Krill Oil Inhibits Cholesterol Synthesis and Stimulated Cholesterol Excretion in Hypercholesterolemic Rats.

The present study aimed to investigate the antihypercholesterolemic effects of krill oil supplementation in high-cholesterol diet-induced hypercholesterolemic rats, and the mechanisms underlying these effects. Rats were divided into five groups: normal control, control (high-cholesterol diet), krill oil 100 mg/kg b.w. (high-cholesterol diet with Krill oil 100 mg/kg b.w.), and krill oil 200 mg/kg b.w. (high-cholesterol diet with Krill oil 200 mg/kg b.w.). After 12 weeks, the rats were sacrificed to observe the effects of krill oil on cholesterol synthesis and excretion. We found that krill oil supplementation suppressed total triglycerides, total cholesterol, and LDL-cholesterol levels, as well as HMG-CoA reductase activity. It stimulated AMPK phosphorylation, LDL receptor and ACAT2 expression in the liver, and the fecal output of cholesterol. Furthermore, it decreased the levels of P-selectin, sVCAM-1, and NO, as well as aortic wall thickness, demonstrating its role in the prevention of atherosclerosis. Thus, we suggest that krill oil supplementation can reduce LDL-cholesterol levels in the blood during hypercholesterolemia by stimulating the uptake of LDL-cholesterol into tissue and cholesterol excretion, as well as inhibition of cholesterol synthesis.

In vitro and in vivo anti-tumor efficacy of krill oil against bladder cancer: Involvement of tumor-associated angiogenic vasculature.

Krill oil (KO) obtained from Euphausia superba is nutrient-rich and has a positive effect on human health. Here, we explored the efficacy of KO in inhibiting tumor progression and tumor vascularization. KO (100-300 µg/mL) repressed the proliferation of bladder tumor cell lines MBT-2 and T24. Treatment of cells with KO raised cell-cycle arrest at G0/G1-phase via modulation of positive regulators and negative regulators in bladder cancer cells. KO treatment regulated phosphorylation of proteins involved in PI3K/AKT and MAPK signaling pathways, including ERK, JNK, and p38 MAPK. Additionally, KO hampered the invasion and migration of both cell lines via reduction of MMP-9 expression levels by disrupting transcriptional binding of Sp-1, AP-1, and NF-κB motifs. Moreover, in animal studies, KO (150-300 mg/kg) significantly decreased tumor growth in xenograft mice bearing T24 tumor cells. No significant toxic effects were observed in acute toxicity tests, including biological analysis and H&E staining. The reduced level of CD31 expression in KO-treated tumor tissues prompted us to investigate the effect of KO on tumor angiogenesis. KO (5-40 µg/mL) treatment impeded VEGF-induced capillary tube formation and proliferation by inhibiting VEGFR2-modulated eNOS/AKT/ERK1/2 signaling axis in HUVECs. Treatment of HUVECs with KO inhibited VEGF-stimulated migration and invasion by reducing MMP-2 expression level. VEGF-driven sprouting capacity of neo-microvessels was suppressed in the presence of KO (20-40 µg/mL), as determined via an ex vivo aortic ring assay. Our results indicated that KO can regulate both tumor growth and tumor-associated angiogenesis via a novel mechanism. Thus, KO may be a promising antitumor candidate, potentially useful to prevent or treat bladder cancer.

Development of a Quantitative PCR Assay for Four Salmon Species Inhabiting the Yangyangnamdae River Using Environmental DNA.

A species-specific quantitative PCR (qPCR) assay using environmental DNA (eDNA) is a promising tool for both qualitative and quantitative analyses of target species directly from water samples. Despite its reliability, an eDNA-based qPCR assay pipeline has not yet developed to monitor salmon species inhabiting Korean waters, which have been rapidly decreasing. We designed species-specific primers for four Oncorhynchus species inhabiting the eastern coastal waters along the Korean Peninsula. These include primers for two native species (Oncorhynchus keta and O. masou) and two that were introduced (O. mykiss and O. kisutch). The limit of detection and limit of quantification for the four qPCR assays ranged from 4.11 to 10.38 copies and from 30 to 81 copies, respectively, indicating a high sensitivity and specificity across all four species. Following optimization, the qPCR assays were used for the quantitative analyses of the four Oncorhynchus species in the Yangyangnamdae River during the spawning and non-spawning seasons in the year 2019-2020, one of the main rivers where salmon migrate during the spawning season in Korea. The raw copy numbers in all of the examined samples were normalized by PCR inhibition rates to standardize and compare with other studies. Among the four Oncorhynchus species examined, the eDNA concentration of O. keta increased significantly (63.60-fold, p < 0.0001) during the spawning season (November) compared with that in the non-spawning season (March), suggesting that O. keta is the main salmon species migrating through the Yangyangnamdae River. In contrast, we did not detect any differences in eDNA concentration for the other three Oncorhynchus species between the spawning and non-spawning seasons, indicating that their presence does not alter during the year. Their eDNA concentration is also relatively low compared to O. keta, which suggests that small numbers of these three species are present in the river. Overall, these newly developed qPCR assays represent useful monitoring tools for the management of four salmon species in Korean waters.

Shifting resource utilization of the lacustrine shrimp Palaemon paucidens in temperate coastal lagoons of Korea as revealed by stable isotopes.

The spatial and seasonal variations in resource use of the lacustrine shrimp Palaemon paucidens were investigated in three different Korean lagoon systems in June and October 2018 by measuring their carbon and nitrogen stable isotope ratios. P. paucidens had much higher δ13C values at the permanently open lagoon (PL) as compared to the intermittently open lagoons (ILs), revealing a disparity in resource utilization. Isotopic niches of the shrimp were relatively wider at the PL than at the ILs, suggesting a greater diversity of carbon pathways in the PL system. These results indicate that the degree of water exchange with the sea, associated with lagoon geomorphology, may be a major factor influencing resource availability for P. paucidens. Our findings suggest that the duration and degree of inlet opening may affect dietary variation at the population level, and may be one of the key components of sustainable management for coastal lagoon ecosystems.

Caffeine induces behavioural sensitization and overexpression of cocaine-regulated and amphetamine-regulated transcript peptides in mice.

This study examined whether repeated administration of caffeine would induce behavioural sensitization and overexpression of cocaine-regulated and amphetamine-regulated transcript (CART) peptides in mice. The involvement of dopaminergic receptors and adenosine receptors in caffeine-induced behavioural sensitization and CART overexpression was studied. The relevance of D1R and D2R, and A1R and A(2A)R in the overexpression of CART peptides in mouse striatum was also evaluated. Repeated administration of caffeine induced behavioural sensitization in mice. Significant increases in CART mRNA levels were observed on day 3 and peaked at day 5 of caffeine administration, and then decreased gradually. Higher proportions of CART⁺ cells were observed in the dorsolateral and ventrolateral part of the caudate putamen than in the nucleus accumbens shell and core. The behavioural sensitization induced by caffeine was inhibited by dopaminergic receptor antagonists and adenosine receptor agonists. D1R and D2R, and cyclic AMP (cAMP)/protein kinase A (PKA)/phospho-cAMP response element-binding protein (pCREB) signalling were activated by caffeine, but A1R and A(2A)R were inhibited. Overexpression of caffeine-induced CART peptides and pCREB activity were blocked by N-cyclopentyladenosine (CPA, an A1R agonist) and 4-[2-[[6-amino-9-(N-ethyl-ß-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride (CGS 21680, an A(2A)R agonist), but not by R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH 23390, a D1R antagonist) or raclopride (a D2R antagonist). Caffeine-induced overexpression of CART peptides was associated with the inhibition of A1R and A(2A)R, and the activation of cAMP/PKA/pCREB signalling. Moreover, the A(2A)R-D2R heterodimer might be involved in the overexpression of CART peptides induced by caffeine.

3,4,5-Trimethoxycinnamic acid (TMCA), one of the constituents of Polygalae Radix enhances pentobarbital-induced sleeping behaviors via GABAAergic systems in mice.

These experiments were performed to investigate whether 3,4,5-trimethoxycinnamic acid (TMCA), one of the constituents derived from Polygalae Radix, enhances pentobarbital-induced sleeping behaviors, and to alter sleep architecture through the γ-aminobutyric acid (GABA)ergic systems in mice. TMCA decreased the locomotor activity. TMCA prolonged total sleep time, and reduced sleep latency induced by pentobarbital, similar to muscimol, a GABAA agonist. From the electrocencephalogram recording for 6 h after TMCA administration, the number of sleep/wake cycles were reduced by TMCA. TMCA also increased the total sleep time and non-rapid eye movement (NREM) sleep. In addition, TMCA increased Cl(-) influx in primary cultured cerebellar granule cells of mice. TMCA increased the activation of glutamic acid decarboxylase (GAD) and the expressions of γ-subunit of GABAA receptors in the cerebellar granule cells. However, α- and ß-subunits proteins of GABAA receptors were not increased. Therefore, TMCA would increase pentobarbital induced-sleep and NREM sleep in mice. These results indicate that TMCA may enhance sleep and alter sleep architecture through GABAAergic systyems.

Cordycepin Increases Nonrapid Eye Movement Sleep via Adenosine Receptors in Rats.

Cordycepin (3'-deoxyadenosine) is a naturally occurring adenosine analogue and one of the bioactive constituents isolated from Cordyceps militaris/Cordyceps sinensis, species of the fungal genus Cordyceps. It has traditionally been a prized Chinese folk medicine for the human well-being. Because of similarity of chemical structure of adenosine, cordycepin has been focused on the diverse effects of the central nervous systems (CNSs), like sleep regulation. Therefore, this study was undertaken to know whether cordycepin increases the natural sleep in rats, and its effect is mediated by adenosine receptors (ARs). Sleep was recorded using electroencephalogram (EEG) for 4 hours after oral administration of cordycepin in rats. Sleep architecture and EEG power spectra were analyzed. Cordycepin reduced sleep-wake cycles and increased nonrapid eye movement (NREM) sleep. Interestingly, cordycepin increased θ (theta) waves power density during NREM sleep. In addition, the protein levels of AR subtypes (A1, A2A, and A2B) were increased after the administration of cordycepin, especially in the rat hypothalamus which plays an important role in sleep regulation. Therefore, we suggest that cordycepin increases theta waves power density during NREM sleep via nonspecific AR in rats. In addition, this experiment can provide basic evidence that cordycepin may be helpful for sleep-disturbed subjects.

Repeated Administration of Korea Red Ginseng Extract Increases Non-Rapid Eye Movement Sleep via GABAAergic Systems.

The current inquiry was conducted to assess the change in sleep architecture after long periods of administration to determine whether ginseng can be used in the therapy of sleeplessness. Following post-surgical recovery, red ginseng extract (RGE, 200 mg/ kg) was orally administrated to rats for 9 d. Data were gathered on the 1st, 5th, and 9th day, and an electroencephalogram was recorded 24 h after RGE administration. Polygraphic signs of unobstructed sleep-wake activities were simultaneously recorded with sleep-wake recording electrodes from 11:00 a.m. to 5:00 p.m. for 6 h. Rodents were generally tamed to freely moving polygraphic recording conditions. Although the 1st and 5th day of RGE treatment showed no effect on power densities in non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, the 9th day of RGE administration showed augmented α-wave (8.0 to 13.0 Hz) power densities in NREM and REM sleep. RGE increased total sleep and NREM sleep. The total percentage of wakefulness was only decreased on the 9th day, and the number of sleep-wake cycles was reduced after the repeated administration of RGE. Thus, the repeated administration of RGE increased NREM sleep in rats. The α-wave activities in the cortical electroencephalograms were increased in sleep architecture by RGE. Moreover, the levels of both α- and ß-subunits of the γ-aminobutyric acid (GABA)A receptor were reduced in the hypothalamus of the RGE-treated groups. The level of glutamic acid decarboxylase was over-expressed in the hypothalamus. These results demonstrate that RGE increases NREM sleep via GABAAergic systems.

A micro-thermoelectric gas sensor for detection of hydrogen and atomic oxygen.

This paper demonstrates the fabrication and performance of a micro-thermoelectric gas sensor for an effective and inexpensive gas analysis system. The proposed micro-thermoelectric gas sensor was fabricated by using a surface micromachining technique. The sensing mechanism, consisting of thermoelectric material and a novel metal catalyst, was fabricated on the highly thermally resistive layer for reduced heat transfer to the substrate allowing for a simple fabrication process. The micro-thermoelectric gas sensor detects target gas species by measuring the reaction heat of the catalytic reaction between the target gas and a novel metal catalyst using Cu-Bi thermopiles. The catalytic reaction occurs only on the hot junction of the sensing thermopile where the metal catalyst is deposited. In order to reduce the external thermal noise, a difference between the output voltage of the sensing and the reference thermopiles was measured by using a differential amplifier. The response of the fabricated sensor was linear to temperature difference. The fabricated sensor can be used to detect various concentrations of hydrogen and atomic oxygen, where the output voltage linearly increased with the gas concentration.