Irradiation increases brain-derived neurotrophic factor precursor signaling in the mouse hippocampus

Blocking salt-inducible kinases with YKL-06-061 prevents PTZ-induced seizures in mice

INTRODUCTION

Epilepsy is one of the most common neurological diseases, while over one third of adults with epilepsy still have inadequate seizure control. Although mutations in salt-inducible kinases (SIKs) have been identified in epileptic encephalopathy, it is not known whether blocking SIKs can prevent pentylenetetrazole (PTZ)-induced seizures.

METHODS

We first determined the time course of SIKs (including SIK 1, 2, and 3) in the hippocampus of PTZ treated mice. And then, we evaluated the effects of anti-epilepsy drug valproate acid (VPA) on the expression of SIK 1, 2, and 3 in the hippocampus of PTZ treated mice. Next, we investigated the effect of different dose of SIKs inhibitor YKL-06-061 on the epileptic seizures and neuronal activation by determining the expression of immediate early genes (IEGs) in the PTZ treated mice.

RESULTS

We found that PTZ selectively induced enhanced expression of SIK1 in the hippocampus, which was blocked by VPA treatment. Notably, YKL-06-061 decreased seizure activity and prevented neuronal overactivity, as indicated by the reduced expression of IEGs in the hippocampus and prefrontal cortex.

CONCLUSION

Our findings provide the first evidence that SIK1 affects gene regulation in neuronal hyperactivity, which is involved in seizure behavior. Targeting SIK1 through the development of selective inhibitors may lead to disease-modifying therapies that reduce epilepsy progression.

Radioprotective potential of probiotics against gastrointestinal and neuronal toxicity: a preclinical study

PURPOSE

Radiotherapy is a critical component of cancer treatment, along with surgery and chemotherapy. Approximately, 90% of cancer patients undergoing pelvic radiotherapy show gastrointestinal (GI) toxicity, including bloody diarrhea, and gastritis, most of which are associated with gut dysbiosis. In addition to the direct effect of radiation on the brain, pelvic irradiation can alter the gut microbiome, leading to inflammation and breakdown of the gut-blood barrier. This allows toxins and bacteria to enter the bloodstream and reach the brain. Probiotics have been proven to prevent GI toxicity by producing short-chain fatty acids and exopolysaccharides beneficial for protecting mucosal integrity and oxidative stress reduction in the intestine and also shown to be beneficial in brain health. Microbiota plays a significant role in maintaining gut and brain health, so it is important to study whether bacterial supplementation will help in maintaining the gut and brain structure after radiation exposure.

METHODS

In the present study, male C57BL/6 mice were divided into control, radiation, probiotics, and probiotics + radiation groups. On the 7th day, animals in the radiation and probiotics + radiation groups received a single dose of 4 Gy to  whole-body. Posttreatment, mice were sacrificed, and the intestine and brain tissues were excised for histological analysis to assess GI and neuronal damage.

RESULTS

Radiation-induced damage to the villi height and mucosal thickness was mitigated by the probiotic treatment significantly (p < 0.01). Further, radiation-induced pyknotic cell numbers in the DG, CA2, and CA3 areas were substantially reduced with bacterial supplementation (p < 0.001). Similarly, probiotics reduced neuronal inflammation induced by radiation in the cortex, CA2, and DG region (p < 0.01). Altogether, the probiotics treatment helps mitigate radiation-induced intestinal and neuronal damage.

CONCLUSION

In conclusion, the probiotic formulation could attenuate the number of pyknotic cells in the hippocampal brain region and decrease neuroinflammation by reducing the number of microglial cells.

Betaine prevents cognitive dysfunction by suppressing hippocampal microglial activation in chronic social isolated male mice

Chronic social isolation (SI) stress, which became more prevalent during the COVID-19 pandemic, contributes to abnormal behavior, including mood changes and cognitive impairment. Known as a functional nutrient, betaine has potent antioxidant and anti-inflammatory properties in vivo. However, whether betaine can alleviate the abnormal behavior induced by chronic SI in mice remains unknown. In this study, we investigated the efficacy of betaine in the treatment of behavioral changes and its underlying mechanism. Three-week-old male mice were randomly housed for 8 weeks in either group housing (GH) or SI. The animals were divided into normal saline-treated GH, normal saline-treated SI, and betaine-treated SI groups in the sixth week. The cognitive and depression-like behavior was determined in the eighth week. We found that long-term betaine administration improved cognitive behavior in SI mice but failed to prevent depression-like behavior. Moreover, long-term betaine administration inhibited hippocampal microglia over-activation and polarized microglia toward the M2 phenotype, which effectively inhibited the expression of inflammatory factors in SI mice. Finally, the protective effect of betaine treatment in SI mice might not be due to altered activity of the hypothalamic-pituitary-adrenal axis. Collectively, our findings reveal that betaine can improve SI-induced cognitive impairment, thus providing an alternative natural source for the prevention of memory loss caused by SI or loneliness.

Systemic treatment with GnRH agonist produces antidepressant-like effects in LPS induced depression male mouse model

Gonadotropin-releasing hormone (GnRH) is at the head of the neuroendocrine reproductive axis. However, the non-reproductive functions of GnRH expressed in various tissues, including hippocampus, are still not known. Here, we unveil a previously unknown effect of GnRH, which mediates depression-like behaviors through the modulation of microglia function during immune challenge. Specifically, we found that either systemic treatment with GnRH agonist or over-expression of endogenous hippocampal GnRH via viral tool abolished the depression-like behavior after LPS challenges in mice. And the anti-depressant of GnRH was dependent on the hippocampal GnRHR signaling, since antagonizing GnRHR by drug treatment or by hippocampal GnRHR knockdown could block the antidepressant-effect of GnRH agonist. Interestingly, we found that the peripheral GnRH treatment prevented the microglia activation mediated inflammation in the hippocampus of mice. In light of the research findings presented here, we propose that, at least in the hippocampus, GnRH appears to act on GnRHR to regulate higher order non-reproductive functions associated with the microglia mediated neuroinflammation. These findings also provide insights into the function and cross-talk of GnRH, a known neuropeptide hormone, in neuro-immune response.

Alternate-day fasting for the protection of cognitive impairment in c57BL/6J mice following whole-brain radiotherapy

NLRP3 inflammasome activation is implicated in irradiation-induced cognitive dysfunction. Alternate-day fasting (ADF) has been demonstrated to improve neuroinflammation as a non-pharmacological intervention. However, the exact mechanism and the anti-inflammatory effect in irradiation-induced cognitive dysfunction still need further in-depth study. The present study examined the effects of eight-week ADF on the cognitive functions of mice as well as inflammasome-mediated hippocampal neuronal loss following irradiation in mouse models of irradiation-induced cognitive deficits using seven-week-old male C57BL/6J mice. The behavioral results of novel place recognition and object recognition tasks revealed that ADF ameliorated cognitive functions in irradiation-induced cognitive dysfunction mice. ADF inhibited the expression of components of the NLRP3 inflammasome (NLRP3, ASC, and Cl.caspase-1), the downstream inflammatory factor (IL-1β and IL-18), and apoptosis-related proteins (caspase-3) via western blotting. Furthermore, an increased number of neurons and activated astrocytes were observed in the hippocampus using immunohistochemistry and Sholl analysis, which was jointly confirmed by western blotting. According to our study, this is the first time we found that ADF improved cognitive dysfunction induced by irradiation, and the anti-inflammatory effect of ADF could be due to inhibition in NLRP3-mediated hippocampal neuronal loss by suppressing astrocyte activation.

Targeting PERK mediated endoplasmic reticulum stress attenuates neuroinflammation and alleviates lipopolysaccharide-induced depressive-like behavior in male mice

Neuroinflammation plays a key role in the development of depression-like behaviors.Endoplasmic reticulum (ER) stress,defined as accumulation of unfolded proteins in the ER,is suggested tocollaboratewithinflammation process to drive sustained neuroinflammation. Protein kinase R-like endoplasmic reticulum kinase (PERK) is ofparticularly attractive target because it plays key rolein the regulation of ER stress-induced neuroinflammation, however, little isknown whether PERKmediatedER stress is implicated in LPS-induced depression-like behaviors.Thus, we aimed to evaluate the induction of PERK pathwayin mice with depression-like behaviors induced by LPS, as well as the alterations in depression-like behaviorsfollowing the blocking of PERK pathway.We found that LPS challenges resulted in enhanced PERK in the hippocampus, with no alteration in the prefrontal cortex. Importantly, we found that PERKinhibitorISRIB reducedthe proinflammatory responsesof microglia in the context of acute LPS-induced brain inflammation, and subsequent the preserved hippocampal neurogenesis, and improvement in depression-like behavioroutcomes following LPS challenges.It was also worth mentioning thatISRIB treatmentreduced the peripheral pro-inflammatory cytokines includingIL-1β, IL-6 and IL-18. Thus, targetingPERK mediated Endoplasmic reticulum stress may be a promising antidepressant and anti-inflammatory candidate drug for the alleviation of neuroinflammationmediated depression, and PERKinhibitorISRIBmay havebenefits for combating major depressive disorder.

Betaine attenuate chronic restraint stress-induced changes in testicular damage and oxidative stress in male mice

SCOPE

Male fertility and sperm quality are negatively affected by psychological stress. Chronic restraint stress (CRS) is a common psychological stress that has a negative effect on sperm. Betaine (BET), an active ingredient isolated from Lycium barbarum, has anti-oxidant, anti-inflammatory and other pharmacological activities. This study aims to explore whether betaine has a therapeutic effect on sperm deformity and vitality under CRS and its mechanism.

METHODS AND RESULTS

Chronic restraint stress was induced in 8-week-old male C57BL/6 J mice by fixation for 6 h a day for 35 days. Mice were intraperitoneally injected with betaine (BET) or normal saline (NS) for 14 days. Thirty-five days later, the animals were sacrificed. The results showed that the detrimental effects of CRS on testes as evident by disrupted histoarchitecture, increased oxidative stress, inflammation and apoptosis that compromised male fertility. BET injections can reverse these symptoms.

CONCLUSIONS

BET can improve spermatogenesis dysfunction caused by CRS, which may provide potential dietary guidance.

Development and Validation of a 7-Gene Inflammatory Signature Forecasts Prognosis and Diverse Immune Landscape in Lung Adenocarcinoma

Background: Inflammatory responses are strongly linked with tumorigenesis and cancer development. This research aimed to construct and validate a novel inflammation response–related risk predictive signature for forecasting the prognosis of patients with LUAD.

Methods: Differential expression analysis, univariate Cox, LASSO, and multivariate Cox regression analyses of 200 inflammatory response–related genes (IRRG) were performed to establish a risk predictive model in the TCGA training cohort. The performance of the IRRG model was verified in eight GEO datasets. GSEA analysis, ESTIMATE algorithms, and ssGSEA analysis were applied to elucidate the possible mechanisms. Furthermore, the relationship analysis between risk score, model genes, and chemosensitivity was performed. Last, we verified the protein expression of seven model genes by immunohistochemical staining or Western blotting.

Results: We constructed a novel inflammatory response–related 7-gene signature (MMP14, BTG2, LAMP3, CCL20, TLR2, IL7R, and PCDH7). Patients in the high-risk group presented markedly decreased survival time in the TCGA cohort and eight GEO cohorts than the low-risk group. Interestingly, multiple pathways related to immune response were suppressed in high-risk groups. The low infiltration levels of B cell, dendritic cell, natural killer cell, and eosinophil can significantly affect the unsatisfactory prognosis of the high-risk group in LUAD. Moreover, the tumor cells’ sensitivity to anticancer drugs was markedly related to risk scores and model genes. The protein expression of seven model genes was consistent with the mRNA expression.

Conclusion: Our IRRG prognostic model can effectively forecast LUAD prognosis and is tightly related to immune infiltration.

TRPV4 inhibitor HC067047 produces antidepressant-like effect in LPS-induced depression mouse model

Inflammation is a crucial component that contributes to the pathogenesis of major depressive disorder. It has been revealed that the nonselective cation channel transient receptor potential vanilloid 4 (TRPV4) profoundly affects a variety of physiological processes, including inflammation. However, its roles and mechanisms in LPS-induced depression are still unclear. Here, for the first time, we found that there was a significant increase in TRPV4 in the hippocampus in a depression mouse model induced by LPS. TRPV4 inhibitor HC067047 or knockdown the hippocampal TRPV4 with TRPV4 shRNA could effectively rescue the aberrant behaviors. Furthermore, TRPV4 inhibitor HC067047 reduced the activation of astrocyte and microglia, decreased expression of CaMKII-NLRP3 inflammasome and increased the expression of neurogenesis marker DCX in the hippocampus. In addition, enhanced neuroinflammation in the serum was also reversed by TRPV4 inhibitor HC067047. Thus, we consider that TRPV4 has an important role in contributing to the depression-like behavior following LPS-induced systemic inflammation.

Amelioration of Scopolamine-induced Learning and Memory Impairment by the TRPV4 Inhibitor HC067047 in ICR Mice

Alzheimer's disease (AD) is one of the most common causes of neurodegenerative diseases in the elderly. Cholinergic dysfunction is one of the pathological hallmarks of AD and leads to learning and memory impairment. Transient receptor potential vanilloid 4(TRPV4), a nonselective cation channel, is involved in learning and memory functions. HC067047, a TRPV4 specific inhibitor, has been reported to protect neurons against cerebral ischemic injury and amyloid-β -(Aβ) 40-induced hippocampal cell death. However, whether HC067047 could improve scopolamine (SCP)-induced cognitive dysfunction in mice is still unknown. The aims of this study were to verify whether HC067047 could ameliorate the SCP-induced learning and memory impairments in mice and to elucidate its underlying mechanisms of action. In this study, we examined the neuroprotective effect of the HC067047 against cognitive dysfunction induced by SCP (5 mg/kg, i.p.), a muscarinic receptor antagonist. The results showed that administration of HC067047(10 mg/kg, i.p.) significantly ameliorated SCP-induced cognitive dysfunction as assessed by the novel place recognition test (NPRT) and novel object recognition test (NORT). In the Y-maze test, HC067047 significantly enhanced the time spent in the novel arm in SCP mice. To further investigate the molecular mechanisms underlying the neuroprotective effect of HC067047, expression of several proteins involved in apoptosis was examined. The results demonstrated that HC067047 treatment decreased the protein levels of proapoptotic proteins such as Bax and caspase-3 in the hippocampus of SCP mice. In addition, HC067047 enhanced expression of the neurogenesis marker DCX and improved levels of the mature neuronal marker NeuN in SCP mice. These findings suggest the neuroprotective potential of the TRPV4 inhibitor HC067047 for the management of dementia with learning and memory loss.