Postischemic fish oil treatment confers task-dependent memory recovery

Developing fish oil emulsion gel enriched with Lentinula edodes single cell protein and its effect on controlling the growth of Acinetobacter baumannii

In this study, the characterization of fish oil (FO) emulsion gel (EGEL) containing single cell protein (SCP) produced from Lentinula edodes (L. edodes) and its potential inhibition against Acinetobacter baumannii (A. baumannii) were investigated. Oil extracted from the fish liver was emulsified with tween 80 and water, and then gelled using gelatin with the assistance of an ultrasonic homogenizer. The characteristics and surface analysis of SCP-EGEL were examined using FTIR (Fourier-transform infrared spectroscopy) and SEM (Scanning electron microscope). The particle size distribution and zeta potential of SCP-EGEL were measured using a Malvern Zetasizer. When SCP-EGEL was applied to the surface of the medium inoculated with A. baumannii, the inhibition zone (IZ) was 8.2 mm. An expansion of the IZ was observed (10.2 mm) when SCP-EGEL was applied to a fish skin (FS) surface prepared in the shape of a 6-mm diameter disc. In the SEM images, when SCP was added to lipo gel, the gel structure appeared flattened or swollen in some areas. The appearance of SCP cells being covered with gel gave the impression that they have a secondary wall. Therefore, the resulting complex can potentially be used as an additive in animal and human nutrition, in functional food coatings to suppress A. baumannii, and in fish feed to enrich it with protein.

Recent progress in fish oil-based emulsions by various food-grade stabilizers: Fabrication strategy, interfacial stability mechanism and potential application

Fish oil, rich in a variety of long-chain ω-3 PUFAs, is widely used in fortified foods due to its broad-spectrum health benefits. However, its undesired characteristics include oxidation sensitivity, poor water solubility, and fishy off-flavor greatly hinder its exploitation in food field. Over the past two decades, constructing fish oil emulsions to encapsulate ω-3 PUFAs for improving their physicochemical and functional properties has undergone great progress. This review mainly focuses on understanding the fabrication strategies, stabilization mechanism, and potential applications of fish oil emulsions, including fish oil microemulsions, nanoemulsions, double emulsions, Pickering emulsions and emulsion gels. Furthermore, the role of oil-water interfacial stabilizers in the fish oil emulsions stability will be discussed with a highlight on food-grade single emulsifiers and natural complex systems for achieving this purpose. Additionally, its roles and applications in food industry and nutrition field are delineated. Finally, possible innovative food trends and applications are highlighted, such as novel fish oil-based delivery systems construction (e.g., Janus emulsions and nutraceutical co-delivery systems), exploring digestion and absorption mechanisms and enhancing functional evaluation (e.g., nutritional supplement enhancer, and novel fortified/functional foods). This review provides a reference for the application of fish oil-based emulsion systems in future precision diet intervention implementations.

Angelica sinensis extract promotes neuronal survival by enhancing p38 MAPK-mediated hippocampal neurogenesis and dendritic growth in the chronic phase of transient global cerebral ischemia in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica sinensis (Oliv.) Diels (ASD), commonly known as Dang Gui, is a popular Chinese herb that has long been used to treat ischemic stroke. However, the effects of ASD in chronic cerebral ischemia and its underlying mechanisms still remain unclear.

AIM OF THE STUDY

This study aimed to determine the effects of the ASD extract on hippocampal neuronal survival at 28 d after transient global cerebral ischemia (GCI) and to investigate the precise mechanisms underlying the p38 mitogen-activated protein kinase (MAPK)-related signaling pathway's involvement in hippocampal neurogenesis.

MATERIALS AND METHODS

Rats underwent 25 min of four-vessel occlusion. The ASD extract was intragastrically administered at doses of 0.25 g/kg (ASD-0.25 g), 0.5 g/kg (ASD-0.5 g), 1 g/kg (ASD-1 g), 1 g/kg after dimethyl sulfoxide administration (D + ASD-1 g), or 1 g/kg after SB203580 (a p38 MAPK inhibitor) administration (SB + ASD-1 g) at 1, 3, 7, 10, 14, 17, 21, and 24 d after transient GCI.

RESULTS

ASD-0.5 g, ASD-1 g, and D + ASD-1 g treatments had the following effects: upregulation of bromodeoxyuridine (BrdU) and Ki67 expression, and BrdU/neuronal nuclei (NeuN) and Ki67/nestin co-expression in the hippocampal dentate gyrus (DG); upregulation of microtubule-associated protein 2/NeuN co-expression, and NeuN and glial fibrillary acidic protein (GFAP) expression, and downregulation of tumor necrosis factor-α/GFAP co-expression in the hippocampal CA1 region; upregulation of phospho-p38 MAPK (p-p38 MAPK), phospho-cAMP response element-binding protein (p-CREB), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor A (VEGF-A) expression in the hippocampus. SB + ASD-1 g treatment abrogated the effects of ASD-1 g on the expression of these proteins.

CONCLUSIONS

ASD-0.5 g and ASD-1 g treatments promotes neuronal survival by enhancing hippocampal neurogenesis. The effects of the ASD extract on astrocyte-associated hippocampal neurogenesis and dendritic growth are caused by the activation of p38 MAPK-mediated CREB/BDNF, GDNF, and VEGF-A signaling pathways in the hippocampus at 28 d after transient GCI.

Cannabidiol Confers Neuroprotection in Rats in a Model of Transient Global Cerebral Ischemia: Impact of Hippocampal Synaptic Neuroplasticity

Evidence for the clinical use of neuroprotective drugs for the treatment of cerebral ischemia (CI) is still greatly limited. Spatial/temporal disorientation and cognitive dysfunction are among the most prominent long-term sequelae of CI. Cannabidiol (CBD) is a non-psychotomimetic constituent of Cannabis sativa that exerts neuroprotective effects against experimental CI. The present study investigated possible neuroprotective mechanisms of action of CBD on spatial memory impairments that are caused by transient global cerebral ischemia (TGCI) in rats. Hippocampal synaptic plasticity is a fundamental mechanism of learning and memory. Thus, we also evaluated the impact of CBD on neuroplastic changes in the hippocampus after TGCI. Wistar rats were trained to learn an eight-arm aversive radial maze (AvRM) task and underwent either sham or TGCI surgery. The animals received vehicle or 10 mg/kg CBD (i.p.) 30 min before surgery, 3 h after surgery, and then once daily for 14 days. On days 7 and 14, we performed a retention memory test. Another group of rats that received the same pharmacological treatment was tested in the object location test (OLT). Brains were removed and processed to assess neuronal degeneration, synaptic protein levels, and dendritic remodeling in the hippocampus. Cannabidiol treatment attenuated ischemia-induced memory deficits. In rats that were subjected to TGCI, CBD attenuated hippocampal CA1 neurodegeneration and increased brain-derived neurotrophic factor levels. Additionally, CBD protected neurons against the deleterious effects of TGCI on dendritic spine number and the length of dendritic arborization. These results suggest that the neuroprotective effects of CBD against TGCI-induced memory impairments involve changes in synaptic plasticity in the hippocampus.

Roflumilast protects against spatial memory impairments and exerts anti-inflammatory effects after transient global cerebral ischemia

Phosphodiesterase 4 (PDE4) inhibitors have been shown to present beneficial effects in cerebral ischemic injury because of their ability to improve cognition and target different phases and mechanisms of cerebral ischemia, including apoptosis, neurogenesis, angiogenesis, and inflammation. The present study investigated whether repeated treatment with the PDE4 inhibitor roflumilast rescued memory loss and attenuated neuroinflammation in rats following transient global cerebral ischemia (TGCI). TGCI caused memory impairments, neuronal loss (reflected by Neuronal nuclei (NeuN) immunoreactivity), and compensatory neurogenesis (reflected by doublecortin (DCX) immunoreactivity) in the hippocampus. Also, increases in the protein expression of the phosphorylated response element-binding protein (pCREB) and inflammatory markers such as the glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule 1 (Iba-1), were detected in the hippocampus in TGCI rats. Repeated treatment with roflumilast (0.003 and 0.01 mg/kg) prevented spatial memory deficits without promoting hippocampal protection in ischemic animals. Roflumilast increased the levels of pCREB, arginase-1, interleukin (IL) 4, and IL-10 in the hippocampus 21 days after TGCI. These data suggest a protective effect of roflumilast against functional sequelae of cerebral ischemia, which might be related to its anti-inflammatory properties.

Protective effects of Chrysin against memory impairment, cerebral hyperemia and oxidative stress after cerebral hypoperfusion and reperfusion in rats

Stroke is devastating and a leading cause of morbidity and mortality worldwide. Cerebral ischemia-reperfusion and its subsequent reactive hyperemia lead to neuronal damage in the hippocampus and cognitive decline. Chrysin (5, 7-dihydroxyflavone) is a well-known member of the flavonoid family with antioxidant and neuroprotective effects. Therefore, in the present study, the aim was to investigate whether chrysin will be able to recover the brain function caused by ischemia-reperfusion (I/R) in rats. Adult male Wistar rats (250-300 g) were randomly divided into five groups: and submitted to cerebral I/R or a sham surgery after three-weeks of pretreatment with chrysin (CH; 10, 30 and 100 mg/kg; P.O.) and/or normal saline containing %5 DMSO. Subsequently, sensorimotor scores, cognition, local cerebral blood flow, extracellular single unit, and histological parameters were evaluated following I/R. Hippocampus was used to evaluate biomarkers including: oxidative stress parameters and prostaglandin E2 (PGE2) using ELISA kits. Data showed that pretreatment with chrysin significantly improved sensorimotor signs, passive avoidance memory, and attenuated reactive hyperemia, and increased the average number of spikes/bin (p < 0.001). Furthermore, chrysin pre-treatment significantly decreased the levels of MDA, NO, and PGE2 (p < 0. 001), while increased the levels of GPX and the number of surviving cells in the hippocampal CA1 region (p < 0.01, p < 0.001; respectively). This study demonstrates that chrysin may have beneficial effects in the treatment of cognitive impairment and help recover the brain dysfunction induced by I/R.

The temporal and spatial changes of actin cytoskeleton in the hippocampal CA1 neurons following transient global ischemia

Transient global ischemia usually results in delayed neuronal death in selective brain regions, prior to which a rapid loss of dendritic spines has been widely reported in these regions. Dendritic spines are characterized by a highly branched meshwork of actin cytoskeleton (F-actin), which is extremely vulnerable to the ATP-depleted conditions such as hypoxia/ischemia. However, the ischemia-induced changes of F-actin are still not clarified in the vulnerable brain areas. This study was designed to examine the temporal and spatial alterations of F-actin in the CA1 subfield of rat hippocampus following reperfusion after global cerebral ischemia. Phalloidin staining and confocal microscopic examination showed that F-actin disappeared from the dentritic spines in the CA1 stratum radiatum, but aggregated into thread- or fiber-like structures on days 1.5-2 after ischemia. This was followed by a nearly complete loss of F-actin in the CA1 subfield on days 3-7 after ischemia. Colocalization analysis demonstrated that the F-actin threads or fibers were located mainly within the dentritic trunks. As revealed by Nissl and Fluoro-Jade B staining, the decrease of F-actin proceeded concurrently with the evolution of ischemic damage. Consistently, western blots detected a significant decrease of F-/G-actin ratio in the dissected CA1 subfield after ischemia. To our knowledge, this is the first report on the change of F-actin in the ischemic brain. Although the underlying mechanisms remain to be elucidated, our findings may provide an important structural clue for the neuronal dysfunction induced by ischemia.

Ethyl-acetate fraction of Trichilia catigua restores long-term retrograde memory and reduces oxidative stress and inflammation after global cerebral ischemia in rats

We originally reported that an ethyl-acetate fraction (EAF) of Trichilia catigua prevented the impairment of water maze learning and hippocampal neurodegeneration after transient global cerebral (TGCI) in mice. We extended that previous study by evaluating whether T. catigua (i) prevents the loss of long-term retrograde memory assessed in the aversive radial maze (AvRM), (ii) confers hippocampal and cortical neuroprotection, and (iii) mitigates oxidative stress and neuroinflammation in rats that are subjected to the four vessel occlusion (4-VO) model of TGCI. In the first experiment, naive rats were trained in the AvRM and then subjected to TGCI. The EAF was administered orally 30min before and 1h after TGCI, and administration continued once per day for 7days post-ischemia. In the second experiment, the EAF was administered 30min before and 1h after TGCI, and protein carbonylation and myeloperoxidase (MPO) activity were assayed 24h and 5days later, respectively. Retrograde memory performance was assessed 8, 15, and 21days post-ischemia. Ischemia caused persistent retrograde amnesia, and this effect was prevented by T. catigua. This memory protection (or preservation) persisted even after the treatment was discontinued, despite the absence of histological neuroprotection. Protein carbonyl group content and MPO activity increased around 43% and 100%, respectively, after TGCI, which were abolished by the EAF of T. catigua. The administration of EAF did not coincide with the days of memory testing. The data indicate that antioxidant and/or antiinflammatory actions in the early phase of ischemia/reperfusion contribute to the long-term antiamnesic effect of T. catigua.