Development of telmisartan in the therapy of spinal cord injury: pre-clinical study in rats

Metformin's therapeutic potential in spinal cord injury: a systematic review and meta-analysis on locomotor recovery, neuropathic pain alleviation, and modulation of secondary injury mechanisms

OBJECTIVE

To evaluate metformin's efficacy in locomotion recovery, alleviating neuropathic pain, and modulating underlying molecular mechanisms in Spinal Cord Injury (SCI) rodent models through a systematic review and meta-analysis.

METHODS

We conducted a comprehensive literature search across Medline, Embase, Scopus, and Web of Science from inception to May 2024. We included studies that utilized rodent models of traumatic SCI treated with metformin versus untreated controls. Data on locomotor recovery, neuropathic pain, and molecular mechanisms related to secondary injury were extracted. Standardized mean differences (SMDs) were synthesized as the pooled effect sizes.

RESULTS

Twenty-three studies comprising 1,567 animals met the inclusion criteria. Metformin significantly enhanced locomotor function (SMD = 2.23, 95% CI: 1.74, 2.73, p < 0.001) and improved both mechanical allodynia (SMD = 1.18; 95% CI, 0.35 to 2.00; p = 0.005) and thermal hyperalgesia (SMD = 2.40; 95% CI, 1.65 to 3.16; p < 0.001). It reduces inflammation, oxidative stress, microglial activation, and astrogliosis and promotes myelination and autophagy flux via activating the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. This resulted in decreased apoptosis and lesion size and increased tissue preservation and neuronal survival. Subgroup analyses indicated greater locomotor improvements when metformin was administered in the acute (< 3 days of injury) phase of the injury (meta-regression coefficient = 1.65; 95% CI, 0.37 to 2.93; p = 0.011).

CONCLUSION

Metformin shows significant therapeutic benefits for SCI in rodent models, promoting locomotor recovery and alleviating neuropathic pain. These results underscore its translational potential for clinical SCI management.

The effect of metformin on ameliorating neurological function deficits and tissue damage in rats following spinal cord injury: A systematic review and network meta-analysis

Spinal cord injury (SCI) is a devastating condition with few treatment options. Metformin, a classical antidiabetic and antioxidant, has extended its application to experimental SCI treatment. Here, we performed a systematic review to evaluate the neurobiological roles of metformin for treating SCI in rats, and to assess the potential for clinical translation. PubMed, Embase, China National Knowledge Infrastructure, WanFang data, SinoMed, and Vip Journal Integration Platform databases were searched from their inception dates to October 2021. Two reviewers independently selected controlled studies evaluating the neurobiological roles of metformin in rats following SCI, extracted data, and assessed the quality of methodology and evidence. Pairwise meta-analyses, subgroup analyses and network analysis were performed to assess the roles of metformin in neurological function and tissue damage in SCI rats. Twelve articles were included in this systematic review. Most of them were of moderate-to-high methodological quality, while the quality of evidence from those studies was not high. Generally, Basso, Beattie, and Bresnahan scores were increased in rats treated with metformin compared with controls, and the weighted mean differences (WMDs) between metformin and control groups exhibited a gradual upward trend from the 3rd (nine studies, n = 164, WMD = 0.42, 95% CI = −0.01 to 0.85, P = 0.06) to the 28th day after treatment (nine studies, n = 136, WMD = 3.48, 95% CI = 2.04 to 4.92, P < 0.00001). Metformin intervention was associated with improved inclined plane scores, tissue preservation ratio and number of anterior horn motor neurons. Subgroup analyses indicated an association between neuroprotection and metformin dose. Network meta-analysis showed that 50 mg/kg metformin exhibited greater protection than 10 and 100 mg/kg metformin. The action mechanisms behind metformin were associated with activating adenosine monophosphate-activated protein kinase signaling, regulating mitochondrial function and relieving endoplasmic reticulum stress. Collectively, this review indicates that metformin has a protective effect on SCI with satisfactory safety and we demonstrate a rational mechanism of action; therefore, metformin is a promising candidate for future clinical trials. However, given the limitations of animal experimental methodological and evidence quality, the findings of this pre-clinical review should be interpreted with caution.

[Effect of renin-angiotensin-aldosterone system inhibitors on functional activity of the spinal cord and nerve roots in patients with degenerative lumbar spine diseases]

High neuroprotective activity of renin-angiotensin-aldosterone system (RAAS) inhibitors in patients with vascular diseases of the brain and spinal cord has been confirmed.

OBJECTIVE

To evaluate the effect of renin-angiotensin-aldosterone system inhibitors on functional activity of the spinal cord and nerve roots in patients with degenerative lumbar spine diseases.

MATERIAL AND METHODS

A retrospective observational cohort study was performed. We evaluated clinical and radiological parameters (gender, age of patients, type of antihypertensive drug, concomitant diseases, ODI (6) and SF-36 (7) scores of patient quality of life), functional recovery, increase of signal intensity and its area in T2WIs, localization and maximum spinal canal stenosis, as well as maximum spinal cord and nerve root compression.

RESULTS

The study included 117 medical records of respondents (88 men and 29 women aged 56.9±13.2 years) who underwent lumbar spine surgery for degenerative diseases. Arterial hypertension was verified in 68 (58.1%) patients, diabetes mellitus in 22 (18.8%) respondents. Age (p=0.002), diabetes mellitus (p=0.007), arterial hypertension (p=0.015) and antihypertensive therapy (p=0.023) were significantly associated with worse clinical and neurological status of patients. Binary logistic regression model demonstrated that only arterial hypertension was significantly associated with low preoperative quality of life (p=0.002).

CONCLUSION

Intake of AT II-1 receptor blockers and angiotensin converting enzyme inhibitors for arterial hypertension is a significant predictor of decrease in signal intensity of the spinal cord and its roots according to T2WIs.

Low-dose metformin treatment in the subacute phase improves the locomotor function of a mouse model of spinal cord injury

Metformin, a first-line drug for type-2 diabetes, has been shown to improve locomotor recovery after spinal cord injury. However, there are studies reporting no beneficial effect. Recently, we found that high dose of metformin (200 mg/kg, intraperitoneal) and acute phase administration (immediately after injury) led to increased mortality and limited locomotor function recovery. Consequently, we used a lower dose (100 mg/kg, i.p.) metformin in mice, and compared the effect of immediate administration after spinal cord injury (acute phase) with that of administration at 3 days post-injury (subacute phase). Our data showed that metformin treatment starting at the subacute phase significantly improved mouse locomotor function evaluated by Basso Mouse Scale (BMS) scoring. Immunohistochemical studies also revealed significant inhibitions of microglia/macrophage activation and astrogliosis at the lesion site. Furthermore, metformin treatment at the subacute phase reduced neutrophil infiltration. These changes were in parallel with the increased survival rate of spinal neurons in animals treated with metformin. These findings suggest that low-dose metformin treatment for subacute spinal cord injury can effectively improve the functional recovery possibly through anti-inflammation and neuroprotection. This study was approved by the Institute Animal Care and Use Committee at the University of Texas Medical Branch (approval No. 1008041C) in 2010.

Telmisartan, an Antagonist of Angiotensin II Receptors, Accentuates Voltage-Gated Na+ Currents and Hippocampal Neuronal Excitability

Telmisartan (TEL), a non-peptide blocker of the angiotensin II type 1 receptor, is a widely used antihypertensive agent. Nevertheless, its neuronal ionic effects and how they potentially affect neuronal network excitability remain largely unclear. With the aid of patch-clamp technology, the effects of TEL on membrane ion currents present in hippocampal neurons (mHippoE-14 cells) were investigated. For additional characterization of the effects of TEL on hippocampal neuronal excitability, we undertook in vivo studies on Sprague Dawley (SD) rats using pilocarpine-induced seizure modeling, a hippocampal histopathological analysis, and inhibitory avoidance testing. In these hippocampal neurons, TEL increased the peak amplitude of I Na , with a concomitant decline in the current inactivation rate. The TEL concentration dependently enhanced the peak amplitude of depolarization-elicited I Na and lessened the inactivation rate of I Na . By comparison, TEL was more efficacious in stimulating the peak I Na and in prolonging the inactivation time course of this current than tefluthrin or (-)-epicatechin-3-gallate. In the continued presence of pioglitazone, the TEL-perturbed stimulation of I Na remained effective. In addition, cell exposure to TEL shifted the steady-state inactivation I Na curve to fewer negative potentials with no perturbations of the slope factor. Unlike chlorotoxin, either ranolazine, eugenol, or KMUP-1 reversed TEL-mediated increases in the strength of non-inactivating I Na . In the cell-attached voltage-clamp recordings, TEL shortened the latency in the generation of action currents. Meanwhile, TEL increased the peak I Na , with a concurrent decrease in current inactivation in HEKT293T cells expressing SCN5A. Furthermore, although TEL did not aggravate pilocarpine-induced chronic seizures and tended to preserve cognitive performance, it significantly accentuated hippocampal mossy fiber sprouting. Collectively, TEL stimulation of peak I Na in combination with an apparent retardation in current inactivation could be an important mechanism through which hippocampal neuronal excitability is increased, and hippocampal network excitability is accentuated following status epilepticus, suggesting further attention to this finding.

The effect of renin-angiotensin system blockers on spinal cord dysfunction and imaging features of spinal cord compression in patients with symptomatic cervical spondylosis

BACKGROUND CONTEXT

Cervical spondylosis may lead to spinal cord compression, poor vascular perfusion, and ultimately, cervical myelopathy. Studies suggest a neuroprotective effect of renin-angiotensin system (RAS) inhibitors in the brain, but limited data exist regarding their impact on the spinal cord.

PURPOSE

To investigate whether RAS blockers and other antihypertensive drugs are correlated with preoperative functional status and imaging markers of cord compression in patients with symptomatic cervical spondylosis.

STUDY DESIGN

Retrospective observational study.

PATIENT SAMPLE

Individuals with symptomatic degenerative cervical stenosis who underwent surgery.

OUTCOME MEASURES

Imaging features of spinal cord compression and functional status (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales).

METHODS

Two hundred sixty-six operative patients with symptomatic degenerative cervical stenosis were included. Demographic data, comorbidities, antihypertensive medications, and functional status (including mJOA and Nurick grading scales) were collected. We evaluated canal compromise, cord compromise, surface area of T2 signal cord change, and pixel intensity of signal cord change compared with normal cord on T2-weighted magnetic resonance imaging sequences.

RESULTS

Of 266 patients, 41.7% were women, 58.3% were men; median age was 57.2 years; 20.6% smoked tobacco; 24.7% had diabetes mellitus. One hundred forty-nine patients (55.8%) had hypertension, 142 (95.3%) of these were taking antihypertensive medications (37 angiotensin-II receptor blockers [ARBs], 44 angiotensin-converting enzyme inhibitors, and 61 other medications). Patients treated with ARBs displayed a higher signal intensity ratio (ie, less signal intensity change in the compressed cord area) compared with untreated patients without hypertension (p=.004). Patients with hypertension had worse preoperative mJOA and Nurick scores than those without (p<.001). In the multivariate analysis, ARBs remained an independent beneficial factor for lower signal intensity change (p=.04), whereas hypertension remained a risk factor for worse preoperative neurological status (p<.01).

CONCLUSIONS

In our study, patients with hypertension who were treated with RAS inhibitors had decreased T2-weighted signal intensity change than untreated patients without hypertension. Patients with hypertension also had worse preoperative functional status. Prospective case-control studies may deepen understanding of RAS modulators in the imaging and functional status of chronic spinal cord compression.

Role of PPAR-β/δ/miR-17/TXNIP pathway in neuronal apoptosis after neonatal hypoxic-ischemic injury in rats

Activation of peroxisome proliferator-activated receptor beta/delta (PPAR-β/δ), a nuclear receptor acting as a transcription factor, was shown to be protective in various models of neurological diseases. However, there is no information about the role of PPAR-β/δ as well as its molecular mechanisms in neonatal hypoxia-ischemia (HI). In the present study, we hypothesized that PPAR-β/δ agonist GW0742 can activate miR-17-5p, consequently inhibiting TXNIP and ASK1/p38 pathway leading to attenuation of apoptosis. Ten-day-old rat pups were subjected to right common carotid artery ligation followed by 2.5 h hypoxia. GW0742 was administered intranasally 1 and 24 h post HI. PPAR-β/δ receptor antagonist GSK3787 was administered intranasally 1 h before and 24 h after HI, antimir-17-5p and TXNIP CRISPR activation plasmid were administered intracerebroventricularly 24 and 48 h before HI, respectively. Brain infarct area measurement, neurological function tests, western blot, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), Fluoro-Jade C and immunofluorescence staining were conducted. GW0742 reduced brain infarct area, brain atrophy, apoptosis, and improved neurological function at 72 h and 4 weeks post HI. Furthermore, GW0742 treatment increased PPAR-β/δ nuclear expression and miR-17-5p level and reduced TXNIP in ipsilateral hemisphere after HI, resulting in inhibition of ASK1/p38 pathway and attenuation of apoptosis. Inhibition of PPAR-β/δ receptor and miR-17-5p and activation of TXNIP reversed the protective effects. For the first time, we provide evidence that intranasal administration of PPAR-β/δ agonist GW0742 attenuated neuronal apoptosis at least in part via PPAR-β/δ/miR-17/TXNIP pathway. GW0742 could represent a therapeutic target for treatment of neonatal hypoxic ischemic encephalopathy (HIE).

Resveratrol improves neuron protection and functional recovery through enhancement of autophagy after spinal cord injury in mice

Resveratrol (Res), a natural phenolic compound, has been proven to have a wide variety of beneficial health effects. For example, resveratrol has neuroprotective effects in different central nervous system diseases. However, the mechanisms underlying resveratrol neuroprotection in spinal cord injury (SCI) remain unclear. In this study, we showed that resveratrol treatment improved the restoration of locomotor function, and decreased the degeneration of neurons in SCI mice, which was paralleled by a reduction of apoptosis. We further examined autophagy markers via western blot and immunofluorescence. Results showed that the beneficial effects of resveratrol were related to the promotion LC3II and beclin-1 expression. In addition, autophagy suppression with chloroquine (CQ) partially abolished apoptosis inhibition and locomotor functional improvement of Res on SCI, which indicated that the beneficial effect of resveratrol on SCI was through autophagy enhancement. In conclusion, these results illustrated that the neuroprotective effects of resveratrol in SCI are partially through autophagy stimulation, and implied that Res is a promising drug for SCI therapy.