Chylomicrons Regulate Lacteal Permeability and Intestinal Lipid Absorption.

BACKGROUND: Lymphatic vessels are responsible for tissue drainage, and their malfunction is associated with chronic diseases. Lymph uptake occurs via specialized open cell-cell junctions between capillary lymphatic endothelial cells (LECs), whereas closed junctions in collecting LECs prevent lymph leakage. LEC junctions are known to dynamically remodel in development and disease, but how lymphatic permeability is regulated remains poorly understood. METHODS: We used various genetically engineered mouse models in combination with cellular, biochemical, and molecular biology approaches to elucidate the signaling pathways regulating junction morphology and function in lymphatic capillaries. RESULTS: By studying the permeability of intestinal lacteal capillaries to lipoprotein particles known as chylomicrons, we show that ROCK (Rho-associated kinase)-dependent cytoskeletal contractility is a fundamental mechanism of LEC permeability regulation. We show that chylomicron-derived lipids trigger neonatal lacteal junction opening via ROCK-dependent contraction of junction-anchored stress fibers. LEC-specific ROCK deletion abolished junction opening and plasma lipid uptake. Chylomicrons additionally inhibited VEGF (vascular endothelial growth factor)-A signaling. We show that VEGF-A antagonizes LEC junction opening via VEGFR (VEGF receptor) 2 and VEGFR3-dependent PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) activation of the small GTPase RAC1 (Rac family small GTPase 1), thereby restricting RhoA (Ras homolog family member A)/ROCK-mediated cytoskeleton contraction. CONCLUSIONS: Our results reveal that antagonistic inputs into ROCK-dependent cytoskeleton contractions regulate the interconversion of lymphatic junctions in the intestine and in other tissues, providing a tunable mechanism to control the lymphatic barrier.

Epileptic activity triggers rapid ROCK1-dependent astrocyte morphology changes.

Long-term modifications of astrocyte function and morphology are well known to occur in epilepsy. They are implicated in the development and manifestation of the disease, but the relevant mechanisms and their pathophysiological role are not firmly established. For instance, it is unclear how quickly the onset of epileptic activity triggers astrocyte morphology changes and what the relevant molecular signals are. We therefore used two-photon excitation fluorescence microscopy to monitor astrocyte morphology in parallel to the induction of epileptiform activity. We uncovered astrocyte morphology changes within 10-20 min under various experimental conditions in acute hippocampal slices. In vivo, induction of status epilepticus resulted in similarly altered astrocyte morphology within 30 min. Further analysis in vitro revealed a persistent volume reduction of peripheral astrocyte processes triggered by induction of epileptiform activity. In addition, an impaired diffusion within astrocytes and within the astrocyte network was observed, which most likely is a direct consequence of the astrocyte remodeling. These astrocyte morphology changes were prevented by inhibition of the Rho GTPase RhoA and of the Rho-associated kinase (ROCK). Selective deletion of ROCK1 but not ROCK2 from astrocytes also prevented the morphology change after induction of epileptiform activity and reduced epileptiform activity. Together these observations reveal that epileptic activity triggers a rapid ROCK1-dependent astrocyte morphology change, which is mechanistically linked to the strength of epileptiform activity. This suggests that astrocytic ROCK1 signaling is a maladaptive response of astrocytes to the onset of epileptic activity.

Vascular smooth muscle ROCK1 contributes to hypoxia-induced pulmonary hypertension development in mice.

Rho kinase (ROCK) is implicated in the development of pulmonary arterial hypertension (PAH) in which abnormal pulmonary vascular smooth muscle (VSM) contractility and remodeling lead to right heart failure. Pharmacologic ROCK inhibitors block experimental pulmonary hypertension (PH) development in rodents but can have off-target effects and do not distinguish between the two ROCK forms, ROCK1 and ROCK2, encoded by separate genes. An earlier study using gene knock out (KO) in mice indicated that VSM ROCK2 is required for experimental PH development, but the role of ROCK1 is not well understood. Here we investigated the in vivo role of ROCK1 in PH development by generating a VSM-targeted homozygous ROCK1 gene KO mouse strain. Adult control mice exposed to Sugen5416 (Su)/hypoxia treatment to induce PH had significantly increased right ventricular systolic pressures (RVSP) and RV hypertrophy versus normoxic controls. In contrast, Su/hypoxia-exposed VSM ROCK1 KO mice did not exhibit significant RVSP elevation, and RV hypertrophy was blunted. Su/hypoxia-induced pulmonary small vessel muscularization was similarly elevated in both control and VSM ROCK1 KO animals. siRNA-mediated ROCK1 knock-down (KD) in human PAH pulmonary arterial SM cells (PASMC) did not affect cell growth. However, ROCK1 KD led to reduced AKT and MYPT1 signaling in serotonin-treated PAH PASMC. The findings suggest that like VSM ROCK2, VSM ROCK1 actively contributes to PH development, but in distinction acts via nonproliferative pathways to promote hypoxemia, and thus may be a distinct therapeutic target in PH.

Clinical Outcomes of Stereotactic Ablative Radiotherapy for All Stages of Non-Small Cell Lung Cancer; Definitive versus Consolidative.

Background and Objectives: Stereotactic ablative radiotherapy (SABR) is not confined to early stage non-small cell lung cancer (NSCLC) and has a potential role in stage IV disease. We aimed to evaluate the effect of SABR on local control rates and survival outcomes in patients with all stages of NSCLC according to the treatment aim. Materials and Methods: We retrospectively reviewed the medical records of 88 patients with NSCLC who received SABR at the Korea University Guro Hospital between January 2015 and March 2021. Among these, 64 patients with stage I-II NSCLC ineligible for surgery were treated with a definitive aim. Twenty-four patients with stage IV limited metastatic NSCLC showing a favorable response to prior systemic therapy were treated with a consolidative aim. Results: The median follow-up time was 34 (range: 5-88) months. Thirty-one patients developed recurrence (35.2%), with distant metastasis being the most common (25/31, 80.6%). In-field local recurrence occurred in four patients (4/88 patients, 4.5%). For patients treated with definitive SABR, the 3-year overall survival (OS) and disease-free survival (DFS) rates were 91.8% and 58.6%, respectively. In patients treated with consolidative SABR, the 3-year OS and DFS rates were 86.7% and 53.8%, respectively. With respect to treatment-related pulmonary toxicity, grade 3 radiation pneumonitis incidence requiring hospitalization was 2.3% (2/88). Conclusions: Definitive SABR is appropriate for medically inoperable or high surgical risk patients with early stage NSCLC with acceptable treatment-related toxicities. Consolidative SABR improves local control rates and helps achieve long-term survival in patients with limited metastatic NSCLC.

LRP1 regulates food intake and energy balance in GABAergic neurons independently of leptin action.

Low-density lipoprotein receptor-related protein 1 (LRP1) is a member of LDL receptor family that plays a key role in systemic glucose and lipid homeostasis. LRP1 also regulates energy balance in the hypothalamus by mediating leptin's anorexigenic action, although the underlying neurocircuitry involved is still unclear. Because GABAergic neurons are a major mediator of hypothalamic leptin action, we studied the role of GABAergic LRP1 in energy balance and leptin action using mice lacking LRP1 in Vgat- or AgRP-expressing neurons (Vgat-Cre; LRP1loxP/loxP or AgRP-Cre; LRP1loxP/loxP). Here, we show that LRP1 deficiency in GABAergic neurons results in severe obesity in male and female mice fed a normal-chow diet. This effect is most likely due to increased food intake and decreased energy expenditure and locomotor activity. Increased adiposity in GABAergic neuron-specific LRP1-deficient mice is accompanied by hyperleptinemia and hyperinsulinemia. Insulin resistance and glucose intolerance in these mice are occurred without change in body weight. Importantly, LRP1 in GABAergic neurons is not required for leptin action, as evidenced by normal leptin's anorexigenic action and leptin-induced hypothalamic Stat3 phosphorylation. In contrast, LRP1 deficiency in AgRP neurons has no effect on adiposity and caloric intake. In conclusion, our data identify GABAergic neurons as a key neurocircuitry that underpins LRP1-dependent regulation of systemic energy balance and body-weight homeostasis. We further find that the GABAergic LRP1 signaling pathway modulates food intake and energy expenditure independently of leptin signaling and AgRP neurons.

Social network types and cognitive decline among older Korean adults: A longitudinal population-based study.

OBJECTIVES: Social network (SN) has been known to impact on cognitive function in late life. However, knowledge regarding the link between SN of various types and cognitive decline (CD) is limited. This study's aim was to investigate which types of SN are associated with reduced risk of CD 2 years later among community-dwelling older adults. METHODS: Secondary analysis of data from 1960 cognitively intact adults 65 years of age or older who participated in the Korean Longitudinal Study of Aging (KLoSA) was employed. K-means cluster analysis was conducted to derive SN types using seven common SN characteristics (marital status, living with children, number of children, frequency of contact with children, frequency of contact with friends, frequency of participation in religious activities, and frequency of participation in social groups). Multivariable linear regression analysis regarding the effects of SN type on CD between 2012 and 2014 was conducted, controlling for covariates. RESULTS: K-means cluster analyses identified a model with five types of SN as being most optimal, and they were named diverse/couple, diverse/family, congregant, restricted/married, and widowed. The average CD 2 years later was most pronounced in those in the widowed network. Compared with the widowed, older adults in the diverse/couple network and the congregant network at baseline had a lower risk of CD 2 years after initial assessment. CONCLUSIONS: Findings show that older Korean adults embedded in widowed network types are at risk for CD and suggest the importance of having a spouse and religious group activities in maintaining cognitive function in later life.

The beneficial effects of empagliflozin, an SGLT2 inhibitor, on atherosclerosis in ApoE -/- mice fed a western diet.

AIMS/HYPOTHESIS: A recent large clinical study has shown that empagliflozin has a lower rate of cardiovascular and all-cause mortality when compared with placebo in patients with type 2 diabetes. We investigated the effect of empagliflozin (compared with glimepiride) on the progression of atherosclerosis, and its possible mechanisms of action. METHODS: Forty-eight 5-week-old male ApoE -/- mice were fed a western diet for 20 weeks and divided into four groups: control (saline, 154 mmol/l NaCl), glimepiride 0.1 mg/kg, empagliflozin 1 mg/kg and empagliflozin 3 mg/kg (n = 12/group). Plaque size and composition in the aortic arch/valve areas and cardiovascular risk variables in the blood and tissues were evaluated. Insulin resistance was estimated by HOMA and adiponectin levels. Body composition was determined using dual-energy x-ray absorptiometry. RESULTS: After 8 weeks of treatment, the empagliflozin and glimepiride groups exhibited decreased blood glucose levels. Atherosclerotic plaque areas in the aortic arch/valve were significantly smaller in the empagliflozin groups than in the control or glimepiride groups. Insulin resistance and circulating concentrations of TNF-α, IL-6, monocyte chemoattractant protein-1 (MCP-1), serum amyloid A and urinary microalbumin decreased after empagliflozin treatment, and this significantly correlated with plaque size. Empagliflozin treatment reduced weight and fat mass, lipid droplets in the liver, fat cell size, mRNA expression of Tnf, Il6 and Mcp-1 (also known as Ccl2) and the infiltration of inflammatory cells in plaque and adipose tissue compared with the control or glimepiride group. Empagliflozin treatment increased adiponectin levels. CONCLUSIONS/INTERPRETATION: Improvements in inflammation and insulin resistance seem to be mechanisms involved in the mitigation of atherosclerosis by empagliflozin.

Urine clusterin/apolipoprotein J is linked to tubular damage and renal outcomes in patients with type 2 diabetes mellitus.

OBJECTIVE: The objective of this study was to evaluate the association of urine clusterin/apolipoprotein J (Apo J) with the development and/or progression of diabetic kidney disease (DKD) in type 2 diabetes. MATERIALS AND METHODS: A total of 159 type 2 diabetic patients and 20 nondiabetic subjects with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 were enrolled. The baseline values of urine clusterin and tubular damage markers were measured. The primary outcome was the annual decline rate in eGFR, and secondary outcomes were the development of chronic kidney disease (CKD) stage 3 or greater and the persistence/progression of albuminuria. The median follow-up duration of enrolled patients was 3.0 (1.0-5.9) years. RESULTS: Baseline clusterin levels in urine were significantly increased in type 2 diabetic subjects compared with those of nondiabetic subjects. The levels of urine clusterin had a significant correlation with urine tubular damage markers. A positive correlation between the annual rate of decline in eGFR and urine clusterin after adjusting for clinical confounding factors was detected. Multivariate analysis further indicated that urine clusterin correlated with the development of CKD stage 3 or greater and persistence/progression of albuminuria. In type 2 diabetic subjects with albuminuria, urine clusterin remained associated with the annual decline rate in eGFR and the progression of CKD stage. CONCLUSIONS: Urine clusterin reflects tubular damage in the early stage of DKD. The increase in urine clusterin along with albuminuria could be an independent predictive marker for the progression of DKD in type 2 diabetes.

Clusterin/ApoJ enhances central leptin signaling through Lrp2-mediated endocytosis.

Hypothalamic leptin signaling plays a central role in maintaining body weight homeostasis. Here, we show that clusterin/ApoJ, recently identified as an anorexigenic neuropeptide, is an important regulator in the hypothalamic leptin signaling pathway. Coadministration of clusterin potentiates the anorexigenic effect of leptin and boosts leptin-induced hypothalamic Stat3 activation. In cultured neurons, clusterin enhances receptor binding and subsequent endocytosis of leptin. These effects are mainly mediated through the LDL receptor-related protein-2 (Lrp2). Notably, inhibition of hypothalamic clusterin, Lrp2 or endocytosis abrogates anorexia and hypothalamic Stat3 activation caused by leptin. These findings propose a novel regulatory mechanism in central leptin signaling pathways.

Which type of social activities may reduce cognitive decline in the elderly?: a longitudinal population-based study.

BACKGROUND: Previous studies have found that social activities are beneficial for the reduction of cognitive decline (CD) in the elderly. However, knowledge regarding the types of social activities that reduce CD in later life is limited. The aim of this study is to examine which type of social activities reduce CD 4 years later among young-old (Y-O) and old-old (O-O) adults. METHODS: We conducted a secondary analysis using data from cognitively intact adults 65 years of age or older who participated in the Korean Longitudinal Study of Aging (KLoSA). Cognitive function was assessed using the Korean version of the Mini-Mental State Examination (MMSE). We computed CD between 2008 and 2012 by subtracting the Wave 4 MMSE score from the Wave 2 MMSE score. Multivariate linear regression analysis was conducted regarding the effects of social activities on CD after adjusting for age, sex, education, income, marital status, activities of daily living (ADL), instrumental activities of daily living (IADL), chronic diseases, quality of life, depressive symptom, change in depressive symptom, and cognitive functioning at baseline. RESULTS: Subjects who participated in senior citizen clubs or senior centers at baseline had a lower risk of CD 4 years later than those who did not in Y-O adults. Frequent contact with offspring by phone or letters was associated with reduced CD in O-O adults. Frequent face-to-face contact with offspring was positively associated with CD in O-O adults. Participating in two or more formal social activities was associated with reduced CD compared with nonparticipation in O-O adults. CONCLUSION: Encouraging older adults to participate in senior citizen clubs or to have frequent contacts with adult children by phone or letters may help reduce CD in later life among older adults. Participation in a variety of formal social activities may also have a beneficial effect on preventing CD in older adults.

ROCK1 isoform-specific deletion reveals a role for diet-induced insulin resistance.

Rho kinase (ROCK) isoforms regulate insulin signaling and glucose metabolism negatively or positively in cultured cell lines and skeletal muscle. However, the in vivo function of the ROCK1 isoform in adipose tissue has not been addressed. To determine the specific role of the adipose ROCK1 isoform in the development of insulin resistance and obesity, mice lacking ROCK1 in adipose tissue globally or selectively were studied. Here, we show that insulin's ability to activate IRS-1/PI3K/Akt signaling was greatly enhanced in adipose tissue of ROCK1(-/-) mice compared with wild-type mice. These effects resulted from the inhibitory effect of ROCK1 on insulin receptor action, as evidenced by the fact that IR tyrosine phosphorylation was abolished in ROCK1(-/-) MEF cells when ROCK1 was reexpressed. Consistently, adipose-specific disruption of ROCK1 increased IR tyrosine phosphorylation in adipose tissue and modestly improved sensitivity to insulin in obese mice induced by high-fat feeding. This effect is independent of any changes in adiposity, number or size of adipocytes, and metabolic parameters, including glucose, insulin, leptin, and triglyceride levels, demonstrating a minimal effect of adipose ROCK1 on whole body metabolism. Enzymatic activity of ROCK1 in adipose tissue remained ∼50%, which likely originated from the fraction of stromal vascular cells, suggesting involvement of these cells for adipose metabolic regulation. Moreover, ROCK isoform activities were increased in adipose tissue of diet-induced or genetically obese mice. These data suggest that adipose ROCK1 isoform plays an inhibtory role for the regulation of insulin sensitivity in diet-induced obesity in vivo.

Serum FGF21 concentration is associated with hypertriglyceridaemia, hyperinsulinaemia and pericardial fat accumulation, independently of obesity, but not with current coronary artery status.

OBJECTIVE: Fibroblast growth factor 21 (FGF21) is an emerging metabolic regulator associated with glucose and lipid metabolism. However, previous studies of FGF21 have been largely confounded by obesity, and data are limited for advanced outcomes such as coronary artery disease (CAD) and ectopic fat accumulation. We investigated the associations between serum FGF21 concentrations and glucose/lipid metabolism, CAD, and pericardial fat deposition in subjects strictly matched for obesity parameters. DESIGN, PATIENTS AND MEASUREMENTS: We enrolled 189 patients who had undergone cardiac multidetector coronary computed tomography. We measured cardiometabolic parameters and serum FGF21 levels within body mass index (BMI)-matched groups. Correlations and linear regressions were analysed among serum FGF21 levels, pericardial fat volumes and cardiometabolic parameters. Serum FGF21 concentrations were compared in patients with and without diabetes, metabolic syndrome (MS) or CAD. RESULTS: Serum FGF21 concentrations were significantly higher in BMI-matched patients with MS (107·2 ± 83·6 vs 82·1 ± 67·4 ng/l without MS, P < 0·05), but not among those with diabetes (84·3 ± 56·4 vs 96·3 ± 98·9 ng/l without diabetes, P = 0·300) or CAD (89·6 ± 65·8 vs 84·2 ± 83·1 ng/l without CAD, P = 0·633). Serum FGF21 concentrations correlated positively with triglycerides, low-density lipoprotein-cholesterol, insulin, HOMA-IR and pericardial fat volume. They showed an independent association with pericardial fat volume (ß = 0·111 ± 0·053, P < 0·05). CONCLUSIONS: Serum FGF21 concentrations were significantly associated with lipid profiles, insulin resistance, pericardial fat volume and MS, independently of obesity, but not with overt CAD or diabetes.

Risk of postprandial insulin resistance: the liver/vagus rapport.

Ingestion of a meal is the greatest challenge faced by glucose homeostasis. The surge of nutrients has to be disposed quickly, as high concentrations in the bloodstream may have pathophysiological effects, and also properly, as misplaced reserves may induce problems in affected tissues. Thus, loss of the ability to adequately dispose of ingested nutrients can be expected to lead to glucose intolerance, and favor the development of pathologies. Achieving interplay of several organs is of upmost importance to maintain effectively postprandial glucose clearance, with the liver being responsible of orchestrating global glycemic control. This dogmatic role of the liver in postprandial insulin sensitivity is tightly associated with the vagus nerve. Herein, we uncover the behaviour of metabolic pathways determined by hepatic parasympathetic function status, in physiology and in pathophysiology. Likewise, the inquiry expands to address the impact of a modern lifestyle, especially one's feeding habits, on the hepatic parasympathetic nerve control of glucose metabolism.

Non-clinical safety assessment of Hwangryunhaedok-tang: 13-week toxicity in Crl:CD Sprague Dawley rats.

Hwangryunhaedok-tang (Huang-Lian-Jie-Du-Tang in Chinese, Oren-gedoku-to in Japanese) is a traditional herbal medicine with a long history of use for anti-inflammatory purposes. In this study, subchronic toxicity of daily oral administration of a Hwangryunhaedok-tang water extract (HHT) at 0, 250, 750, and 2000mg/kg for 13weeks was examined in rats. Mortality, clinical signs, and changes in body weight, food consumption, clinical signs, ophthalmological examination, urinalysis, hematology, serum biochemistry, gross observation, organ weight, and histopathology were monitored in accordance with Good Laboratory Practice and OECD guidelines. We found no mortality or abnormality in clinical signs, body weight, serum biochemistry, or organ weight in HHT-treated groups in either sex. However, there were significant changes in glucose, bilirubin, urobilinogen, protein (only male) in urine after 2000mg/kg/day HHT treatment for both sexes. In hematological examinations, we found a significant decreased number of red blood cells (RBC), whereas, an increased the mean corpuscular volume, number of platelets, and rate of reticulocyte (RET) after 2000mg/kg/day HHT treatment of male rats. In male and female rats, 750 and 2000mg/kg/day HHT treatment decreased the number of RBC and increased RET. Histopathological examinations revealed stomach mucosal erosion in female rats (2000mg/kg/day). No-observed-adverse-effect levels were established for 750mg/kg HHT in rats under the conditions of this study. However, other toxicological studies are necessary to evaluate the safety of HHT fully.

Air pollution accelerates the development of obesity and Alzheimer's disease: the role of leptin and inflammation - a mini-review.

Air pollution is an urgent concern linked to numerous health problems in low- and middle-income countries, where 92% of air pollution-related deaths occur. Particulate matter 2.5 (PM2.5) is the most harmful component of air pollutants, increasing inflammation and changing gut microbiota, favoring obesity, type 2 diabetes, and Alzheimer's Disease (AD). PM2.5 contains lipopolysaccharides (LPS), which can activate the Toll-like receptor 4 (TLR4) signaling pathway. This pathway can lead to the release of pro-inflammatory markers, including interleukins, and suppressor of cytokine signaling-3 (SOCS3), which inhibits leptin action, a hormone that keeps the energy homeostasis. Leptin plays a role in preventing amyloid plaque deposition and hyperphosphorylation of tau-protein (p-tau), mechanisms involved in the neurodegeneration in AD. Approximately 50 million people worldwide are affected by dementia, with a significant proportion living in low-and middle-income countries. This number is expected to triple by 2050. This mini-review focuses on the potential impact of PM2.5 exposure on the TLR4 signaling pathway, its contribution to leptin resistance, and dysbiosis that exacerbates the link between obesity and AD.

A protective role of ABCA5 in response to elevated sphingomyelin levels in Parkinson's disease.

Parkinson's disease (PD) is a chronic neurodegenerative disorder that affects the motor system. Increasing evidence indicates that lysosomal dysfunction is pivotal in the pathogenesis of PD, typically characterized by dysregulation of sphingolipids in lysosomes. ATP-binding cassette subfamily A member 5 (ABCA5) is a lysosomal transporter that mediates the removal of excess sphingomyelin from lysosomes. We therefore investigated whether the expression levels of ABCA5 are associated with sphingomyelin levels and α-synuclein pathology in PD. Firstly, we undertook a comprehensive assessment of the six sphingolipid classes that are part of the lysosomal salvage pathway in the disease-affected amygdala and disease-unaffected visual cortex using liquid chromatography-mass spectrometry. We found that sphingomyelin levels were significantly increased in PD compared to controls and correlated with disease duration only in the amygdala, whereas, the five other sphingolipid classes were slightly altered or unaltered. Concomitantly, the expression of ABCA5 was upregulated in the PD amygdala compared to controls and correlated strongly with sphingomyelin levels. Using neuronal cells, we further verified that the expression of ABCA5 was dependent on cellular levels of sphingomyelin. Interestingly, sphingomyelin levels were strongly associated with α-synuclein in the amygdala and were related to α-synuclein expression. Finally, we revealed that sphingomyelin levels were also increased in PD plasma compared to controls, and that five identical sphingomyelin species were increased in both the brain and the plasma. When put together, these results suggest that in regions accumulating α-synuclein in PD, ABCA5 is upregulated to reduce lysosomal sphingomyelin levels potentially as a protective measure. This process may provide new targets for therapeutic intervention and biomarker development for PD.

Stomach clusterin as a gut-derived feeding regulator.

The stomach has emerged as a crucial endocrine organ in the regulation of feeding since the discovery of ghrelin. Gut-derived hormones, such as ghrelin and cholecystokinin, can act through the vagus nerve. We previously reported the satiety effect of hypothalamic clusterin, but the impact of peripheral clusterin remains unknown. In this study, we administered clusterin intraperitoneally to mice and observed its ability to suppress fasting-driven food intake. Interestingly, we found its synergism with cholecystokinin and antagonism with ghrelin. These effects were accompanied by increased c-fos immunoreactivity in nucleus tractus solitarius, area postrema, and hypothalamic paraventricular nucleus. Notably, truncal vagotomy abolished this response. The stomach expressed clusterin at high levels among the organs, and gastric clusterin was detected in specific enteroendocrine cells and the submucosal plexus. Gastric clusterin expression decreased after fasting but recovered after 2 hours of refeeding. Furthermore, we confirmed that stomachspecific overexpression of clusterin reduced food intake after overnight fasting. These results suggest that gastric clusterin may function as a gut-derived peptide involved in the regulation of feeding through the gut-brain axis. [BMB Reports 2024; 57(3): 149-154].

Erratum to: Stomach clusterin as a gut-derived feeding regulator.

[Erratum to: BMB Reports 2024; 57(3): 149-154, PMID: 37817436, PMCID: PMC10979347] The BMB Reports would like to correct in BMB Rep. 57(3):149-154, titled "Stomach clusterin as a gut-derived feeding regulator". This research was supported by the Creative-Pioneering Researchers Program through Seoul National University. Since grant name and number are incorrect, this information has now been corrected as follows: This work was supported by the National Research Foundation of Korea funded by the Korean government (2020R1A2C3004843, 2022M3E5E8017213 to M-S.K., 2020R1C1C10 08033 to O.K.) and by Creative-Pioneering Researchers Program through Seoul National University (to O.K.). The authors apologize for any inconvenience or confusion that may be caused by this error. The ACKNOWLEDGEMENTS of Original PDF version have been corrected.

LRP1 in GABAergic neurons is a key link between obesity and memory function.

OBJECTIVE: Low-density lipoprotein receptor-related protein-1 (LRP1) regulates energy homeostasis, blood-brain barrier integrity, and metabolic signaling in the brain. Deficiency of LRP1 in inhibitory gamma-aminobutyric acid (GABA)ergic neurons causes severe obesity in mice. However, the impact of LRP1 in inhibitory neurons on memory function and cognition in the context of obesity is poorly understood. METHODS: Mice lacking LRP1 in GABAergic neurons (Vgat-Cre; LRP1loxP/loxP) underwent behavioral tests for locomotor activity and motor coordination, short/long-term and spatial memory, and fear learning/memory. This study evaluated the relationships between behavior and metabolic risk factors and followed the mice at 16 and 32 weeks of age. RESULTS: Deletion of LRP1 in GABAergic neurons caused a significant impairment in memory function in 32-week-old mice. In the spatial Y-maze test, Vgat-Cre; LRP1loxP/loxP mice exhibited decreased travel distance and duration in the novel arm compared with controls (LRP1loxP/loxP mice). In addition, GABAergic neuron-specific LRP1-deficient mice showed a diminished capacity for performing learning and memory tasks during the water T-maze test. Moreover, reduced freezing time was observed in these mice during the contextual and cued fear conditioning tests. These effects were accompanied by increased neuronal necrosis and satellitosis in the hippocampus. Importantly, the distance and duration in the novel arm, as well as the performance of the reversal water T-maze test, negatively correlated with metabolic risk parameters, including body weight, serum leptin, insulin, and apolipoprotein J. However, in 16-week-old Vgat-Cre; LRP1loxP/loxP mice, there were no differences in the behavioral tests or correlations between metabolic parameters and cognition. CONCLUSIONS: Our findings demonstrate that LRP1 from GABAergic neurons is important in regulating normal learning and memory. Metabolically, obesity caused by GABAergic LRP1 deletion negatively regulates memory and cognitive function in an age-dependent manner. Thus, LRP1 in GABAergic neurons may play a crucial role in maintaining normal excitatory/inhibitory balance, impacting memory function, and reinforcing the potential importance of LRP1 in neural system integrity.