Abstract
Diabetic retinopathy (DR) is a neovascular, inflammatory and neurodegenerative disease. The neovascular component is treatable but no therapeutic agents are available for the other two components. Early changes in the diabetic retina include neuronal death of amacrine and retinal ganglion cells (RGC)(Barber et al., J Clin Invest,1998), and elevated levels of inflammatory mediators (Yoshimura et al., Plos One,2009). Nerve Growth factor (NGF) receptors, namely TrkA and p75NTR, are expressed in RGC. The TrkA receptor activates prosurvival, while p75NTR activates inflammatory and apoptotic pathways (Mysona et al., Expert Rev Ophthalmol,2014). Dehydroepiandrosterone (DHEA) binds to both receptors, mimicking NGF. It affords anti-apoptotic, neuroprotective and anti-inflammatory effects in the retina (Kokona et al., Neuro-pharmacol, 2012, Straub et al., J Clin Endocrinol, 1998). The therapeutic use of DHEA is restricted due to its metabolic products. The main objective of this study was to investigate and compare the neuroprotective and anti-inflammatory effects of DHEA and its spiro-epoxy derivatives BNN27 and BNN20(Calogeropoulou et al., J Med Chem,2009) (not metabolized to estrogens and androgens), in the rat streptozotocin model of DR. BNN27, via TrkA activation, protected in a dose-dependent manner (2, 10, 50mg/kg, ip) bNOS (brain nitric oxide synthetase) and TH (tyrosine hydroxylase) expressing amacrine cells and ganglion axons (NFL immunoreactivity) similar to DHEA’s actions, while BNN20 was less effective. BNN27 activated the TrkA prosurvival signaling pathway ERK1/2 kinase. It reduced the activation of SAPK/JNK kinase and the expression of p75NTR. BNN27 also increased the expression of anti-inflammatory cytokines (IL10). These results suggest that NGF TrkA receptor is involved in the neuroprotective and anti-inflammatory effects of BNN27 and is a valuable target via which BNN27 could afford efficacious therapeutics for the treatment of DR.
Highlights
Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by progressive dementia
The results of the present study indicate that development of the neuronal hypoxic tolerance induced by the three-trial, in contrast to one-trial, mild hypoxic preconditioning is apparently largely associated with the activation of CREB, as well as brain-derived neurotrophic factor (BDNF) and Bcl-2 overexpression
No significant differences in serum level of Solubile form of RAGE (sRAGE) where found between rapidly progressing and slow progressing subgroup of multiple sclerosis (MS) patients.Our results suggest for the role of sRAGE in MS ethiopathogenesis, but we did not find any association of sRAGE in serum with the rate of MS disability progression
Summary
Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by progressive dementia. The aim of the study was to characterize the effects of streptozocin (STZ)-indced diabetes on learning and memory of 5XFAD and wild-type (WT) mice in Morris water maze (MWM) at ages 2 and 6 months and on brain amyloid load. Existing evidence suggests GABAergic system is involved in pathophysiology of Alzheimer’s disease (AD) via inhibitory interneuron deficits (Verret et al, 2012) and decrease in functional GABAA receptors (Limon et al, 2012). Our concept: low doses of muscimol may prevent learning/memory deficits in intracerebroventricular (icv) streptozocin (STZ)-induced AD nontransgenic rat model. The Sigma-1 receptor is a chaperone protein that modulates intracellular calcium signalling of the endoplasmatic reticulum and is involved in learning and memory processes.The aim of the present study was to compare in vitro Ca2+ concentration modulating activity and in vivo behavioural effects of enantiomers of methylphenylpiracetam, a novel positive allosteric modulator of Sigma-1 receptors
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