The Role of Iron Overload in Diabetic Cognitive Impairment: A Review.

It is well documented that diabetes mellitus (DM) is strongly associated with cognitive decline and structural damage to the brain. Cognitive deficits appear early in DM and continue to worsen as the disease progresses, possibly due to different underlying mechanisms. Normal iron metabolism is necessary to maintain normal physiological functions of the brain, but iron deposition is one of the causes of some neurodegenerative diseases. Increasing evidence shows that iron overload not only increases the risk of DM, but also contributes to the development of cognitive impairment. The current review highlights the role of iron overload in diabetic cognitive impairment (DCI), including the specific location and regulation mechanism of iron deposition in the diabetic brain, the factors that trigger iron deposition, and the consequences of iron deposition. Finally, we also discuss possible therapies to improve DCI and brain iron deposition.

Effects of liraglutide on astrocyte polarization and neuroinflammation in db/db mice: focus on iron overload and oxidative stress.

Neuroinflammation plays a crucial role in the occurrence and development of cognitive impairment in type 2 diabetes mellitus (T2DM), but the specific injury mechanism is not fully understood. Astrocyte polarization has attracted new attention and has been shown to be directly and indirectly involved in neuroinflammation. Liraglutide has been shown to have beneficial effects on neurons and astrocytes. However, the specific protection mechanism still needs to be clarified. In this study, we assessed the levels of neuroinflammation and A1/A2-responsive astrocytes in the hippocampus of db/db mice and examined their relationships with iron overload and oxidative stress. First, in db/db mice, liraglutide alleviated the disturbance of glucose and lipid metabolism, increased the postsynaptic density, regulated the expression of NeuN and BDNF, and partially restored impaired cognitive function. Second, liraglutide upregulated the expression of S100A10 and downregulated the expression of GFAP and C3, and decreased the secretion of IL-1ß, IL-18, and TNF-α, which may confirm that it regulates the proliferation of reactive astrocytes and A1/A2 phenotypes polarize and attenuate neuroinflammation. In addition, liraglutide reduced iron deposition in the hippocampus by reducing the expression of TfR1 and DMT1 and increasing the expression of FPN1; at the same time, liraglutide by up-regulating the levels of SOD, GSH, and SOD2 expression, as well as downregulation of MDA levels and NOX2 and NOX4 expression to reduce oxidative stress and lipid peroxidation. The above may attenuate A1 astrocyte activation. This study preliminarily explored the effect of liraglutide on the activation of different astrocyte phenotypes and neuroinflammation in the hippocampus of a T2DM model and further revealed its intervention effect on cognitive impairment in diabetes. Focusing on the pathological consequences of astrocytes may have important implications for the treatment of diabetic cognitive impairment.

Huperzine A-Liposomes Efficiently Improve Neural Injury in the Hippocampus of Mice with Chronic Intermittent Hypoxia.

Background: Chronic intermittent hypoxia (CIH) could cause neuronal damage, accelerating the progression of dementia. However, safe and effective therapeutic drugs and delivery are needed for successful CIH therapy. Purpose: To investigate the neuroprotective effect of Huperzine A (HuA) packaged with nanoliposomes (HuA-LIP) on neuronal damage induced by CIH. Methods: The stability and release of HuA-LIP in vitro were identified. Mice were randomly divided into the Control, CIH, HuA-LIP, and HuA groups. The mice in the HuA and HuA-LIP groups received HuA (0.1 mg/kg, i.p.), and HuA-LIP was administered during CIH exposure for 21 days. HuA-LIP contains the equivalent content of HuA. Results: We prepared a novel formulation of HuA-LIP that had good stability and controlled release. First, HuA-LIP significantly ameliorated cognitive dysfunction and neuronal damage in CIH mice. Second, HuA-LIP elevated T-SOD and GSH-Px abilities and decreased MDA content to resist oxidative stress damage induced by CIH. Furthermore, HuA-LIP reduced brain iron levels by downregulating TfR1, hepcidin, and FTL expression. In addition, HuA-LIP activated the PKAα/Erk/CREB/BDNF signaling pathway and elevated MAP2, PSD95, and synaptophysin to improve synaptic plasticity. Most importantly, compared with HuA, HuA-LIP showed a superior performance against neuronal damage induced by CIH. Conclusion: HuA-LIP has a good sustained-release effect and targeting ability and efficiently protects against neural injury caused by CIH.

Liraglutide attenuates hepatic iron levels and ferroptosis in db/db mice.

Liver pathological changes are as high as 21%-78% in diabetic patients, and treatment options are lacking. Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor that is widely used in the clinic and is approved to treat obesity and diabetes. However, the specific protection mechanism needs to be clarified. In the present study, db/db mice were used to simulate Type 2 diabetes mellitus (T2DM), and they were intraperitoneally injected daily with liraglutide (200 µg/kg/d) for 5 weeks. Hepatic function, pathologic changes, oxidative stress, iron levels, and ferroptosis were evaluated. First, liraglutide decreased serum AST and ALT levels, and suppressed liver fibrosis in db/db mice. Second, liraglutide inhibited the ROS production by upregulating SOD, GSH-PX, and GSH activity as well as by downregulating MDA, 4-HNE, and NOX4 expression in db/db mice. Furthermore, liraglutide attenuated iron deposition by decreasing TfR1 expression and increasing FPN1 expression. At the same time, liraglutide decreased ferroptosis by elevating the expression of SLC7A11 and the Nrf2/HO-1/GPX4 signaling pathway in the livers of db/db mice. In addition, liraglutide decreased the high level of labile iron pools (LIPs) and intracellular lipid ROS induced by high glucose in vitro. Therefore, we speculated that liraglutide played a crucial role in reducing iron accumulation, oxidative damage and ferroptosis in db/db mice.

Banxia-Houpu decoction diminishes iron toxicity damage in heart induced by chronic intermittent hypoxia.

CONTEXT: Obstructive sleep apnoea (OSA) causes chronic intermittent hypoxia (CIH), which results in mitochondrial dysfunction and generates reactive oxygen species (ROS) in the heart. Excessive free iron could accelerate oxidative damage, which may be involved in this process. Banxia-Houpu decoction (BHD) was reported to improve the apnoea hypopnoea index in OSA patients, but the specific mechanism was still unclear. OBJECTIVE: To investigate whether BHD could reduce CIH-induced heart damage by regulating iron metabolism and mitochondrial function. MATERIALS AND METHODS: C57BL/6N mice were randomly divided into control, CIH and BHD groups. Mice were exposed to CIH (21 - 5% O2, 20 times/h, 8 h/d) and administered BHD (3.51, 7.01 and 14.02 g/kg, intragastrically) for 21 d. Cardiac and mitochondrial function, iron levels, apoptosis and mitophagy were determined. RESULTS: BHD (7.01 g/kg) significantly improved cardiac dysfunction, pathological change and mitochondrial structure induced by CIH. BHD increased the Bcl-2/Bax ratio (1.4-fold) and inhibited caspase 3 cleavage in CIH mice (0.45-fold). BHD activated mitophagy by upregulating Parkin (1.94-fold) and PINK1 (1.26-fold), inhibiting the PI3K-AKT-mTOR pathway. BHD suppressed ROS generation by decreasing NOX2 (0.59-fold) and 4-HNE (0.83-fold). BHD reduced the total iron in myocardial cells (0.72-fold) and mitochondrial iron by downregulating Mfrn2 (0.81-fold) and MtFt (0.78-fold) proteins, and upregulating ABCB8 protein (1.33-fold). Rosmarinic acid, the main component of Perilla Leaf in BHD, was able to react with Fe2+ and Fe3+ in vitro. DISCUSSION AND CONCLUSIONS: These findings encourage the use of BHD to resist cardiovascular injury and provide the theoretical basis for clinical treatment in OSA patients.

Liraglutide Alleviates Cognitive Deficit in db/db Mice: Involvement in Oxidative Stress, Iron Overload, and Ferroptosis.

Studies have shown that diabetes is associated with the occurrence of neurodegenerative diseases and cognitive decline. However, there is currently no effective treatment for diabetes-induced cognitive dysfunction. The superior efficacy of liraglutide (LIRA) for cognitive impairment and numerous neurodegenerative diseases has been widely demonstrated. This study determined the effects of LIRA on diabetic cognitive impairment and on the levels of oxidative stress, lipid peroxidation, iron metabolism and ferroptosis in the hippocampus. Mice were injected daily with liraglutide (200 µg/kg/d) for 5 weeks. LIRA could repair damaged neurons and synapses, and it increased the protein expression levels of PSD 95, SYN, and BDNF. Furthermore, LIRA significantly decreased oxidative stress and lipid peroxidation levels by downregulating the production of ROS and MDA and upregulating SOD and GSH-Px in the serum and hippocampus, and the upregulation of SOD2 expression was also proven. The decreased levels of TfR1 and the upregulation of FPN1 and FTH proteins observed in the LIRA-treated db/db group were shown to reduce iron overload in the hippocampus, whereas the increased expression of Mtft and decreased expression of Mfrn in the mitochondria indicated that mitochondrial iron overload was ameliorated. Finally, LIRA was shown to prevent ferroptosis in the hippocampus by elevating the expression of GPX4 and SLC7A11 and suppressing the excessive amount of ACSL4; simultaneously, the damage to the mitochondria observed by TEM was also repaired. For the first time, we proved in the T2DM model that ferroptosis occurs in the hippocampus, which may play a role in diabetic cognitive impairment. LIRA can reduce oxidative stress, lipid peroxidation and iron overload in diabetic cognitive disorders and further inhibit ferroptosis, thereby weakening the damage to hippocampal neurons and synaptic plasticity and ultimately restoring cognitive function.

Involvement of Hepcidin in Cognitive Damage Induced by Chronic Intermittent Hypoxia in Mice.

Obstructive sleep apnea (OSA) patients exhibit different degrees of cognitive impairment, which is related to the activation of reactive oxygen species (ROS) production by chronic intermittent hypoxia (CIH) and the deposition of iron in the brain. As a central regulator of iron homeostasis, whether hepcidin is involved in OSA-induced cognitive impairment has not been clarified. In order to simulate OSA, we established the mouse model by reducing the percentage of inspired O2 (FiO2) from 21% to 5%, 20 times/h for 8 h/day. We found hepcidin was rising during CIH, along with increasing iron levels and neuron loss. Then, we constructed a mouse with astrocyte-specific knockdown hepcidin gene (shHamp). During CIH exposure, the shHamp mice showed a lower level of total iron and neuronal iron in the hippocampus, via stabilizing ferroportin 1 (FPN1) and decreasing L-ferritin (FTL) levels, when compared with wild-type (WT) mice. Furthermore, the shHamp mice showed a decrease of ROS by downregulating the elevated NADPH oxidase (NOX2) and 4-hydroxynonenal (4-HNE) levels mediated by CIH. In addition, the shHamp mice presented improved cognitive deficit by improving synaptic plasticity and BDNF expression in the hippocampus when subjected to CIH. Therefore, our data revealed that highly expressed hepcidin might promote the degradation of FPN1, resulting in neuronal iron deposition, oxidative stress damage, reduced synaptic plasticity, and impaired cognitive performance during CIH exposure.

Huperzine A, reduces brain iron overload and alleviates cognitive deficit in mice exposed to chronic intermittent hypoxia.

Chronic intermittent hypoxia (CIH) is a consequence of obstructive sleep apnea (OSA), which increases reactive oxygen species (ROS) generation, resulting in oxidative damage and neurocognitive impairment. This study was designed to determine whether abnormal iron metabolism occurs in the brain under conditions of CIH and whether Huperzine A (HuA) could improve abnormal iron metabolism and neurological damage. The mouse model of CIH was established by reducing the percentage of inspired O2 (FiO2) from 21% to 9% 20 times/h for 8 h/day, and Huperzine A (HuA, 0.1 mg/kg, i.p.) was administered during CIH exposure for 21 days. HuA significantly improved cognitive impairment and neuronal damage in the hippocampus of CIH mice via increasing the ratio of Bcl-2/Bax and inhibiting caspase-3 cleavage. HuA considerably decreased ROS levels by downregulating the high levels of NADPH oxidase (NOX 2, NOX 4) mediated by CIH. There was an overload of iron, which was characterized by high levels of ferritin (FTL and FTH) and transferrin receptor 1 (TfR1) and low levels of ferroportin 1 (FPN1) in the hippocampus of CIH mice. Decreased levels of TfR1 and FTL proteins observed in HuA treated CIH group, could reduce iron overload in hippocampus. HuA increased PSD 95 protein expression, CREB activation and BDNF protein expression to protect against synaptic plasticity impairment induced by CIH. HuA acts as an effective iron chelator to attenuate apoptosis, oxidative stress and synaptic plasticity mediated by CIH.

Hydrogen protects against chronic intermittent hypoxia induced renal dysfunction by promoting autophagy and alleviating apoptosis.

AIMS: Hydrogen gas (H2) has a diversity of effects such as anti-apoptotic, anti-inflammatory and anti-oxidative properties. However, molecular mechanism underlying the potential effect of H2 on chronic intermittent hypoxia (CIH) induced renal injury remains obscure. MATERIALS AND METHODS: In the present study, adult male Sprague-Dawley rats were randomly allocated into four groups: control (CON) group, CIH group, CIH with H2 treatment (CIH + H2) group, and control with H2 treatment (CON + H2) group. Oxidative stress, autophagy and endoplasmic reticulum (ER) stress were detected to determine how H2 affected the renal function of CIH exposed rats. KEY FINDINGS: We demonstrated that rats who inhale hydrogen gas showed improved renal function, alleviated pathological damage, oxidative stress and apoptosis in CIH rats. Meanwhile, CIH-induced endoplasmic reticulum stress was decreased by H2 as the expressions of CHOP, caspase-12, and GRP78 were down-regulated. Furthermore, relative higher levels of LC3-II/I ratio and Beclin-1, with decreased expression of p62, were found after H2 administrated. Inhibition of mTOR may be involved in the upregulation of autophagy by H2. Finally, increased phosphorylation of p38 and JNK was involved in the CIH-induced pathological process. H2 could inhibit the activation of p38 and JNK, suggesting H2 played an active part in resisting renal injury via MAPK. SIGNIFICANCE: Taken together, our study reveals that H2 can ameliorate CIH-induced kidney injury by decreasing endoplasmic reticulum stress and activating autophagy through inhibiting oxidative stress-dependent p38 and JNK MAPK activation.

Hydrogen and Oxygen Mixture to Improve Cardiac Dysfunction and Myocardial Pathological Changes Induced by Intermittent Hypoxia in Rats.

Obstructive sleep apnea (OSA) can cause intermittent changes in blood oxygen saturation, resulting in the generation of many reactive oxygen species (ROS). To discover new antioxidants and clarify the endoplasmic reticulum (ER) stress involved in cardiac injury in OSA, we established a chronic intermittent hypoxia (CIH) rat model with a fraction of inspired O2 (FiO2) ranging from 21% to 9%, 20 times/h for 8 h/day, and the rats were treated with H2-O2 mixture (67% hydrogen and 33% oxygen) for 2 h/day for 35 days. Our results showed that H2-O2 mixture remarkably improved cardiac dysfunction and myocardial fibrosis. We found that H2-O2 mixture inhalation declined ER stress-induced apoptosis via three major response pathways: PERK-eIF2α-ATF4, IRE 1-XBP1, and ATF 6. Furthermore, we revealed that H2-O2 mixture blocked c-Jun N-terminal kinase- (JNK-) MAPK activation, increased the ratio of Bcl-2/Bax, and inhibited caspase 3 cleavage to protect against CIH-induced cardiac apoptosis. In addition, H2-O2 mixture considerably decreased ROS levels via upregulating superoxide dismutase (SOD) and glutathione (GSH) as well as downregulating NADPH oxidase (NOX 2) expression in the hearts of CIH rats. All the results demonstrated that H2-O2 mixture significantly reduced ER stress and apoptosis and that H2 might be an efficient antioxidant against the oxidative stress injury induced by CIH.

Hydrogen gas reduces chronic intermittent hypoxia-induced hypertension by inhibiting sympathetic nerve activity and increasing vasodilator responses via the antioxidation.

Molecular hydrogen is reported to be used medically to ameliorate various systemic pathological conditions. This study aimed to investigate the effect of hydrogen (H2 ) gas on hypertension induced by intermittent hypoxia in rats. The adult rats were exposed to chronic intermittent hypoxia (CIH) 8 hours/day for 5 weeks and/or H 2 gas 2 hours/day. We found that the systolic and diastolic blood pressure (BP) increased significantly in rats exposed to intermittent hypoxia, both of which were markedly attenuated after H treatment. Furthermore, intermittent hypoxia exposure elevated renal sympathetic nerve activity, consistent with plasma norepinephrine. Additionally, H 2 gas significantly improved CIH-induced abnormal vascular relaxation. Nevertheless, inhalation of H 2 gas alone did not cause such changes. Moreover, H 2 gas-treated rats exposed to CIH showed a significant reduction in 8-hydroxy-2 deoxyguanosine content and increases in superoxide dismutase activity, indicating improved oxidative stress. Taken together, these results indicate that H 2 gas has significant effects on the reduction of BP without any side effects. Mechanistically, inhibition of sympathetic activity and reduction of systemic vascular resistance may participate in this process via the antioxidant activity of H 2 .

Hydrogen ameliorates chronic intermittent hypoxia-induced neurocognitive impairment via inhibiting oxidative stress.

Obstructive sleep apnea (OSA) is a very common breathing and sleep disorder characterized by intermittent hypoxia (IH), which is often associated with behavioral and neurocognitive functions impairment. Hydrogen (H2), as a novel and effective antioxidant, is reported to be a potential neuroprotective agent. The aim of this study is to investigate whether H2 could improve CIH-induced neurocognitive impairment and the related mechanism. Rats were exposed to IH for 5 weeks (8 h/day) and/or inhalation of H2 gas 2 h/day. Morris Water Maze test was used to appraise the spatial reference and working memory. The oxidative stress was evaluated through the level of MDA and SOD and apoptosis of hippocampal neurons was assayed with Bcl-2/Bax ratio and TUNEL staining. Our results showed that H2 treatment improved the CIH-induced spatial learning and memory impairments. Moreover, inhalation of H2 gas reduced the level of MDA and increased in the activity of SOD, indicating suppressed CIH-induced oxidative stress. In addition, H2 could increase expression of Bcl-2/Bax ratio and inhibited neurons apoptosis in hippocampus. In conclusion, these results suggest that inhalation of H2 could attenuate the CIH-induced neurocognitive functions impairment via anti-oxidant and anti-apoptosis effect. Additional, our findings may provide a potential therapeutic for neurocognitive diseases in patients with OSA.

Coiling method combined with bloodletting from the corpus cavernosum for penile incarceration with a metal ring: A case report and literature review / 中华男科学杂志

Objective@#To explore the treatment of penile incarceration with a metal ring.@*METHODS@#Based on our experience in the successful management of a case of penile incarceration with a metal ring by coiling and bloodletting from the corpus cavernosum, we reviewed the relevant literature and analyzed the indications, advantages and disadvantages of different methods for the treatment of penile incarceration with a circular foreign body.@*RESULTS@#The clamping and cutting methods were non-invasive, fast, effective, and with few complications, which could be applied to the treatment of penile strangulation at all levels. However, clamping was not desirable enough for a hard metal ring and the cutting method took a longer time and might increase the risk of unnecessary damage to the penile skin, urethra and cavernous body. Prepuce edema decompression and the thin tube-coiling method, with the advantages of minimal invasiveness, simple operation and no need of special tools, were suitable for penile strangulation injury under level 3, but might cause penile skin injury and potential postoperative erectile dysfunction. Surgical resection, as an invasive procedure, could be applied to severe penile strangulation at level 4 or 5.@*CONCLUSIONS@#The principle for the treatment of penile incarceration with a circular foreign body is to remove the foreign object as soon as possible and not to add secondary damage.

Finasteride inhibits microvascular density and VEGF expression in the seminal vesicle of rats / 中华男科学杂志

<p><b>Objective</b>To investigate the effect of finasteride on the microvascular density (MVD) and the expression of the vascular endothelial growth factor (VEGF) in the seminal vesicle of rats.</p><p><b>METHODS</b>Forty male SD rats were randomly and equally divided into groups A, B, C and D, those in groups A and B fed with normal saline as the control and those in C and D with finasteride at 40 mg per kg of the body weight per day, A and C for 14 days and B and D for 28 days. Then the seminal vesicles of the animals were harvested for HE staining, measurement of MVD, determination of the expressions of CD34 and VEGF by immunohistochemistry, and observation of histomorphological changes in the seminal vesicle.</p><p><b>RESULTS</b>The expressions of CD34 in groups C and D were decreased by 6.7% and 15.8% as compared with those in A and B (P<0.01), and that in group D decreased by 9.3% in comparison with that in C (P<0.01). The expression indexes of VEGF in groups C and D were decreased by 6.9% and 14.1% as compared with those in A and B (P<0.01), and that in group D decreased by 9.0% in comparison with that in C (P<0.01).</p><p><b>CONCLUSIONS</b>Finasteride can inhibit the expression of VEGF in the seminal vesicle tissue of the rat and hence suppress the angiogenesis of microvessels of the seminal vesicle.</p>

Compound graft of porcine small intestinal submucosa with Schwann cells to reconstruct injured cavernous nerves and restore erectile function / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the restoration of rat penile erection by reconstructing injured cavernous nerves (CN) with a compound graft prepared from porcine small intestinal submucosa (SIS) and Schwann cells (SC).</p><p><b>METHODS</b>SCs were cultured in vitro and a compound graft was prepared from the SCs and SIS. Thirty-three healthy SD rats were randomly divided into three groups of equal number, sham-operation, CN ablation, and SIS + SC graft. Three months after the operation, all the rats underwent the apomorphine test, followed by immunohistochemical staining of the tissues from the middle part of the corpus cavernosum penis.</p><p><b>RESULTS</b>Combined use of mechanical stripping, mixed-enzyme digestion, different-speed adhesion, short-term Ara-C and some other methods yielded SCs of a purity high enough for nerve tissue engineering. The SIS prepared by mechanical and chemical methods exhibited a good biocompatibility with SCs, which could adhere, grow, propagate and differentiate on its surface. The apomorphine test showed that both the rate and frequency of penile erection were significantly higher in the SIS + SC graft than in the CN ablation group (P < 0.01), but lower than in the sham operation group (P < 0.01). The number of nNOS positive nerve fibers in the SIS + SC graft group was significantly different from that of the CN ablation (P < 0.01), but both were smaller than that of the sham-operation group.</p><p><b>CONCLUSION</b>The compound of SIS with SCs, as a nerve graft, can be used to reconstruct injured cavernous nerves, and to some extent, restore penile erectile function.</p>