Vagus nerve stimulation alleviates cardiac dysfunction and inflammatory markers during heart failure in rats.

Vagus nerve stimulation (VNS) is under clinical investigation as a therapy for heart failure with reduced ejection fraction (HFrEF). This study aimed to investigate its therapeutic effects on three main components of heart failure: cardiac function, cardiac remodeling and central neuroinflammation using a pressure overload (PO) rat model. Male Sprague-Dawley rats were divided into four groups: PO, PO + VNS, PO + VNS sham, and controls. All rats, except controls, underwent a PO surgery to constrict the thoracic aorta (~50 %) to induce HFrEF. Open loop VNS therapy was continuously administered to PO + VNS rats at 20 Hz, 1.0 mA for 60 days. Evaluation of cardiac function and structure via echocardiograms showed decreases in stroke volume and relative ejection fraction and increases in the internal diameter of the left ventricle during systole and diastole in PO rats (p < 0.05). However, these PO-induced adverse changes were alleviated with VNS therapy. Additionally, PO rats exhibited significant increases in myocyte cross sectional areas indicating hypertrophy, along with significant increases in myocardial fibrosis and apoptosis, all of which were reversed by VNS therapy (p < 0.05). Furthermore, VNS mitigated microglial activation in two central autonomic nuclei: the paraventricular nucleus of the hypothalamus and locus coeruleus. These findings demonstrate that when VNS therapy is initiated at an early stage of HFrEF progression (<10 % reduction in relative ejection fraction), the supplementation of vagal activity is effective in restoring multi organ homeostasis in a PO model.

Transcutaneous and Direct Electrical Stimulation of Mouse Sciatic Nerve Accelerates Functional Recovery After Nerve Transection and Immediate Repair.

BACKGROUND: Electrical stimulation can accelerate peripheral nerve regeneration after injury and repair. Clinically, direct electrical stimulation (DES) may involve longer operating times, increasing risks of perioperative complications. Transcutaneous electrical stimulation (TCES) is a noninvasive alternative. In this study, we investigate how transcutaneous and DES compare for accelerating functional nerve recovery in a mouse sciatic nerve model. METHODS: Twenty-eight mice were divided into sham (n = 4), axotomy (n = 8), DES (n = 8), and TCES (n = 8) groups. After sciatic nerve transection and repair, the proximal nerve was subjected to DES or TCES at 20 Hz for 1 hour. Sciatic functional index was measured before the injury, and at weeks 1, 2, 4, 6, 8, 10, and 12 by walking-track analysis. Electrophysiological measures were taken at week 12. RESULTS: Kinematic studies showed significant improvement from the 8th week to the 12th week for both electrical stimulation groups compared with the axotomy group (P < 0.05), with no difference between the electrical stimulation groups. At the 12th week, both DES and TCES groups had significantly faster average conduction velocity than the axotomy group. CONCLUSIONS: Functional recovery was significantly better from 8 weeks onward in mice receiving either DES or TCES stimulation when compared with axotomy and repair alone. Transcutaneous electrical stimulation is a minimally invasive alternative treatment for accelerating functional recovery after peripheral nerve injury.

Heterozygous Dcc Mutant Mice Have a Subtle Locomotor Phenotype.

Axon guidance receptors such as deleted in colorectal cancer (DCC) contribute to the normal formation of neural circuits, and their mutations can be associated with neural defects. In humans, heterozygous mutations in DCC have been linked to congenital mirror movements, which are involuntary movements on one side of the body that mirror voluntary movements of the opposite side. In mice, obvious hopping phenotypes have been reported for bi-allelic Dcc mutations, while heterozygous mutants have not been closely examined. We hypothesized that a detailed characterization of Dcc heterozygous mice may reveal impaired corticospinal and spinal functions. Anterograde tracing of the Dcc+/- motor cortex revealed a normally projecting corticospinal tract, intracortical microstimulation (ICMS) evoked normal contralateral motor responses, and behavioral tests showed normal skilled forelimb coordination. Gait analyses also showed a normal locomotor pattern and rhythm in adult Dcc+/- mice during treadmill locomotion, except for a decreased occurrence of out-of-phase walk and an increased duty cycle of the stance phase at slow walking speed. Neonatal isolated Dcc+/- spinal cords had normal left-right and flexor-extensor coupling, along with normal locomotor pattern and rhythm, except for an increase in the flexor-related motoneuronal output. Although Dcc+/- mice do not exhibit any obvious bilateral impairments like those in humans, they exhibit subtle motor deficits during neonatal and adult locomotion.

Spinal cord injury modulates the lung inflammatory response in mechanically ventilated rats: a comparative animal study.

Mechanical ventilation (MV) is widely used in spinal injury patients to compensate for respiratory muscle failure. MV is known to induce lung inflammation, while spinal cord injury (SCI) is known to contribute to local inflammatory response. Interaction between MV and SCI was evaluated in order to assess the impact it may have on the pulmonary inflammatory profile. Sprague Dawley rats were anesthetized for 24 h and randomized to receive either MV or not. The MV group included C4-C5 SCI, T10 SCI and uninjured animals. The nonventilated (NV) group included T10 SCI and uninjured animals. Inflammatory cytokine profile, inflammation related to the SCI level, and oxidative stress mediators were measured in the bronchoalveolar lavage (BAL). The cytokine profile in BAL of MV animals showed increased levels of TNF-α, IL-1ß, IL-6 and a decrease in IL-10 (P = 0.007) compared to the NV group. SCI did not modify IL-6 and IL-10 levels either in the MV or the NV groups, but cervical injury induced a decrease in IL-1ß levels in MV animals. Cervical injury also reduced MV-induced pulmonary oxidative stress responses by decreasing isoprostane levels while increasing heme oxygenase-1 level. The thoracic SCI in NV animals increased M-CSF expression and promoted antioxidant pulmonary responses with low isoprostane and high heme oxygenase-1 levels. SCI shows a positive impact on MV-induced pulmonary inflammation, modulating specific lung immune and oxidative stress responses. Inflammation induced by MV and SCI interact closely and may have strong clinical implications since effective treatment of ventilated SCI patients may amplify pulmonary biotrauma.

Progressive disorganization of paranodal junctions and compact myelin due to loss of DCC expression by oligodendrocytes.

Paranodal axoglial junctions are critical for maintaining the segregation of axonal domains along myelinated axons; however, the proteins required to organize and maintain this structure are not fully understood. Netrin-1 and its receptor Deleted in Colorectal Cancer (DCC) are proteins enriched at paranodes that are expressed by neurons and oligodendrocytes. To identify the specific function of DCC expressed by oligodendrocytes in vivo, we selectively eliminated DCC from mature myelinating oligodendrocytes using an inducible cre regulated by the proteolipid protein promoter. We demonstrate that DCC deletion results in progressive disruption of the organization of axonal domains, myelin ultrastructure, and myelin protein composition. Conditional DCC knock-out mice develop balance and coordination deficits and exhibit decreased conduction velocity. We conclude that DCC expression by oligodendrocytes is required for the maintenance and stability of myelin in vivo, which is essential for proper signal conduction in the CNS.

Atorvastatin is beneficial for muscle reinnervation after complete sciatic nerve section in rats.

Nerve regeneration and functional recovery are often incomplete after peripheral neurotmetic lesion. Atorvastatin has been shown to be neuroprotective after transient ischaemia or traumatic injury. The aim of this study was to establish if systemic administration of Atorvastatin could improve functional muscle reinnervation after complete sciatic nerve section. Sixteen female Sprague-Dawley rats were used in this study. After a complete right sciatic nerve section, end-to-end microsuture repair was performed and fibrin glue was added. Three groups were studied: (1) sutures (S) + fibrin glue (F) only + saline administration for 14 days; (2) S+F+Atorvastatin administration for 14 days; and (3) uninjured nerve. Five months later, the sciatic nerve and the gastrocnemius muscle were isolated to perform in vivo electrophysiological measurements. Better kinematics was observed in atorvastatin-treated rats 5 months after its administration. Indeed, a larger excursion of the hip-ankle-toe angle during walking was observed. This effect was associated with the preservation of electromyographic activity (2.91 mV vs 0.77 mV) and maximal muscle force (85.1 g vs 28.6 g) on stimulation of the proximal nerve section. Five months after a neurotmetic lesion, the recovery is incomplete when using suture and fibrin glue only. Furthermore, the systemic administration of Atorvastatin for 14 days after lesion was beneficial in improving locomotion capability associated with the re-establishment of muscle strength and EMG activity.

Most effective adjuvant treatments after surgery in peripheral nerve laceration: Systematic review of the literature on rodent models.

Surgical repair alone does not lead to satisfactory recovery after nerve laceration injury, yet no adjuvant clinical treatments are available. The goal of this review is to systematically survey all adjuvant treatments after surgery investigated in rat and mouse models. Both PubMed and Embase were explored with a systematic bibliographic search algorithm. Inclusion criteria consisted of treatments applied to rats or mice after complete transection and microsurgical repair of lower-limb motor or mixed nerves. Effect size statistics enabled numerical comparison between outcomes of treated and untreated animals and ranked the best treatments. 1,553 articles were found according to our search strategies, and 22 of them corresponded to our pre-defined inclusion criteria. After data extraction and analysis, the top 3 adjuvant strategies in terms of combined average effect size were citicoline, neurotrophin-4, and nitric oxide synthesis inhibitor, with values of 5.52, 5.14 and 4.08, respectively. Definitive treatment comparison was difficult due to the lack of uniformity in outcome evaluation in the experiments performed. Animal studies, comparing treatments administered within the same experimental protocol, are needed to truly assess efficiency and to provide solid recommendations for future clinical investigation.

The Timed Up and Go test is an early predictor of functional outcome after hemiarthroplasty for femoral neck fracture.

BACKGROUND: The ability to predict the long-term physical function and prognosis of hip fracture patients during the early postoperative period is essential for surgeons and physical therapists as well as for patients and their families. The purpose of this study was to determine whether early functional assessment correlated with and/or predicted long-term function after surgery to treat a displaced femoral neck fracture. METHODS: Sixty-two patients undergoing hemiarthroplasty for a displaced femoral neck fracture were evaluated prospectively; a minimum follow-up of two years was required. Validated functional assessments, including the Lower Extremity Measure and the Timed Up and Go test, were utilized, and scores were analyzed with respect to patient baseline data. RESULTS: The functional level of patients decreased significantly after the injury, with the mean Lower Extremity Measure score decreasing from 87.7 to 62.4 and the need for a walking aid increasing from 36% to 54% at two years postoperatively (p < 0.05 for both). The Timed Up and Go test scores at four days and three weeks postoperatively were significantly higher in patients who needed a walking aid at two years compared with independently walking patients (p < 0.05). Receiver operating characteristic curve analysis of the Timed Up and Go test scores revealed that the optimal threshold for predicting the need for a walking aid at two years was fifty-eight seconds at four days postoperatively and twenty-six seconds at three weeks. Also, the need for a walking aid at two years was ninetyfold higher when the Timed Up and Go test score at three weeks postoperatively exceeded the twenty-six seconds threshold. CONCLUSIONS: The Timed Up and Go test was an early clinical indicator of future physical function in patients with a hip fracture treated with hemiarthroplasty. Innovative clinical approaches to anticipate future function will contribute to increasing the efficiency of overall management of this growing set of patients.

Rolipram attenuates acute oligodendrocyte death in the adult rat ventrolateral funiculus following contusive cervical spinal cord injury.

Rolipram, an inhibitor of phosphodiesterase 4 (PDE4) proteins that hydrolyze cAMP, increases axonal regeneration following spinal cord injury (SCI). Recent evidence indicate that rolipram also protects against a multitude of apoptotic signals, many of which are implicated in secondary cell death post-SCI. In the present study, we used immunohistochemistry and morphometry to determine potential spinal cord targets of rolipram and to test its protective potential in rats undergoing cervical spinal cord contusive injury. We found that 3 PDE4 subtypes (PDE4A, B, D) were expressed by spinal cord oligodendrocytes. OX-42 immunopositive microglia only expressed the PDE4B subtype. Oligodendrocyte somata were quantified within the cervical ventrolateral funiculus, a white matter region critical for locomotion, at varying time points after SCI in rats receiving rolipram or vehicle treatments. We show that rolipram significantly attenuated oligodendrocyte death at 24 h post-SCI continuing through 72 h, the longest time point examined. These results demonstrate for the first time that spinal cord glial cells express PDE4 subtypes and that the PDE4 inhibitor rolipram protects oligodendrocytes from secondary cell death following contusive SCI. They also indicate that further investigations into neuroprotection and axonal regeneration with rolipram are warranted for treating SCI.

Passive exercise and fetal spinal cord transplant both help to restore motoneuronal properties after spinal cord transection in rats.

Spinal cord transection influences the properties of motoneurons and muscles below the lesion, but the effects of interventions that conserve muscle mass of the paralyzed limbs on these motoneuronal changes are unknown. We examined the electrophysiological properties of rat lumbar motoneurons following spinal cord transection, and the effects of two interventions shown previously to significantly attenuate the associated hindlimb muscle atrophy. Adult rats receiving a complete thoracic spinal cord transection (T-10) were divided into three groups receiving: (1) no further treatment; (2) passive cycling exercise for 5 days/week; or (3) acute transplantation of fetal spinal cord tissue. Intracellular recording of motoneurons was carried out 4-5 weeks following transection. Transection led to a significant change in the rhythmic firing patterns of motoneurons in response to injected currents, as well as a decrease in the resting membrane potential and spike trigger level. Transplants of fetal tissue and cycling exercise each attenuated these changes, the latter having a stronger effect on maintenance of motoneuron properties, coinciding with the reported maintenance of structural and biochemical features of hindlimb muscles. The mechanisms by which these distinct treatments affect motoneuron properties remain to be uncovered, but these changes in motoneuron excitability are consistent with influences on ion conductances at or near the initial segment. The results may support a therapeutic role for passive limb manipulation and transplant of stem cells in slowing the deleterious responses of motoneurons to spinal cord injury, such that they remain more viable for subsequent alternative strategies.

Chitosan-DNA nanoparticles as non-viral vectors in gene therapy: strategies to improve transfection efficacy.

Currently, the major drawback of gene therapy is the gene transfection rate. The two main types of vectors that are used in gene therapy are based on viral or non-viral gene delivery systems. The viral gene delivery system shows a high transfection yield but it has many disadvantages, such as oncogenic effects and immunogenicity. However, cationic polymers, like chitosan, have potential for DNA complexation and may be useful as non-viral vectors for gene therapy applications. Chitosan is a natural non-toxic polysaccharide, it is biodegradable and biocompatible, and protects DNA against DNase degradation and leads to its condensation. The objective of this paper was to summarize the state of the art in gene therapy and particularly the use of chitosan to improve the transfection efficiency in vivo and in vitro.