Polymer nanotherapeutics: A promising approach toward microglial inhibition in neurodegenerative diseases.

Nanoparticles (NPs) that target multiple transport mechanisms facilitate targeted delivery of active therapeutic agents to the central nervous system (CNS) and improve therapeutic transport and efficacy across the blood-brain barrier (BBB). CNS nanotherapeutics mostly target neurons and endothelial cells, however, microglial immune cells are the first line of defense against neuronal damage and brain infections. Through triggering release of inflammatory cytokines, chemokines and proteases, microglia can however precipitate neurological damage-a significant factor in neurodegenerative diseases. Thus, microglial inhibitory agents are attracting much attention among those researching and developing novel treatments for neurodegenerative disorders. The most established inhibitors of microglia investigated to date are resveratrol, curcumin, quercetin, and minocycline. Thus, there is great interest in developing novel agents that can bypass or easily cross the BBB. One such approach is the use of modified-nanocarriers as, or for, delivery of, therapeutic agents to the brain and wider CNS. For microglial inhibition, polymeric NPs are the preferred vehicles for choice. Here, we summarize the immunologic and neuroinflammatory role of microglia, established microglia inhibitor agents, challenges of CNS drug delivery, and the nanotherapeutics explored for microglia inhibition to date. We also discuss applications of the currently considered "most useful" polymeric NPs for microglial-inhibitor drug delivery in CNS-related diseases.

Cardioprotective effects of minocycline against doxorubicin-induced cardiotoxicity.

BACKGROUND: Doxorubicin (Dox)-induced cardiotoxicity has limited its use. Inflammation, oxidative stress, and apoptosis have important roles in Dox-induced cardiotoxicity. Minocycline (Min) is an antibiotic with anti-inflammatory, anti-oxidant and anti-apoptotic properties. Here, the cardioprotective effects of Min against Dox-induced cardiotoxicity in adult male rats were evaluated. METHODS: Forty-two adult male rats were divided into six groups including control group (normal saline), Dox group, Min groups (Min 45 mg/kg and Min 90 mg/kg), and treatment groups (Dox + Min 45 mg/kg and Dox + Min 90 mg/kg). Dox (2.5 mg/kg) was administered three times a week for two weeks, and Min once a day for three weeks via intraperitoneal route. Cardiac tissue sections were stained with hematoxylin and eosin for histological examination. The activities of lactate dehydrogenase (LDH) and creatine kinase MB (CK-MB) in serum as well as the activity of catalase and superoxide dismutase (SOD) in cardiac tissue were measured. Cardiac tissue levels of malondialdehyde (MDA), TNF-α, and IL-1ß were also measured using ELISA. RESULTS: Compared with the Dox group, treatment with Min significantly decreased the activity of LDH and CK-MB. Min also increased the activity of catalase and SOD in the tissue samples. The results showed that the levels of MDA, TNF-α, and IL-1ß in cardiac tissue samples were significantly lower in the Min groups compared with the Dox group. In addition, histopathological results showed that Min reduced the tissue damage caused by Dox. CONCLUSION: Min reduced Dox-induced cardiotoxicity. The anti-oxidant and anti-inflammatory properties of Min may contribute to its protective effects.

Neuroprotective effects of minocycline on focal cerebral ischemia injury: a systematic review.

To review the neuroprotective effects of minocycline in focal cerebral ischemia in animal models. By searching in the databases of PubMed, ScienceDirect, and Scopus, and considering the inclusion and exclusion criteria of the study. Studies were included if focal cerebral ischemia model was performed in mammals and including a control group that has been compared with a minocycline group. Written in languages other than English; duplicate data; in vitro studies and combination of minocycline with other neuroprotective agents were excluded. Neurological function of patients was assessed by National Institute of Health Stroke Scale, modified Rankin Scale, and modified Barthel Index. Neuroprotective effects were assessed by detecting the expression of inflammatory cytokines. We examined 35 papers concerning the protective effects of minocycline in focal cerebral ischemia in animal models and 6 clinical trials which had evaluated the neuroprotective effects of minocycline in ischemic stroke. These studies revealed that minocycline increases the viability of neurons and decreases the infarct volume following cerebral ischemia. The mechanisms that were reported in these studies included anti-inflammatory, antioxidant, as well as anti-apoptotic effects. Minocycline also increases the neuronal regeneration following cerebral ischemia. Minocycline has considerable neuroprotective effects against cerebral ischemia-induced neuronal damages. However, larger clinical trials may be required before using minocycline as a neuroprotective drug in ischemic stroke.

Neuroprotective Effect of Paroxetine on Memory Deficit Induced by Cerebral Ischemia after Transient Bilateral Occlusion of Common Carotid Arteries in Rat.

Memory deficit is the most visible symptom of cerebral ischemia. The hippocampus is sensitive against cerebral ischemia. Oxidative stress and inflammation are involved in the pathological process after cerebral ischemic injury. Paroxetine has anti-oxidative and anti-inflammatory effects. In this study, the effect of paroxetine on memory deficit after cerebral ischemia was investigated. Cerebral ischemia/reperfusion (I/R) injury model was established using the bilateral occlusion of common carotid artery method. Paroxetine (10 mg/kg) was intraperitoneally injected into rats, 24 h before surgery or once a day for 7 days after surgery. Learning and memory were evaluated using the Morris water maze task, then the brain tissue was fixed and hippocampal CA1 pyramidal cells damage was analyzed using the Nissl staining method. In the ischemia group the escape latency time (ELT) and the swimming path length (SPL) were significantly increased and the time spent in target quadrant (TSTQ) was significantly decreased compared with the control group. The ELT and the SPL were significantly shortened and the TSTQ was significantly increased compared with the ischemia group after Pre- or post-ischemic administration of paroxetine. The percentage of viable pyramidal cells in the ischemia group was significantly decreased compared with the control group. The percentage of viable cells was significantly increased following pre-or post-ischemic administration of paroxetine compared with the ischemia group. Memory deficit due to I/R was improved and the percentage of viable cells in CA1 region was increased after administration of paroxetine. Therefore, paroxetine may have a neuroprotective effect against cerebral ischemia.

Neuroprotective effect of minocycline on cognitive impairments induced by transient cerebral ischemia/reperfusion through its anti-inflammatory and anti-oxidant properties in male rat.

Memory deficit is the most visible symptom of cerebral ischemia that is associated with loss of pyramidal cells in CA1 region of the hippocampus. Oxidative stress and inflammation may be involved in the pathogenesis of ischemia/reperfusion (I/R) damage. Minocycline, a semi-synthetic tetracycline derived antibiotic, has anti-inflammatory and antioxidant properties. We evaluated the neuroprotective effect of minocycline on memory deficit induced by cerebral I/R in rat. I/R was induced by occlusion of common carotid arteries for 20min. Minocycline (40mg/kg, i.p.) was administered once daily for 7days after I/R. Learning and memory were assessed using the Morris water maze test. Nissl staining was used to evaluate the viability of CA1 pyramidal cells. The effects of minocycline on the microglial activation was also investigated by Iba1 (Ionized calcium binding adapter molecule 1) immunostaining. The content of malondialdehyde (MDA) and pro-inflammatory cytokines (IL-1ß and TNF-α) in the hippocampus were measured by thiobarbituric acid reaction substances method and ELISA, respectively. Minocycline reduced the increase in escape latency time and in swimming path length induced by cerebral I/R. Furthermore, the ischemia-induced reduction in time spent in the target quadrant during the probe trial was increased by treatment with minocycline. Histopathological results indicated that minocycline prevented pyramidal cells death and microglial activation induced by I/R. Minocycline also reduced the levels of MDA and pro-inflammatory cytokines in the hippocampus in rats subjected to I/R. Minocycline has neuroprotective effects on memory deficit induced by cerebral I/R in rat, probably via its anti-inflammatory and antioxidant properties.

Neuroprotective effects of pretreatment with minocycline on memory impairment following cerebral ischemia in rats.

Cerebral ischemia leads to memory impairment that is associated with loss of hippocampal CA1 pyramidal neurons. Neuroinflammation and oxidative stress may be implicated in the pathogenesis of ischemia/reperfusion damage. Minocycline has anti-inflammatory and antioxidant properties. We investigated the neuroprotective effects of minocycline in rats subjected to cerebral ischemia/reperfusion injury. Thirty male rats were divided into three groups: control, sham, and minocycline-pretreated group. Minocycline (40 mg/kg) was injected intraperitoneally immediately before surgery, and then ischemia was induced by occlusion of common carotid arteries for 20 min. Seven days after reperfusion, the Morris water-maze task was used to evaluate memory. Nissl staining was also performed to analyze pyramidal cell damage. We measured the contents of malondialdehyde and proinflammatory cytokines in the hippocampus by the thiobarbituric acid method and enzyme-linked immunosorbent assay, respectively. Microglial activation was also investigated by Iba1 immunostaining. The results showed that pretreatment with minocycline prevented memory impairment induced by cerebral ischemia/reperfusion. Minocycline pretreatment also significantly attenuated ischemia-induced pyramidal cell death and microglial activation in the CA1 region and reduced the levels of malondialdehyde and proinflammatory cytokines (interleukin-1ß and tumor necrosis factor-α) in the hippocampus of ischemic rats. Minocycline showed neuroprotective effects on cerebral ischemia-induced memory deficit probably through its anti-inflammatory and antioxidant activities.

Antigenotoxic activities of the natural dietary coumarins umbelliferone, herniarin and 7-isopentenyloxy coumarin on human lymphocytes exposed to oxidative stress.

The antigenotoxic effects of umbelliferone (UMB), herniarin (HER) and 7-isopentenyloxy coumarin (7-IP), common natural dietary coumarins, were evaluated on the human lymphocyte DNA damage using single-cell gel electrophoresis. H(2)O(2)-induced DNA break was measured based on the percentage of DNA in tail, and the antigenotoxic effects of the tested compounds were compared with that of ascorbic acid (10, 25, 50, 100 and 200 µM). UMB, HER and 7-IP did not show any genotoxicity, as compared to phosphate-buffered saline. Treatment with UMB, HER and 7-IP led to a significant reduction in the percentage of DNA in tail induced by H(2)O(2) (p < 0.001) at all concentrations. The presence of prenyl moiety in the chemical structure of 7-IP may contribute to its better antigenotoxic property, compared to UMB. The results of this study showed that 7-IP possessed the best antigenotoxic activity among the tested compounds.