been impaired due to thoracic contusion SCI. Adult female Sprague Dawley rats received a unilateral contusion of the T9 spinal cord (n=10). Bladder function (cystometry) and coordination with the external urethral sphincter (EUS) were assessed five days post-SCI under urethane anesthesia. Data were compared to responses in spinal intact rats (n=8). The \"low impact\" ampakine CX1739 (5, 10, or 15 mg/kg) or vehicle (HPCD) was administered intravenously. The HPCD vehicle had no discernable impact on voiding. In contrast, following CX1739, the pressure threshold for inducing bladder contraction, voided volume, and the interval between bladder contractions were significantly reduced. These responses occurred in a dose-dependent manner. We conclude that modulating AMPA receptor function using ampakines can rapidly improve bladder voiding capability at sub-acute time points following contusion SCI. These results may provide a new and translatable method for therapeutic targeting of bladder dysfunction acutely after SCI.Neurogenic bladder dysfunction causes urological complications and reduces the quality of life in persons with spinal cord injury (SCI). Glutamatergic signaling via AMPA receptors is fundamentally important to the neural circuits controlling bladder voiding. Ampakines are positive allosteric modulators of AMPA receptors that can enhance the function of glutamatergic neural circuits after SCI. We hypothesized that ampakines can acutely stimulate bladder voiding that has been impaired due to thoracic contusion SCI. Adult female Sprague Dawley rats received a unilateral contusion of the T9 spinal cord (n=10). Bladder function (cystometry) and coordination with the external urethral sphincter (EUS) were assessed five days post-SCI under urethane anesthesia. Data were compared to responses in spinal intact rats (n=8). The \"low impact\" ampakine CX1739 (5, 10, or 15 mg/kg) or vehicle (HPCD) was administered intravenously. The HPCD vehicle had no discernable impact on voiding. In contrast, following CX1739, the pressure threshold for inducing bladder contraction, voided volume, and the interval between bladder contractions were significantly reduced. These responses occurred in a dose-dependent manner. We conclude that modulating AMPA receptor function using ampakines can rapidly improve bladder voiding capability at sub-acute time points following contusion SCI. These results may provide a new and translatable method for therapeutic targeting of bladder dysfunction acutely after SCI.