Vibrissae Movements Research Articles

Hypoxic Bone Mesenchymal Stem Cell-Derived Exosomes Direct Schwann Cells Proliferation, Migration, and Paracrine to Accelerate Facial Nerve Regeneration via circRNA_Nkd2/miR-214-3p/MED19 Axis.

Facial nerves have the potential for regeneration following injury, but this process is often challenging and slow. Schwann cells (SCs) are pivotal in this process. Bone mesenchymal stem cells (BMSC)-derived exosomes promote tissue repair through paracrine action, with hypoxic preconditioning enhancing their effects. The main purpose of this study was to determine whether hypoxia-preconditioned BMSC-derived exosomes (Hypo-Exos) exhibit a greater therapeutic effect on facial nerve repair/regeneration and reveal the mechanism. CCK-8, EdU, Transwell, and ELISA assays were used to evaluate the functions of Hypo-Exos in SCs. Histological analysis and Vibrissae Movements (VMs) recovery were used to evaluate the therapeutic effects of Hypo-Exos in rat model. circRNA array was used to identify the significantly differentially expressed exosomal circRNAs between normoxia-preconditioned BMSC-derived exosomes (Nor-Exos) and Hypo-Exos. miRDB, TargetScan, double luciferase assay, qRT-PCR and WB were used to predict and identify potential exosomal cirRNA_Nkd2-complementary miRNAs and its target gene. The function of exosomal circRNA_Nkd2 in facial nerve repair/regeneration was evaluated by cell and animal experiments. This study confirmed that Hypo-Exos more effectively promote SCs proliferation, migration, and paracrine function, accelerating facial nerve repair following facial nerve injury (FNI) compared with Nor-Exos. Furthermore, circRNA analysis identified significant enrichment of circRNA_Nkd2 in Hypo-Exos compared with Nor-Exos. Exosomal circRNA_Nkd2 positively regulates mediator complex subunit 19 (MED19) expression by sponging rno-miR-214-3p. Our results demonstrated a mechanism by which Hypo-Exos enhanced SCs proliferation, migration, and paracrine function and facial nerve repair and regeneration following FNI through the circRNA_Nkd2/miR-214-3p/Med19 axis. Hypoxic preconditioning is an effective and promising method for optimizing the therapeutic action of BMSC-derived exosomes in FNI.

Functional anatomy of mystacial active sensing in rats.

Rats' whisking motion and objects' palpation produce tactile signals sensed by mechanoreceptors at the vibrissal follicles. Rats adjust their whisking patterns to target information type, flow, and resolution, adapting to their behavioral needs and the changing environment. This coordination requires control over the activity of the mystacial pad's intrinsic and extrinsic muscles. Studies have relied on muscle recording and stimulation techniques to describe the roles of individual muscles. However, these methods lack the resolution to isolate the mystacial pad's small and compactly arranged muscles. Thus, we propose functional anatomy as a complementary approach for studying the individual and coordinated effects of the mystacial pad muscles on vibrissae movements. Our functional analysis addresses the kinematic measurements of whisking motion patterns recorded in freely exploring rats. Combined with anatomical descriptions of muscles and fascia elements of the mystacial pad in situ, we found: (1) the contributions of individual mystacial pad muscles to the different whisking motion patterns; (2) active touch by microvibrissae, and its underlying mechanism; and (3) dynamic position changes of the vibrissae pivot point, as determined by the movements of the corium and subcapsular fibrous mat. Finally, we hypothesize that each of the rat mystacial pad muscles is specialized for a particular function in a way that matches the architecture of the fascial structures. Consistent with biotensegrity principles, the muscles and fascia form a network of structural support and continuous tension that determine the arrangement and motion of the embedded individual follicles.

Cathelicidin-derived antiviral peptide inhibits herpes simplex virus 1 infection.

Herpes simplex virus 1 (HSV-1) is a widely distributed virus. HSV-1 is a growing public health concern due to the emergence of drug-resistant strains and the current lack of a clinically specific drug for treatment. In recent years, increasing attention has been paid to the development of peptide antivirals. Natural host-defense peptides which have uniquely evolved to protect the host have been reported to have antiviral properties. Cathelicidins are a family of multi-functional antimicrobial peptides found in almost all vertebrate species and play a vital role in the immune system. In this study, we demonstrated the anti-HSV-1 effect of an antiviral peptide named WL-1 derived from human cathelicidin. We found that WL-1 inhibited HSV-1 infection in epithelial and neuronal cells. Furthermore, the administration of WL-1 improved the survival rate and reduced viral load and inflammation during HSV-1 infection via ocular scarification. Moreover, facial nerve dysfunction, involving the abnormal blink reflex, nose position, and vibrissae movement, and pathological injury were prevented when HSV-1 ear inoculation-infected mice were treated with WL-1. Together, our findings demonstrate that WL-1 may be a potential novel antiviral agent against HSV-1 infection-induced facial palsy.

Morphofunctional regeneration by mesenchymal stem cell and IGF-1 inoculation in a model of facial nerve crush injury in rats.

To analyze the morphofunctional regeneration process of facial nerve injury in the presence of insulin-like growth factor-1 and mesenchymal stem cells. Fourteen Wistar rats suffered unilateral facial nerve crushing and were randomly divided into two groups. All received insulin-like growth factor-1 inoculation, but only half of the animals received an additional inoculation of mesenchymal stem cells. The animals were followed for 90 days and facial nerve regeneration was analyzed via spontaneous facial motor function tests and immunohistochemistry in the nerve motor nucleus. The group that received the growth factor and stem cells showed a statistically superior mean in vibrissae movements (p < 0.01), touch reflex (p = 0.05) and eye closure (p < 0.01), in addition to better immunohistochemistry reactivity. There was a statistically significant difference in the mean number of cells in the facial nerve nucleus between the experimental groups (p = 0.025), with the group that received the growth factor and stem cells showing the highest mean. The association between growth factor and stem cells potentiates the morphofunctional regeneration of the facial nerve, occurring faster and more effectively. 4, degree of recommendation C.

Mammalian facial muscles contain muscle spindles.

Muscle spindles are sensory receptors in skeletal muscle that provide information on muscle length and velocity of contraction. Previous studies noted that facial muscles lack muscle spindles, but recent reports indicate that the human platysma muscle and "buccal" muscles contain spindles. Mammalian facial muscles are active in social communication, vibrissa movement, and vocalizations, including human speech. Given these functions, we hypothesized that facial muscles contain muscle spindles, and we predicted that humans would have the greatest number, given the role our lips play in speech. We examined previously sectioned and stained (with H&E and trichrome stains) orbicularis oris (upper fibers) and zygomaticus (major) muscles across a broad phylogenetic range of mammalian species, spanning a wide distribution of body size and ecological niche, to assess the presence of muscle spindles. We also stained several sections with Sirius red to highlight the muscle spindle capsule. Our results indicate that mammalian facial muscles contain muscle spindles, supporting our hypothesis. Contrary to our prediction, though, humans (and other primates) had the lowest number of muscle spindles. We instead found that the carnivoran sample and the horse sample had the greatest number of spindles. Larger body size and nocturnality were also associated with a greater number of spindles. These results must be viewed with caution, though, as our sample size was small and there are critical mammalian taxa missing. Future work should use an expanded phylogenetic range of mammalian species to ascertain the role that phylogeny plays in muscle spindle presence and count.

Nicotinamide Adenine Dinucleotide Phosphate Oxidase 2 Expression and Effects of Alpha Lipoic Acid on Recovery in a Rat Model of Facial Nerve Injury.

Background: NOX2 (nicotinamide adenine dinucleotide phosphate oxidase 2), which is upregulated by a variety of neurodegenerative factors, is neuroprotective and capable of reducing detrimental aspects of pathology following ischemic and traumatic brain injury, as well as in chronic neurodegenerative disorders. The purpose of this study was to investigate NOX2 expression and the degree of functional recovery following different types of facial nerve injury and assess the effects of antioxidant intervention on nerve regeneration. Methods: A total of 40 mature (6-week-old) male Sprague-Dawley (SD) rats were used. After inducing facial injury (compression injury or cutting injury), we randomized rats into four groups: A, crushing injury only; B, crushing injury with alpha lipoic acid (ALA); C, axotomy only; and D, axotomy with ALA. Recovery from facial nerve injury was evaluated 4 and 14 days after injury by performing behavioral assessments (observational scale of vibrissae movement, modified scale of eye closing and blinking reflex) and measuring changes in NOX2 experimental/control ratio in the injured (left, experimental) facial nerve relative to that in the uninjured (right, control) facial nerve. Results: A comparison between groups according to the type of injury showed a higher NOX2 expression ratio in the axotomy group than in the crushing group (p < 0.001). Regardless of injury type, both groups that received an injection of ALA exhibited a trend toward a higher NOX2 expression ratio, although this difference reached statistical significance only in the axotomy group (p < 0.001). In behavioral assessments, overall behavioral test scores were significantly higher in the crushing injury group immediately after the injury compared with that in the axotomy group. Additionally, in behavioral tests conducted 4 days after the crushing injury, the group injected with ALA showed better results than the group without injection of ALA (p = 0.031). Conclusions: Our study showed that NOX2 expression trended higher with facial nerve injury, exhibiting a significant increase with cutting-type injury. Furthermore, intraperitoneally injection with ALA may be an efficient strategy for accelerating peripheral facial nerve recovery after a crushing injury.

Muscle-Nerve-Nerve Grafting Improves Facial Reanimation in Rats Following Facial Nerve Injury.

Nerve injury resulting in muscle paralysis from trauma or surgery is a major medical problem. Repair of such injuries with existing nerve grafting and reconstructive techniques often results in less than optimal outcomes. After previously demonstrating significant return of function using muscle-nerve-muscle (MNM) grafting in a rat facial nerve model, this study compares a variant of the technique, muscle-nerve-nerve (MNN) neurotization to MNM and interposition (IP) nerve grafting. Thirty male rats were randomized into four groups (1) control with no intervention, (2) repair with IP grafts, (3) MNM grafts and (4) MNN grafts. All groups had the buccal and marginal mandibular branches of the right facial nerve resected. Return of vibrissae movement, orientation, and snout symmetry was measured over 16 weeks. Functional recovery and muscle atrophy were assessed and quantified. All interventions resulted in significant improvement in vibrissae movement and orientation as compared to the control group (p < 0.05). The MNM and MNN groups had significantly less time to forward vibrissae movement as compared to controls (p < 0.05), and a large number of animals in the MNN group had coordinated vibrissae movement at 16 weeks. MNN and IP grafts retained significantly more muscle mass as compared to control (p < 0.05). Thus, MNN grafting is a promising adjuvant or alternative technique for reanimation for patients with unilateral peripheral nerve injury who are not candidates for primary neurorrhaphy.

Neuroprotective Effect of Brimonidine against Facial Nerve Crush Injury in Rats via Suppressing GFAP/PAF Activation and Neuroinflammation

Objective: This study aimed to investigate the potential neuroprotective action of brimonidine against facial nerve crush injury in rats and the possible underlying mechanisms. Methods: Sixty Wistar adult rats were randomly and equally divided into 3 groups: 40 rats underwent unilateral facial nerve crush injury and were administered with either saline (intraperitoneal, n = 20) or brimonidine 1 mg/kg/day (intraperitoneal, n = 20) for 5 consecutive days. Functional and electromyographic recovery was recorded postoperatively. The facial nucleus of 5 mice in each group was analyzed for mRNA expression levels of GFAP, PAF, NT-4, P75^NTR, NF-κB, TNF-α, IL-6, and α₂-ARs by qRT-PCR. Results: Brimonidine promoted the recovery of vibrissae movement, eyelid closure, and electrophysiological function in a rat model of nerve crush injury. Hematoxylin and eosin staining and electron microscopy showed significant recovery of Schwann cells and axons in the brimonidine group. Brimonidine attenuated the crush-induced upregulation in GFAP and PAF mRNA (p < 0.05), as well as enhanced the mRNA levels of NT-4 and P75^NTR (p < 0.05), while decreased the expression of NF-κB, TNF-α and IL-6 (p < 0.05). Conclusions: Brimonidine could promote the recovery of facial nerve crush injury in rats via suppressing of GFAP/PAF activation and neuroinflammation and increasing neurotrophic factors. Brimonidine may be apromising candidate agent for the treatment of facial nerve injury.

Facial nerve regeneration using silicone conduits filled with ammonia-functionalized graphene oxide and frankincense-embedded hydrogel

BackgroundSilicone tube (ST) conduits have been accepted as a therapeutic alternative to direct nerve suturing in the treatment of nerve injuries; however, the search for optimal adjuncts to maximize the outcomes is still ongoing. Frankincense (Fr) and graphene oxide (GO) have both been cited as neuroregenerative compounds in the literature. This study assesses the efficacy of these materials using a ST conduit in a rat facial nerve motor neuron axotomy model, distal to the stylomastoid foramen.MethodsAmmonia-functionalized graphene oxide (NH2-GO) and/or Fr extract were embedded in a collagen-chitosan hydrogel and were injected inside a ST. The ST was inserted in the gap between the axotomized nerve stumps. Return of function in eye closure, blinking reflex, and vibrissae movements were assessed and compared to control groups through 30 days following axotomy. To assess the histological properties of regenerated nerves, biopsies were harvested distal to the axotomy site and were visualized through light and fluorescence microscopy using LFB and anti-MBP marker, respectively.ResultsThere was no significant difference in behavioral test results between groups. Histological analysis of the nerve sections revealed increased number of regenerating axons and mean axon diameter in NH2-GO group and decreased myelin surface area in Fr group. Using both NH2-GO and Fr resulted in increased number of regenerated axons and myelin thickness compared to the hydrogel group.ConclusionsThe findings suggest a synergistic effect of the substances above in axon regrowth, notably in myelin regeneration, where Fr supposedly decreases myelin synthesis.

Study on facial nerve activation pathway based on nanometric magnetic beads

This study was conducted to investigate the mechanism of facial nerve recovery through Toll-like receptor 2 (TLR2)/nuclear factor kappa B (NF-κB) after facial nerve trunk damage. Facial nerve surgery was performed on rats to establish a paralyzed animal model with or without intraperitoneal (i.p.) injection of Pam3CSK4 (TLR2 agonist). All nucleic acids were extracted using nanometer magnetic beads. At 1, 4, 7, 10, 13, and 16 days after the surgery, the score of the blink reflex, the motion of vibrissae, and the motion of nose were analyzed to assess the function of facial nerves. Evaluated using transmission electron microscopy (TEM) and immunofluorescence staining (IF), Morphological changes in facial nerve and brainstem were analyzed. The expressions of TLR2 and NF-κB p65 in the brainstem were detected by quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR), western blotting, and IF. TEM revealed that the facial nerve fiber diameter was shortened, and the organelle was swollen and demyelinated in the operation group. The IF results revealed that the expressions of NF-κB p65 and TLR2 in the brainstem were increased significantly in the operation group together with the control group. RT-PCR demonstrated that the mRNA expressions of TLR2 and NF-κB p65 in the brainstem were low in the control group, as well as in the sham group, whereas there were significant increases in the mRNA expressions of TLR2 and NF-κB p65 in the operation group. Western blotting revealed a significant increase in the expression of TLR2 protein after the surgery compared to that in the control group. After subjecting the rats to facial nerve surgery and i.p. injection of Pam3CSK4, the protein expressions of TLR2 and NF-κB p65 were upregulated dramatically in the Pam3CSK4-operation group compared to that in the control group and were also significantly increased than those in the operation group. Both facial nerve dysfunction caused due to facial nerve surgery (exacerbated by co-treatment with Pam3CSK4) and the expressions of NF-κB p65 and TLR2 were increased significantly. TLR2 might be an innovative gene target and a novel option for the clinical applications of facial paralysis immunotherapy.

Interaction between muscles and fascia in the mystacial pad of whisking rodents.

In whisking rodents, the mystacial pad is supplied with vibrissae and contains a collagenous skeleton that is a part of the snout fascia. The collagenous skeleton is composed of three interconnected layers: superficial, deep spongy mesh and subcapsular fibrous mat. We found that the first two layers contain diverse fascial structures, such as sheets of subcutaneous connective tissue, tendons, ligaments and follicular capsules which transmit muscle efforts to vibrissae and are thus involved in whisking. Subcapsular fibrous mat is built of oriented rostro-caudal wavy fibrils. It maintains spatial arrangement of whisker follicles, provides a quick response to deformation and connects entire mystacial pad to the skull. To move vibrissae, the forces of intrinsic muscles are applied directly to the capsules of the vibrissa follicles, whereas the forces of extrinsic muscles are applied to other parts of the collagenous skeleton, which transmit the forces to the capsules. According to the spatial distribution and anchoring sites of the muscles and fascia, extrinsic muscles provide vibrissa protraction or retraction by pulling the superficial layer of the collagenous skeleton rostral or caudal, respectively. Vibrissae can be also retracted when the efforts of extrinsic muscles are applied to the subcapsular fibrous mat. When the muscles relax, fascial structures return the vibrissae to their resting position. The deep spongy layer encompasses vibrissal follicles providing a uniform distribution of stresses and strains during whisking. In the mystacial pad, fascia is a dominant type of tissue that maintains the integrity of the vibrissa motor plant, translates muscular momentum to the vibrissae, and plays a role in vibrissae movements.

Distinct neurotoxic effects of select local anesthetics on facial nerve injury and recovery.

Local anesthetic toxicity has been well-documented to cause neuronal injury, death, and dysfunction, particularly in a susceptible nerve. To determine whether select local anesthetics affect neuron survival and/or functional recovery of an injured nerve. This report describes 6 separate experiments that test immediate or delayed application of local anesthetics in 3 nerve injury models. Adult C57/black6 male mice underwent a facial nerve sham, transection, or crush injury. Local anesthetic or saline was applied to the facial nerve at the time of injury (immediate) or 1 day after injury (delayed). Average percent facial motoneuron (FMN) survival was evaluated four-weeks after injury. Facial nerve regeneration was estimated by observing functional recovery of eye blink reflex and vibrissae movement after facial nerve crush injury. FMN survival after: transection + immediate treatment with ropivacaine (54.8%), bupivacaine (63.2%), or tetracaine (66.9%) was lower than saline (85.5%) and liposomal bupivacaine (85.0%); crush + immediate treatment with bupivacaine (92.8%) was lower than saline (100.7%) and liposomal bupivacaine (99.3%); sham + delayed treatment with bupivacaine (89.9%) was lower than saline (96.6%) and lidocaine (99.5%); transection + delayed treatment with bupivacaine (67.3%) was lower than saline (78.4%) and liposomal bupivacaine (77.6%); crush + delayed treatment with bupivacaine (85.3%) was lower than saline (97.9%) and lidocaine (96.0%). The average post-operative time for mice to fully recover after: crush + immediate treatment with bupivacaine (12.83 days) was longer than saline (11.08 days) and lidocaine (10.92 days); crush + delayed treatment with bupivacaine (16.79 days) was longer than saline (12.73 days) and lidocaine (11.14 days). Our data demonstrate that some local anesthetics, but not all, exacerbate motoneuron death and delay functional recovery after a peripheral nerve injury. These and future results may lead to clinical strategies that decrease the risk of neural deficit following peripheral nerve blocks with local anesthetics.

Dysfunction of cortical GABAergic neurons leads to sensory hyper-reactivity in a Shank3 mouse model of ASD.

Hyper-reactivity to sensory input is a common and debilitating symptom in individuals with autism spectrum disorders (ASD), but the neural basis underlying sensory abnormality is not completely understood. Here we examined the neural representations of sensory perception in the neocortex of a Shank3B−/− mouse model of ASD. Male and female Shank3B−/− mice were more sensitive to relatively weak tactile stimulation in a vibrissa motion detection task. In vivo population calcium imaging in vibrissa primary somatosensory cortex (vS1) revealed increased spontaneous and stimulus-evoked firing in pyramidal neurons but reduced activity in interneurons. Preferential deletion of Shank3 in vS1 inhibitory interneurons led to pyramidal neuron hyperactivity and increased stimulus sensitivity in the vibrissa motion detection task. These findings provide evidence that cortical GABAergic interneuron dysfunction plays a key role in sensory hyper-reactivity in a Shank3 mouse model of ASD and identify a potential cellular target for exploring therapeutic interventions.

A Mouse Model of Dysphagia After Facial Nerve Injury.

Dysphagia is common following facial nerve injury; however, research is sparse regarding swallowing-related outcomes and targeted treatments. Previous animal studies have used eye blink and vibrissae movement as measures of facial nerve impairment and recovery. The purpose of this study was to create a mouse model of facial nerve injury that results in dysphagia to enhance translational research outcomes. Prospective animal study. Twenty C57BL/6J mice underwent surgical transection of the main trunk (MT) (n = 10) or marginal mandibular branch (MMB) (n = 10) of the left facial nerve. Videofluoroscopic swallow study (VFSS) assays for drinking and eating were performed at baseline and 14 days postsurgery to quantify several deglutition-related outcome measures. VFSS analysis revealed that MT transection resulted in significantly slower lick and swallow rates during drinking (P ≤ .05) and significantly slower swallow rates and longer inter-swallow intervals during eating (P ≤ .05), congruent with oral and pharyngeal dysphagia. After MMB transection, these same VFSS metrics were not statistically significant (P > .05). The main finding of this study was that transection of the facial nerve MT leads to oral and pharyngeal stage dysphagia in mice; MMB transection does not. These results from mice provide novel insight into specific VFSS metrics that may be used to characterize dysphagia in humans following facial nerve injury. We are currently using this surgical mouse model to explore promising treatment modalities such as electrical stimulation to hasten recovery and improve outcomes following various iatrogenic and idiopathic conditions affecting the facial nerve. NA Laryngoscope, 131:17-24, 2021.

Effect of the local application of stem cells on repairing facial nerve defects: a systematic review

To systematically evaluate the repairing effect of stem cells on facial nerve defects. Articles regarding the regenerating effect of stem cells on facial nerves in animals were collected from the databases of Pubmed, Cochrane Library, Web of Science, Embase, Scopus, and CBM. Two professionals independently completed the article screening, data extraction, and bias risk assessment. RevMan 5.3 and random-effects models were used for the statistical analysis, and the results were presented in the form of mean differences (MD) with a 95%CI. The results of functional evaluation (vibrissae movement, facial paralysis) and histological evaluation (density of myelinated fibers, diameter of fibers, thickness of myelin sheath, G ratio) of facial nerve were Meta-analyzed. A total of 4 614 articles were retrieved from the 6 databases, and 15 of these articles were included in the Meta-analysis. For vibrissae movement and facial paralysis, the stem cell group scored significantly higher than the non-stem cell group (P<0.05). The density of myelinated fibers and thickness of the myelin sheath in the stem cell group were higher than those in the non-stem cell group (P<0.05). The G ratio in the stem cell group was smaller than that in the non-stem cell group (P=0.001). There was no significant difference in fiber diameter (P=0.08). Stem cells have potential in promoting facial nerve regeneration.

Criteria for assessing peripheral nerve injury. Behavioral and functional assessment in non-operated Wistar rats.

PurposeTo evaluate the normality pattern in functional tests of peripheral nerves.MethodsSixty female and sixty male Wistar rats were submitted to vibrissae movement and nictitating reflex for facial nerve; grooming test and grasping test for brachial plexus; and walking tracking test and horizontal ladder test for lumbar plexus. The tests were performed separately, with an interval of seven days between each.ResultsAll animals showed the best score in vibrissae movement, nictitating reflex, grooming test, and horizontal ladder test. The best score was acquired for the first time in more than 90% of animals. The mean of strength on the grasping test was 133.46±12.08g for the right and 121.74±8.73g for the left anterior paw. There was a difference between the right and left sides. There was no difference between the groups according to sex. There is no statistical difference comparing all functional indexes between sex, independent of the side analyzed. The peroneal functional index showed higher levels than the sciatic and tibial functional index on both sides and sex.ConclusionsThe behavioral and functional assessment of peripheral nerve regeneration are low-cost, easy to perform, and reliable tests. However, they need to be performed by experienced researchers to avoid misinterpretation.

Platelet-rich plasma can release nutrient factors to promote facial nerve crush injury recovery in rats.

Objectives:To evaluate the effects of platelet-rich plasma (PRP) on promoting neural repair after facial nerve compression in rats and the mechanism by which this occurs.Methods:Adult Wistar rats (n=100) were divided into 3 groups: healthy controls, surgery-only, and surgery+PRP groups. The rats underwent nerve crush injury to establish a facial palsy model. The blood from the rats was used to prepare the PRP for application to the injury site. The evaluation methods included vibrissae movement, eyelid closure, and electrophysiology. Electron microscopy, immunohistochemistry, and real-time polymerase chain reaction (PCR) were used to detect nutrient factor expression in the brain and nerve sections. This study was conducted in Shandong Provincial ENT Hospital Affiliated to Shandong University, Shandong, China between January and November 2018.Results:Platelet-rich plasma promotes the recovery of vibrissae movement, eyelid closure, and electrophysiological function in a rat model of nerve crush injury. Hematoxylin and eosin staining, toluidine blue staining, and electron microscopy showed significant recovery of Schwann cells and axons in the PRP group. Polymerase chain reaction results showed that PRP releases growth factors, which include nerve growth factor and brain-derived neurotrophic factor. Immunohistochemistry also demonstrated higher levels of S-100 protein expression in the PRP group compared to the other groups.Conclusions:Platelet-rich plasma releases nutrient factors in the brainstem, and the use of PRP can promote injury recovery.

Electroacupuncture promotes peripheral nerve regeneration after facial nerve crush injury and upregulates the expression of glial cell-derived neurotrophic factor.

The efficacy of electroacupuncture in the treatment of peripheral facial paralysis is known, but the specific mechanism has not been clarified. Glial cell-derived neurotrophic factor (GDNF) has been shown to protect neurons by binding to N-cadherin. Our previous results have shown that electroacupuncture could increase the expression of N-cadherin mRNA in facial neurons and promote facial nerve regeneration. In this study, the potential mechanisms by which electroacupuncture promotes nerve regeneration were elucidated through assessing the effects of electroacupuncture on GDNF and N-cadherin expression in facial motoneurons of rabbits with peripheral facial nerve crush injury. New Zealand rabbits were randomly divided into a normal group (normal control, n = 21), injury group (n = 45) and electroacupuncture group (n = 45). Model rabbits underwent facial nerve crush injury only. Rabbits in the electroacupuncture group received facial nerve injury, and then underwent electroacupuncture at Yifeng (TE17), Jiache (ST6), Sibai (ST2), Dicang (ST4), Yangbai (GB14), Quanliao (SI18), and Hegu (LI4; only acupuncture, no electrical stimulation). The results showed that in behavioral assessments, the total scores of blink reflex, vibrissae movement, and position of apex nasi, were markedly lower in the EA group than those in the injury group. Hematoxylin-eosin staining of the right buccinator muscle of each group showed that the cross-sectional area of buccinator was larger in the electroacupuncture group than in the injury group on days 1, 14 and 21 post-surgery. Toluidine blue staining of the right facial nerve tissue of each group revealed that on day 14 post-surgery, there was less axonal demyelination and fewer inflammatory cells in the electroacupuncture group compared with the injury group. Quantitative real time-polymerase chain reaction showed that compared with the injury group, N-cadherin mRNA levels on days 4, 7, 14 and 21 and GDNF mRNA levels on days 4, 7 and 14 were significantly higher in the electroacupuncture group. Western blot assay displayed that compared with the injury group, the expression of GDNF protein levels on days 7, 14 and 21 were significantly upregulated in the electroacupuncture group. The histology with hematoxylin-eosin staining and Nissl staining of brainstem tissues containing facial neurons in the middle and lower part of the pons exhibited that on day 7 post-surgery, there were significantly fewer apoptotic neurons in the electroacupuncture group than in the injury group. By day 21, there was no significantly difference in the number of neurons between the electroacupuncture and normal groups. Taken together, these results have confirmed that electroacupuncture promotes regeneration of peripheral facial nerve injury in rabbits, inhibits neuronal apoptosis, and reduces peripheral inflammatory response, resulting in the recovery of facial muscle function. This is achieved by up-regulating the expression of GDNF and N-cadherin in central facial neurons.

A Descending Circuit Derived From the Superior Colliculus Modulates Vibrissal Movements.

The superior colliculus (SC) is an essential structure for the control of eye movements. In rodents, the SC is also considered to play an important role in whisking behavior, in which animals actively move their vibrissae (mechanosensors) to gather tactile information about the space around them during exploration. We investigated how the SC contributes to vibrissal movement control. We found that when the SC was unilaterally lesioned, the resting position of the vibrissae shifted backward on the side contralateral to the lesion. The unilateral SC lesion also induced an increase in the whisking amplitude on the contralateral side. To explore the anatomical basis for SC involvement in vibrissal movement control, we then quantitatively evaluated axonal projections from the SC to the brainstem using neuronal labeling with a virus vector. Neurons of the SC mainly sent axons to the contralateral side in the lower brainstem. We found that the facial nucleus received input directly from the SC, and that the descending projections from the SC also reached the intermediate reticular formation and pre-Bötzinger complex, which are both considered to contain neural oscillators generating rhythmic movements of the vibrissae. Together, these results indicate the existence of a neural circuit in which the SC modulates vibrissal movements mainly on the contralateral side, via direct connections to motoneurons, and via indirect connections including the central pattern generators.

Projection Patterns of Corticofugal Neurons Associated with Vibrissa Movement.

Rodents actively whisk their vibrissae, which, when they come in contact with surrounding objects, enables rodents to gather spatial information about the environment. Cortical motor command of whisking is crucial for the control of vibrissa movement. Using awake and head-fixed rats, we investigated the correlations between axonal projection patterns and firing properties in identified layer 5 neurons in the motor cortex, which are associated with vibrissa movement. We found that cortical neurons that sent axons to the brainstem fired preferentially during large-amplitude vibrissa movements and that corticocallosal neurons exhibited a high firing rate during small vibrissa movements or during a quiet state. The differences between these two corticofugal circuits may be related to the mechanisms of motor-associated information processing.