Calpeptin Reduces Neurobehavioral Deficits and Neuronal Apoptosis Following Subarachnoid Hemorrhage in Rats

Efficacy and Mechanism Study of 6S-5-Methyltetrahydrofolate-Calcium Against Telencephalon Infarction Injury in Zebrafish Model of Ischemic Stroke

Ischemic stroke is a heterogeneous brain injury with complex pathophysiology and it is also a time sensitive neurological injury disease. At present, the treatment options for ischemic stroke are still limited. 6S-5-methyltetrahydrofolate-calcium (MTHF-Ca) is the calcium salt of the predominant form of dietary folate in circulation. MTHF-Ca has potential neuroprotective effect on neurocytes, but whether it can be used for ischemic stroke treatment remains unknown. We established zebrafish ischemic stroke model through photothrombotic method to evaluate the protective effect of MTHF-Ca on the ischemic brain injury of zebrafish. We demonstrated that MTHF-Ca reduced the brain damage by reducing motor dysfunction and neurobehavioral defects of zebrafish with telencephalon infarction injury. MTHF-Ca counteracted oxidative damages after Tel injury by increasing the activities of GSH-Px and SOD and decreasing the content of MDA. RNA-seq and RT-qPCR results showed that MTHF-Ca played a neuroprotective role by alleviating neuroinflammation, inhibiting blood coagulation, and neuronal apoptosis processes. Overall, we have demonstrated that MTHF-Ca has neuroprotective effect in ischemic stroke and can be used as a potential treatment for ischemic stroke.

The mechanism and relevant mediators associated with neuronal apoptosis and potential therapeutic targets in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a dominant cause of death and disability worldwide. A sharp increase in intracranial pressure after SAH leads to a reduction in cerebral perfusion and insufficient blood supply for neurons, which subsequently promotes a series of pathophysiological responses leading to neuronal death. Many previous experimental studies have reported that excitotoxicity, mitochondrial death pathways, the release of free radicals, protein misfolding, apoptosis, necrosis, autophagy, and inflammation are involved solely or in combination in this disorder. Among them, irreversible neuronal apoptosis plays a key role in both short- and long-term prognoses after SAH. Neuronal apoptosis occurs through multiple pathways including extrinsic, mitochondrial, endoplasmic reticulum, p53 and oxidative stress. Meanwhile, a large number of blood contents enter the subarachnoid space after SAH, and the secondary metabolites, including oxygenated hemoglobin and heme, further aggravate the destruction of the blood-brain barrier and vasogenic and cytotoxic brain edema, causing early brain injury and delayed cerebral ischemia, and ultimately increasing neuronal apoptosis. Even there is no clear and effective therapeutic strategy for SAH thus far, but by understanding apoptosis, we might excavate new ideas and approaches, as targeting the upstream and downstream molecules of apoptosis-related pathways shows promise in the treatment of SAH. In this review, we summarize the existing evidence on molecules and related drugs or molecules involved in the apoptotic pathway after SAH, which provides a possible target or new strategy for the treatment of SAH.

Calpain Inhibitor Calpeptin Improves Alzheimer's Disease-Like Cognitive Impairments and Pathologies in a Diabetes Mellitus Rat Model

Diabetes mellitus (DM) has been considered an accelerator of Alzheimer's disease (AD), but the cellular and molecular mechanisms underlying this effect are not fully understood. Here, we attempted to determine the role and regulatory mechanism of calpain in the AD-like cognitive decline and pathological changes in rats caused by DM. In the initial stages, our results verified that DM model rats showed cognitive impairment, as well as a loss of neurons, decreased pericyte marker (PDGFR-β and α-SMA), and calpain-2 expression and amyloid-β (Aβ) deposition in the hippocampal tissues. In high glucose-induced primary pericytes, the cell apoptotic rate was increased, and cell proliferation was inhibited in a time-dependent manner. The protein level of calpain-2 was also upregulated by HG induction, but the level of calpain-1 did not change with HG treatment, which was also observed in DM model rats. Subsequently, some DM model rats were administered calpeptin, an inhibitor of calpain. Our data revealed that calpeptin treatment significantly suppressed calpain-1 and calpain-2 expression in the hippocampal tissues and effectively improved the cognitive impairments of DM model rats. Neuronal loss, Aβ accumulation, pericyte loss, inflammation, and oxidative stress injury in the hippocampal tissues of DM model rats were also partly rescued by calpeptin administration. Our work demonstrated that the calpain inhibitor calpeptin could alleviate DM-induced AD-like cognitive impairments and pathological changes in rats, and this effect may be associated with pericytes. Calpeptin may become a promising drug to treat the AD-like complications of DM.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Calpain Inhibitors as Potential Therapeutic Modulators in Neurodegenerative Diseases

It is considered a significant challenge to understand the neuronal cell death mechanisms with a suitable cure for neurodegenerative disorders in the coming years. Calpains are one of the best-considered "cysteine proteases activated" in brain disorders. Calpain is an important marker and mediator in the pathophysiology of neurodegeneration. Calpain activation being the essential neurodegenerative factor causing apoptotic machinery activation, it is crucial to develop reliable and effective approaches to prevent calpain-mediated apoptosis in degenerating neurons. It has been recently seen that the "inhibition of calpain activation" has appeared as a possible therapeutic target for managing neurodegenerative diseases. A systematic literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was conducted. The present article reviews the basic pathobiology and role of selective calpain inhibitors used in various neurodegenerative diseases as a therapeutic target.

Salvia officinalis Extract and 17β-Estradiol Suppresses Ovariectomy Induced Osteoporosis in Female Rats

<b>Background and Objective:</b> Osteoporosis is a progressive metabolic disorder characterized by an impaired bone formation that leads to increased morbidity and mortality.<i> Salvia officinalis </i>is a source of phytoestrogens that could help mitigate the risk of osteoporotic rat fracture by exerting sex hormones. Therefore, the present study was designed to investigate the curative effect of <i>Salvia officinalis </i>Extract<i> </i>(SOE) and<i> </i>17β-estradiol (E<sub>2</sub>) and their combination<i> </i>on bone loss in female rats with ovariectomy-induced estrogen deficiency <b>Materials and Methods:</b> Forty adult female albino rats were divided into five groups, which included Sham control (Sham), ovariectomy (OVX), OVX+SOE, OVX+E<sub>2</sub> and OVX +SOE+E<sub>2</sub>.<i> </i>SOE (10 mL kg<sup></sup><sup>1</sup>) and E<sub>2</sub> (30 μg kg<sup></sup><sup>1</sup>) had been daily gavaged in the OVX+SOE, OVX+E<sub>2</sub> and OVX+SOE+E<sub>2</sub>, respectively for 6-weeks. <b>Results:</b> The model of ovariectomy resulted in osteoporosis as demonstrated by the decreased serum Ca, P, vitamin D, E<sub>2</sub> level associated with a significant increase in PTH levels in comparison to the sham control group. Besides, OVX to rats caused up-regulation in the levels of CTX-1, P1NP, BALP, OC and RANKL comparable to the sham control group. Moreover, SOE and E<sub>2</sub> significantly modulated the calciotropic parameters and improved all bone turnover markers as well as RANKL as compared to the OVX group. However, Histopathological and immunohistochemical results showed defective mineralization with the destruction of the bone matrix and increased TNF-α expression from the OVX group relative to the treated groups. <b>Conclusion:</b> These results suggest that both SOE and E<sub>2</sub> or their combined administration are efficient inhibitors against ovariectomy-induced bone loss in female rats.

Calpastatin peptide attenuates early brain injury following experimental subarachnoid hemorrhage

Calpain activation may have an important role in early brain injury (EBI) following subarachnoid hemorrhage (SAH). The present study investigated the effects of the calpastatin peptide, a cell-permeable peptide that functions as a potent inhibitor of calpain, on EBI in a rat SAH model. It was revealed that calpastatin peptide treatment significantly reduced SAH-induced body weight loss and neurological deficit at 72 h when compared with untreated SAH controls. Furthermore, the quantification of brain water content and the extravasation of Evans blue dye revealed a significant reduction in SAH-induced brain edema and blood-brain barrier permeability at 72 h due to treatment with the calpastatin peptide when compared with untreated SAH controls. Finally, calpastatin peptide treatment significantly attenuated the protein levels of Bax, cytochrome c, cleaved caspase-9 and cleaved caspase-3, and reduced the number of terminal deoxynucleotidyl transferase dUTP nick end labelling-positive cells in the basal cortex at 72 h after SAH when compared with untreated SAH controls. These results indicated that the calpastatin peptide may ameliorate EBI following SAH in rat models.

Exogenous brain-derived neurotrophic factor attenuates neuronal apoptosis and neurological deficits after subarachnoid hemorrhage in rats

Brain-derived neurotrophic factor (BDNF) is a growth factor crucial for neuronal survival, while its role in subarachnoid hemorrhage (SAH)-induced neuronal apoptosis remains unclear. The aim of the present study was to investigate whether administering exogenous BDNF can protect against neuronal apoptosis and neurological deficits following SAH in a rat model. The BDNF level was found to be significantly decreased in the basal cortex at 6, 12, 24, 48 and 72 h following SAH. Exogenous BDNF significantly decreased the expression of Bax and reduced activation of caspase-3 and caspase-9 and the number of apoptotic neurons. Moreover, exogenous BDNF treatment significantly improved the neurological deficits at 72 h and long-term behavioral deficits (day 14) following SAH in a rat model. These findings indicate that exogenous BDNF attenuated SAH-induced neuronal injury in rats.