Noriko Ishizuka

Enhanced expression of nesfatin/nucleobindin-2 in white adipose tissue of ventromedial hypothalamus-lesioned rats.

Nesfatin-1, an anorexigenic protein, is ubiquitously expressed in the body. However, the exact mechanism underlying the in vivo regulation of production of nesfatin/nucleobindin-2 (NUCB2), a precursor protein of nesfatin-1, is unknown. We investigated the influence of modulation of autonomic nerve activity by a ventromedial hypothalamus (VMH) lesion and the subsequent effect on nesfatin/NUCB2 production in rat tissues innervated by the peripheral nervous system. Nesfatin/NUCB2 is strongly expressed in the pancreas and liver, moderately expressed in subcutaneous and visceral fat tissues and interscapular brown adipose tissue (iBAT), but is weakly expressed in the skeletal muscles. Our study results showed that the VMH lesion in VMH-lesioned rats did not affect nesfatin/NUCB2 expression in the pancreas, liver, skeletal muscle, and iBAT; however, the protein expression was significantly high in both subcutaneous and visceral fat tissues. In addition, continuous peripheral administration of carbachol for 5 days did not affect nesfatin/NUCB2 expression, but chemical sympathectomy using 6-hydroxydopamine mimicked the effect of VMH lesion by showing significantly high nesfatin/NUCB2 expression in the subcutaneous fat tissues. These results show that VMH lesion can modulate the autonomic nervous system activity and balance and increase nesfatin/NUCB2 expression in white adipose tissues of rats. Further, this action may be mediated via inhibition of the sympathetic nerve activity.

Gene expression profiling in rat pancreas after ventromedial hypothalamic lesioning.

Objective: We previously reported that vagal hyperactivity produced by ventromedial hypothalamic (VMH) lesions stimulated cell proliferation of rat pancreatic islet B and acinar cells primarily through a cholinergic receptor mechanism. Methods: This study examined how gene families involved in cell proliferation are regulated after VMH lesions formation. Total pancreatic RNA was extracted, and differences in the gene expression profiles between rats at day 3 after VMH lesioning and sham-VMH-lesioned rats were investigated using DNA microarray and real-time polymerase chain reaction. Results: The VMH lesions regulated the genes that are involved in functions related to cellular growth and proliferation and neuronal development in the pancreas. Real-time polymerase chain reaction also confirmed that gene expressions of angiotensin II receptor-like 1 (AGTRL1) and proline rich 15 (PRR15) were down-regulated at day 3 after the VMH lesions. Conclusions: Ventromedial hypothalamic lesions may change the expression of cell proliferation-related genes and neuron-related genes in a rat pancreas.Abbreviations: AGTRL1 - angiotensin II receptor-like 1, AKAP8L - a kinase (PRKA) anchor protein 8-like, APJR - apelin receptor, ASPN - asporin, BZW2 - basic leucine zipper and W2 domains 2, COL11A - &agr;2(XI) collagen gene, C1QTNF2 - C1q and tumor necrosis factor-related protein 2, CTTNBP2 - cortactin-binding protein 2, DRP2 - dystrophin-related protein 2, ETFB - electron-transfer flavoprotein, beta polypeptide, FMO4 - flavin-containing monooxygenase 4, GCG - glucagon, HTR2C - 5-hydroxytryptamine (serotonin) receptor 2C, IFT122 - intraflagellar transport 122 homolog, IQUB - IQ motif and ubiquitin domain containing, KIF16B - kinesin family member 16B, KRT78 - keratin 78, MCAM - melanoma cell adhesion molecule, MT1E - metallothionein 1E, MUG1 - murinoglobulin 1, MMP19 - matrix metallopeptidase 19, NAGS - N-acetylglutamate synthase, NLGN2 - neuroligin 2, NR2F2 - nuclear receptor subfamily 2 group F member 2, PCR - polymerase chain reaction, PDE1C - phosphodiesterase 1C, calmodulin-dependent 70 kd, POLA2 - polymerase (DNA-directed), alpha 2 (70-kd subunit), PKIB - protein kinase (cAMP-dependent, catalytic) inhibitor beta, PRMT3 - protein arginine methyltransferase 3, RNF39 - ring finger protein 39, PRR15 - proline rich 15, ROCK2 - Rho-associated, coiled coil-containing protein kinase 2, SENP7 - SUMO1/sentrin-specific peptidase 7, ST3GAL2 - ST3 &bgr;-galactoside &agr;-2,3-sialyltransferase 2, SUMO - small ubiquitin-related modifiers, TDH - l-threonine 3-dehydrogenase, TNRC6A - trinucleotide repeat containing 6A, TSPAN5 - tetraspanin 5, TXNRD2 - thioredoxin reductase 2, VMH - ventromedial hypothalamus

Vagal Hyperactivity Due to Ventromedial Hypothalamic Lesions Increases Adiponectin Production and Release

In obese humans and animals, adiponectin production and release in adipose tissue are downregulated by feedback inhibition, resulting in decreased serum adiponectin. We investigated adiponectin production and release in ventromedial hypothalamic (VMH)-lesioned animals. VMH-lesioned mice showed significant increases in food intake and body weight gain, with hyperinsulinemia and hyperleptinemia at 1 and 4 weeks after VMH-lesioning. Serum adiponectin was elevated in VMH-lesioned mice at 1 and 4 weeks, despite adipocyte hypertrophy in subcutaneous and visceral adipose tissues and increased body fat. Adiponectin production and mRNA were also increased in both adipose tissues in VMH-lesioned mice at 1 week. These results were replicated in VMH-lesioned rats at 1 week. Daily atropine administration for 5 days or subdiaphragmatic vagotomy completely reversed the body weight gain and eliminated the increased adiponectin production and release in these rats, with reversal to a normal serum adiponectin level. Parasympathetic nerve activation by carbachol infusion for 5 days in rats increased serum adiponectin, with increased adiponectin production in visceral and subcutaneous adipose tissues without changes of body weight. These results demonstrate that activation of the parasympathetic nerve by VMH lesions stimulates production of adiponectin in visceral and subcutaneous adipose tissues and adiponectin release, resulting in elevated serum adiponectin.

Enhanced exercise‐induced muscle damage and muscle protein degradation in streptozotocin‐induced type 2 diabetic rats

Aims/Introduction:  The effects of 5‐day voluntary exercise on muscle damage and muscle protein degradation were investigated in a streptozotocin‐induced rat model of moderately glycemic, uncontrolled, type 2 diabetes.

Masked function of amino acid sensors on pancreatic hormone secretion in ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia

SUMMARY In neural regulation of the endocrine pancreas, there is much evidence to suggest that vagal efferents alter insulin and glucagon secretion, but less information on the effects of vagal afferents. In this study, we investigated the role and function of afferent fibers of the vagus nerve in normal and ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia. In normal rats, hepatic vagotomy was associated with intraperitoneal (ip) arginine-induced enhancement of insulin and glucagon secretion without an accompanying change in blood glucose levels, ip leucine induced enhancement of insulin secretion accompanied by a decrease in blood glucose levels, and ip alanine-induced enhancement of glucagon secretion accompanied by an increase in blood glucose levels. In VMH lesioned rats with marked hyperinsulinemia, none of these amino acids caused significant changes in insulin and glucagon secretion. We conclude that amino acid sensors in normal rats inhibit excess release of pancreatic hormones induced directly by intake of amino acids, such as that in excess protein ingestion, and maintain blood glucose levels within the normal range. In contrast, in VMH lesioned rats with marked hyperinsulinemia, the function of the amino acid sensors is masked due to the marked hyperinsulinemia in these rats.:

Ventromedial hypothalamic lesions enhance small intestinal cell proliferation in mice

SUMMARY BACKGROUND We have found previously that ventromedial hypothalamic lesions (VMH) enhance cell proliferation in the visceral organs through vagal hyperactivity in rats. The goal of the current study was to determine the characteristics and nature of cell proliferation in the small intestine in VMH-lesioned mice. METHODS The weight and length of the small intestine, thickness of the mucosal and muscle layers, number of proliferating cell nuclear antigen (PCNA)-positive cells, and mitotic cell count in the mucosal layer in VMH-lesioned and Sham VMH-lesioned mice were determined at 7 days after the operation. RESULTS The weight and length of the small intestine in VMH-lesioned mice were significantly greater than those in Sham VMH-lesioned mice, by 11.6% and 15.0%, respectively. The thicknesses of the mucosal and muscle layers of the small intestine in VMH-lesioned mice were also significantly greater than those in Sham VMH-lesioned mice, by 12.7% and 12.5%, respectively. PCNA-positive cells and mitotic cells in the mucosal layer were densely present in crypts in VMH-lesioned mice, and were significantly increased by 31.9% and 71.7%, respectively, compared to Sham VMH-lesioned mice. CONCLUSIONS These results demonstrate that VMH lesions in mice enhance cell proliferation in the mucosal layers and cause cell hypertrophy or cell proliferation in the muscle layers of the small intestine, which increases the weight and length of the small intestine. VMH lesions in mice may be a new tool for identifying growth factors and related genes involved in enlarging the small intestine mainly through cell proliferation.

Cell proliferation in ventromedial hypothalamic lesioned rats inhibits acute gastric mucosal lesions

AIM The role of mucosal layer thickness on prevention of acute gastric mucosal lesions (AGMLs) was examined in ventromedial hypothalamic (VMH)-lesioned rats. MATERIALS AND METHODS The incidence of AGMLs after 48-h fasting and 60% ethanol injection into the stomach after 24-h fasting, aggressive factors (gastric acid and serum gastrin) and defensive factors [hexosamine, gastric mucosal blood flow (GMBF), serum thiobarbituric acid reacting substances (TBARS), and thickness of the gastric mucosal layer] were evaluated in VMH-lesioned rats. The effects of cell proliferation on the gastric mucosal layer of these rats were evaluated by H-E staining and immunostaining with proliferating cell nuclear antigen (PCNA). RESULTS After 48-h fasting, no AGMLs were observed in VMH-lesioned and sham VMH-lesioned rats (controls). With 60% ethanol administration after 24-h fasting, the numbers of AGMLs were similar in the two groups, but the ulcer index, a marker of ulcer formation, was lower in VMH-lesioned rats compared to that in sham VMH-lesioned rats. VMH-lesioned rats showed increased gastric acid secretion and serum gastrin compared to sham VMH-lesioned rats, indicating an increase in aggressive factors in VMH-lesioned rats. The two groups had similar levels of gastric mucosal hexosamine, GMBF, and gastric mucosal TBARS, but VMH-lesioned rats had an increased thickness of the mucosal cell layer, indicating an increase in defensive factors in these rats. Histologically, VMH-lesioned rats had an increased total mucosal cell layer, especially for the surface epithelial cell layer, and an increased PCNA-labeling index, a marker of cell proliferation, especially in the proliferative zones of gastric mucosa, indicating increased cell proliferation in the proliferative zone of the gastric mucosa. CONCLUSION VMH-lesioned rats are resistant to AGML formation due to increased cell proliferation in gastric mucosa through elevating the levels of defensive factors over those of aggressive factors.

Beneficial effects of ventromedial hypothalamus (VMH) lesioning on function and morphology of the liver after hepatectomy in rats

Liver has a high regenerative capacity and restores its mass and function shortly after partial hepatectomy through increased proliferation and metabolic modification of hepatocytes. The proliferation of hepatocytes can be triggered by its mass reduction after hepatectomy or by the neural factors including lesioning of the ventromedial hypothalamus (VMH). In the present study, we examined the effect of VMH lesioning on liver regeneration in hepatectomized rats by evaluating liver function and morphology. We found that functional deficits caused by partial hepatectomy [prolonged prothrombin time (PT), increased indocyanine green (ICG) retention, and decrease in PAS (periodic Acid-Schiff staining)-positive hepatocytes] were restored by VMH lesioning at 1 week after the surgery, whereas these alterations disappeared at 4 weeks. Morphologically, lipid microdroplets, which are considered to be important for maintaining contiguous liver function via supplying fuel for cell proliferation, were found to accumulate in hepatocytes of the hepatectomized rats at early period (1 day) after partial hepatectomy. Interestingly, such lipid microdroplets were also detected in the VMH lesioned rats and the more abundantly in the VMH lesioned, hepatectomized rats up to 1 week after the surgery. In conclusion, our results suggest that VMH lesioning in rats promotes recovery of liver anatomically and functionally after partial hepatectomy by promoting cell proliferation process.

High cardiovascular risk factors among obese children in an urban area of Japan.

SUMMARY The association between degree of obesity and cardiovascular and related metabolic risk factors were examined in 355 Japanese obese school children from 11 to 12 years old. The parameters evaluated were blood pressure, serum lipids, fasting blood glucose, and serum ALT and AST. ALT, AST and triglycerides were more commonly evaluated in obese boys than in obese girls, while HDL-cholesterol was more commonly lowered in obese girls. Hypercholesterolemia was 2-fold, and abnormal liver functions were 3-fold more common in severely obese than in moderate obese children. Thus, cardiovascular and related metabolic risk factors are present in obesity in school-aged children, particularly in boys.:

VMH lesions downregulate the expression of Per2 gene in the pancreas in the rat

The mammalian circadian system contains both central and peripheral oscillators. It was reported that the rhythmic expressions of period homolog 2 (per2) mRNA in peripheral tissues were abolished by the suprachiasmatic nucleus (SCN) lesions. However, there are no reports that ventromedial hypothalamic (VMH) lesions can directly affect the expression of clock genes in pancreas and liver. In the present study, we examined whether VMH lesions can affect the expression of the clock gene, per2 in these organs. Total RNA was extracted from rat pancreas and liver tissues, and differences in the gene expression profiles between rats at day 3 after VMH lesioning and sham-VMH-lesioned rats were investigated using DNA microarray and real-time quantitative analysis. These results showed that VMH lesions downregulated the expression of the clock gene, per2 in the pancreas, but not the liver in the morning. There is a possibility that VMH lesions may affect the expression of the clock gene, per2 in the pancreas.