scholarly journals Mitochondrial dysfunction in diabetic neuropathy may be involved in the development of neuropathic pain via a reduction in neurosteroid synthesis

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 506
Author(s):  
Stephen R. Humble
Keyword(s):  
Neuropathic Pain ◽  
Diabetic Neuropathy ◽  
Mitochondrial Dysfunction ◽  
Cortical Neurons ◽  
Therapeutic Benefit ◽  
Translocator Protein ◽  
Patch Clamp Technique ◽  
Pain Pathway ◽  
Layer 2 ◽  
Inhibitory Tone

Background: Recent work in a model of diabetic neuropathy revealed that layer 2/3 cortical pyramidal neurones of the pain pathway exhibited reduced endogenous neurosteroid modulation of the GABAAR and exogenously applied neurosteroids had an exaggerated impact. It is postulated that this is related to reduced precursor synthesis, due to mitochondrial dysfunction in diabetic neuropathy. Benzodiazepines are also known to activate neurosteroidogenesis by binding to mitochondrial translocator protein (TSPO). This study explored the differential effect of diazepam on GABAAR modulation via neurosteroidogenesis in diabetic and wild type (WT) mice. Methods: Whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from layer 2/3 cortical pyramidal neurons of the pain pathway from mice with type-II diabetic neuropathy (ob/ob) and WT controls aged 60-80 days. Results: There was a key difference in the response of the WT and ob/ob cortical neurons to simultaneous incubation with diazepam and flumazenil. In contrast, diazepam and the 5a-reductase inhibitor finasteride, individually or in combination, produced the same response in both strains. Conclusions: The exaggerated effect of diazepam on GABAergic inhibitory tone in the ob/ob, despite the presence of the GABAAR benzodiazepine antagonist flumazenil is likely observed due to physiological upregulation of key neurosteroidogenic enzymes in response to the reduced pregnenolone synthesis by the mitochondria. By increasing pregnenolone via TSPO activation, it is possible to promote enhanced neurosteroidogenesis and increase GABAergic inhibitory tone via an alternate route. In diabetic neuropathic pain, mitochondrial dysfunction may play an important role. Enhancing the GABAergic neurosteroid tone could be of potential therapeutic benefit.

scholarly journals Mitochondrial dysfunction in an animal model of diabetic neuropathy is associated with a reduction of neurosteroid synthesis.

F1000Research ◽  
2018 ◽  
Vol 6 ◽  
pp. 506
Author(s):  
Stephen R. Humble
Keyword(s):  
Diabetic Neuropathy ◽  
Mitochondrial Dysfunction ◽  
Cortical Neurons ◽  
Pyramidal Neurons ◽  
Therapeutic Benefit ◽  
Translocator Protein ◽  
Patch Clamp Technique ◽  
Pain Pathway ◽  
Layer 2 ◽  
Inhibitory Tone

Background: Recent work in a model of diabetic neuropathy revealed that layer 2/3 cortical pyramidal neurones of the pain pathway exhibited reduced endogenous neurosteroid modulation of the GABAAR and exogenously applied neurosteroids had an exaggerated impact. It is postulated that this is related to reduced precursor synthesis, due to mitochondrial dysfunction in diabetic neuropathy. Benzodiazepines are also known to activate neurosteroidogenesis by binding to mitochondrial translocator protein (TSPO). This study explored the differential effect of diazepam on GABAAR modulation via neurosteroidogenesis in diabetic and wild type (WT) mice. Methods: Whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from layer 2/3 cortical pyramidal neurons of the pain pathway from mice with type-II diabetic neuropathy (ob/ob) and WT controls aged 60-80 days. Results: There was a key difference in the response of the WT and ob/ob cortical neurons to simultaneous incubation with diazepam and flumazenil. In contrast, diazepam and the 5a-reductase inhibitor finasteride, individually or in combination, produced the same response in both strains. Conclusions: The exaggerated effect of diazepam on GABAergic inhibitory tone in the ob/ob, despite the presence of the GABAAR benzodiazepine antagonist flumazenil is likely observed due to physiological upregulation of key neurosteroidogenic enzymes in response to the reduced pregnenolone synthesis by the mitochondria. By increasing pregnenolone via TSPO activation, it is possible to promote enhanced neurosteroidogenesis and increase GABAergic inhibitory tone via an alternate route. In diabetic neuropathy, mitochondrial dysfunction may play an important role. Enhancing the GABAergic neurosteroid tone could be of potential therapeutic benefit.

scholarly journals Neurosteroids are reduced in diabetic neuropathy and may be associated with the development of neuropathic pain

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 1923 ◽  
Author(s):  
Stephen R. Humble
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Diabetic Neuropathy ◽  
Developmental Change ◽  
Diabetic Mice ◽  
Patch Clamp Technique ◽  
Thermal Nociception ◽  
Analgesic Effects ◽  
Electrophysiological Recordings ◽  
Pain Pathway

Introduction: Peripheral and central sensitisation are implicated in the development of neuropathic pain. Hypersensitivity of pain pathway neurons has been described in animal models of diabetic neuropathy, which is postulated to be related to an imbalance between inhibitory and excitatory signals within the spinal cord. GABAergic neurons within the pain pathway are vital for the transmission of painful stimuli to higher centres. A developmental change in the rate of exponential decay of GABAergic synaptic events has been observed in other types of neurons and this may be associated with fluctuations in endogenous neurosteroid tone.  Methods: The whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from wild type mice between the ages of 6 and 80 days in the spinal cord, the nucleus reticularis of the thalamus and the cerebral cortex. Recordings were also obtained from mice with diabetic neuropathy (ob/ob and db/db) between the ages of 60 and 80 days. Behavioural experiments were performed to examine mechanical and thermal nociception. Results: Electrophysiological recordings from cortical pain pathway neurons from mature type-2 diabetic mice revealed that the endogenous neurosteroid tone is reduced compared to control. However, selected neurosteroid compounds had a more pronounced effect on the GABAA receptors of these diabetic mice. ob/ob mice exhibit mechanical hyperalgesia and allodynia, which was reduced by neurosteroids applied exogenously. Conclusions: The reduced endogenous neurosteroid tone in ob/ob mice may be linked to their hypersensitivity. Neurosteroids may exert analgesic effects in pathological pain states by attempting to restore the physiological GABAergic inhibitory tone.

Flavonoids as Potential Therapeutic Agents for the Management of Diabetic Neuropathy

2020 ◽  
Vol 26 (42) ◽  
pp. 5468-5487 ◽  
Author(s):  
Ankita Sood ◽  
Bimlesh Kumar ◽  
Sachin Kumar Singh ◽  
Pankaj Prashar ◽  
Anamika Gautam ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Diabetic Neuropathy ◽  
Glucose Utilization ◽  
Antioxidant Properties ◽  
Therapeutic Agents ◽  
Secondary Complications ◽  
Naturally Occurring ◽  
Glycation End Products ◽  
Treatment Of Diabetes ◽  
Pharmaceutical Industries

Flavonoids are secondary metabolites that are widely distributed in plants. These phenolic compounds are classified into various subgroups based on their structures: flavones, flavonols, isoflavones, flavanones, and anthocyanins. They are known to perform various pharmacological actions like antioxidant, anti-inflammatory, anticancer, antimicrobial, antidiabetic and antiallergic, etc. Diabetes is a chronic progressive metabolic disorder that affects several biochemical pathways and leads to secondary complications such as neuropathy, retinopathy, nephropathy, and cardiomyopathy. Among them, the management of diabetic neuropathy is one of the major challenges for physicians as well as the pharmaceutical industries. Naturally occurring flavonoids are extensively used for the treatment of diabetes and its related complications due to their antioxidant properties. Moreover, flavonoids inhibit various pathways that are involved in the progression of diabetic neuropathy like the reduction of oxidative stress, decrease in glycogenolysis, increase glucose utilization, decrease in the formation of advanced glycation end products, and inhibition of the α-glucosidase enzyme. This review entails current updates on the therapeutic perspectives of flavonoids in the treatment of neuropathic pain. This manuscript explains the pathological aspects of neuropathic pain, the chemistry of flavonoids, and their application in amelioration of neuropathic pain through preclinical studies either alone or in combination with other therapeutic agents.

scholarly journals Neurotherapeutic Effect of Inula britannica var. Chinensis against H2O2-Induced Oxidative Stress and Mitochondrial Dysfunction in Cortical Neurons

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 375
Author(s):  
Jin Young Hong ◽  
Hyunseong Kim ◽  
Junseon Lee ◽  
Wan-Jin Jeon ◽  
Seung Ho Baek ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dysfunction ◽  
Cortical Neurons ◽  
Inflammatory Diseases ◽  
Neuroprotective Effect ◽  
Neuroprotective Effects ◽  
Neuronal Viability ◽  
Inula Britannica ◽  
Oxidative Effects

Inula britannica var. chinensis (IBC) has been used as a traditional medicinal herb to treat inflammatory diseases. Although its anti-inflammatory and anti-oxidative effects have been reported, whether IBC exerts neuroprotective effects and the related mechanisms in cortical neurons remain unknown. In this study, we investigated the effects of different concentrations of IBC extract (5, 10, and 20 µg/mL) on cortical neurons using a hydrogen peroxide (H2O2)-induced injury model. Our results demonstrate that IBC can effectively enhance neuronal viability under in vitro-modeled reaction oxygen species (ROS)-generating conditions by inhibiting mitochondrial ROS production and increasing adenosine triphosphate level in H2O2-treated neurons. Additionally, we confirmed that neuronal death was attenuated by improving the mitochondrial membrane potential status and regulating the expression of cytochrome c, a protein related to cell death. Furthermore, IBC increased the expression of brain-derived neurotrophic factor and nerve growth factor. Furthermore, IBC inhibited the loss and induced the production of synaptophysin, a major synaptic vesicle protein. This study is the first to demonstrate that IBC exerts its neuroprotective effect by reducing mitochondria-associated oxidative stress and improving mitochondrial dysfunction.

scholarly journals [18F]FEDAC translocator protein positron emission tomography–computed tomography for early detection of mitochondrial dysfunction secondary to myocardial ischemia

2021 ◽  
Author(s):  
Rui Luo ◽  
Lei Wang ◽  
Fei Ye ◽  
Yan-Rong Wang ◽  
Wei Fang ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Early Detection ◽  
Myocardial Ischemia ◽  
Mitochondrial Dysfunction ◽  
High Performance ◽  
Dynamic Imaging ◽  
Translocator Protein ◽  
Emission Tomography ◽  
Positron Emission

Abstract Background This study aimed to evaluate the biodistribution and kinetics of [18F]FEDAC targeting the translocator protein TSPO in the myocardium, and to explore its use for the identification of mitochondrial dysfunction. We also assessed the feasibility of [18F]FEDAC for the early detection of mitochondrial dysfunction associated with myocardial ischemia (MI). Methods The radiochemical purity and stability of [18F]FEDAC were analyzed by radio-high-performance liquid chromatography (radio-HPLC). Its biodistribution and kinetics were evaluated by dissection and dynamic imaging using micro-positron emission tomography–computed tomography (micro-PET–CT) in healthy mice. [18F]FEDAC was also applied in an MI rat model and in sham-operated controls. Mitochondrial changes were observed by immunohistochemical staining and electron microscopy. Results Radioactivity levels (%ID/g) in the myocardium in normal mice, determined by [18F]FEDAC, were 8.32 ± 0.80 at 5 min and 2.40 ± 0.10 at 60 min. PET showed significantly decreased uptake by injured cardiac tissue in MI rats, with maximal normal-to-ischemic uptake ratios of 10.47 ± 3.03 (1.5 min) and 3.92 ± 1.12 (27.5 min) (P = 0.025). Immunohistochemistry confirmed that TSPO expression was decreased in MI rats. Mitochondrial ultrastructure demonstrated significant swelling and permeability. Conclusion [18F]FEDAC uptake is reduced in the injured myocardium, consistent with mitochondrial dysfunction. These results may provide new evidence to aid the early detection of mitochondrial dysfunction associated with myocardial ischemic injury.

Effect of aerobic exercise on innate immune responses and inflammatory mediators in the spinal cord of diabetic rats

2020 ◽  
Vol 16 (4) ◽  
pp. 293-301
Author(s):  
A. Kaki ◽  
M. Nikbakht ◽  
A.H. Habibi ◽  
H.F. Moghadam
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Immune Responses ◽  
Diabetic Neuropathy ◽  
Aerobic Exercise ◽  
Inflammatory Mediators ◽  
Innate Immune ◽  
Moderate Intensity ◽  
Innate Immune Responses ◽  
Tnf Α

Neuronal inflammation is one of the pathophysiological causes of diabetes neuropathic pain. The purpose of this research was to determine the effect of aerobic exercise on innate immune responses and inflammatory mediators in the spinal dorsal horn in rats with diabetic neuropathic pain. 40 eight-week-old male Wistar rats (weight range 220±10.2 g) were randomly divided into four groups of (1) sedentary diabetic neuropathy (SDN), (2) training diabetic neuropathy (TDN), (3) training control (TC), and (4) sedentary control (SC). Diabetes was induced by injection of streptozocin (50 mg/kg). Following confirmation of behavioural tests for diabetes neuropathy, the training groups performed 6 weeks of moderate-intensity aerobic exercise on the treadmill. The expression of Toll like receptor (TLR)4, TLR2, tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-10 genes in L4-L6 spinal cord sensory neurons was measured by Real Time PCR. Two-way ANOVA and Bonferroni’s post hoc tests were used for statistical analysis. After performing aerobic exercise protocol, the TDN compared to the SDN showed a significant decrease in the mean score of pain in the formalin test and a significant increase in the latency in Tail-Flick test was observed. The expression of TLR4, TLR2, TNF-α and IL-1β genes was significantly higher in the SDN than in the SC group (P<0.05). The expression of the above genes in the TDN was significantly lower than the SDN group (P<0.05). Also, the expression level of IL-10 gene was significantly higher in the TDN than the SDN group (P<0.05). Aerobic exercise improved sensitivity of nociceptors to pain-inducing agents in diabetic neuropathy due to inhibition of inflammatory receptors and increased levels of anti-inflammatory agents in the nervous system. Thus, aerobic exercise should be used as a non-pharmacological intervention for diabetic patients to reduce neuropathic pain.

PACAP38 Modulates Activity of NMDA Receptors in Cultured Chick Cortical Neurons

1997 ◽  
Vol 78 (4) ◽  
pp. 2231-2234 ◽  
Author(s):  
Guo Jun Liu ◽  
Barry W. Madsen
Keyword(s):  
Nmda Receptor ◽  
Nmda Receptors ◽  
Cortical Neurons ◽  
Second Messengers ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Low Concentrations ◽  
Channel Opening ◽  
Pituitary Adenylate Cyclase ◽  
Intracellular Second Messengers

Liu, Guo Jun and Barry W. Madsen. PACAP38 modulates activity of NMDA receptors in cultured chick cortical neurons. J. Neurophysiol. 78: 2231–2234, 1997. The outside-out recording mode of the patch-clamp technique was used to study modulatory effects of pituitary adenylate cyclase-activating polypeptide (PACAP38) on N-methyl-d-aspartate (NMDA) receptor activity in cultured chick cortical neurons. Biphasic concentration-dependent effects of PACAP38 on channel opening frequency induced by NMDA (20 μM) and glycine (1 μM) were found, with low concentrations (0.5–2 nM) of PACAP38 increasing activity and higher concentrations (10–1,000 nM) causing inhibition. These effects were reversible, reduced with higher concentrations of glycine (2–10 μM) but not by 200 μM NMDA, and inhibited by 10 μM 7-chlorokynurenic acid. In addition, 1 μM PACAP6–38 (a PACAP antagonist) inhibited channel activity due to 20 μM NMDA and 1 μM glycine by 66%, and this inhibition was reduced to 13% in the additional presence of 2 nM PACAP38. These observations suggest thatPACAP38 has a direct modulatory effect on the NMDA receptor that is independent of intracellular second messengers and probably mediated through the glycine coagonist site(s).

Dysregulation of p53 and Parkin Induce Mitochondrial Dysfunction and Leads to the Diabetic Neuropathic Pain

Neuroscience ◽  
2019 ◽  
Vol 416 ◽  
pp. 9-19 ◽  
Author(s):  
Ayahiro Yamashita ◽  
Yutaka Matsuoka ◽  
Megumi Matsuda ◽  
Kenshiro Kawai ◽  
Teiji Sawa ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Mitochondrial Dysfunction ◽  
Diabetic Neuropathic Pain
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