minocycline and Ischemia

Testicular torsion is a serious urological disease leading to testicular damage. This study aimed to assess the effect of minocycline on testicular ischaemia/reperfusion (I/R) injury caused by testicular torsion/detorsion. Male adult Wistar rats (n = 32) were assigned into four groups of sham, I/R, I/R + minocycline and minocycline. I/R injury was induced by two sets of surgical operations, including the rotation of the left testis (720°, counterclockwise), followed by detorsion after 4 hr. The administration of minocycline was carried out 30 min before detorsion and then continued for 8 weeks. At the end of the 8th week, rats were killed and sampling was done. Johnson's score, the height of seminiferous tubule epithelium, the mean seminiferous tubule diameter, as well as biochemical parameters, SOD, GPx and CAT, were significantly enhanced in the I/R + minocycline group compared with the I/R group. The administration of minocycline led to a marked decrease in expression levels of Caspase-3, Bax, IL-1β and TNF-α genes, and a remarkable increase in expression levels of Bcl-2, 3β-HSD and 17β-HSD3 genes compared with the I/R group. Administration of minocycline could also reduce the rate of germ cell apoptosis (TUNEL staining). Hence, minocycline was useful in the management of testicular torsion/detorsion.

Topics: Animals; Humans; Ischemia; Male; Malondialdehyde; Minocycline; Rats; Rats, Wistar; Reperfusion; Reperfusion Injury; Spermatic Cord Torsion; Testis

It has become increasingly evident the serotonergic (5-hydroxytryptamine, 5-HT) system is an important central neuronal network disrupted following neonatal hypoxic-ischemic (HI) insults. Serotonin acts via a variety of receptor subtypes that are differentially associated with behavioural and cognitive mechanisms. The 5-HT

Topics: Animals; Brain; Female; Hypoxia-Ischemia, Brain; Ischemia; Microglia; Minocycline; Neurons; Rats, Sprague-Dawley; Receptors, Serotonin; Serotonin

The role of microglia in the pathophysiology of ischemic retinal diseases has been extensively studied. Retinal microglial activation may be correlated with retinal neovascularization in oxygen-induced retinopathy (OIR), an animal model that has been widely used in retinopathy of prematurity (ROP) research. Minocycline is an antibiotic that decreases microglial activation following hyperoxic and hypoxic-ischemic phases in neonatal rodents. Here, we investigated the effects of minocycline on vascularization and visual function. In our results, we found that after the administration of minocycline, microglial reactivity was reduced in the retina, which was accompanied by an increase in the avascular area at P12, P14 and P17. Although microglial reactivity was reduced at P17, minocycline treatment did not attenuate retinal neovascularization. A changing trend in microglial number was observed, and the apoptosis and proliferation states on different days partly contributed to this change. Further study also revealed that although minocycline downregulated the levels of proinflammatory factors, visual function appeared to be significantly worsened. Collectively, we demonstrated that minocycline disturbed the physiological vascularization of the avascular area and exacerbated visual dysfunction, indicating that minocycline may not be an effective drug and may even be detrimental for the treatment of ischemic retinopathy in immature mammals.

Topics: Animals; Animals, Newborn; Anti-Bacterial Agents; Cytokines; Disease Models, Animal; Gene Expression; Ischemia; Mice, Inbred C57BL; Microglia; Minocycline; Neovascularization, Physiologic; Oxygen; Retina; Retinal Neovascularization; Retinopathy of Prematurity; Visual Fields

Reprogramming of toll-like receptor 4 (TLR4) by brief ischemia or lipopolysacharide (LPS) contributes to superintending tolerance against destructive ischemia in brain. However, beneficial roles of TLR4 signaling in ischemic retina are not well known. This study demonstrated that preconditioning with LPS 48 h prior to the retinal ischemia prevents the cellular damage in morphology with hematoxylin and eosin (H&E) staining and functions of retina with electroretinogram (ERG), while post-ischemia treatment deteriorated it. The preventive effects of LPS preconditioning showed the cell type-specificity of retinal cells. There was complete rescue of ganglion cells, partial rescue of bipolar and photoreceptor cells or no rescue of amacrine cells, respectively. LPS treatment caused the proliferation and migration of retinal microglia and its preconditioning prevented the ischemia-induced microglial activation. Preventive actions from cell damages following LPS preconditioning prior to retinal ischemia were abolished in TLR4 knock-out mice, and by pre-treatments with anti-TLR4 antibody or minocycline, a microglia inhibitor, which themselves had no effects on the retinal ischemia-induced damages or microglia activation. Thus, this study revealed that TLR4 mediates the LPS preconditioning-induced preventive effects through microglial activation in the retinal ischemia model.

Topics: Animals; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Electroretinography; Eye Proteins; Gene Expression Regulation; Ischemia; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Minocycline; Retina; Retinal Diseases; Signal Transduction; Time Factors; Toll-Like Receptor 4

High mobility group box-1 (HMGB1), a non-histone DNA-binding protein, is massively released into the extracellular space from neuronal cells after ischemic insult and exacerbates brain tissue damage in rats. Minocycline is a semisynthetic second-generation tetracycline antibiotic which has recently been shown to be a promising neuroprotective agent. In this study, we found that minocycline inhibited HMGB1 release in oxygen-glucose deprivation (OGD)-treated PC12 cells and triggered the activation of p38mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK1/2). The ERK kinase (MEK)1/2 inhibitor U-0126 and p38MAPK inhibitor SB203580 blocked HMGB1 release in response to OGD. Furthermore, HMGB1 triggered cell death in a dose-dependent fashion. Minocycline significantly rescued HMGB1-induced cell death in a dose-dependent manner. In light of recent observations as well as the good safety profile of minocycline in humans, we propose that minocycline might play a potent neuroprotective role through the inhibition of HMGB1-induced neuronal cell death in cerebral infarction.

Topics: Animals; Apoptosis; Butadienes; Cattle; Enzyme Inhibitors; Glucose; HMGB1 Protein; Ischemia; Minocycline; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurons; Nitriles; Oxygen; p38 Mitogen-Activated Protein Kinases; PC12 Cells; Rats

Minocycline, a broad-spectrum antimicrobial tetracycline, acts neuroprotectively in ischemia. Recently, however, minocycline has been revealed to have ambiguous effects on nerve regeneration. Thus its effects in a rat sciatic nerve transplantation model and on cultivated Schwann cells stressed by oxygen glucose deprivation (OGD) were studied. The negative effect of minocycline on Wallerian degeneration, the essential initial phase of degeneration/regeneration after nerve injury, that was recently demonstrated, was excluded by using predegenerated nerve and Schwann cell-enriched muscle grafts, both free of Wallerian degeneration. They were compared with common nerve grafts. The principle findings were that in vitro minocycline provided protective effects against OGD-induced death of Schwann cells by preventing permeability of the mitochondrial membrane. It suppressed the OGD-mediated induction of HIF-1alpha and BAX, and stabilized/induced BCL-2. Cytochrome c release and cleavage of procaspase-3 were diminished; release and translocation of AIF and cytotoxic cleavage of actin into fractin were stopped. In common nerve grafts, minocycline, besides its direct anti-ischemic effect, hampered revascularization by down-regulation of MMP9 and VEGF prolonging ischemia and impeding macrophage recruitment. In bioartificial nerve grafts that were free of Wallerian degeneration and revealed lower immunogenicity, minocycline aided the regeneration process. Here, the direct anti-ischemic effect of minocycline on Schwann cells, which are mandatory for successful peripheral nerve regeneration, dominated the systemic anti-angiogenic/pro-ischemic effects. In common nerve grafts, however, where Wallerian degeneration is a prerequisite, the anti-angiogenic and macrophage-depressing effect is an obstacle for regeneration.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Bioartificial Organs; Cells, Cultured; Growth Cones; Ischemia; Male; Matrix Metalloproteinase 9; Membrane Potential, Mitochondrial; Minocycline; Muscle, Skeletal; Neovascularization, Physiologic; Nerve Regeneration; Neuroprotective Agents; Peripheral Nerves; Rats; Rats, Wistar; Schwann Cells; Sciatic Neuropathy; Vascular Endothelial Growth Factor A; Wallerian Degeneration

The involvement of matrix metalloproteinases (MMPs) in ischemic tissue damage and remodeling has been reported by many investigators. Our study was designed to investigate the involvement of MMPs and of tissue inhibitors of metalloproteinases (TIMPs) in rat retinal ischemic injury, the effect of nitric oxide synthase (NOS) inhibitors on MMPs' activity in this model and whether minocycline (an MMP inhibitor) is protective in retinal ischemia.. Ninety-four rats were used in the study. Ischemia was induced by 90 min elevation of intraocular pressure. MMPs' activities and the effect of NOS inhibitors [aminoguanidine (AG) or N-nitro-L-arginine (NNA)] and minocycline on MMPs' activities were assessed by zymography and TIMPs expression by Western analysis. Morphological damage was quantified by morphometry of hematoxylin and eosin-stained retinal sections.. Retinal extracts exhibited activities of proMMP-9 and proMMP-2. The activity of proMMP-9 increased immediately post ischemia (PI) and peaked to 4.6 times that of normal untreated controls in ischemic retinas and to 2.6 times that of controls in retinas of fellow sham-treated eyes at 24 h PI. The relative amount of TIMP-1 increased to 1.9-fold following ischemia and 2.5-fold in fellow sham-treated eyes at 24 h PI. ProMMP-2 activity increased more than two-fold immediately, at 24 h and at 48 h PI in ischemic retinas, and insignificantly in fellow sham-treated eyes. Treatment with 25 mg/kg AG or NNA caused a non-significant increase in proMMP-9 activity at 24 h PI (3.7- and 2.9-fold, respectively, p>0.6). There was no effect of AG or NNA on the activity of proMMP-2. Minocycline significantly attenuated the retinal ischemic damage, primarily by partially preserving ganglion cells and the inner plexiform layer. Minocyline (0.5 mg/ml or 5 mg/ml) inhibited MMPs' activities in ischemic retinal extracts in vitro.. MMPs participated in morphological ischemic damage to rat retina. Treatment with minocycline dramatically attenuated damage to the retina.

Topics: Animals; Blotting, Western; Disease Models, Animal; Enzyme Inhibitors; Guanidines; Ischemia; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Minocycline; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Sprague-Dawley; Retinal Diseases; Retinal Vessels; Tissue Inhibitor of Metalloproteinase-1

The neuroprotective effects of minocycline-which is broadly protective in neurologic-disease models featuring cell death and is being evaluated in clinical trials-were investigated both in vitro and in vivo. For the in vivo study, focal cerebral ischemia was induced by permanent middle cerebral artery occlusion in mice. Minocycline at 90 mg/kg intraperitoneally administered 60 min before or 30 min after (but not 4 h after) the occlusion reduced infarction, brain swelling, and neurologic deficits at 24 h after the occlusion. For the in vitro studies, we used cortical-neuron cultures from rat fetuses in which neurotoxicity was induced by 24-h exposure to 500 microM glutamate. Furthermore, the effects of minocycline on oxidative stress [such as lipid peroxidation in mouse forebrain homogenates and free radical-scavenging activity against diphenyl-p-picrylhydrazyl (DPPH)] were evaluated to clarify the underlying mechanism. Minocycline significantly inhibited glutamate-induced cell death at 2 microM and lipid peroxidation and free radical scavenging at 0.2 and 2 microM, respectively. These findings indicate that minocycline has neuroprotective effects in vivo against permanent focal cerebral ischemia and in vitro against glutamate-induced cell death and that an inhibition of oxidative stress by minocycline may be partly responsible for these effects.

Topics: Animals; Antioxidants; Benzimidazoles; Benzoxazoles; Biphenyl Compounds; Brain Edema; Brain Infarction; Cell Death; Cell Survival; Cells, Cultured; Cerebral Cortex; Chromans; Dose-Response Relationship, Drug; Drug Interactions; Embryo, Mammalian; Fluorescent Dyes; Glutamic Acid; Hydrazines; Infarction, Middle Cerebral Artery; Inhibitory Concentration 50; Ischemia; Lipid Peroxidation; Male; Mice; Minocycline; Neurons; Neuroprotective Agents; Oxidative Stress; Picrates; Quinolinium Compounds; Saponins; Tetrazolium Salts; Time Factors

Robust neuroprotective effects have been shown for minocycline. Whether it also protects nonneuronal cells or tissues is unknown. More importantly, the mechanisms of minocycline protection appear multifaceted and remain to be clarified. Here we show that minocycline can protect kidney epithelial cells in vitro and protect the kidneys from ischemic injury in vivo. We further show that Bcl-2 is a key molecular determinant of minocycline protection. Minocycline protected kidney epithelial cells against apoptosis induced by hypoxia, azide, cisplatin, and staurosporine. The protection occurred at mitochondria, involving the suppression of Bax accumulation, outer membrane damage, and cytochrome c release. Minocycline induced Bcl-2, which accumulated in mitochondria and interacted with death-promoting molecules including Bax, Bak, and Bid. Down-regulation of Bcl-2 by specific antisense oligonucleotides abolished the cytoprotective effects of minocycline. Thus, minocycline can protect neuronal as well as nonneuronal cells and tissues. One mechanism for minocycline protection involves the induction of Bcl-2, an antiapoptotic protein.

Topics: Animals; Anti-Bacterial Agents; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Caspases; Cell Death; Cells, Cultured; Cisplatin; Cytosol; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Activation; Epithelial Cells; Hypoxia; In Situ Nick-End Labeling; Ischemia; Kidney; Male; Membrane Proteins; Microscopy, Fluorescence; Minocycline; Mitochondria; Oligonucleotides, Antisense; Precipitin Tests; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sodium Azide; Staurosporine; Subcellular Fractions; Time Factors; Up-Regulation

Minocycline mediates neuroprotection in experimental models of neurodegeneration. It inhibits the activity of caspase-1, caspase-3, inducible form of nitric oxide synthetase (iNOS) and p38 mitogen-activated protein kinase (MAPK). Although minocycline does not directly inhibit these enzymes, the effects may result from interference with upstream mechanisms resulting in their secondary activation. Because the above-mentioned factors are important in amyotrophic lateral sclerosis (ALS), we tested minocycline in mice with ALS. Here we report that minocycline delays disease onset and extends survival in ALS mice. Given the broad efficacy of minocycline, understanding its mechanisms of action is of great importance. We find that minocycline inhibits mitochondrial permeability-transition-mediated cytochrome c release. Minocycline-mediated inhibition of cytochrome c release is demonstrated in vivo, in cells, and in isolated mitochondria. Understanding the mechanism of action of minocycline will assist in the development and testing of more powerful and effective analogues. Because of the safety record of minocycline, and its ability to penetrate the blood-brain barrier, this drug may be a novel therapy for ALS.

Topics: Age of Onset; Amyotrophic Lateral Sclerosis; Animals; Caspases; Cell Death; Cells, Cultured; Cerebral Cortex; Cytochrome c Group; Disease Progression; Enzyme Activation; Humans; Infarction, Middle Cerebral Artery; Ischemia; Mice; Mice, Inbred C57BL; Minocycline; Mitochondria; Mitochondrial Swelling; N-Methylaspartate; Permeability; Rats; Survival Rate; Tumor Cells, Cultured