• The Korean Journal of Physiology and Pharmacology
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• 제15권3호
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• pp.163-169
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• 2011

Corticosterone is known to modulate GABAergic synaptic transmission in the hypothalamic paraventricular nucleus. However, the underlying receptor mechanisms are largely unknown. In the anterior hypothalamic area (AHA), the sympathoinhibitory center that project GABAergic neurons onto the PVN, we examined the expression of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) of GABAergic neurons using intact GAD65-eGFP transgenic mice, and the effects of corticosterone on the burst firing using adrenalectomized transgenic mice. GR or MR immunoreactivity was detected from the subpopulations of GABAergic neurons in the AHA. The AHA GABAergic neurons expressed mRNA of GR (42%), MR (38%) or both (8%). In addition, in brain slices incubated with corticosterone together with RU486 (MR-dominant group), the proportion of neurons showing a burst firing pattern was significantly higher than those in the slices incubated with vehicle, corticosterone, or corticosterone with spironolactone (GR-dominant group; 64 vs. 11~14%, p<0.01 by $x^2$-test). Taken together, the results show that the corticosteroid receptors are expressed on the GABAergic neurons in the AHA, and can mediate the corticosteroid-induced plasticity in the firing pattern of these neurons. This study newly provides the experimental evidence for the direct glucocorticoid modulation of GABAergic neurons in the AHA in the vicinity of the PVN.

• BMB Reports
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• 제54권12호
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• pp.620-625
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• 2021

Microglia are known to be activated in the hypothalamic paraventricular nucleus (PVN) of rats with cardiovascular diseases. However, the exact role of microglial activation in the plasticity of presympathetic PVN neurons associated with the modulation of sympathetic outflow remains poorly investigated. In this study, we analyzed the direct link between microglial activation and spontaneous firing rate along with the underlying synaptic mechanisms in PVN neurons projecting to the rostral ventrolateral medulla (RVLM). Systemic injection of LPS induced microglial activation in the PVN, increased the frequency of spontaneous firing activity of PVN-RVLM neurons, reduced GABAergic inputs into these neurons, and increased plasma NE levels and heart rate. Systemic minocycline injection blocked all the observed LPS-induced effects. Our results indicate that LPS increases the firing rate and decreases GABAergic transmission in PVN-RVLM neurons associated with sympathetic outflow and the alteration is largely attributed to the activation of microglia. Our findings provide some insights into the role of microglial activation in regulating the activity of PVN-RVLM neurons associated with modulation of sympathetic outflow in cardiovascular diseases.

• 대한수의학회지
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• 제40권2호
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• pp.275-282
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• 2000

Substantia nigra is known to highly express glibenclamide binding site, a protein associated to ATP-sensitive $K^{+}$ ($K_{ATP}$) channel in the brain. However, the functional expression of $K_{ATP}$ channels in the area is not yet known. In this work, we attempted to estimate the functional expression of $K_{ATP}$ channels in neurons of the substantia nigra pars compacta (SNC) in young rats using slice patch clamp technique. Membrane properties and whole cell currents attributable to $K_{ATP}$ channel were examined by the current and voltage clamp method, respectively. In SNC, two sub-populations of neurons were identified. Type I (rhythmic) neurons had low frequency rebound action potentials ($4.5{\pm}0.25Hz$, n=75) with rhythmic pattern. Type II (phasic) neurons were characterized by faster firing ($22.7{\pm}3.16Hz$, n=12). Both time constants and membrane capacitance in rhythmic neurons ($34.0{\pm}1.27$ ms, $270.0{\pm}11.83$ pF) and phasic neurons ($23.7{\pm}4.16$ ms, $184{\pm}35.2$ pF) were also significantly different. The current density of $K_{ATP}$ channels was $6.1{\pm}1.47$ pA/pF (2.44~15.43 pA/pF, n=8) at rhythmic neurons of young rats. Our data show that in SNC there are two types of neurons with different electrical properties and the density of $K_{ATP}$, channel of rhythmic neuron is about 600 channels per neuron.

• 한국식품저장유통학회지
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• 제17권4호
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• pp.500-506
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• 2010

본 연구는 최근 기능성 차 소재로 알려져 있는 mate의 특유의 맛과 향을 개선하기 위하여 발효공정을 적용하였으며 발효공정 단계별 유용성분 분석을 통해 품질특성을 비교하였다. 발효 전 mate 추출물에서는 탄닌 함량이 $5.81{\pm}0.02\;{\mu}g/mL$로 측정되었으나 발효 후 덖기 과정 및 최종 건조과정을 거침에 따라 각각 $5.56{\pm}0.03\;{\mu}g/mL$, $5.49{\pm}0.04\;{\mu}g/mL$로 유의성 있게 감소하였다. 총 폴리페놀 및 총 플라보노이드 함량은 발효 전 mate 추출물에서 각각 43.45 mg/g, 0.86 mg/g이었으며 발효 후 덖음 과정을 거친 구간이 각각 38.20 mg/g, 0.73 mg/g으로 나타나 발효공정이 진행 될수록 낮아지는 경향이었다. 발효 전 mate추출물의 카페인 함량은 6.78 mg/g이었으나 발효 후 덖음 과정을 거친 후 4.30 mg/g으로 나타나 발효공정이 진행될수록 낮아지는 경향이었으며 최종 건조완료 후 3.65 mg/g이었다. 발효공정이 진행됨에 따라 유리아미노산과 필수아미노산은 낮아지는 경향이었으며, 발효 후 덖기과정을 거친 mate의 유리아미노산과 필수아미노산 함량은 각각 $690.95\;{\mu}g/mL$, $93.68\;{\mu}g/mL$이었다. 종합적인 기호도는 발효공정이 진행될수록 높은 점수를 얻어 풍미가 향상되었음을 알 수 있었는데, 발효를 통해 단맛 및 구수한 맛은 증가하였고 쓴맛과 떫은맛은 감소하여 종합적인 기호도는 증가하였다.