minocycline and Diabetic-Neuropathies

We aimed to explore the evidence of brain microglia activation in diabetic neuropathic pain (DNP) and the effect and mechanism of glucagon-like peptide-1 receptor agonist (GLP-RA) on DNP via brain microglia.. Brain microglia activation was observed in DNP rats by positron emission tomography/computed tomography. The behavior of neuropathic pain was assessed in DNP rats after intracerebroventricular administration of GLP-1RA or microglial inhibitor minocycline. RNA sequencing was performed to explore the target of GLP-1RA on brain microglia. NOD-like receptor protein 3 (NLRP3) expression in brain microglia was evaluated in mentioned-above DNP rats, and the activation of NLRP3 inflammasome was analyzed in microglia treated with GLP-1RA.. Microglia were activated in the cortex and thalamus of DNP rats. The thermal and mechanical allodynia were alleviated in DNP rats via intracerebroventricular administration of GLP-1RA or minocycline. And the activation of brain microglia was attenuated in DNP rats by intracerebroventricular administration of GLP-1RA. The expression of NLRP3 in brain microglia, which was found by RNA sequencing, was reduced in DNP rats by administration of GLP-1RA. Furthermore, GLP-1RA attenuated NLRP3 inflammasome activation in microglia triggered by LPS.. GLP-1RA could alleviate DNP, possibly mediated by the suppression of brain microglia NLRP3 inflammasome activation.

Topics: Animals; Brain; Diabetes Mellitus; Diabetic Neuropathies; Glucagon-Like Peptide-1 Receptor; Humans; Inflammasomes; Microglia; Minocycline; Neuralgia; NLR Family, Pyrin Domain-Containing 3 Protein; NLR Proteins; Rats

In this study, we hypothesized that reduction of immune cell activation as well as their oxidant or inflammatory mediators with minocycline (MCN), liposome-encapsulated clodronate (LEC), or anti-Ly6G treatments can be neuroprotective approaches in diabetic neuropathy. MCN (40 mg/kg) for reduction of microglial activation, LEC (25 mg/kg) for of macrophage inhibition, or anti-Ly6G (150 μg/kg) for neutrophil suppression injected to streptozotocin (STZ)-induced diabetic rats twice, 3 days, and 1 week (half dose) after STZ. Animal mass and blood glucose levels were measured; thermal and mechanical sensitivities were tested for in pain sensations. The levels of chemokine C-X-C motif ligand 1 (CXCL1), CXCL8, and C-C motif ligand 2 (CCL2), CCL3, and total oxidant status (TOS) and total antioxidant status (TAS) were measured in the spinal cord and sciatic nerve tissues of rats. LEC significantly reduced the glucose level of diabetic rats compared with drug control. However, MCN or anti-LY6G did not change the glucose level. While diabetic rats showed a marked decrease in both thermal and mechanical sensations, all treatments alleviated these abnormal sensations. The levels of chemokines and oxidative stress parameters increased in diabetic rats. All drug treatments significantly decreased the CCL2, CXCL1, and CXCL8 levels of spinal cord tissues and ameliorated the neuronal oxidative stress compared with control treatments. Present findings suggest that the neuroprotective actions of MCN, LEC, or anti-Ly6G treatments may be due to the modulation of neuronal oxidative stress and/or inflammatory mediators of immune cells in diabetic rats with neuropathy.

Topics: Animals; Antigens, Ly; Antioxidants; Blood Glucose; Chemokines; Clodronic Acid; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Inflammation; Liposomes; Male; Minocycline; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar; Streptozocin

We studied the effects of minocycline (an inhibitor of microglial activation) on the expression and activity of Notch-1 receptor, and explored the therapeutic efficacy of minocycline combined with Notch inhibitor DAPT in the treatment of diabetic neuropathic pain (DNP). Diabetic rat model was established by intraperitoneal injection (ip) of Streptozotocin (STZ). Expression and activity of Notch-1 and expression of macrophage/microglia marker Iba-1 were detected by WB. Diabetes induction significantly attenuated sciatic nerve conduction velocity, and dramatically augmented the expression and the activity of Notch-1 in the lumbar enlargement of the spinal cord. Minocycline treatment, however, accelerated the decreased conduction velocity of sciatic nerve and suppressed Notch-1expression and activity in diabetic rats. Similar to DAPT treatment, minocycline administration also prolonged thermal withdrawal latency (TWL) and increase mechanical withdrawal threshold (MWT) in diabetic rats in response to heat or mechanical stimulation via inhibition the expression and the activity of Notch-1 in spinal cord. Combination of DAPT and minocycline further inhibited Notch-1 receptor signaling and reduce neuropathic pain exhibited as improved TWL and MWT. Our study revealed a novel mechanism of Notch-1 receptor inhibition in spinal cord induced by minocycline administration, and suggested that the combination of minocycline and DAPT has the potential to treat DNP.

Topics: Animals; Body Weight; Diabetic Neuropathies; Dipeptides; Glucose; Minocycline; Neural Conduction; Rats, Sprague-Dawley; Receptors, Notch; Signal Transduction; Spinal Cord; Sural Nerve

Diabetic neuropathy (DN) is the most common complication of diabetes and pain is one of the main symptoms of diabetic neuropathy, however, currently available drugs are often ineffective and complicated by adverse events. The purpose of this research was to evaluate the antinociceptive interaction between gabapentin and minocycline in a mice experimental model of DN by streptozocin (STZ).. The interaction of gabapentin with minocycline was evaluated by the writhing and hot plate tests at 3 and 7 days after STZ injection or vehicle in male CF1 mice.. STZ (150 mg/kg, i.p.) produced a marked increase in plasma glucose levels on day 7 (397.46 ± 29.65 mg/dL) than on day 3 (341.12 ± 35.50 mg/dL) and also developed neuropathic pain measured by algesiometric assays. Gabapentin produced similar antinociceptive activity in both writhing and hot plate tests in mice pretreated with STZ. However, minocycline was more potent in the writhing than in the hot plate test in the same type of mice. The combination of gabapentin with minocycline produced synergistic interaction in both test.. The combination of gabapentin with minocycline in a 1:1 proportion fulfills all the criteria of multimodal analgesia and this finding suggests that the combination provide a therapeutic alternative that could be used for human neuropathic pain management.

Topics: Amines; Analgesics; Animals; Cyclohexanecarboxylic Acids; Diabetic Neuropathies; Dose-Response Relationship, Drug; Drug Interactions; Drug Therapy, Combination; Gabapentin; gamma-Aminobutyric Acid; Male; Mice; Minocycline; Pain Measurement

A common and devastating complication of diabetes mellitus is painful diabetic neuropathy (PDN) that can be accompanied by emotional disorders such as depression. A few studies have suggested that minocycline that inhibits microglia may attenuate pain hypersensitivity in PDN. Moreover, a recent study reported that minocycline has an acute antidepressive-like effect in diabetic animals. Here we studied whether (i) prolonged minocycline treatment suppresses pain behaviour in PDN, (ii) the minocycline effect varies with submodality of pain, and (iii) the suppression of pain behaviour by prolonged minocycline treatment is associated with antidepressive-like effect. The experiments were performed in streptozotocin-induced rat model of type-1 diabetes. Pain behaviour was evoked by innocuous (monofilaments) and noxious (paw pressure) mechanical stimulation, innocuous cold (acetone drops) and noxious heat (radiant heat). Depression-like behaviour was assessed using forced swimming test. Minocycline treatment (daily 80mg/kg per os) of three-week duration started four weeks after induction of diabetes. Diabetes induced mechanical allodynia and hyperalgesia, cold allodynia, heat hypoalgesia, and depression-like behaviour. Minocycline treatment significantly attenuated mechanical allodynia and depression-like behaviour, while it failed to produce significant changes in mechanical hyperalgesia, cold allodynia or heat hypoalgesia. The results indicate that prolonged per oral treatment with minocycline has a sustained mechanical antiallodynic and antidepressive-like effect in PDN. These results support the proposal that minocycline might provide a treatment option for attenuating sensory and comorbid emotional symptoms in chronic PDN.

Topics: Analgesics; Animals; Antidepressive Agents; Cold Temperature; Depressive Disorder; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Hyperalgesia; Hypoglycemic Agents; Male; Minocycline; Random Allocation; Rats, Wistar; Touch

Neuroinflammation and neurodegeneration have been observed in the brain in type 1 diabetes (T1D). However, little is known about the mediators of these effects. In T1D mice with 12- and 35-wk duration of diabetes we examined two mechanisms of neurodegeneration, loss of the neuroprotective factors insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) and changes in indoleamine 2,3-dioxygenase (IDO) expression in the brain, and compared the response to age-matched controls. Furthermore, levels of matrix metalloproteinase-2 (MMP-2), nucleoside triphosphate diphosphohydrolase-1 (CD39), and ionized calcium-binding adaptor molecule 1 (Iba-1) were utilized to assess inflammatory changes in astrocytes, microglia, and blood vessels. In the diabetic hypothalamus (HYPO), we observed 20% reduction in neuronal soma diameter (P<0.05) and reduced neuronal expression of IGFBP-3 (-32%, P<0.05) and IGF-I (-15%, P<0.05) compared with controls at 35 wk. In diabetic HYPO, MMP-2 expression was increased in astrocytes (46%, P<0.01), and IDO⁺ cell density rose by (62%, P<0.05). CD39 expression dropped by 30% (P<0.05) in microglia and blood vessels. With 10 wk of systemic treatment using minocycline, an anti-inflammatory agent that crosses the blood-brain barrier, MMP-2, IDO, and CD39 levels normalized (P<0.05). Our results suggest that increased IDO and early loss of CD39⁺ protective cells lead to activation of inflammation in sympathetic centers of the CNS. As a downstream effect, the loss of the neuronal survival factors IGFBP-3 and IGF-I and the neurotoxic products of the kynurenine pathway contribute to the loss of neuronal density observed in the HYPO in T1D.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Astrocytes; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Disease Progression; Down-Regulation; Encephalitis; Hypothalamus; Indoleamine-Pyrrole 2,3,-Dioxygenase; Inflammation Mediators; Insulin-Like Growth Factor Binding Protein 3; Insulin-Like Growth Factor I; Macrophages; Male; Mice, Inbred C57BL; Microglia; Minocycline; Nerve Tissue Proteins; Neurons; Sympathetic Nervous System; Up-Regulation

A single streptozotocin (STZ) injection in mice can induce significant neuropathic pain along with an increase in plasma glucose levels and a decrease in body weight. Seven days after the administration of STZ, an upregulation of C1q-positive cells was observed. Additionally, interleukins (IL-1beta, IL-3, IL-4, IL-6, IL-9, IL12p70, IL-17); proteins of the tumor necrosis factor (TNF) family, e.g., IFNgamma and sTNF RII, were upregulated. Chronic administration of minocycline increases antinociceptive factors (IL-1alpha, IL-2, IL-10, sTNFRII) in diabetic mice. Minocycline also reduces the occurrence of neuropathic pain and significantly potentiates the antiallodynic and antihyperalgesic effects of morphine.

Topics: Analgesics, Opioid; Animals; Diabetic Neuropathies; Disease Models, Animal; Inflammation Mediators; Interleukins; Male; Mice; Minocycline; Morphine; Neuralgia; Up-Regulation

Diabetic neuropathic pain (DNP) plays a major role in decreased life quality of type 2 diabetes patients, however, the molecular mechanisms underlying DNP remain unclear. Emerging research implicates the participation of spinal glial cells in some neuropathic pain models. However, it remains unknown whether spinal glial cells are activated under type 2 diabetic conditions and whether they contribute to diabetes-induced neuropathic pain. In the present study, using a db/db type 2 diabetes mouse model that displayed obvious mechanical allodynia, we found that spinal astrocyte but not microglia was dramatically activated. The mechanical allodynia was significantly attenuated by intrathecally administrated l-α-aminoadipate (astrocytic specific inhibitor) whereas minocycline (microglial specific inhibitor) did not have any effect on mechanical allodynia, which indicated that spinal astrocytic activation contributed to allodynia in db/db mice. Further study aimed to identify the detailed mechanism of astrocyte-induced allodynia in db/db mice. Results showed that spinal activated astrocytes dramatically increased interleukin (IL)-1β expression which may induce N-methyl-D-aspartic acid receptor (NMDAR) phosphorylation in spinal dorsal horn neurons to enhance pain transmission. Together, these results suggest that spinal activated astrocytes may be a crucial component of mechanical allodynia in type 2 diabetes and "Astrocyte-IL-1β-NMDAR-Neuron" pathway may be the detailed mechanism of astrocyte-induced allodynia. Thus, inhibiting astrocytic activation in the spinal dorsal horn may represent a novel therapeutic strategy for treating DNP.

Topics: 2-Aminoadipic Acid; Animals; Astrocytes; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Disease Models, Animal; Excitatory Amino Acid Antagonists; Hyperalgesia; Injections, Spinal; Interleukin-1beta; Mice; Mice, Inbred C57BL; Minocycline; Pain Measurement; Spinal Cord; Treatment Outcome

neuronal hyperactivity at the spinal cord during mechanical hyperalgesia induced by diabetes may result from a decrease in the local expression of the potassium chloride co-transporter 2 (KCC2), which shifts the action of the neurotransmitter γ-amminobutiric acid (GABA) from inhibitory to excitatory. In this study, we evaluated the effects of spinal microglia inhibition or brain-derived neurotrophic factor (BDNF) blockade on KCC2 expression, spinal neuronal activity and mechanically induced pain responses of streptozotocin (STZ)-diabetic rats.. four weeks after induction of diabetes, the STZ-diabetic rats received daily intrathecal injections, for 3 days, of minocycline (microglia inhibitor), TrkB/Fc (BDNF sequester) or saline. Behavioural responses to mechanical nociceptive stimulation of STZ-diabetic rats were evaluated by the Randall-Selitto test. The lumbar spinal cord was immunoreacted against the Fos protein (marker of neuronal activation) or KCC2, which was also quantified by western blotting. BDNF levels at the spinal cord were quantified by an enzyme-linked immunosorbent assay (ELISA).. minocycline treatment reversed the mechanical hyperalgesia, increased Fos expression and decreased the KCC2 expression detected in STZ-diabetic rats to control levels. Treatment with TrkB/Fc was less effective, inducing moderate effects in mechanical hyperalgesia and Fos expression and only a partial correction of KCC2 expression. BDNF levels were not increased in STZ-diabetic rats.. this study demonstrates that the microglial activation at the spinal cord contributes to mechanical hyperalgesia and spinal neuronal hyperactivity induced by diabetes, apparently by regulating the KCC2 expression. These effects do not seem to be mediated by BDNF, which is an important difference from other chronic pain conditions. New targets directed to prevent spinal microglia activation should be considered for the treatment of mechanical hyperalgesia induced by diabetes.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Hyperalgesia; Male; Microglia; Minocycline; Potassium Chloride; Rats; Rats, Wistar; Spinal Cord; Symporters; Synaptic Transmission; Up-Regulation

Painful neuropathy, a common complication of diabetes mellitus is characterized by allodynia and hyperalgesia. Recent studies emphasized on the role of non-neuronal cells, particularly microglia in the development of neuronal hypersensitivity. The purpose of the present study is to evaluate the effect of minocyline, a selective inhibitor of microglial activation to define the role of neuroimmune activation in experimental diabetic neuropathy. Cold allodynia and thermal and chemical hyperalgesia were assessed and the markers of inflammation and oxidative and nitrosative stress were estimated in streptozotocin-induced diabetic rats. Chronic administration of minocycline (40 and 80 mg/kg, i.p.) for 2 weeks started 2 weeks after diabetes induction attenuated the development of diabetic neuropathy as compared to diabetic control animals. In addition, minocyline treatment reduced the levels of interleukin-1β and tumor necrosis factor-α, lipid peroxidation, nitrite and also improved antioxidant defense in spinal cords of diabetic rats as compared to diabetic control animals. In contrast, minocycline (80 mg/kg, per se) had no effect on any of these behavioral and biochemical parameters assessed in age-matched control animals. The results of the present study strongly suggest that activated microglia are involved in the development of experimental diabetic neuropathy and minocycline exerted its effect probably by inhibition of neuroimmune activation of microglia. In addition, the beneficial effects of minocycline are partly mediated by its anti-inflammatory effect by reducing the levels of proinflammatory cytokines and in part by modulating oxidative and nitrosative stress in the spinal cord that might be involved in attenuating the development of behavioral hypersensitivity in diabetic rats.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Behavior, Animal; Biomarkers; Blood Glucose; Body Weight; Cold Temperature; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Formaldehyde; Hyperalgesia; Interleukin-1beta; Male; Minocycline; Oxidative Stress; Pain; Rats; Rats, Wistar; Reactive Nitrogen Species; Spinal Cord; Tumor Necrosis Factor-alpha

Enhanced production of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in diabetes leads to degradation of extracellular matrix in blood vessels and leads to complications of diabetes. In the present study, we have targeted MMP-2 and MMP-9 overactivation in diabetic neuropathy using a known MMP-2 and MMP-9 inhibitor, minocycline, with a non-selective COX inhibitor, aspirin. Streptozotocin-induced diabetic neuropathy was carried out in male Wistar rats and monitored by measuring the sensory nerve conduction velocity (SNCV), motor nerve conduction velocity (MNCV), tail flick latency and hot plate latency. Three weeks of treatment with a combination of minocycline and aspirin showed significant improvement in SNCV, MNCV, hot plate latency and tail flick latency when compared with diabetic control. The results of the present study suggest that MMP-2 and MMP-9 inhibition in the presence of COX inhibitor prevents the development of experimental diabetic neuropathy in rats and can be a potential approach for the treatment.

Topics: Animals; Aspirin; Cyclooxygenase Inhibitors; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Drug Therapy, Combination; Male; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Minocycline; Protease Inhibitors; Rats; Rats, Wistar