Cytosolic phospholipase A2 inhibition is involved in the protective effect of nortriptyline in primary astrocyte cultures exposed to combined oxygen-glucose deprivation

Beneficial effects of Cyclosporine A in combination with Nortriptyline on germ cell-specific apoptosis, oxidative stress and epididymal sperm qualities following testicular ischemia/reperfusion in rats: a comparative study

Background

Testicular torsion is a pathological condition which needs emergency surgical intervention. However, after surgical reperfusion, oxidative stress factors cause to germ cell apoptosis. The study was planned to evaluate the efficacy of simultaneous use of Cyclosporine A (CsA) and Nortriptyline (Nort) to repair testicular damages in an experimental torsion/detorsion (T/D) rat model.

Methods

Male rats (n = 112) were allocated into 7 groups 16 each in; (Group 1); Control group, (Group 2); T/D group, (Group 3–4); CsA 1 and 5 mg/kg, (Group 5–6); Nort 2 and 10 mg/kg and (Group 7); concurrent group, CsA (1 mg/kg) + Nort (2 mg/kg). Right uni-lateral torsion was inducted by twisting testis 720 degrees in the clockwise direction for 1 h. For short-term and mid-term studies, lipid peroxidation, antioxidant enzyme activities, caspase-3 level, histopathological changes and germ cell apoptosis were evaluated. Moreover, in long-term investigation, semen analysis was performed.

Results

After T/D induction, testis abnormalities both functional and structural were appeared. Pre- and post-treatment with CsA and Nort, separately, reduced MDA and caspase-3 levels, normalized antioxidant levels, ameliorate tissue injury and improved sperm criteria.

Conclusion

The antioxidant and anti-apoptotic characteristics of CsA and Nort and their protective effects have been shown in our study. Concurrent administration of CsA and Nort in selected low-dose indicated a significant positive effect as compared to the individual drug interventions on the reversal of T/D induced oxidative stress in short-term, apoptosis, and histologic changes in mid-term, as well as semen criteria in the long-term appraisal.

Protection of FK506 against neuronal apoptosis and axonal injury following experimental diffuse axonal injury

Diffuse axonal injury (DAI) is the most common and significant pathological features of traumatic brain injury (TBI). However, there are still no effective drugs to combat the formation and progression of DAI in affected individuals. FK506, also known as tacrolimus, is an immunosuppressive drug, which is widely used in transplantation medicine for the reduction of allograft rejection. Previous studies have identified that FK506 may play an important role in the nerve protective effect of the central nervous system. In the present study, apoptosis of neuronal cells was observed following the induction of experimental DAI. The results demonstrated that it was closely related with the upregulation of death-associated protein kinase 1 (DAPK1). It was hypothesized that FK506 may inhibit the activity of DAPK1 by inhibiting calcineurin activity, which may be primarily involved in anti-apoptosis following DAI induction. Through researching the expression of nerve regeneration associated proteins (NF-H and GAP-43) following DAI, the present study provides novel data to suggest that FK506 promotes axon formation and nerve regeneration following experimental DAI. Therefore, FK506 may be a potent therapeutic for inhibiting nerve injury, as well as promoting the nerve regeneration following DAI.

Targeting astrocytes in major depression

Astrocytes represent a highly heterogeneous population of neural cells primarily responsible for the homeostasis of the CNS. Astrocytes express multiple receptors for neurotransmitters, including the serotonin 5-HT2B receptors and interact with neurones at the synapse. Astroglia contribute to neurological diseases through homeostatic response, neuroprotection and reactivity. In major depression, astrocytes show signs of degeneration and are decreased in numbers, which may lead to a misbalance in neurotransmission and aberrant synaptic connectivity. In this review, we summarize astroglia-specific effects of major antidepressants and outline future strategies for astroglia-specific therapy in neuropsychiatric disorders.

Synthetic and natural inhibitors of phospholipases A2: their importance for understanding and treatment of neurological disorders

Phospholipases A2 (PLA2) are a diverse group of enzymes that hydrolyze membrane phospholipids into arachidonic acid and lysophospholipids. Arachidonic acid is metabolized to eicosanoids (prostaglandins, leukotrienes, thromboxanes), and lysophospholipids are converted to platelet-activating factors. These lipid mediators play critical roles in the initiation, maintenance, and modulation of neuroinflammation and oxidative stress. Neurological disorders including excitotoxicity; traumatic nerve and brain injury; cerebral ischemia; Alzheimer's disease; Parkinson's disease; multiple sclerosis; experimental allergic encephalitis; pain; depression; bipolar disorder; schizophrenia; and autism are characterized by oxidative stress, inflammatory reactions, alterations in phospholipid metabolism, accumulation of lipid peroxides, and increased activities of brain phospholipase A2 isoforms. Several old and new synthetic inhibitors of PLA2, including fatty acid trifluoromethyl ketones; methyl arachidonyl fluorophosphonate; bromoenol lactone; indole-based inhibitors; pyrrolidine-based inhibitors; amide inhibitors, 2-oxoamides; 1,3-disubstituted propan-2-ones and polyfluoroalkyl ketones as well as phytochemical based PLA2 inhibitors including curcumin, Ginkgo biloba and Centella asiatica extracts have been discovered and used for the treatment of neurological disorders in cell culture and animal model systems. The purpose of this review is to summarize information on selective and potent synthetic inhibitors of PLA2 as well as several PLA2 inhibitors from plants, for treatment of oxidative stress and neuroinflammation associated with the pathogenesis of neurological disorders.

A3 Adenosine receptors mediate oligodendrocyte death and ischemic damage to optic nerve

Adenosine receptor activation is involved in myelination and in apoptotic pathways linked to neurodegenerative diseases. In this study, we investigated the effects of adenosine receptor activation in the viability of oligodendrocytes of the rat optic nerve. Selective activation of A3 receptors in pure cultures of oligodendrocytes caused concentration-dependent apoptotic and necrotic death which was preceded by oxidative stress and mitochondrial membrane depolarization. Oligodendrocyte apoptosis induced by A3 receptor activation was caspase-dependent and caspase-independent. In addition to dissociated cultures, incubation of optic nerves ex vivo with adenosine and the A3 receptor agonist 2-CI-IB-MECA(1-[2-Chloro-6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxy-N-methyl-b-D-ribofuranuronamide)-induced caspase-3 activation, oligodendrocyte damage, and myelin loss, effects which were prevented by the presence of caffeine and the A3 receptor antagonist MRS 1220 (N-[9-Chloro-2-(2-furanyl)[1,2,4]-triazolo [1,5-c]quinazolin-5-yl]benzene acetamide). Finally, ischemia-induced injury and functional loss to the optic nerve was attenuated by blocking A3 receptors. Together, these results indicate that adenosine may trigger oligodendrocyte death via activation of A3 receptors and suggest that this mechanism contributes to optic nerve and white matter ischemic damage.