The low and high doses administration of lutein improves memory and synaptic plasticity impairment through different mechanisms in a rat model of vascular dementia.

BACKGROUND AND AIM: Vascular dementia (VD) is a common type of dementia. This study aimed to evaluate the effects of low and high doses of lutein administration in bilateral-carotid vessel occlusion (2VO) rats. EXPERIMENTAL PROCEDURE: The rats were divided into the following groups: the control, sham-, vehicle (2VO+V) groups, and two groups after 2VO were treated with lutein 0.5 (2VO+LUT-o.5) and 5mg/kg (2VO+LUT-5). The passive-avoidance and Morris water maze were performed to examine fear and spatial memory. The field-potential recording was used to investigate the properties of basal synaptic transmission (BST), paired-pulse ratio (PPR), as an index for measurement of neurotransmitter release, and long-term potentiation (LTP). The hippocampus was removed to evaluate hippocampal cells, volume, and MDA level. RESULT: Treatment with low and high doses improves spatial memory and LTP impairment in VD rats, but only the high dose restores the fear memory, hippocampal cell loss, and volume and MDA level. Interestingly, low-dose, but not high-dose, increased PPR. However, BST recovered only in the high-dose treated group. CONCLUSIONS: Treatment with a low dose might affect neurotransmitter release probability, but a high dose affects postsynaptic processes. It seems likely that low and high doses improve memory and LTP through different mechanisms.

NADPH oxidase 5 activation; a novel approach to human sperm cryoinjury.

Sperm cryopreservation leads to various structural and functional damages, some of which induce by oxidative stress. The reactive oxygen species (ROS) generates by mitochondria and membrane NADPH oxidases (NOXs). Among the NOXs, only NOX5 has been identified in the cell membrane of human sperm. This study was designed to clarify the possible role of NOX5 on sperm cryoinjury. Forty human semen samples were washed and randomly divided into fresh and cryopreserved groups. Each group was divided into 4 subgroups containing Ham's F10 (control), 0.1% DMSO (vehicle), 100 nM of PMA (phorbol 12-myristate 13-acetate) and 1 µM of DPI (diphenyleneiodonium), as NOX5 activator and inhibitor. The samples of cryopreserved groups were preserved in liquid nitrogen for 1 month. The sperm kinematics, membrane integrity, ROS production, apoptosis rate, mitochondrial membrane potential (MMP), intracellular ATP and calcium concentration [Ca2+]i were evaluated. The percent of sperm with intact membrane and motile sperm reduced significantly after thawing (p ≤ 0.01). The ROS production (p ≤ 0.01) and the apoptotic rate increased, MMP dissipated, and the percentage of live cells with high [Ca2+]i decreased significantly in the cryopreserved control group relative to the fresh control group. DPI, in contrast to PMA, improved sperm progressive motility (p ≤ 0.01), membrane integrity in fresh and cryopreserved groups and reduced the ROS amount in cryopreserved group (p ≤ 0.01). Apoptotic rate, [Ca2+]i, ATP, and MMP did not change with DPI and PMA in cryopreserved groups. We conclude that NOX5 activity in fresh sperm is low, and it increases during cryopreservation. NOX5 inhibition improves the cryopreserved sperm quality.

Epidermal neural crest stem cell transplantation as a promising therapeutic strategy for ischemic stroke.

INTRODUCTION: Cell-based therapy is considered as promising strategy to cure stroke. However, employing appropriate type of stem cell to fulfill many therapeutic needs of cerebral ischemia is still challenging. In this regard, the current study was designed to elucidate therapeutic potential of epidermal neural crest stem cells (EPI-NCSCs) compared to bone marrow mesenchymal stem cells (BM-MSCs) in rat model of ischemic stroke. METHODS: Ischemic stroke was induced by middle cerebral artery occlusion (MCAO) for 45 minutes. Immediately after reperfusion, EPI-NCSCs or BM-MSCs were transplanted via intra-arterial or intravenous route. A test for neurological function was performed before ischemia and 1, 3, and 7 days after MCAO. Also, infarct volume ratio and relative expression of 15 selected target genes were evaluated 7 days after transplantation. RESULTS: EPI-NCSCs transplantation (both intra-arterial and intravenous) and BM-MSCs transplantation (only intra-arterial) tended to result in a better functional outcome, compared to the MCAO group; however, this difference was not statistically significant. The infarct volume ratio significantly decreased in NCSC-intra-arterial, NCSC-intravenous and MSC-intra-arterial groups compared to the control. EPI-NCSCs interventions led to higher expression levels of Bdnf, nestin, Sox10, doublecortin, ß-III tubulin, Gfap, and interleukin-6, whereas neurotrophin-3 and interleukin-10 were decreased. On the other hand, BM-MSCs therapy resulted in upregulation of Gdnf, ß-III tubulin, and Gfap and down-regulation of neurotrophin-3, interleukin-1, and interleukin-10. CONCLUSION: These findings highlight the therapeutic effects of EPI-NCSCs transplantation, probably through simultaneous induction of neuronal and glial formation, as well as Bdnf over-expression in a rat model of ischemic stroke.

Renal ischemia/reperfusion induced learning and memory deficit in the rat: Insights into underlying molecular and cellular mechanisms.

Distance organ dysfunction is the major cause of death in the patients with acute kidney injury (AKI). However, the neurobiological basis of AKI-induced brain disorders and their mediators are poorly understood. This study was aimed to find out the links between AKI and brain injury and also the underlying cellular and electrophysiological mechanisms of memory deficit following induction of AKI via different experimental models of renal ischemia with or without uremia and uremia without renal ischemia. Fifty four male Sprague-Dawley rats were divided into 4 groups that underwent 1-h bilateral or 2-h unilateral renal ischemia followed by 1-day reperfusion (BIR and UIR, respectively), and 1-day following bilateral nephrectomy (BNX) or sham-operation. There were 2 subgroups in each group, which blood-brain barrier (BBB) integrity was evaluated in one subgroup. The other subgroup was used for recordings electrophysiological activities of the hippocampus; and after blood sampling and sacrificing animal, the cerebral hemispheres were removed and preserved for performing stereological study and Western-blotting of caspase-3 in the left and right hippocampus, respectively. Plasma urea and creatinine and CA1 neuronal loss were largely increased by BNX and BIR, but slightly by UIR. Apoptosis was stimulated in the hippocampus intensively by BIR but moderately by UIR and BNX. However, BIR and UIR were associated with profoundly disturbed BBB, increased CA1 neuronal excitability, impaired LTP induction and memory deficit. Therefore, AKI most likely through inflammatory mediators leads to hippocampal apoptosis and electrophysiological impairments, BBB disruption and memory loss, whereas uremia may contribute to necrotic neuronal death.

Inhibition of inflammation is not enough for recovery of cognitive impairment in hepatic encephalopathy: Effects of minocycline and ibuprofen.

There is evidence that hyperammonia and inflammation play crucial roles in hepatic encephalopathy. This study intends to determine neuroprotective effects of minocycline (MINO) and ibuprofen (IBU), and also set out to assess whether inhibition of inflammation is enough to achieve optimal improvement of hepatic encephalopathy symptoms. The hepatic encephalopathy was induced by bile-duct ligation (BDL), and the animals received first dose of MINO and/or IBU 15 days later and then every day until the 28 day. The rats were divided into the 6 groups of control, sham, BDL + V and BDL + IBU, BDL + MINO and BDL + MINO + IBU, which each group had 3 sub-groups for evaluations of blood-brain barrier (BBB), memory performance, synaptic-plasticity and apoptosis. The long-term potentiation (LTP) and short-term potentiation were evaluated by field potential recording. The memory performance, apoptosis and BBB integrity were assessed via passive avoidance, Western-blotting of caspase-3 and Evans-blue dye extravasation, respectively. The MINO, IBU or their co-treatment in the BDL rats did not improve liver dysfunction. The BDL increased hippocampal apoptosis and BBB disruption, which were fully recovered by all three pharmacological interventions. The MINO treatment alone or combined with IBU had similar neuroprotective effects on the BDL-induced disturbances of hippocampal basal synaptic transmission, LTP and memory performance, whereas they were not ameliorated by the single IBU therapy. Therefore, it seems likely that inhibition of inflammation is not able to improve functionally impaired memory and LTP in the hepatic encephalopathy, and they may be recovered by the direct neuroprotective effects of the MINO.

Modulation of sphingosine-1-phosphate receptor by FTY720 contributes in improvement of hepatic encephalopathy induced by bile duct ligation.

Hepatic encephalopathy (HE) is a complex neuropsychiatric disorder, which is associated with memory loss and behavioral abnormalities. The cellular and molecular mechanisms that led to hippocampal dysfunction in bile duct ligation (BDL)-induced HE and neuroprotective mechanisms of FTY720 administration were evaluated using whole-cell patch clamp, field-potential recording, western blot, stereology and behavioral experiments. The animals were divided into 4 groups of control (n = 24), sham (n = 21), BDL + V (n = 21) and BDL + FTY720 (n = 20), each having three subgroups. The first subgroup was used for field potential, western blot and stereology experiments. The second and third subgroups were used for behavioral experiments and whole cell patch clamp recording, respectively. The BDL led to considerable loss of hippocampal neurons and apoptosis, along with large impairments in their intrinsic electrophysiological properties, including decrease of firing frequency and increases of first spike latency (FSL), AHP amplitude, irregularity of firing, and half-width, as well as impaired long-term synaptic plasticity and memory. Importantly, FTY720 decreased AHP amplitude probably by direct inhibition of Ca2+ channels and/or KCa2+ currents and improved the FSL and firing irregularity and frequency possibly by decreasing A-type K+ currents in the BDL + FTY720 group. FTY720 administration in the BDL rats also decreased the release probability, which was evident by the increased paired-pulse ratio, but the increased number of readily releasable pool (RRP) of neurotransmitter. Moreover, the AHP improvement and RRP increment most likely led to recovery of LTP and memory performance. In total, FTY720 ameliorated brain disorders in the BDL rats via its direct neuroprotective and/or indirect anti-inflammatory effects.

Effect of CatSper and Hv1 Channel Inhibition on Progesterone Stimulated Human Sperm.

BACKGROUND: Intracellular calcium and proton concentrations are important factors for activating human sperm. Calcium ion (Ca2+) enters sperm through voltage-dependent calcium channel of sperm (CatSper). Proton was extruded from sperm through voltage-gated proton channel (Hv1). In the present study, the selective inhibitors of the CatSper and Hv1 channels, NNC 55-0396 (NNC) and zinc ion, respectively, were used to investigate functions of these channels. METHODS: Normal semen samples (n=24) were washed and diluted to 20×106sperm/ml. The diluted sample was divided into 8 groups, containing Ham's F-10 (the control group), 2 µM NNC, 1 mM ZnCl2 and NNC+Zn. The other 4 groups were the same as above, except that they contained 1 µM progesterone. The computer assisted analysis was done by VT-Sperm 3.1 to determine the percentage of motile sperm and sperm velocity. Acrosomal status was monitored by FITC-PSA and viability assessed by Eosin-Y staining. Statistical comparisons were made using ANOVA followed by Tukey post hoc test. The p<0.05 was considered significant. RESULTS: The percentage of viable and motile sperm, curvilinear velocity and other parameters of motility was reduced in all groups containing NNC, zinc and NNC+ zinc. Progesterone-induced acrosome reaction was abolished by each of these inhibitors. The combination effect of NNC plus zinc on motility and progesterone-induced acrosome reaction was not stronger than NNC by itself. CONCLUSION: CatSper and Hv1 channels play a critical role in human sperm function and viability. It seems that a functional relationship exists between CatSper and Hv1 channels.

Pre-Treatment with Erythropoietin Attenuates Bilateral Renal Ischemia-Induced Cognitive Impairments.

One of the most common causes of mortality in acute kidney injury is brain dysfunction. Here we investigated the possible protective effect of erythropoietin (EPO) on cognitive impairments induced by bilateral renal ischemia (BRI). Eighty male Wistar rats were allocated into 8 groups: 1, 2) Sham +V (Vehicle), 3, 4) Sham+EPO, 5, 6) BRI+V, 7, 8) BRI+EPO. The groups followed by the reperfusion periods of 24hours (24 h) and 1week (1w). EPO or saline was administrated 30 min before surgery (1000 IU/kg, i.p). The cognitive function was assessed by passive avoidance learning and Morris water maze tests. Hippocampal brain-derived neurotrophic factor (BDNF) protein expression was assessed by western blotting. BUN (blood urea nitrogen) and creatinine (Cr) concentrations were significantly increased in BRI+V group 24 h after reperfusion. BRI+V rats had just an increased level of BUN but not Cr 1w after reperfusion. EPO reversed passive avoidance learning impairments observed in BRI+V group 24 h after reperfusion. There were no significant differences in spatial and passive avoidance learning between experimental groups 1w after reperfusion and histological evaluation confirmed the behavioral data. BRI significantly decreased the BDNF protein expression in the hippocampus and EPO increased that 24 h after operation. These observations showed protective effect of EPO against cognitive dysfunctions following BRI 24 h after reperfusion through increase in BDNF protein expression.

Netrin-1 improves the amyloid-ß-mediated suppression of memory and synaptic plasticity.

The aim of this study was to investigate the effects of netrin-1 (NT-1) on amyloid-beta (Aß)-induced impairments in learning-memory and synaptic plasticity. The NT-1 or its vehicle was administered four times into the Aß+NT or Aß+V groups, respectively. The Aß+SNT group received a single dose of NT-1. The Aß+HNT group received heat-inactivated NT-1. For the learning-memory and synaptic plasticity assessment, field potentials recording and behavioral experiment were used. Bilateral injection of Aß1-42 inhibits induction of long-term potentiation (LTP) and decreased memory performance in all the behavioral tasks. However, only by repeated injection of NT-1, significant recovery of LTP and memory was seen. Although, the delivery of HFS to Aß+NT group recovered EPSP slope of the maintenance phase when compared with Aß+V, but it failed to recover the induction phase. It can be assumed that NT-1 may have regulatory effects on the synthesis of key proteins and/or structural changes that are responsible for LTP induction, since the protein synthesis and/or structural changes are required for the maintenance phase of LTP.

Contribution of nitric oxide synthase (NOS) activity in blood-brain barrier disruption and edema after acute ischemia/reperfusion in aortic coarctation-induced hypertensive rats.

BACKGROUND: Nitric oxide synthase (NOS) activity is increased during hypertension and cerebral ischemia. NOS inactivation reduces stroke-induced cerebral injuries, but little is known about its role in blood-brain barrier (BBB) disruption and cerebral edema formation during stroke in acute hypertension. Here, we investigated the role of NOS inhibition in progression of edema formation and BBB disruptions provoked by ischemia/reperfusion injuries in acute hypertensive rats. METHODS: Rats were made acutely hypertensive by aortic coarctation. After 7 days, the rats were randomly selected for the recording of carotid artery pressure, or regional cerebral blood flow (rCBF) using laser Doppler. Ishcemia induced by 60-min middle cerebral artery occlusion (MCAO), followed by 12-h reperfusion. A single i.p. dose of L-NAME (1 mg/kg) was injected before MCAO. After evaluation of neurological disabilities, rats were slaughtered under deep anesthesia to assess cerebral infarction volume, edema, or BBB disruption. RESULTS: A 75-85% reduction in rCBF was occurred during MCAO which returned to pre-occluded levels during reperfusion. Profound neurological disabilities were evidenced after MCAO alongside with severe cerebral infarctions (628 ± 98 mm3), considerable edema (4.05 ± 0.52%) and extensive BBB disruptions (Evans blue extravasation, 8.46 ± 2.03 mug/g). L-NAME drastically improved neurological disabilities, diminished cerebral infarction (264 ± 46 mm3), reduced edema (1.49 ± 0.47%) and BBB disruption (2.93 ± 0.66 mug/g). CONCLUSION: The harmful actions of NOS activity on cerebral microvascular integrity are intensified by ischemia/reperfusion injuries during acute hypertension. NOS inactivation by L-NAME preserved this integrity and diminished cerebral edema.