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BACKGROUND: Preovulatory gonadotropin-releasing hormone and luteinizing hormone (LH) surges depend on activation of estrogen-inducible progesterone receptors (PRs) in the hypothalamus. Although testosterone treatment can suppress LH secretion under some circumstances, how androgens affect the release of preovulatory hormone surges, and the cellular mechanisms by which androgens exert any such effects, remains unknown. OBJECTIVE: This study examined the hypothesis that testosterone can block the release of estrogen-induced gonadotropin surges via attenuation of estrogen's ability to induce PRs in the preoptic area (POA)-hypothalamus. METHODS: In experiment 1, proestrus rats were implanted with capsules filled with crystalline testosterone or empty control capsules. Four days later, animals were bled via atrial catheters at 30-minute intervals from noon to 9:00 pm. In experiment 2, proestrus rats received testosterone-filled or empty control capsules, and 3 days later were ovariectomized (OVX) and injected with estradiol benzoate (EB) 30 mug SC or sesame oil vehicle. The next day, blood samples were obtained from the rats. In experiment 3, proestrus rats similarly implanted with testosterone-filled or empty control capsules, OVX, and injected with EB or vehicle were sacrificed, and POA-hypothalamic tissue was collected for quantitative reverse transcription-polymerase chain reaction analysis of PR messenger RNA. RESULTS: In experiment 1, radioimmunoassay of serum revealed that testosterone completely blocked release of LH surges that were fully evident in the control group. In experiment 2, LH radioimmunoassay revealed that high-physiologic testosterone exposure completely abolished the release of EB-induced LH surges. In experiment 3, although EB treatment was found to induce an increase in PR expression in control animals, no such induction of PR expression was observed in the testosterone-treated rats. CONCLUSIONS: Our findings are consistent with the hypothesis that hyperandrogenic interference in the release of preovulatory LH surges is mediated by the suppressive effects of androgens on PR expression in POA-hypothalamic tissue. These findings may have important implications in the understanding of reproductive dysregulation in female hyperandrogenic syndromes, including polycystic ovary syndrome. [ABSTRACT FROM AUTHOR]

Objective: To examine the merits of using microRNAs (miRNAs) as biomarkers of disorders of consciousness (DoC) due to traumatic brain injury (TBI)., Settings: Acute and subacute beds., Participants: Patients remaining in vegetative and minimally conscious states (VS, MCS), an average of 1.5 years after TBI, and enrolled in a randomized clinical trial ( n = 6). Persons without a diagnosed central nervous system disorder, neurotypical controls ( n = 5)., Design: Comparison of whole blood miRNA profiles between patients and age/gender-matched controls. For patients, correlational analyses between miRNA profiles and measures of neurobehavioral function., Main Measures: Baseline measures of whole blood miRNAs isolated from the cellular and fluid components of blood and measured using miRNA-seq and real-time polymerase chain reaction (RT-PCR). Baseline neurobehavioral measures derived from 7 tests., Results: For patients, relative to controls, 48 miRNA were significantly ( P < .05)/differentially expressed. Cluster analysis showed that neurotypical controls were most similar to each other and with 2 patients (VS: n = 1; and MCS: n = 1). Three patients, all in MCS, clustered separately. The only female in the sample, also in MCS, formed an independent group. For the 48 miRNAs, the enriched pathways identified are implicated in secondary brain damage and 26 miRNAs were significantly ( P < .05) correlated with measures of neurobehavioral function., Conclusions: Patients remaining in states of DoC an average of 1.5 years after TBI showed a different and reproducible pattern of miRNA expression relative to age/gender-matched neurotypical controls. The phenotypes, defined by miRNA profiles relative to persisting neurobehavioral impairments, provide the basis for future research to determine the miRNA profiles differentiating states of DoC and the basis for future research using miRNA to detect treatment effects, predict treatment responsiveness, and developing targeted interventions. If future research confirms and advances reported findings, then miRNA profiles will provide the foundation for patient-centric DoC neurorehabilitation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc.)

Repetitive mild traumatic brain injury (rmTBI) results in a myriad of symptoms, including vestibular impairment. The mechanisms underlying vestibular dysfunction in rmTBI patients remain poorly understood. Concomitantly, acute hypogonadism occurs following TBI and can persist chronically in many patients. Using a repetitive mild closed-head animal model of TBI, the role of testosterone on vestibular function was tested. Male Long Evans Hooded rats were randomly divided into sham or rmTBI groups. Significant vestibular deficits were observed both acutely and chronically in the rmTBI groups. Systemic testosterone was administered after the development of chronic vestibular dysfunction. rmTBI animals given testosterone showed improved vestibular function that was sustained for 175 days post-rmTBI. Significant vestibular neuronal cell loss was, however, observed in the rmTBI animals compared to Sham animals at 175 days post-rmTBI and testosterone treatment significantly improved vestibular neuronal survival. Taken together, these data demonstrate a critical restorative role of testosterone in vestibular function following rmTBI. This study has important clinical implications because it identifies testosterone treatment as a viable therapeutic strategy for the long-term recovery of vestibular function following TBI., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Charous, Hutz, Bialek, Schumacher and Foecking.)

Background: Biomarkers that can advance precision neurorehabilitation of the traumatic brain injury (TBI) are needed. MicroRNAs (miRNAs) have biological properties that could make them well suited for playing key roles in differential diagnoses and prognoses and informing likelihood of responsiveness to specific treatments., Objective: To review the evidence of miRNA alterations after TBI and evaluate the state of science relative to potential neurorehabilitation applications of TBI-specific miRNAs., Methods: This scoping review includes 57 animal and human studies evaluating miRNAs after TBI. PubMed, Scopus, and Google Scholar search engines were used., Results: Gold standard analytic steps for miRNA biomarker assessment are presented. Published studies evaluating the evidence for miRNAs as potential biomarkers for TBI diagnosis, severity, natural recovery, and treatment-induced outcomes were reviewed including statistical evaluation. Growing evidence for specific miRNAs, including miR21, as TBI biomarkers is presented., Conclusions: There is evidence of differential miRNA expression in TBI in both human and animal models; however, gaps need to be filled in terms of replication using rigorous, standardized methods to isolate a consistent set of miRNA changes. Longitudinal studies in TBI are needed to understand how miRNAs could be implemented as biomarkers in clinical practice., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Local anesthetic toxicity has been well-documented to cause neuronal injury, death, and dysfunction, particularly in a susceptible nerve., Objective: To determine whether select local anesthetics affect neuron survival and/or functional recovery of an injured nerve., Methods: 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., Results: 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)., Conclusions: 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.

Purpose: POAG is a progressive optic neuropathy that is currently the leading cause of irreversible blindness worldwide. While the underlying cause of POAG remains unclear, TGF-β2-dependent remodeling of the extracellular matrix (ECM) within the trabecular meshwork (TM) microenvironment is considered an early pathologic consequence associated with impaired aqueous humor (AH) outflow and elevated IOP. Early studies have also demonstrated markedly elevated levels of oxidative stress markers in AH from POAG patients along with altered expression of antioxidant defenses. Here, using cultured primary or transformed human TM cells, we investigated the role oxidative stress plays at regulating TGF-β2-mediated remodeling of the ECM., Methods: Primary or transformed (GTM3) human TM cells conditioned in serum-free media were incubated in the absence or presence of TGF-β2 and relative changes in intracellular reactive oxygen species (ROS) were measured using oxidation-sensitive fluorogenic dyes CellROX green or 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate (carboxy-H2DCFDA). TGF-β2-mediated changes in the content of connective tissue growth factor (CTGF) and collagen types 1α1 (COL1A1) and 4α1 (COL4A1) mRNA or collagens I and IV isoform proteins were determined in the absence or presence of mitochondrial-targeted antioxidants (XJB-5-131 or MitoQ) and quantified by quantitative PCR or by immunoblot and immunocytochemistry. Smad-dependent canonic signaling was determined by immunoblot, whereas Smad-dependent transcriptional activity was quantified using a Smad2/3-responsive SBE-luciferase reporter assay., Results: Primary or transformed human TM cells cultured in the presence of TGF-β2 (5 ng/mL; 2 hours) exhibited marked increases in CellROX or fluorescein fluorescence. Consistent with previous reports, challenging cultured human TM cells with TGF-β2 elicited measurable increases in regulated Smad2/3 signaling as well as increases in CTGF, COL1A1, and COL4A1 mRNA and collagen protein content. Pretreating human TM cells with mitochondrial-targeted antioxidants XJB-5-131 (10 μM) or MitoQ (10 nM) attenuated TGF-β2-mediated changes in Smad-dependent transcriptional activity., Conclusions: The multifunctional profibrotic cytokine TGF-β2 elicits a marked increase in oxidative stress in human TM cells. Mitochondrial-targeted antioxidants attenuate TGF-β2-mediated changes in Smad-dependent transcriptional activity, including marked reductions in CTGF and collagen isoform gene and protein expression. These findings suggest that mitochondrial-targeted antioxidants, when delivered directly to the TM, exhibit potential as a novel strategy by which to slow the progression of TGF-β2-mediated remodeling of the ECM within the TM.

Introduction: Facial nerve denervation can be devastating for patients. Primary neurorrhaphy and interposition (IP) nerve grafting are common reinnervation techniques. Muscle-nerve-muscle (MNM) grafting is a lesser known alternative. After previously demonstrating significant return of function using MNM grafting in a rat facial nerve model, the authors compare the use of multiple MNM nerve grafts with that of single MNM and IP nerve grafts., Methods: Thirty-six male rats were randomized into 4 groups: (1) repair with IP grafts, (2) 1 MNM graft, (3) 3 MNM grafts, and (4) control with no intervention. All groups had the lower zygomatic, buccal, and marginal mandibular branches of the right facial nerve removed. Return of movement and snout symmetry was measured over 16 weeks. Axonal regeneration and muscle atrophy were assessed and quantified., Results: All intervention groups had significantly improved movement and snout symmetry compared with control. Rats in the IP group had significantly increased axon density compared with those in the MNM groups but with smaller axonal diameter than control rats. No difference in axon density or diameter was observed between MNM groups. Use of 3 MNM grafts and IP grafts resulted in preservation of similar muscle mass compared with the control and 1-MNM groups., Conclusion: MNM grafting may be an alternative when other reanimation techniques are not possible., Level of Evidence: NA.

Objective: Facial paralysis is a devastating condition leaving patients with a myriad of aesthetic and functional consequences. Muscle-nerve-muscle (MNM) neurotization is a reinnervation technique that involves implanting an autogenous nerve graft as a conduit between an innervated "donor" muscle and a denervated "recipient" muscle. We investigated the use of MNM reinnervation, alone or in combination with electrical stimulation (ES) and testosterone propionate (TP) in comparison to nerve reanastomosis (RE), on functional recovery following rat facial nerve injury., Methods: Thirty-one male, Sprague-Dawley rats were assigned to groups: no graft (control), MNM grafting alone (MNM), MNM grafting with ES and TP (MNM+ES+TP), or RE. Harvested right facial nerve branches were used as the MNM graft. Functional recovery was assessed by behavioral observations and electromyographic recordings., Results: The MNM grafting improved muscle tone and vibrissae movement. The ES+TP treatment further enhanced muscle tone as well as reduced recovery time for coordinated movement in a manner that is comparable to those of RE. Electromyographic recordings demonstrated electrical conductance across all MNM grafts., Conclusion: These data have important implications for patients with unilateral paralysis from facial or laryngeal nerve injury, particularly those who are not candidates for nerve reanastomosis.

Objectives: (1) To recognize factors that contribute to vocal fold paralysis (VFP) after esophagectomy. (2) To describe the morbidity associated with VFP after esophagectomy., Study Design: Retrospective cohort study., Setting: Tertiary care academic medical center., Subjects and Methods: The medical records of 91 patients undergoing esophagectomy for malignancy were reviewed (2008-2014). Twenty-two patients with postoperative VFP were compared with 69 patients without VFP with regard to preoperative variables, surgical approach (transcervical vs other), and postoperative outcomes. A subset analysis of cervical approaches was performed, including those where an otolaryngologist assisted., Results: There were no significant differences in preoperative variables between patients with and without VFP. Cervical approaches were associated with increased VFP (P < .0001). Recurrent laryngeal nerve (RLN) identification was associated with increased VFP (P = .0001). RLN dissection by head and neck surgeons was associated with decreased VFP (P = .0223). Patients with VFP had longer lengths of stay (P = .0078), higher rates of tracheotomy (P = .0439), and required more outpatient swallow evaluations (P = .0017). Mean time to diagnosis of VFP was 45.6 days (median, 7.5 days)., Conclusions: Cervical approaches are associated with increased VFP in patients undergoing esophagectomy for malignancy. When cervical approaches and mobilization are required, the inclusion of an experienced cervical surgeon to identify the RLN may improve the rate of postoperative VFP. Patients with VFP after esophagectomy experience significantly more morbidity. Due to the potential delay in diagnosis and treatment of postoperative VFP, routine assessment of inpatient vocal fold function may be beneficial., (© American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.)

An increased risk of ALS has been reported for veterans, varsity athletes, and professional football players. The mechanism underlying the increased risk in these populations has not been identified; however, it has been proposed that motor nerve injury may trigger immune responses which, in turn, can accelerate the progression of ALS. Accumulating evidence indicates that abnormal immune reactions and inflammation are involved in the pathogenesis of ALS, but the specific immune cells involved have not been clearly defined. To understand how nerve injury and immune responses may contribute to ALS development, we investigated responses of CD4(+) T cell after facial motor nerve axotomy (FNA) at a presymptomatic stage in a transgenic mouse model of ALS (B6SJL SOD1(G93A)). SOD1(G93A) mice, compared with WT mice, displayed an increase in the basal activation state of CD4(+) T cells and higher frequency of Th17 cells, which were further enhanced by FNA. In conclusion, SOD1(G93A) mice exhibit abnormal CD4(+) T cell activation with increased levels of Th17 cells prior to the onset of neurological symptoms. Motor nerve injury exacerbates Th17 cell responses and may contribute to the development of ALS, especially in those who carry genetic susceptibility to this disease.

Objective: This study investigated the effects of a combinatorial treatment, consisting of a brief period of nerve electrical stimulation (ES) and systemic supraphysiologic testosterone, on functional recovery following a crush of the recurrent laryngeal nerve (RLN)., Study Design: Prospective, controlled animal study., Methods: After a crush of the left RLN, adult male Sprague-Dawley rats were divided into four treatment groups: 1) no treatment, 2) ES, 3) testosterone propionate (TP), and 4) ES + TP. Each group was subdivided into 1, 2, 3, or 4 weeks post-operative survival time points. Groups had an n of 4- 9. Recovery of vocal fold mobility (VFM) was assessed., Results: Brief ES of the proximal nerve alone or in combination with TP accelerated the initiation of functional recovery. TP administration by itself also produced increased VFM scores compared to controls, but there were no statistical differences between the ES-treated and TP-treated animals. Treatment with brief ES alone was sufficient to decrease the time required to recover complete VFM. Animals with complete VFM were seen in treatment groups as early as 1 week following injury; in the untreated group, this was not observed until at least 3 weeks post-injury, translating into a 66% decrease in time to complete recovery., Conclusions: Brief ES, alone or in combination with TP, promise to be effective therapeutic interventions for promoting regeneration following RLN injury.

Background: Several population studies demonstrated an increased risk of allergic rhinitis in patients exposed to acetaminophen. However, no histologic studies have been conducted to assess the relationship between acetaminophen exposure and allergic rhinitis., Objective: In this study, we investigated the association between chronic acetaminophen exposure and the development of allergic rhinitis in a rat model., Methods: Ten female Sprague-Dawley rats were randomly assigned to either a control (n = 5) or an acetaminophen group (n = 5). The acetaminophen group received 200 mg/kg/day of acetaminophen suspended in yogurt via oral gavage for 120 days. The control group received only the yogurt vehicle. Allergic behavioral responses, including nose rub, eye rub, ear scratching, and neck and/or face scratching, were quantified. The rats were killed, and the noses were harvested. The portion of the nose, including the nasal septum and the inferior turbinates, was embedded in paraffin, sectioned, and stained with hematoxylin and eosin to quantify the inflammatory infiltrate., Results: The average number of allergic responses per animal was 13.2 in the acetaminophen group versus 6.2 in the control group (p = 0.032). All the rats in the acetaminophen group (100%) had mast cells infiltrating the lamina propria of the inferior turbinate, whereas mast cells were detected in only 40% of the animals in the control group. The average number of mast cells per animal in the acetaminophen group was 134 versus 21 in the control group (p = 0.048)., Conclusions: Our study was the first to demonstrate a histologic association between chronic exposure to acetaminophen and rhinitis. Further research to elucidate the mechanism that underlies these findings is necessary.

Objectives: The purpose of this study was to (1) assess the degree of motoneuron cell loss and (2) the combinatorial effects of electrical stimulation (ES) and testosterone propionate (TP) on cell survival following an intracranial facial nerve crush injury and (3) compare these results to distal injuries., Study Design: Prospective, randomized, controlled animal study., Methods: Sprague-Dawley rats were randomly divided into 3 groups: intracranial sham surgery or intracranial crush injury with or without ES and TP treatments. The intracranial sham group underwent exposure of the meatal segment of the right facial nerve. The intracranial crush groups underwent a crush of the meatal segment following exposure with or without ES and TP treatment immediately following the injury and followed for 8 weeks. Brain sections were thionin-stained, and facial motor nuclei (FMN) were counted using light microscopy. Results were compared to intratemporal and extracranial facial nerve crush injuries., Results: Intracranial crush injury resulted in a significant decrease in cell survival (n = 6) of 65.6% as compared to the sham group (99.4%; n = 9). The treatments increased cell survival to 93.8% (n = 2). The cell loss in the intracranial facial nerve injury is more substantial than the intratemporal (85.8%; n = 7) and extracranial (103.3%; n = 4) injuries., Conclusions: Intracranial injury results in a more profound cell loss compared to the distal injuries. These data suggest a critical importance for the development of treatment modalities that can help improve cell survival following facial nerve injuries., (© American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.)

Vicodin, the combination drug of acetaminophen and the opioid hydrocodone, is one of the most prescribed drugs on the market today. Opioids have demonstrated the ability to paradoxically cause increased pain sensitivity to users in a phenomena called opioid-induced hyperalgesia (OIH). While selected opioids have been shown to produce OIH symptoms in an animal model, hydrocodone and the combination drug Vicodin have yet to be studied. The purpose of this study was to explore the effect of exposure to chronic high dose Vicodin or its components on the sensitivity to both thermal and mechanical pain. Animals were randomly divided into 4 groups, Vicodin, acetaminophen, hydrocodone, or vehicle control, and administered the drug daily for 120 days. Rats were subsequently tested for thermal and mechanical sensitivity. The rats in the Vicodin group displayed a significant decrease in withdrawal time to thermal pain. The rats receiving acetaminophen, hydrocodone, and vehicle showed no statistically significant hypersensitivity in thermal testing. None of the groups demonstrated statistically significant hypersensitivity to mechanical testing. The data suggests Vicodin produces signs of OIH in a rodent model. However, increased pain sensitivity was only noted in the thermal pathway and the hypersensitivity was only seen with the opioid combination drug, not the opioid alone. The results of this study both support the results of previous rodent opioid studies while generating further questions about the specific properties of Vicodin that contribute to pain hypersensitivity. The growing use of Vicodin to treat chronic pain necessitates further research looking into this paradoxical pain response.

Purpose: To investigate the effects of the androgen testosterone propionate (TP), on regeneration of the recurrent laryngeal nerve (RLN) after unilateral crush injury using assessment of vocal fold mobility (VFM) as a measure of behavioral recovery., Methods: 48 adult male rats underwent standardized crush injury of left RLN and received treatment in the form of 2 silastic capsules containing TP or controls receiving a blank capsule (untreated). Direct laryngoscopic assessment of vocal cord mobility was performed before, immediately following and 1, 2, 3, 4, 5 or 6 weeks post injury., Results: Treatment with TP enhanced the recovery of full VFM following crush injury of the RLN compared to controls. There was statistically significant improvement in VFM seen at the 1 and 2 week time points (p < 0.05). By 4 weeks TP-treated rats displayed a 100% recovery of VFM function, compared to only 50% by the control group., Conclusions: TP enhances RLN functional recovery following a crush injury, which further supports its potential general applicability as a therapeutic agent in peripheral nerve injury.

Objective: (1) Explain the need for an animal model to study intracranial injuries to the facial nerve. (2) Describe various techniques attempted to identify and crush the intracranial segment of the facial nerve in a rat model. (3) Describe in detail a successful rat model of intracranial facial nerve crush injury., Study Design: Randomized controlled animal study., Setting: Animal laboratory., Subjects and Methods: Multiple attempts at surgical approaches to the cerebellopontine angle were attempted on cadaveric rats. Once a successful approach was derived, this was used on 19 live rats under anesthesia. Fourteen rats had a 1-minute facial nerve crush performed, and 5 had a sham surgery with complete surgical exposure of the facial nerve but no crush. Rats were followed for a 12-week duration evaluating immediate postoperative facial nerve function, complications, and survival., Results: All 14 (100%) rats that underwent surgery with crush injury had complete facial paralysis postoperatively. Complete facial paralysis was defined as loss of eye-blink reflex, flat vibrissae, and lack of vibrissae movement. The 5 sham surgery rats had complete facial function postoperatively. Surgery was performed by 2 separate surgeons with no difference in outcome between the 2. Complications occurred in only 1 animal (1/19, 5.3%), which was a corneal abrasion requiring sacrifice., Conclusion: Our group describes a consistent method for performing an intracranial crush injury in the rat. This new model and its applications in translational facial nerve research are promising, particularly with tumors or lesions at the cerebellopontine angle.

Peripheral nerve injuries lead to a variety of pathological conditions, including paresis or paralysis when the injury involves motor axons. We have been studying ways to enhance the regeneration of peripheral nerves using daily electrical stimulation (ES) following a facial nerve crush injury. In our previous studies, ES was not initiated until 24 h after injury. The current experiment tested whether ES administered immediately following the crush injury would further decrease the time for complete recovery from facial paralysis. Rats received a unilateral facial nerve crush injury and an electrode was positioned on the nerve proximal to the crush site. Animals received daily 30 min sessions of ES for 1 d (day of injury only), 2 d, 4 d, 7 d, or daily until complete functional recovery. Untreated animals received no ES. Animals were observed daily for the return of facial function. Our findings demonstrated that one session of ES was as effective as daily stimulation at enhancing the recovery of most functional parameters. Therefore, the use of a single 30 min session of ES as a possible treatment strategy should be studied in human patients with paralysis as a result of acute nerve injuries.

Objectives/hypothesis: Injuries of cranial nerves that are distal to but near the motor nucleus might result in retrograde motoneuron cell death. The hypothesis of this article is that an intratemporal crush injury of the facial nerve in rats can cause facial motor nuclei cell death., Study Design: Prospective, randomized, controlled animal study., Methods: Sprague-Dawley rats were randomly divided into four groups: intratemporal sham, intratemporal crush injury, extratemporal crush injury, and extratemporal sham. The intratemporal (n = 9) and extratemporal crush injury (n = 4) groups underwent a 60-second crush of the nerve at the facial nerve tympanic segment or main facial nerve trunk distal to the stylomastoid foramen, respectively. The intratemporal sham group (n = 4) underwent identical exposure to the intratemporal crush without subsequent injury. Both sham groups and the extratemporal crush group were sacrificed at 4 weeks. The intratemporal crush group was subdivided into 4- (n = 4) and 8-week (n = 5) postinjury groups. Brain sections were stained with thionin and facial motor nuclei were counted under magnification. The contralateral uninjured facial motor nucleus was used to compare motor nucleus cell survival., Results: Intratemporal crush injury resulted in increased cell loss at 4 (89.43% ± 8.57% standard error of mean) and 8 weeks (85.78% ± 3.15%) after injury compared to sham injury (119.09% ± 13.35%) (P <.05). No significant change in cell survival was noted between the distal crush (103.29% ± 6.34%) and sham group (111.71% ± 3.24%) (P >.05)., Conclusions: A rat intratemporal crush injury resulted in approximately 15% facial motor nuclei cell loss compared to an intratemporal sham injury. An extratemporal crush injury did not lead to any significant facial motor nuclei cell loss. This might have future translational implications in humans with intratemporal facial nerve injuries.

Objectives/hypothesis: To investigate the effects of various combinatorial treatments, consisting of a tapering dose of prednisone (P), a brief period of nerve electrical stimulation (ES), and systemic testosterone propionate (TP) on improving functional recovery following an intratemporal facial nerve crush injury., Study Design: Prospective, controlled animal study., Methods: After a right intratemporal facial nerve crush, adult male Sprague-Dawley rats were divided into the following eight treatment groups: 1) no treatment, 2) P only, 3) ES only, 4) ES + P, 5) TP only, 6) TP + P, 7) ES + TP, and 8) ES + TP + P. For each group n = 4-8. Recovery of the eyeblink reflex and vibrissae orientation and movement were assessed. Changes in peak amplitude and latency of evoked response, in response to facial nerve stimulation, was also recorded weekly., Results: : Brief ES of the proximal nerve stump most effectively accelerated the initiation of functional recovery. Also, ES or TP treatments enhanced recovery of some functional parameters more than P treatment. When administered alone, none of the three treatments improved recovery of complete facial function. Only the combinatorial treatment of ES + TP, regardless of the presence of P, accelerated complete functional recovery and return of normal motor nerve conduction., Conclusions: Our findings suggest that a combinatorial treatment strategy of using brief ES and TP together promises to be an effective therapeutic intervention for promoting regeneration following facial nerve injury. Administration of P neither augments nor hinders recovery.

As functional recovery following peripheral nerve injury is dependent upon successful repair and regeneration, treatments that enhance different regenerative events may be advantageous. Using a rat facial nerve crush axotomy model, our lab has previously investigated the effects of a combinatorial treatment strategy, consisting of electrical stimulation (ES) of the proximal nerve stump and testosterone propionate (TP) administration. Results indicated that the two treatments differentially enhance facial nerve regenerative properties, whereby ES reduced the delay before sprout formation, TP accelerated the overall regeneration rate, and the combinatorial treatment had additive effects. To delineate the molecular mechanisms underlying such treatments, the present study investigated the effects of ES and TP on expression of specific regeneration-associated genes. Following a right facial nerve crush at the stylomastoid foramen, gonadectomized adult male rats were administered only ES, only TP, a combination of both, or left untreated. Real time RT-PCR analysis was used to assess fold changes in mRNA levels in the facial motor nucleus at 0 h, 6 h, 1 d, 2 d, 7 d, and 21 d post-axotomy. The candidate genes analyzed included two tubulin isoforms (alpha(1)-tubulin and beta(II)-tubulin), 43-kiloDalton growth-associated protein (GAP-43), brain derived neurotrophic factor (BDNF), pituitary adenylate cyclase-activating peptide (PACAP), and neuritin (candidate plasticity-related gene 15). The two treatments have differential effects on gene expression, with ES leading to early but transient upregulation and TP producing late but steady increases in mRNA levels. In comparison to individual treatments, the combinatorial treatment strategy has the most enhanced effects on the transcriptional program activated following injury., (Copyright 2009 Elsevier Inc. All rights reserved.)

Androgens have a variety of protective and therapeutic effects in both the central and peripheral nervous systems. Here we review these effects as they related specifically to spinal and cranial motoneurons. Early in development, androgens are critical for the formation of important neuromuscular sex differences, decreasing the magnitude of normally occurring cell death in select motoneuron populations. Throughout the lifespan, androgens also protect against motoneuron death caused by axonal injury. Surviving motoneurons also display regressive changes to their neurites as a result of both direct axonal injury and loss of neighboring motoneurons. Androgen treatment enhances the ability of motoneurons to recover from these regressive changes and regenerate both axons and dendrites, restoring normal neuromuscular function. Androgens exert these protective effects by acting through a variety of molecular pathways. Recent work has begun to examine how androgen treatment can interact with other treatment strategies in promoting recovery from motoneuron injury.

Purpose: The neurotherapeutic effects of nerve electrical stimulation and gonadal steroids have independently been demonstrated. The purpose of this study was to investigate the therapeutic potential of a combinatorial treatment strategy of electrical stimulation and gonadal steroids on peripheral nerve regeneration., Methods: Following a facial nerve crush axotomy in gonadectomized adult male rats, testosterone propionate (TP), dihydrotestosterone (DHT), or estradiol (E(2)) was systemically administered with/without daily electrical stimulation of the proximal nerve stump. Facial nerve outgrowth was assessed at 4 and 7 days post-axotomy using radioactive labeling., Results: Administration of electrical stimulation alone reduced the estimated delay in sprout formation but failed to accelerate the overall regeneration rate. Conversely, TP treatment alone accelerated the regeneration rate by approximately 10% but had no effect on the sprouting delay. Combining TP with electrical stimulation, however, maintained the enhanced rate and reduced the sprouting delay. DHT treatment alone failed to alter the regeneration rate but combining it with electrical stimulation increased the rate by 10%. E(2) treatment alone increased the regeneration rate by approximately 5% but with electrical stimulation, there was no additional effect., Conclusions: Electrical stimulation and gonadal steroids differentially enhanced regenerative properties. TP, an aromatizable androgen, augmented regeneration most, suggesting a synergism between androgenic and estrogenic effects. Therapeutically, combining electrical stimulation with gonadal steroids may boost regenerative properties more than the use of either treatment alone.

Androgen exposure during intrauterine life in nonhuman primates and in sheep results in a phenocopy of the reproductive and metabolic features of polycystic ovary syndrome (PCOS). Such exposure also results in reproductive features of PCOS in rodents. We investigated whether transient prenatal androgen treatment produced metabolic abnormalities in adult female rats and the mechanisms of these changes. Pregnant dams received free testosterone or vehicle injections during late gestation, and their female offspring were fed regular or high-fat diet (HFD). At 60 days of age, prenatally androgenized (PA) rats exhibited significantly increased body weight; parametrial and subcutaneous fat; serum insulin, cholesterol and triglyceride levels; and hepatic triglyceride content (all P < 0.0125). There were no significant differences in insulin sensitivity by intraperitoneal insulin tolerance test or insulin signaling in liver or skeletal muscle. HFD had similar effects to PA on body weight and composition as well as on circulating triglyceride levels. HFD further increased hepatic triglyceride content to a similar extent in both PA and control rats. In PA rats, HFD did not further increase circulating insulin, triglyceride, or cholesterol levels. In control rats, HFD increased insulin levels, but to a lesser extent than PA alone ( approximately 2.5- vs. approximately 12-fold, respectively). We conclude that transient prenatal androgen exposure produces features of the metabolic syndrome in adult female rats. Dyslipidemia and hepatic steatosis appear to be mediated by PA-induced increases in adiposity, whereas hyperinsulinemia appears to be a direct result of PA.

Objective: To study the effect of electrical stimulation on accelerating facial nerve functional recovery from a crush injury in the rat model., Study Design: Experimental., Method: The main trunk of the right facial nerve was crushed just distal to the stylomastoid foramen, causing right-sided facial paralysis in 17 Sprague-Dawley rats. An electrode apparatus was implanted in all rats. Nine rats underwent electrical stimulation and eight were sham stimulated until complete facial nerve recovery. Facial nerve function was assessed daily by grading eyeblink reflex, vibrissae orientation, and vibrissae movement., Results: An electrical stimulation model of the rat facial nerve following axotomy was established. The semi-eyeblink returned significantly earlier (3.71 + 0.97 vs 9.57 + 1.86 days post axotomy) in stimulated rats (P = 0.008). Stimulated rats also recovered all functions earlier, and showed less variability in recovery time., Conclusion: Electrical stimulation initiates and accelerates facial nerve recovery in the rat model as it significantly reduces recovery time for the semi-eyeblink reflex, a marker of early recovery. It also hastens recovery of other functions.

Objective: We investigated the combined effects of electrical stimulation and testosterone propionate on overall recovery time in rats with extracranial crush injuries to the facial nerve., Study Design: Male rats underwent castration 3 to 5 days prior to right facial nerve crush injury and electrode implantation. Rats were randomly assigned to two groups: crush injury + testosterone or crush injury with electrical stimulation + testosterone. Recovery was assessed by daily subjective examination documenting vibrissae orientation/movement, semi-eye blink, and full eye blink., Results: Milestones of early recovery were noted to be significantly earlier in the groups with electrical stimulation, with/without testosterone. The addition of testosterone to electrical stimulation showed significant earlier return of late recovery parameters and complete overall recovery., Conclusion: Electrical stimulation may decrease cell death or promote sprouting to accelerate early recovery. Testosterone may affect the actual rate of axonal regeneration and produce acceleration in functional recovery. By targeting different stages of neural regeneration, the synergy of electrical stimulation and testosterone appears to have promise as a neurotherapeutic strategy for facial nerve injury.

Androgens exert significant organizational and activational effects on the nervous system and behavior. Despite the fact that female mammals generally produce low levels of androgens, relative to the male of the same species, increasing evidence suggests that androgens can exert profound effects on the normal physiology and behavior of females during fetal, neonatal, and adult stages of life. This review examines the effects of exposure to androgens at three stages of development--as an adult, during early postnatal life and as a fetus, on reproductive hormone secretions in female rats. We examine the effects of androgen exposure both as a model of neuroendocrine sexual differentiation and with respect to the role androgens play in the normal female. We then discuss the hypothesis that androgens may cause epigenetic modification of estrogen target genes in the brain. Finally we consider the clinical consequences of excess androgen exposure in women.

Androgens act on the CNS to affect motor function through interaction with a widespread distribution of intracellular androgen receptors (AR). This review highlights our work on androgens and process outgrowth in motoneurons, both in vitro and in vivo. The actions of androgens on motoneurons involve the generation of novel neuronal interactions that are mediated by the induction of androgen-dependent neurite or axonal outgrowth. Here, we summarize the experimental evidence for the androgenic regulation of the extension and regeneration of motoneuron neurites in vitro using cultured immortalized motoneurons, and axons in vivo using the hamster facial nerve crush paradigm. We place particular emphasis on the relevance of these effects to SBMA and peripheral nerve injuries.

Preovulatory GnRH and LH surges depend on activation of estrogen (E2)-inducible progesterone receptors (PGRs) in the preoptic area (POA). Surges do not occur in males, or in perinatally androgenized females. We sought to determine whether prenatal androgen exposure suppresses basal or E2-induced Pgr mRNA expression or E2-induced LH surges (or both) in adulthood, and whether any such effects may be mediated by androgen receptor activation. We also assessed whether prenatal androgens alter subsequent GnRH pulsatility. Pregnant rats received testosterone or vehicle daily on Embryonic Days 16-19. POA-hypothalamic tissues were obtained in adulthood for PgrA and PgrB (PgrA+B) mRNA analysis. Females that had prenatal exposure to testosterone (pT) displayed reduced PgrA+B mRNA levels (P < 0.01) compared with those that had prenatal exposure to vehicle (pV). Additional pregnant animals were treated with vehicle or testosterone, or with 5alpha-dihydrotestosterone (DHT). In adult ovariectomized offspring, estradiol benzoate produced a 2-fold increase (P < 0.05) in PgrA+B expression in the POA of pV females, but not in pT females or those that had prenatal exposure to DHT (pDHT). Prenatal testosterone and DHT exposure also prevented estradiol benzoate-induced LH surges observed in pV rats. Blood sampling of ovariectomized rats revealed increased LH pulse frequency in pDHT versus pV females (P < 0.05). Our findings support the hypothesis that prenatal androgen receptor activation can contribute to the permanent defeminization of the GnRH neurosecretory system, rendering it incapable of initiating GnRH surges, while accelerating basal GnRH pulse generator activity in adulthood. We propose that the effects of prenatal androgen receptor activation on GnRH neurosecretion are mediated in part via permanent impairment of E2-induced PgrA+B gene expression in the POA.