Calcitriol modulate post-ischemic TLR signaling pathway in ischemic stroke patients.

BACKGROUND: Neuroinflammation is a significant contributor to post-ischemic neuronal death after stroke, and Toll-Like Receptors (TLRs) are one of the essential mediators in many inflammatory pathways. TLRs activate the nuclear factor kappa ß (NF-kß), which promotes the expression of various pro-inflammatory genes such as interleukin (IL-1ß) and IL-6. 1,25(OH)2D3, also known as calcitriol, is an active form of vitamin D3 that acts as a neurosteroid compound with anti-inflammatory properties. This study aimed to determine the modulatory effects of calcitriol hormone on post-ischemic immunity response. METHODS: Neurological tests and conventional blood factors were evaluated in patients with stroke symptoms upon arrival (n = 38) to confirm the stroke. A blood sample was taken from each stroke patient immediately upon admission and again after 24 h. The experimental group was given 10 µg calcitriol orally. The gene expression levels of TLR4, TLR2, NF-kß, IL-1ß, and IL-6 pro-inflammatory factors were measured using real-time PCR. The protein expression of TLR4 and NF-kß markers was assessed using the flow cytometry technique. RESULTS: TLR4, NF-kß, and pro-inflammatory factors IL-1ß and IL-6 expression increased significantly after an ischemic stroke, and calcitriol could modulate the TLR4/NF-kß signaling pathway 24 h after ischemia. CONCLUSIONS: Calcitriol may be considered a protective reagent after ischemia by reducing the TLR4/NF-kB activation cascade and probably plays a beneficial role in reducing and improving ischemic stroke patients' symptoms. TRIAL REGISTRATION: Iranian Registry of Clinical Trials identifier: IRCT2017012532174N1.

The effect of female sex hormones on Hsp27 phosphorylation and histological changes in prefrontal cortex after tMCAO.

BACKGROUND: Female sex hormones are protective factors against many neurological disorders such as brain ischemia. Heat shock protein like HSP27 is activated after tissue injury. The main purpose of the present study is to determine the effect of a combined estrogen / progesterone cocktail on the morphology of astrocytes, neurons and Hsp27 phosphorylation after cerebral ischemia. METHODS: One hour after the MCAO induction, a single dose of estrogen and progesterone was injected. The infarct volume was calculated by TTC staining 24 h after ischemia. Immunohistochemistry was used to show the effects of estrogen and progesterone on astrocyte and neuron morphology, as well as the Western blot technique used for the quantitation of phosphorylated Hsp27. RESULTS: The combined dose of estrogen and progesterone significantly decreased astrocytosis after ischemia and increased neuron survival. There was a large increase in Hsp27 phosphorylation in the penumbra ischemic region after stroke, which was significantly reduced by hormone therapy. CONCLUSION: Our results indicate that the neuroprotective effect of neurosteroids in the brain may be due to the modulation of heat shock proteins.

Gonadal steroids block the calpain-1-dependent intrinsic pathway of apoptosis in an experimental rat stroke model.

OBJECTIVES: Apoptosis plays an important role in the progression of the ischemic penumbra after reperfusion. Estrogen and progesterone have neuroprotective effects against ischemic brain damage, however the exact mechanisms of neuroprotection and signaling pathways is not completely understood. In this study, we investigated the possible regulatory effects of a combined steroid treatment on extrinsic and intrinsic apoptotic signaling pathways after cerebral ischemia. METHODS: Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (tMCAO) using an intraluminal filament technique for 1 h followed by 23 h reperfusion. Estrogen and progesterone were immediately injected after tMCAO subcutaneously. Sensorimotor functional tests and the infarct volume were evaluated 24 h after ischemia. Protein expression of calpain-1 and Fas receptor (FasR), key members of intrinsic and extrinsic apoptosis, were determined in the penumbra region of the ischemic brain using western blot analysis, immunohistochemistry, and TUNEL staining. RESULTS: Neurological deficits and infarct volume were significantly reduced following hormone therapy. Calpain-1 up-regulation and caspase-3 activation were apparent 24 h after ischemia in the peri-infarct area of the cerebral cortex. Steroid hormone treatment reduced infarct pathology and attenuated the induction of both proteases. FasR protein levels were not affected by ischemia and hormone application. CONCLUSION: We conclude that a combined steroid treatment inhibits ischemia-induced neuronal apoptosis through the regulation of intrinsic pathways.

Morphology of Rat Hippocampal CA1 Neurons Following Modified Two and Four-Vessels Global Ischemia Models.

BACKGROUND: An appropriate animal model of ischemia stroke is essential for evaluation of different therapeutic methods. Two and four-vessel global ischemia models are one of the most common types of transient cerebral ischemia. OBJECTIVES: In this study, the morphology of rat hippocampal CA1 neurons in modified models of two and four-vessel ischemia and reperfusion were evaluated. MATERIALS AND METHODS: In this study, 20 Wistar rats were randomly divided into five groups. In group 2 and 3, both common carotid arteries were occluded for 10 minutes in either 3 or 24 hours of reperfusions, respectively. In group 4 and 5, both common carotid and vertebral arteries were occluded for 10 minutes in either 3 or 24 hours of reperfusions, respectively. Group 1 as control, underwent the whole surgery without any arteries occlusion. Hippocampi of the rats in all groups were processed and tissue sections were stained using the Nissl method. The morphology of CA1 neurons were studied under a light microscope and compared different groups. RESULTS: In all groups ischemic changes were apparently observed in hippocampus CA1 neurons. In two-vessel occlusion model, after 3 and 24 hours of reperfusions, ischemic cells accounted for 14.9% and 23.2%, respectively. In four-vessel occlusion model, after 3 and 24 hours of reperfusions, ischemic cells accounted for 7.6% and 44.9% (P < 0.0001), respectively. CONCLUSIONS: Modified four-vessel occlusion model resulted in significant ischemic changes after 24 hours of reperfusion in CA1 neurons of rat hippocampus.