• Journal of Korean Neurosurgical Society
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• 제47권6호
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• pp.415-419
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• 2010

Objective : It is usually difficult to perform the neuroendoscopic procedure in patients without hydrocephalus due to difficulties with ventricular cannulation. The purpose of this study was to find out the value of navigation guided neuroendoscopic biopsy in patients with peri- or intraventricular tumors without hydrocephalus. Methods : Six patients with brain tumors without hydrocephalus underwent navigation-guided neuroendoscopic biopsy. The procedure was indicated for verification of the histological diagnosis of the neoplasm, which was planned to be treated by chemotherapy and/or radiotherapy as the first line treatment, or establishment of the pathological diagnosis for further choice of the most appropriate treatment strategy. Results : Under the guidance of navigation, targeted lesion was successfully approached in all patients. Navigational tracking was especially helpful in entering small ventricles and in approaching the third ventricle through narrow foramen Monro. The histopathologic diagnosis was established in all of 6 patients : 2 germinomas, 2 astrocytomas, 1 dysembryoplastic neuroepithelial tumor and 1 pineocytoma. The tumor biopsy sites were pineal gland (n = 2), suprasellar area (n = 2), subcallosal area (n = 1) and thalamus (n = 1). There were no operative complications related to the endoscopic procedure. Conclusion : Endoscopic biopsy or resection of peri- or intraventricular tumors in patients without hydrocephalus is feasible. Image-guided neuroendoscopic procedure improved the accuracy of the endoscopic approach and minimized brain trauma. The absence of ventriculomegaly in patients with brain tumor may not be served as a contraindication to endoscopic tumor biopsy.

• 대한수의학회지
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• 제45권4호
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• pp.553-562
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• 2005

Melatonin, the principal hormone of the vertebral pineal gland, participates in the regulation of cardiovascular system in vitro and in vivo. Lithium inhibits both inositol polyphosphate phosphatase (IPPase) and inositol monophosphatase (IMPase), which are involved in a wide range of signal transduction pathways. The aim of the present study was to assess the effect of lithium on endothelial-dependent relaxation to melatonin and on the melatonin-induced inhibition of contraction by phenylephrine (PE) in isolated rat aorta. Melatonin induced a concentration-dependent relaxation in PE-precontracted in endothelium-intact (+E) aortic rings. Melatonin inhibited a PE-induced sustained contraction in +E aortic rings. These effects of melatonin on relaxation and contractile responses were inhibited by pretreatment with lithium. In PE-precontracted +E aortic rings, the melatonin-induced vasorelaxations and the inhibitory effects of melatonin on maximal contractions were inhibited by endothelium removal or by pretreatment with L-$N^G$-nitro-arginine (L-NNA), 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ) and nifedipine and verapamil, but not by tetrabutylammonium, clotrimazole and glibenclamide, However, in endothelium-denuded (-E) aortic rings and in the presence of L-NNA and ODQ in +E aortic rings, the melatonin-induced residual relaxations and the melatonin-induced residual contractile responses to PE were not affected by lithium. It is concluded that the inositol phosphate pathway may be involved in endothelial-dependent relaxation induced by melatonin.

• 대한수의학회지
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• 제45권4호
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• pp.507-515
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• 2005

Melatonin, the principal hormone of the vertebral pineal gland, participates in the regulation of cardiovascular system in vitro and in vivo. However, the effects of melatonin on vascular tissues are still vague. The aim of this study was to assess the relationship between phospholipase C (PLC) and nitric oxide synthase (NOS)/cyclic guanosine 3',5'-monophosphate (cGMP) signaling cascade in the relaxatory action of melatonin in isolated rat aorta. Melatonin induced a concentration-dependent relaxation in phenylephrine (PE)- and KCl-precontracted endothelium intact (+E) aortic rings. In KCl-precontracted +E aortic rings, the melatonin-induced vasorelaxation was not inhibited by endothelium removal or by pretreatment with NOS inhibitors, L-$N^G$-nitor-arginine (L-NNA) and L-$N^G$-nitor-arginine methyl ester (L-NAME), guanylate cyclase (GC) inhibitors, methylene blue (MB) and 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ). In PE-precontracted +E aortic rings, the melatonin-induced vasorelaxation was inhibited by endothelium removal or by pretreatment with L-NNA, L-NAME, MB, ODQ and 2-nitro-4-carboxyphenyl-n,n-diphenylcarbamate (NCDC). Moreover, in without endothelium (-E) aortic rings and in the presence of L-NNA, L-NAME, MB and ODQ in +E aortic rings, the melatonin-induced residual relaxations and residual contractile responses to PE were not affected by NCDC, a PLC inhibitor. It is concluded that melatonin can evoke vasorelaxation due to inhibition of PLC pathway through the protein kinase G activation of endothelial NOS/cGMP signaling cascade.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2001년도 International Symposium on Food,Nutrition and Health for 21st Century
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• pp.22-37
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• 2001

Melatonin is secreted during the hours of darkness and is thought to influence the circadian and seasonal timing of a variety of physiological processes. Serotonin N-acetyltransferase (AA-NAT) which is found to be expressed in pineal gland, retina, and various tissues, catalyses the conversion of serotonin to N-acetylserotonin and is known as the rate-limiting enzyme in the biosynthetic pathway of melatonin. The compounds that modulate the activity of AA-NAT can be used to treat serotonin-and melatonin-related diseases such as insomnia, depression and seasonal affective disorders (SAD). Several assay methods have been developed by which to measure AA-NAT activity. We have also developed a simple, rapid and sensitive AA-NAT assay method that takes advantage of differences in the organic solubilities between acetyl CoA and N-acetyltryptamine. We screened modulators of AA-NAT activity from the water extracts of the medicinal plants. We found MNP1005 which strongly inhibited the activity of AA-NAT ($IC_{50}$=2.2$\mu$M). Enzyme inhibitory kinetic studies revealed that MNP1005 exhibited a noncompetitive inhibition toward tryptamine. The antidepressant effect of MNP1005 was investigated on behavioral despair test so called forced swimming test (FST). MNP1005 significantly increased swimming behavior by reducing immobility with treatment of 10 mg/kg when compared to the vehicle-treated control group (P < 0.05). This suggests that MNP1005 possesses antidepressant activity. The influence of chronic MNP1005 treatment on the expression of brain-derived neurotrophic factor (BDNF) was examined by in situ hybridization and Northern blot. Chronic treatment of MNP1005 blocked the downregulation of BDNF mRNA in the frontal cortex and other cortex regions in response to restraint stress.

• The Korean Journal of Physiology and Pharmacology
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• 제25권5호
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• pp.449-457
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• 2021

The sleep-wake cycle is regulated by the alternating activity of sleep- and wake-promoting neurons. The dorsal raphe nucleus (DRN) secretes 5-hydroxytryptamine (5-HT, serotonin), promoting wakefulness. Melatonin secreted from the pineal gland also promotes wakefulness in rats. Our laboratory recently demonstrated that daily changes in nitric oxide (NO) production regulates a signaling pathway involving with-no-lysine kinase (WNK), Ste20-related proline alanine rich kinase (SPAK)/oxidative stress response kinase 1 (OSR1), and cation-chloride co-transporters (CCC) in rat DRN serotonergic neurons. This study was designed to investigate the effect of melatonin on NO-regulated WNK-SPAK/OSR1-CCC signaling in wake-inducing DRN neurons to elucidate the mechanism underlying melatonin's wake-promoting actions in rats. Ex vivo treatment of DRN slices with melatonin suppressed neuronal nitric oxide synthase (nNOS) expression and increased WNK4 expression without altering WNK1, 2, or 3. Melatonin increased phosphorylation of OSR1 and the expression of sodium-potassium-chloride co-transporter 1 (NKCC1), while potassium-chloride co-transporter 2 (KCC2) remained unchanged. Melatonin increased the expression of tryptophan hydroxylase 2 (TPH2, serotonin-synthesizing enzyme). The present study suggests that melatonin may promote its wakefulness by modulating NO-regulated WNK-SPAK/OSR1-KNCC1 signaling in rat DRN serotonergic neurons.

• 한국전기전자재료학회논문지
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• 제37권5호
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• pp.486-493
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• 2024

Lighting has been used for a long time as a medium to convey brightness from darkness, and through incandescent lamps and fluorescent lamps, LED light sources have now become the standard in the lighting industry. Recently, the lighting equipment industry has been undergoing rapid digital transformation, starting with smart lighting, and is evolving into smart lighting customized for individuals and spaces through the development of IoT technology, cloud-based services, and data analysis. However, the blue light emitted from digital devices (computers, smartphones, tablets, etc.) or LED lights stimulates the melanopsin in the optic ganglion cells in the retina of the eye, which in turn stimulates the secretion of melatonin through the pineal gland, which regulates the secretion of melatonin. This can reduce sleep quality or disrupt biological rhythms. This interaction between blue light and melatonin has such a significant impact on human sleep patterns and overall health that it is essential to reduce exposure to blue light, especially in the evening. Human-centered lighting refers to lighting that takes into account the effects of light on the physical and mental areas, such as human activity and awakening, improvement of sleep quality, and health management. Many research institutes study the effects in the visible area and the non-visible area. By studying the impact, it is expected to improve the quality of human life. In this study, we plan to study ways to implement human-centered lighting by collecting sunrise and sunset data and linking commercialized LED packages and control devices with open-source hardware.

• Reproductive and Developmental Biology
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• 제34권2호
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• pp.89-94
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• 2010

Melatonin is induced by light information through the retina and leads to growth factor activation. Thus, we investigated the effects of melatonin by controlling the photoperiod of growing young rats. Male Sprague-Dawley rats (n=6; 4 weeks old) were divided into two experimental groups: the L/D group (normal photoperiod; light/dark: 12/12 h; lights on at 9:00 a.m.) and the L/L group (light/light: 24 h). Rat body weight and food consumption were measured daily for 8 weeks. After 8 weeks, the rats were anesthetized with a mixture of ketamine (50 mg/kg) and xylazine (10 mg/kg) and sacrificed. Tissue was then collected for RNA isolation (from brain, heart, liver, kidney, adrenal gland, testis, tibia, hind limb muscles). Also, serum was isolated from blood using a centrifugal separation. The L/L group had significantly lower body weight than the L/D group from 4 to 6 weeks (p<0.05). The L/D group had increased tissue mass, compared with the L/L group, but the difference was not statistically significant. The L/D group had a significantly higher melatonin concentration than the L/L group between the hours of midnight and 2:00 a.m (p<0.01). These results indicate that photoperiod length may affect the secretion of melatonin from the pineal gland. Also, the reduction of nocturnal melatonin secretion may retard the development of growing young rats. In future studies, we plan to compare exogenous melatonin administration with endogenous melatonin concentration induced by photoperiod control. Moreover, we will confirm whether the effects seen in pathological animal models can be reversed by controlling the photoperiod.

• 한국발생생물학회지:발생과생식
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• 제12권2호
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• pp.125-132
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• 2008

멜라토닌(N-acetyl-5-methoxytryptamine)은 포유동물의 뇌의 송과선에서 분비되는 호르몬으로 수면과 생체 리듬 등을 조절하고 난소 기능과 번식에도 영향을 미친다. 또한, 강력한 scavenger로서 항산화제의 역할을 한다. 이 연구의 목적은 멜라토닌이 생쥐 난구세포-핵낭(germinal vesicle, GV) 시기 난자 복합체의 체외성숙에 미치는 영향을 알아보는 것이다. 3주령의 ICR 암컷 생쥐의 난소에서 회수된 난자-난구세포 복합체를 0, 0.1 nM, 10 nM, 1,000 nM의 멜라토닌이 첨가된 배양액에서 18시간 동안 배양하고, 제1극체의 방출 여부를 확인하여 성숙율을 확인하였다. 체외성숙 후 TUNEL assay와 성숙율이 가장 높게 나타났다. 체외성숙된 난자에서는 세포자연사가 나타나지 않았으나 난구세포에서는 관찰되었으며, 1,000 nM을 첨가하여 배양한 군의 난구세포는 유의하게 낮은 세포자연사를 나타냈다. 그리고 1,000 nM의 멜라토닌을 첨가한 군의 난구세포에서 멜라토닌 수용체의 mRNA가 대조군에 비해 낮게 발현되었다. 이상의 결과를 종합하면 체외성숙 배양액에 첨가된 멜라토닌은 난구세포의 세포자연사를 줄여줌으로써 생쥐 미성숙 난자의 체외성숙을 향상시키는 역할을 하는 것으로 사료된다.

• 한국발생생물학회지:발생과생식
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• 제5권2호
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• pp.181-187
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• 2001

포유동물의 혈중 프로락틴 농도는 일주기와 연주기의 변화를 나타내며 송과체에서 분비되는 멜라토닌이 조절인자로 관여한다. 인위적인 송과체의 기능 억제는 혈중 프로락틴 농도를 증가시킨다. 임신 후반기에 태반에서는 수종의 프로락틴군 호르몬들이 분비되어 태반기능 및 배아발생에 중요한 역할을 한다. 그러나 이들 호르몬 유전자들의 발현 조절기작과 조절 인자들에 관한 연구 결과는 미비하다. 본 연구에서는 RT-PCR과, in situ hybridization 방법으로 흰쥐의 태반에서 Me $l_{la}$ 유전자의 발현을 확인하였다. 발현되는 주요 세포는 junctional zone과 labyrinth zone의 spongiotrophoblast 세포와 trophoblast giant세포였다. 특이한 것은junctional zone의 Me $l_{la}$ 유전자의 발현이 밤시간(22:00)에 비하여 낮시간(16:00)에 높게 조사되었다. 그리고 멜라토닌 수용체 agonist인 chloromelatonin은 PLP-A 유전자의 발현을 억제하였다. 이러한 결과들로 보아 흰쥐의 태반에서 Me $l_{la}$ 유전자가 발현되며, 멜라토닌에 의해 유도되는 Me $l_{la}$ 의 활성화는 PLP-A유전자의 발현에 중요한 조절인자로 작용할 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5835-5842
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• 2015

Background: Melatonin, which is mainly produced by the pineal gland, has a good inhibitory effect on cell growth of multiple cancer types. However, the underlying molecular mechanisms of anti-tumor activity for colon cancer have not been fully elucidated. In this study, we investigated the effects of melatonin on migration in human colon cancer RKO cells and the potential molecular mechanisms. Materials and Methods: The viability of RKO cells was investigated by MTT assay after treatment with melatonin, SB203580 (p38 inhibitor) and phorbol 12-myristate 13-acetate (PMA, MAPK activator) alone or in combination for 48h. The effects of melatonin, and ML-7, a selective inhibitor of myosin light chain kinase (MLCK), and SB203580, and PMA on the migration of RKO cells were analyzed by in vitro scratch-wound assay. The relative mRNA levels of MLCK was assessed by real-time quantitative RT-PCR. Western blotting analysis was performed to examine the expression of MLCK, phosphorylation of myosin light chain (pMLC) and p38 (pp38). Results: The proliferation and migration of human colon cancer RKO cells were inhibited significantly after treatment with melatonin. The expression levels of MLCK and phosphorylation of MLC of RKO cells were reduced, and real-time quantitative RT-PCR showed that melatonin had significant effects on suppressing the expression of MLCK. Furthermore, the phosphorylation level of p38, which showed the same trend, was also reduced when cells were treated by melatonin. In addition, ML-7 (25umol/l) could down-regulate the phosphorylation of p38. Conclusions: Melatonin could inhibit the proliferation and migration of RKO cells, and further experiments confirmed that p38 MAPK plays an important role in regulating melatonin-induced migration inhibition through down-regulating the expression and activity of MLCK.