Leptin Suppresses Glutamate-Induced Apoptosis Through Regulation of ERK1/2 Signaling Pathways in Rat Primary Astrocytes

Park, Hyunju,Ahn, So-Hee,Jung, Yieun,Yoon, Joo Chun,Choi, Youn-Hee S. Karger AG 2017 CELLULAR PHYSIOLOGY AND BIOCHEMISTRY Vol.44 No.6

<P>Background/Aims: Leptin is a hormone expressed by adipose tissue that regulates body energy homeostasis and weight loss by activating leptin receptors in the hypothalamus. Leptin receptors are also expressed in astrocytes. An anti-apoptosis effect of leptin in brain has recently been reported. However, the anti-apoptosis mechanism of leptin in the brain is unknown. Methods: To investigate whether leptin exerts protective effects against glutamate-induced apoptosis in astrocytes, we performed cell viability assays and apoptosis assays using rat primary astrocytes. Intracellular signaling pathways involved in anti-apoptosis effects of leptin were analyzed by immunoblotting together with a leptin mutant (S120A/T121A) with antagonist function and pharmacological inhibitors. Results: We found that glutamate-induced apoptosis in rat primary astrocytes was significantly decreased by treatment with leptin. Leptin inhibited glutamate-induced phosphorylation of ERK1/2 in astrocytes. The leptin S120A/T121A mutant did not inhibit glutamate-induced ERK1/2 phosphorylation and ERK1/2-mediated apoptosis. Conclusions: Collectively, our results provide initial evidence that leptin exerts an anti-apoptotic effect against glutamate toxicity through activation of intracellular signaling pathways which reverse glutamate-induced ERK1/2 phosphorylation in primary astrocytes. Therefore, our findings suggest that leptin might be considered a candidate for potential therapeutic applications in glutamate-induced brain excitotoxicity. (C) 2017 The Author(s) Published by S. Karger AG, Basel</P>

비만아에서의 leptin, adiponectin, interleukin-6, tumor necrosis factor-α에 대한 연구

길주현,이정아,김지영,홍영미,Gil, Joo Hyun,Lee, Jung Ah,Kim, Ji Young,Hong, Young Mi 대한소아청소년과학회 2008 Clinical and Experimental Pediatrics (CEP) Vol.51 No.6

목 적 : 비만은 지방세포의 축적과 인슐린 내성으로 제 2형 당뇨병을 초래하고, 고 인슐린혈증과 고혈당이 염증 과정의 전구 물질과 함께 작용하여 혈관 내피의 이상, 혈청 지질의 이상, 고혈압과 혈관 염증을 일으켜 동맥경화와 심혈관 질환을 야기하는 것으로 알려져 왔다. Leptin은 adiopnectin과 함께 지방 세포로부터 생산되는 가장 풍부한 adipocytokine으로서, 일차적으로는 식욕 조절과 체내 지방 축적 조절의 기능을 하지만, IL-6, IL-12, TNF-${\alpha}$와 같은 다른 사이토카인과 함께 염증과정의 전구 물질이 되며 여러 면역 관련 질환에서 중요한 매개체가 된다. 이번 연구에서는 비만 청소년에서 leptin과 여러 cytokine과의 상관관계를 알아보고자 하였다. 방 법 : 16세 이상부터 18세 미만의 66명의 중등도 이상의 비만 청소년을 대상군으로 하였고, 같은 연령의 정상 청소년 26명을 대조군으로 하였다. 신장, 체중을 이용하여 비만도와 체질량지수를 산출하였고, 혈청 지질, 간 효소치를 측정하였다. 효소면역 측정법을 이용하여 IL-6, TNF-${\alpha}$를 측정하였고, 방사면역 측정법을 이용하여 adiponectin, leptin, 인슐린을 측정하였다. 이 후 leptin과 각 측정치와의 상관성을 알아보았다. 결 과 : Leptin은 비만군에서 대조군보다 유의하게 높았고, TNF-${\alpha}$와 IL-6도 비만군에서 대조군보다 유의하게 높았다. 인슐린도 비만군에서 대조군보다 유의하게 높았고 adiponectin은 비만군에서 유의하게 낮았다. Leptin은 비만도, 체질량지수, IL-6과 유의한 양의 상관관계를 보였으며, 또한 IL-6와 TNF-${\alpha}$간에 유의한 양의 상관관계를 보였다. 결 론 : 비만 청소년에서 leptin, TNF-${\alpha}$, IL-6와 같은 cytokine과 insulin이 성인병으로 진행되는데 중요한 요소가 될 것이며, leptin을 성인병의 예측 인자 및 임상치료의 척도로 사용하기 위해 더 많은 연구가 필요할 것으로 생각된다. Purpose : Obesity is associated with insulin resistance. Insulin resistance and the presence of pro-inflammatory mediators are thought to cause a state of vascular endothelial dysfunction, an abnormal lipid profile, hypertension, and vascular inflammation. These chronic inflammatory responses, which are characterized by abnormal cytokine production, lead to activation of a pro-inflammatory signaling pathway. Leptin is an important mediator of inflammatory processes and immune-mediated diseases. The purpose of this study was to investigate the relationship between leptin and various cytokines associated with obesity in adolescents. Methods : Sixty-six obese adolescents (between 16-17 years of age, obesity index >130%) and 26 normal controls were included in this study. Obesity index and body mass index (BMI) were calculated. Serum lipid profile, AST and ALT were tested after 10 hours of fasting. Tumor necrosis factor alpha (TNF-${\alpha}$) and Interleukin-6 (IL-6) levels were measured by ELISA. Insulin, adiponectin, and leptin levels were estimated by radioimmunoassay. Results : Leptin was significantly higher in the obese adolescents compared to the control adolescents ($12.0{\pm}6.8ng/mL$ vs $6.3{\pm}1.0ng/mL$). TNF-${\alpha}$, IL-6, and insulin were significantly higher in the obese adolescents. Adiponectin was significantly lower in the obese group than the control group ($3.3{\pm}1.9{\mu}g/mL$ vs $5.0{\pm}1.4{\mu}g/mL$). Leptin had positive correlations with obesity index, BMI, and IL-6. Conclusion : In obese adolescents, leptin, TNF-${\alpha}$, IL-6, and insulin might be important mediators of obesity. Further clinical research is necessary to ascertain leptin as a predictor of cardiovascular diseases and to develop a guideline for clinical intervention.

ELISA법으로 측정한 소아 혈중 LEPTIN 치에 관한 연구

송수호,정용헌,Song, Soo-Ho,Chung, Young-Hun 대한소아소화기영양학회 2000 Pediatric gastroenterology, hepatology & nutrition Vol.3 No.2

목 적: Leptin은 지방세포에서 분비되어 hypothalamus에 작용함으로써 식욕과 에너지소모를 조절한다고 알려졌다. 그러나 비만아에서는 Leptin 수용체의 저항성 증가에 의해 비만이 지속된다고 보고된다. 최근들어 국내에서도 비만아에서의 Leptin 농도에 대해 많은 연구가 이루어지고 있으나 그 결과가 일치하지 않고 대부분의 연구는 Leptin RIA kit를 이용하여 이루어진 바 저자들은 human leptin ELISA kit를 이용하여 혈중 leptin 농도를 측정하여 ELISA법의 유용성을 규명하고 비만아와 정상아 및 연령과 성별에 따른 차이를 비교해 보고자 본 연구를 실시하였다. 방 법: 1999년 2월 1일부터 1999년 6월 30일까지 충남대학교병원에 내원한 아동을 대상으로 총 67명(남아 41명, 여아 26명)의 소아를 무작위로 추출 하였다. 1999년도 대한소아과학회의 신장별 표준체중치를 이용하여 각 연령별, 성별 신장대비 표준체중의 120% 이상 되는 환아를 비만으로 정의하여 비만아동 19명(남아 12명, 여아 7명)과 정상아동 48명(남아 29명, 여아 19명)으로 분류하였다. 67명의 대상아동에 대해 신장, 체중, 비만도, 체질량지수를 조사하고 ELISA법을 이용하여 Leptin 농도를 측정하였다. 이것을 비만군과 정상군, 체질량지수별, 성별, 연령별로 나누어 비교분석 하였다. 결 과: 1) 정상아의 평균 Leptin 치는 $7.69{\pm}8.83\;ng/ml$이었다. 2) 비만아에서 평균 Leptin 치는 $36.34{\pm}18.57\;ng/ml$이었다. 3) 체질량 지수가 20 이상인 군에서 20 미만인 군보다 혈중 leptin 치가 유의하게 높았다(p<0.01). 4) 10세 이상인 군에서 10세 미만인 군보다 유의하게 높았다(p<0.01). 5) 남녀간의 혈중 leptin 치는 유의한 차이가 없었다(p>0.05). 결 론: ELISA법을 이용한 혈중 leptin 치는 RIA법을 이용한 혈중 leptin 치와 같이 비만한 군에서 높게 나타났으며, 이에 관련된 인자로는 비만도, 체질량 지수 및 연령 등이 있었다. 특수 시설이 필요한 RIA법보다 일반 검사실에서 용이하게 측정할 수 있는 ELISA법이 널리 활용될 수 있을 것으로 사료된다. Purpose: Leptin is an adipocyte-derived blood-borne satiety factor that acts on its cognate leptin receptor in the hypothalamus, thereby regulating food intake and energy expenditure. We measured the leptin concentrations in serum of normal and obese children with human leptin ELISA kit, unlike previous study with leptin RIA kit and investigated the relationship between leptin concentrations and body mass index, gender, and age. Methods: We measured serum concentrations of leptin in 67 children who were visited to the Department of Pediatrics, Chungnam National University Hospital during the period of 5 months from February, 1999 to June, 1999. Height, weight, obesity index, and body mass index were measured in 67 subjects. Leptin values in serum were measured by sandwich ELISA method. Data analysis was done according to the obesity, body mass index, gender and age. Results: The mean concentration of leptin was $7.69{\pm}8.83\;ng/ml$ in normal children group and $36.34{\pm}18.57\;ng/ml$ in obese group. Serum leptin concentrations were significant correlation with the body mass index (p<0.01). Serum leptin concentration was significant higher in the group of over 10 years of age (p<0.01). Leptin levels showed no significant difference by gender. Conclusion: Serum leptin levels were significantly higher in obesity group than in control one, and they were correlated with body mass index and age. Measurements of leptin value by sandwich ELISA method are very useful and easily applicable to determine obesity.

소아비만증 환아들의 혈중 Leptin 농도

정소정,김덕희 대한소아내분비학회 1999 Annals of Pediatirc Endocrinology & Metabolism Vol.4 No.2

Leptin and Leptin Receptor Expression in Breast Cancer

김희성 대한암학회 2009 Cancer Research and Treatment Vol.41 No.3

Purpose : Leptin is a multifunctional hormone that’s produced by adipose tissue and leptin is involved in the regulation of food intake and energy balance. The aims of this study were to determine the leptin and leptin receptor (Ob-R) expressions in human breast cancer and their corresponding influence on the prognosis of patients with breast cancer. Materials and Methods : We examined the correlations between the leptin and Ob-R expressions and the breast cancer-related pathobiologic markers by performing immunohistochemistry in 517 patients with breast cancer. We analyzed the leptin and Ob-R expressions with respect to overall survival and relapse-free survival (RFS). Results : Positive cytoplasmic immunoreactivity for leptin was noted in 39% of the patients and 79% of the patients showed positive cytoplasmic immunoreactivity for Ob-R. The expression of leptin in breast cancer was correlated with a high Ki-67 labeling index (p=0.019). Based on the univariate survival analysis, the clinicopathologic variables with prognostic value included the histologic grade, the T stage, the N stage, the HER2 status, the Bcl-2, p53 and Ki-67 expressions (p<0.05). The patients with leptin-positive breast cancers and a negative hormone receptor status had a significantly longer overall survival (p=0.021). Multivariate survival analysis showed that a positive expression of leptin was an independent prognostic marker for overall survival (hazard ratio, 0.20; 95% CI, 0.04??0.99; p=0.05). Conclusion : A leptin expression in breast cancer is significantly associated with the Ki-67 labeling index, and this suggests there is an association of a leptin expression with the proliferation activity. In addition, a leptin expression is an indicator of better survival for breast cancer patients.

소아 비만에서 Leptin과 골대사의 연관성

김은영,노영일,양은석,문경래,박상기,박영봉,이영화,Kim, Eun Young,Rho, Young il,Yang, Eun Seok,Moon, Kyung Rae,Park, Sang Kee,Park, Yeong Bong,Lee, Young Hwa 대한소아소화기영양학회 2006 Pediatric gastroenterology, hepatology & nutrition Vol.9 No.2

목 적: 체중과 지방량이 골밀도와 밀접한 연관이 있는 것으로 알려져 왔다. 비만아에서는 지방 조직에서 합성 분비되는 leptin이 증가되는데, 증가된 leptin이 비만아의 골 대사에 미치는 영향에 대해 알아보고자 연구를 하였다. 방 법: 2005년 11월부터 2006년 5월까지 조선대학교병원 외래를 방문한 50명의 남자(비만아 25명, 정상 체중의 대조군 25명)를 대상으로 하였다. 체질량 지수, 체지방률, 삼두박근 피부주름 두께와 견갑골하 피부주름 두께를 측정하고 혈청 leptin과 골대사 지표인 B-ALP, CICP 및 total DPD 농도를 검사하였다. 비만군과 대조군의 신체 계측, leptin 및 골대사 지표 농도를 비교하고, leptin과 골대사 지표와의 상관성을 알아보았다. 결 과: 비만군에서 체질량 지수(r=0.551, p<0.05), 체지방률(r=0.584, p<0.05)과 유의한 양의 상관관계가 있었다. Leptin은 골형성 지표인 B-ALP (r=-0.613, p=0.026) 및 CICP (r=-0.583, p=0.037)와 유의한 음의 상관성을 보였다. 그러나 골흡수 지표인 total DPD (r=0.103)와는 유의한 상관성이 없었다. 대조군에서 leptin과 유의한 상관성이 있는 인자는 없었다. 골대사에 영향을 주는 체중을 통제하고 상관성을 알아본 결과에서도 비만군에서 leptin은 B-ALP (r=-0.728, p=0.007) 및 CICP (r=-0.684, p=0.014)와 유의한 음의 상관성을 보였으나 total DPD와는 연관성이 없었다. 대조군에서는 leptin과 연관성 있는 골대사 지표는 없었다. 비만군에서 골대사 지표에 영향을 미치는 인자에 대해 다중 단계별 회귀 분석을 시행한 결과 종속변수인 B-ALP는 leptin과 유의한 음의 상관성을 보였으며(Y=-39.653X+356.341, p=0.026), CICP도 leptin과 유의한 음의 상관성을 보였다(Y=-13.437X+116.013, p=0.037). 결 론: 비만아에서 leptin은 골형성 지표인 B-ALP 및 CICP와 음의 상관성이 있었으며, 골 흡수가 아닌 골 형성을 저하시키는 것을 알 수 있었다. Purpose: The aim of this study was to evaluate the influence of leptin on biochemical markers of bone metabolism in childhood obesity. Methods: A total of 50 male children (25 obese and 25 controls) were recruited from the pediatric outpatient clinic at the Chosun University Hospital from November 1st 2005 to May 30th 2006. BMI, body fat percentage, serum leptin, bone-specific alkaline phosphatase (B-ALP), C-terminal propeptide of type 1 collagen (CICP), total deoxypyridinoline crosslinks (total DPD) were measured. The correlations of leptin with BMI, body fat percentage, B-ALP, CICP, total DPD were analyzed by Pearson's correlation. In a multiple stepwise regression analysis, leptin after correction for body weight was evaluated if there was a correlation with biochemical markers of bone formation and resorption respectively. Results: The leptin levels of the obese group were significantly higher than those of the control group (p=0.012). In the obese group, the leptin level was significantly positively correlated with the BMI (r=0.551, p=0.01) and the percentage of body fat (r=0.584, p=0.018). In the obese group, of bone markers, B-ALP (r=-0.613, p=0.026) and CICP (r=-0.583, p=0.037) were negatively correlated with leptin. B-ALP (r=-0.728, p=0.007) and CICP (r=-0.684, p=0.014) were negatively correlated with leptin when corrected for body weight. In the control group, bone markers were not correlated with leptin. In the multiple stepwise regression analyses, there was a negative correlation between the leptin and B-ALP (Y=-39.653X+356.341, p=0.026), CICP (Y=-13.437X+ 116.013, p=0.037) respectively in the obese group. Conclusion: Leptin was a significant factor in the bone formation but not in bone resorption in childhood obesity.

Expression of Leptin and Its Receptor in Rat Ovary

김명신,양현원,권혁찬,황경주,윤현숙,박금자,김세광,윤용달 한국발생생물학회 1998 발생과 생식 Vol.2 No.2

비만유전자 산물인 leptin은 지방 조직에서 생성되어 혈액으로 분비되며, 신진대사, 식욕, 체열 등을 조절하여 비만의 억제 조절 물질로 작용하는 것으로 알려져 있다. 또한 leptin은 비만 뿐만 아니라 생식 생리와도 관련이 있는 것으로 보이며, 이러한 leptin의 작용이 난소에 직접적인지 혹은 시상하부나 뇌하수체를 매개로 하는지는 아직 정확하게 밝혀지지 않고 있으며, 난소에서의 leptin 및 leptin 수용체의 발현 양상에 대한 연구 또한 미진 Leptin, the product of the obese gene, is produced by adipose tissue and is known to be a hormone concerned with regulation of appetite and metabolism. Recent reports have shown that leptin is associated not only with obesity but also with female reproduction, but it has not yet been ascertained whether leptin acts directly on the ovaries or indirectly via the hypothalamus or pituitary pathway. The object of this study is to determine the expression of leptin and its receptor in the ovaries of 3 and 8 weeks old rats by immunohistochemistry and RT-PCR. In the ovaries of 3 and 8 weeks old rats, leptin was stained in the theca cells and portions of granulosa cells of atretic follicles, whereas leptin receptors was stained in interstitial cells and ova of preantral follicles. The RT-PCR results showed that leptin receptor mRNA was expressed in the ovaries of both immature and adult rats, while leptin mRNA was not. In conclusion, leptin mRNA was not expressed in the ovaries, however, leptin was detected by immunohistochemistry. Compared to leptin itself, leptin receptors in the ovaries were ascertained by both RT-PCR and immunohistochemistry. These results suggest that leptin is related to the regulation of the physiological functions of the ovaries.

월경 주기 이상을 보이는 10 대 및 20 대 초반 여성에서 혈중 Leptin 농도의 임상적 중요성

한국선(Kuk Sun Han),윤병구(Byung Koo Yoon),이제호(Je Ho Lee),최두석(Doo Seok Choi) 대한산부인과학회 2001 Obstetrics & Gynecology Science Vol.44 No.6

N/A Objective : Leptin is known as an endocrinologic mediator which acts on the hypothalamic- pituitary-ovarian axis. This study was undertaken to evaluate whether the serum leptin level affects the menstrual cycles of adolescents and to analyze the clinical features of adolescents with abnormal serum leptin levels. Methods : Seventeen normal controls and 118 patients with menstrual abnormalities were included in this study. The ages of patients ranged from 15 to 25 years. Patients with menstrual abnormality were divided into five subgroups according to the etiologies: group I; premature ovarian failure(n=8), group II; primary amenorrhea without congenital structural abnormality(n=14), group Ⅲ; oligomenorrhea(n=12), group IV; secondary amenorrhea(n=53), group V; dysfunctional uterine bleeding(n=31). After collection of blood samples, the serum leptin levels were measured with a radioimmunoassay kit. The serum leptin level and the corrected leptin level(leptin/body mass index(BMI)) were compared and the clinical features of those with abnormal leptin concentration (>mean+standard deviation, <mean-standard deviation) were analyzed. Results : The serum leptin level was closely correlated with BMI in both the control and the patient group(r=0.730, 0.737 p<0.01). There were no significant differences in the serum leptin level, BMI and leptin/BMI among the control group and the patient group and the subgroups. The most common clinical manifestation in those with abnormal leptin level was secondary amenorrhea. In particular, most of the secondary amenorrhea patients had a history of sudden weight loss of more than 5㎏ within a 3 month period. Conclusion : From our results, seeing as there were wide variantion of individual serum leptin levels(mean±SD: 9.59±6.07), and as minor change of serum leptin level did not seem to affect the menstrual cycle, but sudden change or extreme value of serum leptin levels might cause menstrual abnormalities. Therefore serum leptin may play a permissive role rather than a regulatory role in the adolescent menstrual cycle.

Type Ⅱ 당뇨병 환자에 있어서 경구 당부하 검사시 Lept in 농도의 변화

안규정,정운원,이승관,이창규 高麗大學校 倂設 保健大學 保健科學硏究所 2000 保建科學硏究論集 Vol.9 No.1

Leptin, the peptide encoded by the ob gene, is synthesized and secreted in adipocytes, which plays a role in regulating food intake, energy expenditure and adiposity. Serum leptin levels are highly correlated with body fat mass in human. Obese individuals have significantly higher circulating leptin than normal, lean subjects. In addition, females have higher serum leptin than males with equivalent fat mass. Insulin, cortisol and cytokines stimulates the production of leptin in adipose cells but beta-adrenaline and cAMP suppesses it. Insulin administration maintaining over 4hrs showed leptin increase in serum. No change of leptin concentrating during oral GTT have been reported .In this study, we investigated whether leptin in type D diabetes mellitus during oral GTT is increased or not. The fasting serum leptin concentration were higher in female than in male and glucose, insulin and C-peptide increased significantly but leptin levels decreased significantly in during short-term glucose loading. It should not excluded the possibility that increased insulin brought from glucose intake did not execute leptin decrements because other leptin - stimulating factors including GI-related hormone interfere insulin action on Stimulation the production of leptin. Further studies are needed to define the exact role of oral GTT in the regulation of leptin synthesis and secretion.

Leptin-Evoked Catecholamine Release Through Activation of Protein Kinase and Its Receptors in the Rat Adrenal Medulla

Kim, Ki-Soo,Seo, Yu-Seok,Na, Gwang-Moon,Na, Duck-Mi,Shin, Hye-Gyeong,Lim, Dong-Yoon 朝鮮大學校 附設 醫學硏究所 2006 The Medical Journal of Chosun University Vol.31 No.1

The aim of the present study was to examine the interactions of protein kinase inhibitors and leptin receptor antagonist on leptin-evoked CA release in the isolated perfused model of the rat adrenal gland, and to establish its mechanism of action. Leptin (100 ng/㎖), when perfused into an adrenal vein of the rat adrenal gland for 60 min, Produced the considerable secretory responses of CA, but it was weak. Leptin alone produced a weak secretory response of the CA. However, in the presence of anti-leptin (100 ng/㎖), an antagonist of Ob receptor, leptin (100 ng/㎖) no longer enhanced the CA secretory responses evoked by ACh (5.32 nM), excess K^(+) (56 mM, a membrane depolarizer), DMPP (100 uM, a selective neuronal nicotinic N_(n)-receptor agonist) and McN-A-343 (100 uM, a selective M_(1)-muscarinic agonist). During the simultaneous perfusion of anti-leptin (100 ng/㎖) and leptin (100 ng/㎖) for 60 min, the CA CA secretory responses evoked by BAY-K-8644 (10 uM, an activator of the dihydropyridine L-type Ca^(2) channels) and cyclopiazonic acid (10 uM, an inhibitor of cytoplasmic Ca^(2+) ATPase) were also not influenced in comparison to their control release, respectively. Also, in the presence of U0126 (1 uM), an inhibitor of MAPK kinase, or staurosporine (30 nM, an inhibitor of protein kinase, leptin no longer enhanced the CA secretion evoked by ACh and DMPP. Collectively, these experimental results suggest that leptin causes the CA secretion from the perfuse ratadrenal medulla, although it was weak. It seems that this facilitatory effect of leptin may be mediated by activation of both U0126-sensitive MAPK kinase and staurosporine-sensitive protein kinase through the leptin receptors, which is probably relevant to the activation of the dihydropyridine L-type Ca^(2+) channels located on the rat adrenomedullary cromaffin cells.