Salidroside promotes peripheral nerve regeneration following crush injury to the sciatic nerve in rats

The GLCCI1/STAT3 pathway: a novel pathway involved in diabetic cognitive dysfunction and the therapeutic effect of salidroside

Diabetic cognitive dysfunction (DCD) is a complication of diabetes that seriously affects quality of life. Glucocorticoid-induced transcript 1 (GLCCI1) has been found to be involved in inflammation, apoptosis and autophagy in various diseases. However, the distribution of GLCCI1 in the brain and its role in DCD have not yet been revealed. In addition, the potential therapeutics effects of salidroside (SAL), a phenyl propyl glycoside compound known for its neuroprotective effects in treating DCD are unknow. In the present study, we found that GLCCI1 was localized in hippocampal neurons. C57BL/6 J mice with DCD presented downregulation of GLCCI1 and Bcl-2 and upregulation of p-STAT3/STAT3, Bax, Cleaved Caspase-3/Caspase-3. Overexpression of GLCCI1 or SAL administration relieved DCD, reversed the changes in the expression of these cytokines, and alleviated morphological alterations in hippocampal neurons. Interestingly, SAL alleviated DCD and attenuated the expression of GLCCI1 and p-STAT3, showing similar effects as GLCCI1 overexpression. These findings suggest that the GLCCI1/STAT3 axis plays a crucial role in DCD and is involved in SAL-mediated attenuation of DCD.

Hyaluronic acid hybrid formulations optimised for 3D printing of nerve conduits and the delivery of the novel neurotrophic-like compound tyrosol to enhance peripheral nerve regeneration via Schwann cell proliferation

Peripheral nerve injuries, predominantly affecting individuals aged 20-40, pose significant healthcare challenges, with current surgical methods often failing to achieve complete functional recovery. This study focuses on the development of 3D printed hydrogel nerve conduits using modified hyaluronic acid (HA) for potentially enhancing peripheral nerve regeneration. Hyaluronic acid was chemically altered with cysteamine HCl and methacrylic anhydride to create thiolated HA (HA-SH) and methacrylated HA (HA-MA), achieving a modification degree of approximately 20 %. This modification was crucial to maintain the receptor interaction of HA. The modified HA was rigorously tested to ensure cytocompatibility in neuronal and glial cell lines. Subsequently, various 3D printed HA formulations were evaluated, focusing on improving HA's inherent mechanical weaknesses. These formulations were assessed for cytotoxicity through direct contact and elution extract testing, confirming their safety over a 24-h period. Among the neurotrophic compounds tested, Tyrosol emerged as the most effective in promoting Schwann cell proliferation in vitro. The 3D printed HA system demonstrated proficiency in loading and releasing Tyrosol at physiological pH. The findings from this research highlight the promising role of 3D printed HA and Tyrosol in the field of nerve tissue engineering, offering a novel approach to peripheral nerve regeneration.

Reduced Gene Expression of KCC2 Accelerates Axonal Regeneration and Reduces Motor Dysfunctions after Tibial Nerve Severance and Suturing

Gamma-aminobutyric acid and glycine (GABA/Gly) are predominantly inhibitory neurotransmitters in the mature central nervous system; however, they mediate membrane potential depolarization during development. These differences in actions depend on intracellular Cl- concentrations ([Cl-]i), which are primarily regulated by potassium chloride cotransporter 2 (KCC2). After nerve injury, KCC2 expression markedly decreases and GABA/Gly mediate depolarization. Following nerve regeneration, KCC2 expression recovers and GABA/Gly become inhibitory, suggesting that KCC2 reduction and GABA/Gly excitation may be crucial for axonal regeneration. To directly clarify their involvement in regeneration, we analyzed recovery processes after tibial nerve severance and suturing between heterozygous KCC2 knockout mice (HT), whose KCC2 levels are halved, and their wild-type littermates (WT). Compared with WT mice, the sciatic functional index-indicating lower limb motor function-was significantly higher until 28 days after operation (D28) in HT mice. Furthermore, at D7, many neurofilament-positive fibers were elongated into the distal part of the sutured nerve in HT mice only, and myelinated axonal density was significantly higher at D21 and D28 in HT animals. Electron microscopy and galanin immunohistochemistry indicated a shorter nerve degeneration period in HT mice. Moreover, a less severe decrease in choline acetyltransferase was observed in HT mice. These results suggest that nerve degeneration and regeneration proceed more rapidly in HT mice, resulting in milder motor dysfunction. Via similar microglial activation, nerve surgery may reduce KCC2 levels more rapidly in HT mice, followed by earlier increased [Cl-]i and longer-lasting GABA/Gly excitation. Taken together, reduced KCC2 may accelerate nerve regeneration via GABA/Gly excitation.

Lacosamide alleviates bilateral cavernous nerve injury-induced erectile dysfunction in the rat model by ameliorating pathological changes in the corpus cavernosum

Bilateral cavernous nerve injury-related erectile dysfunction (BCNI-ED) shows a limited response to type 5 phosphodiesterase inhibitors. Furthermore, lacosamide (LCM) can alleviate peripheral neuropathy. To explore whether LCM can improve the erectile response after BCNI, we randomly divided 30 young Sprague-Dawley rats into three groups (n = 10 per group), namely, the sham operation, 0.9% normal saline-treated (BCNI + 0.9% NS), and LCM-treated BCNI (BCNI + LCM) groups. LCM was injected intraperitoneally at a dose of 90 mg/kg/day for 7 consecutive days. Erectile function was assessed by measuring the ratio of peak intracavernous pressure (ICP) to mean arterial pressure (MAP), and tissues were harvested for transmission electron microscopy, immunofluorescence, Masson's trichrome staining, TUNEL staining, and Western blot analysis. The BCNI + 0.9% NS group showed reduced ICP/MAP ratio (0.93 ± 0.04 vs. 0.44 ± 0.05, P < 0.0001). An increased proportion of TUNEL-positive cells (0.04 ± 0.01 vs 0.87 ± 0.03, P < 0.0001) and a decreased smooth muscle/collagen ratio (0.44 ± 0.01 vs. 0.33 ± 0.01, P < 0.001) were observed in the BCNI + 0.9% NS compared with the sham group. Administration of LCM significantly restored the ICP/MAP ratio (0.44 ± 0.05 vs. 0.74 ± 0.05, P < 0.001) and decreased the proportion of TUNEL positive cells (0.87 ± 0.03 vs. 0.60 ± 0.04, P < 0.0001) in the corpus cavernosum following BCNI. The ratio of smooth muscle to collagen (0.43 ± 0.01vs. 0.33 ± 0.01, P < 0.01) and expression of α-SMA (P < 0.0001) in the BCNI + LCM group significantly increased compared with BCNI + 0.9% NS group, indicating alleviation of fibrosis. Apoptotic markers, including Bax/Bcl-2 (P < 0.01) and Caspase-3 (P < 0.0001) in the BCNI + LCM group was significantly lower than that in the BCNI + 0.9% NS group. LCM treatment partially upregulated the expression of vWF and eNOS in cavernous tissue in rats subjected to BCNI (P < 0.05). Increases in S100-β and nNOS expression in the major pelvic ganglion (MPG) were observed after LCM administration. In summary, LCM can recover erectile function in BCNI-ED rat model by suppressing corporal apoptosis and fibrosis, and protecting the cavernous nerve.

Rhodiola rosea and Salidroside commonly induce hormesis, with particular focus on longevity and neuroprotection

The biological effects of Rhodiola rosea extracts and one of its major constituents, Salidroside, were evaluated for their capacity to induce hormesis/hormetic effects. The findings indicate that the Rhodiola rosea extracts and Salidroside commonly induce hormetic dose responses within a broad range of biological models, cell types and across a broad range of endpoints, with particular emphasis on longevity and neuroprotective endpoints. This paper represents the first integrative documentation and assessment of Rhodiola rosea extracts and Salidroside induction of hormetic effects. These findings have important biomedical applications and should have an important impact with respect to critical study design, dose selection and other experimental features.

Salidroside Alleviates Diabetic Cognitive Dysfunction Via B3galt2/F3/Contactin Signaling Pathway in Mice

Diabetes is frequently accompanied by cognitive impairment with insidious onset, and progressive cognitive and behavioral changes. β-1, 3-galactosyltransferase 2 (B3galt2) contributes to glycosylation, showing a clue for neuronal apoptosis, proliferation and differentiation. However, the role of B3galt2 in diabetic cognitive dysfunction (DCD) has not been investigated. In the present study, we aimed to explore the role of B3galt2 in DCD. Additionally, the potential therapeutic effects of salidroside on DCD was also explored. Diabetic C57BL/6J mice showed cognitive dysfunction together with down-regulated B3galt2. Overexpression of B3galt2 reversed the cognitive decline of diabetic C57BL/6J. Moreover, cognitive impairment was aggravated in B3galt2^+/- diabetic mice compared with C57BL/6J diabetic mice. Immunohistochemistry fluorescence indicated that B3galt2 and F3/Contactin were co-localized in the hippocampal regions. Importantly, the expression of F3/Contactin can be regulated by the manipulation of B3galt2, overexpression of which assuaged hippocampal neuronal damage, protected the synapsin, and reduced neuronal apoptosis in diabetic mice. Interestingly, SAL alleviated DCD and reversed the expression of B3galt2 in diabetic C57BL/6J mice. These findings indicate that inhibition of B3galt2/F3/Contactin pathway contributes to DCD, and participates in SAL reversed DCD.

Slow progression of sciatic nerve degeneration and regeneration after loose ligation through microglial activation and decreased KCC2 levels in the mouse spinal cord ventral horn

Peripheral nerve injury affects motor functions. To reveal the mechanisms underlying motor dysfunction and recovery after nerve compression, which have not been precisely examined, we investigated the temporal relationship among changes in motor function, nerve histopathology, and marker molecule expression in the spinal cord after loose ligation of the mouse sciatic nerve. After ligation, sciatic motor function suddenly declined, and axons gradually degenerated. During degeneration, galanin was localized in motor neuron cell bodies. Then, in the ventral horn, microglia were activated, and expression of choline acetyltransferase (ChAT), a synthetic enzyme of acetylcholine, and potassium chloride co-transporter 2 (KCC2), which shifts the action of γ-amino butyric acid (GABA) and glycine to inhibitory, decreased. Motor function recovery was insufficient although axonal regeneration was complete. ChAT levels gradually recovered during axonal regeneration. When regeneration was nearly complete, microglial activation declined, and KCC2 expression started to increase. The KCC2 level sufficiently recovered when axonal regeneration was complete, suggesting that the excitatory action of GABA/glycine may participate in axonal regeneration. Furthermore, these changes proceeded slower than those after severance, suggesting that loose ligation, compression, may mediate slower progression of degeneration and regeneration than severance, and these changes may cause the motor dysfunction and its recovery.

Revisiting the Role of Biologically Active Natural and Synthetic Compounds as an Intervention to Treat Injured Nerves

Traumatic lesions in nerves present high incidence and may culminate in sensorimotor and/or autonomic dysfunctions or a total loss of function, affecting the patient's quality of life. Although the microenvironment favors peripheral nerve regeneration, the regenerative process is not always successful. Some herbs, natural products, and synthetic drugs have been studied as potential pro-regenerative interventions. We reviewed and discussed the most recent articles published over the last ten years in high impact factor journals. Even though most of the articles contemplated in this review were in vitro and animal model studies, those with herbs showed promising results. Most of them presented antioxidant and anti-inflammatory effects. Drugs of several pharmacological classes also showed optimistic outcomes in nerve functional recovery, including clinical trials. The results are hopeful; however, mechanisms of action need to be elucidated, and there is a need for more high-quality clinical studies. The study presents careful compilation of findings of dozens of compounds with consistent pro-regenerative evidence published in respected scientific journals. It may be valuable for health professionals and researchers in the field.

Therapeutic Potential of Complementary and Alternative Medicines in Peripheral Nerve Regeneration: A Systematic Review

Despite the progressive advances, current standards of treatments for peripheral nerve injury do not guarantee complete recovery. Thus, alternative therapeutic interventions should be considered. Complementary and alternative medicines (CAMs) are widely explored for their therapeutic value, but their potential use in peripheral nerve regeneration is underappreciated. The present systematic review, designed according to guidelines of Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols, aims to present and discuss the current literature on the neuroregenerative potential of CAMs, focusing on plants or herbs, mushrooms, decoctions, and their respective natural products. The available literature on CAMs associated with peripheral nerve regeneration published up to 2020 were retrieved from PubMed, Scopus, and Web of Science. According to current literature, the neuroregenerative potential of Achyranthes&nbsp;bidentata, Astragalus&nbsp;membranaceus, Curcuma&nbsp;longa, Panax&nbsp;ginseng, and Hericium&nbsp;erinaceus are the most widely studied. Various CAMs enhanced proliferation and migration of Schwann cells in vitro, primarily through activation of MAPK pathway and FGF-2 signaling, respectively. Animal studies demonstrated the ability of CAMs to promote peripheral nerve regeneration and functional recovery, which are partially associated with modulations of neurotrophic factors, pro-inflammatory cytokines, and anti-apoptotic signaling. This systematic review provides evidence for the potential use of CAMs in the management of peripheral nerve injury.

Enhanced effects of salidroside on erectile function and corpora cavernosa autophagy in a cavernous nerve injury rat model

We explored the efficacy and mechanisms of salidroside treatment for erectile dysfunction induced by bilateral cavernous nerve injury (BCNI). Forty male rats were divided into four groups as follows: sham (cavernous nerves exposed only) (S); BCNI (M); BCNI + rapamycin (M + rapamycin); and BCNI + salidroside (M + salidroside). Erectile function in the rats was measured by intracavernosal pressure. Penile tissue was harvested for transmission electron microscopy, immunohistochemistry, immunofluorescence, Masson's trichrome staining, haematoxylin-eosin staining, TdT-mediated dUTP Nick End Labeling and western blotting. The M group exhibited a decrease in erectile responses and increased apoptosis and fibrosis compared to these in the S group. Meanwhile, nerve content and the penile atrophy index were also decreased in the M group. Treatment with salidroside and rapamycin for 3 weeks partially restored erectile function and significantly attenuated corporal apoptosis, fibrosis, nerve content and penile atrophy in the M group. Moreover, the autophagy level was further enhanced in the M + salidroside group, which was the same as that in the positive observation group (M + rapamycin). Salidroside treatment not only improved erectile function in rats with BCNI, but also inhibited apoptosis and fibrosis and ameliorated the loss of nerve content and endothelial and corpus cavernosum smooth muscle cells by promoting protective autophagy.

Salidroside: A review of its recent advances in synthetic pathways and pharmacological properties

Salidroside has been identified as one of the most potent compounds isolated from various Rhodiola plants, which have been used for a long time as adaptogens in traditional Chinese medicine. However, due to the severe growing environment of herbal medicine and large-scale excavation, the content of natural salidroside is extremely small. Most of the previous studies focused on herbal medicine, and there were few reviews on the synthesis of its main active ingredient salidroside. This paper presents different synthetic routes of salidroside to resolve the contradiction between supply and demand and lays the foundation for new drug research and development. Furthermore, emerging evidence indicates that salidroside, a promising environmentally-adapted drug with low toxicity and few side effects, possesses a wide spectrum of pharmacological properties, including activities on the cardiovascular system and central nervous system, anti-hypoxia, anti-fatigue and anti-aging activities, anticancer activity, anti-inflammatory activity, antioxidant activity, antivirus and immune stimulation activities, antidiabetic activity, anti-osteoporotic activity, and so on. Although the former researches have summarized the pharmacological effects of salidroside, focusing on the central nervous system, diabetes, and cancer, the overall pharmacological aspects of it have not been analyzed. This review highlights biological characteristics and mechanisms of action from 2009 to now as well as toxicological and pharmacokinetic data of the analyzed compound reported so far, with a view to providing a reference for further development and utilization of salidroside.

The influence of drugs on peripheral nerve regeneration

Currently, there are no established adjuvant drugs for the acceleration of peripheral nerve regeneration. In this paper, we reviewed the literature from the last 10 years and described the drugs proved to accelerate the functional and histological regeneration of the peripheral nerves, either after trauma or in neuropathy experimental models. The vast majority of the studies were experimental with very few small clinical studies, which indicates the need for prospective randomized studies to identify the best drugs to use as adjuvants for nerve regeneration.

Therapeutic Effect of Vinorine on Sciatic Nerve Injured Rat

Vinorine is a monoterpenoid indole alkaloid, a type of natural alkaloids. Growing reports exhibited the numerous pharmacology activities of vinorine such as anti-inflammation, anti-bacterial and anti-tumor. In this study, the effect of vinorine injection (7.5, 15 and 30 mg/kg) on motor function, sensation and nerve regeneration in sciatic nerve crush injury rat was investigated. The results of behavioral analysis, electrophysiological analysis and muscle histological analysis suggested that vinorine promoted the motor function recovery after sciatic nerve injury. The results of mechanical withdrawal thresholds assay and hot plate test demonstrated that vinorine improved the sensation recovery after sciatic nerve injury. The results of Fluoro-gold retrograde labeling, transmission electron microscope assay, toluidine blue and HE staining showed that vinorine attenuated the nerve damage caused by sciatic nerve injury and promoted the nerve regeneration. Furthermore, nerve growth factor (NGF) and its downstream extracellular signal-regulated kinase (ERK) signaling pathway participated in the neuro-recovery effect of vinorine after crush. In conclusion, vinorine treatment accelerated the sciatic nerve regeneration, motor function recovery and sensation recovery after crush injury via regulation of NGF and ERK activity. These results suggested that vinorine is a promising agent for never injury therapy.

Salidroside Protects against MPP+-Induced Neuronal Injury through DJ-1-Nrf2 Antioxidant Pathway

Parkinson's disease (PD) is the second most common neurodegenerative disorder. We have found that salidroside (Sal) exhibited neuroprotective effects against MPP+ toxicity. However, the molecular mechanism is not fully understood. In this study, we found that Sal significantly prevented MPP+-induced decrease of mRNA and protein expression of Nrf2, GCLc, SOD1, and SOD2 in SH-SY5Y cells. Moreover, silencing of Nrf2 significantly inhibited Sal-induced increase in mRNA and protein expression of GCLc, SOD1, and SOD2. But Nrf2 silence did not significantly impact Sal-exhibited effects on DJ-1 expression. Silencing of Nrf2 significantly suppressed the decrease of apoptosis induced by Sal in MPP+-treated SH-SY5Y cells. Sal significantly prevented MPP+-induced decrease of the mRNA and protein expression of DJ-1 in SH-SY5Y cells. Moreover, silencing of DJ-1 significantly inhibited Sal-induced increase in mRNA and protein expression of Nrf2, GCLc, SOD1, and SOD2 in MPP+-treated SH-SY5Y cells. These results indicated that DJ-1 was an upstream regulator of Nrf2 in the neuroprotective effects of Sal. Furthermore, silencing of DJ-1 significantly suppressed the decrease of apoptosis induced by Sal in MPP+-treated SH-SY5Y cells. In conclusion, Sal prevented MPP+-induced neurotoxicity through upregulation of DJ-1-Nrf2-antioxidant pathway. Our findings provide novel insights into the neuroprotective effects of Sal against PD.

The Proliferation Enhancing Effects of Salidroside on Schwann Cells In Vitro

Derived from Rhodiola rosea L., which is a popular plant in Eastern Europe and Asia, salidroside has pharmacological properties including antiviral, anticancer, hepatoprotective, antidiabetic, and antioxidative effects. Recent studies show that salidroside has neurotrophic and neuroprotective effects. However, the effect of salidroside on Schwann cells (SCs) and the underlying mechanisms of the salidroside-induced neurotrophin secretion have seldom been studied. In this study, the effect of salidroside on the survival, proliferation, and gene expression of Schwann cells lineage (RSC96) was studied through the examinations of the cell viability, proliferation, morphology, and expression of neurotrophic factor related genes including BDNF, GDNF, and CDNF at 2, 4, and 6 days, respectively. These results showed that salidroside significantly enhanced survival and proliferation of SCs. The underlying mechanism might involve that salidroside affected SCs growth through the modulation of several neurotrophic factors including BDNF, GDNF, and CDNF. As for the concentration, 0.4 mM, 0.2 mM, and 0.1 mM of salidroside were recommended, especially 0.2 mM. This investigation indicates that salidroside is capable of enhancing SCs survival and function in vitro, which highlights the possibility that salidroside as a drug agent to promote nerve regeneration in cellular nerve scaffold through salidroside-induced neurotrophin secretion in SCs.

Salidroside promotes peripheral nerve regeneration based on tissue engineering strategy using Schwann cells and PLGA: in vitro and in vivo

Salidriside (SDS), a phenylpropanoid glycoside derived from Rhodiola rosea L, has been shown to be neuroprotective in many studies, which may be promising in nerve recovery. In this study, the neuroprotective effects of SDS on engineered nerve constructed by Schwann cells (SCs) and Poly (lactic-co-glycolic acid) (PLGA) were studied in vitro. We further investigated the effect of combinational therapy of SDS and PLGA/SCs based tissue engineering on peripheral nerve regeneration based on the rat model of nerve injury by sciatic transection. The results showed that SDS dramatically enhanced the proliferation and function of SCs. The underlying mechanism may be that SDS affects SCs growth through the modulation of neurotrophic factors (BDNF, GDNF and CNTF). 12 weeks after implantation with a 12 mm gap of sciatic nerve injury, SDS-PLGA/SCs achieved satisfying outcomes of nerve regeneration, as evidenced by morphological and functional improvements upon therapy by SDS, PLGA/SCs or direct suture group assessed by sciatic function index, nerve conduction assay, HE staining and immunohistochemical analysis. Our results demonstrated the significant role of introducing SDS into neural tissue engineering to promote nerve regeneration.

Curcumin improves tendon healing in rats: a histological, biochemical, and functional evaluation

Curcumin, a compound extracted from the roots of Zingiberaceae, has been proposed as a treatment for tissue injury but studies are yet to be done on its effect on tendon healing. Therefore, we performed a series of experiments to test our hypothesis that curcumin has positive effects on tendon repair. Patellar tendon window defect was created in Sprague-Dawley rats and these were divided into two groups: (i) control and (ii) curcumin-treated. Curcumin (100 mg/kg body weight) was applied by oral gavage. Its potential for promoting tendon healing was assessed by histological evaluation, mRNA expression of tenocyte-related genes, malondialdehyde (MDA) levels, manganese-dependent superoxide dismutase (MnSOD) activity, quantification of hydroxyproline (HOPro), and biomechanical testing. In this tendon injury model, curcumin significantly improved the healing properties as evidenced by extensive deposition of well-organized collagen fibers, decreased MDA levels, and increase in the biomechanical properties and MnSOD activity of the regenerated tendon tissues. The current study showed that curcumin can improve the quality of tendon rupture healing, and thus represents a promising strategy in the management of injured tendon tissue.

Water extract of Acer tegmentosum reduces bone destruction by inhibiting osteoclast differentiation and function

The stem of Acer tegmentosum has been widely used in Korea for the treatment of hepatic disorders. In this study, we investigated the bone protective effect of water extract of the stem of Acer tegmentosum (WEAT). We found that WEAT inhibits osteoclast differentiation induced by receptor activator of nuclear factor-κB ligand (RANKL), an essential cytokine for osteoclast differentiation. In osteoclast precursor cells, WEAT inhibited RANKL-induced activation of JNK, NF-κB, and cAMP response element-binding protein, leading to suppression of the induction of c-Fos and nuclear factor of activated T cells cytoplasmic 1, key transcription factors for osteoclast differentiation. In addition, WEAT inhibited bone resorbing activity of mature osteoclasts. Furthermore, the oral administration of WEAT reduced RANKL-induced bone resorption and trabecular bone loss in mice. Taken together, our study demonstrates that WEAT possesses a protective effect on bone destruction by inhibiting osteoclast differentiation and function.