Hypothalamic regulatory peptides in obese and lean Zucker rats

1991 ◽  
Vol 80 (5) ◽  
pp. 419-426 ◽  
Author(s):  
Gareth Williams ◽  
Helena M. Cardoso ◽  
Ying C. Lee ◽  
Joanna M. Ball ◽  
Mohammad A. Ghatei ◽  
...  
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Neuropeptide Y ◽  
Regulatory Peptides ◽  
Zucker Rats ◽  
Zucker Rat ◽  
Obese Rats ◽  
Neuromedin B ◽  
Per Se ◽  
Obesity Syndrome

1. Hypothalamic concentrations of nine peptides with experimental effects on energy balance were compared in obese (fa/fa) and lean (Fa/?) male Zucker rats. To determine whether any peptide differences between obese and lean rats might be due to the overweight condition per se, separate groups of obese rats were food-restricted to reduce their body weight to lean values. 2. Concentrations of neuromedin B, a bombesin-like peptide, in the central hypothalamus were significantly higher in obese than in lean rats. This difference was not affected in food-restricted obese rats. 3. Hypothalamic levels of neuropeptide Y, an extremely potent central appetite stimulant, were similar in lean and freely fed obese rats but central hypothalamic levels of neuropeptide Y rose significantly in food-restricted obese rats. 4. These findings suggest that disturbances in hypothalamic neuromedin B concentrations may be involved in the obesity syndrome of the fa/fa Zucker rat. Increased central hypothalamic levels of neuropeptide Y in food-restricted rats suggest that this peptide may help to defend body weight by stimulating eating after weight loss.

The effects of ileal transposition on food intake and body weight loss in VMH-obese rats

1982 ◽  
Vol 35 (2) ◽  
pp. 284-293 ◽  
Author(s):  
H S Koopmans ◽  
A Sclafani ◽  
C Fichtner ◽  
P F Aravich
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Food Intake ◽  
Body Weight Loss ◽  
Ileal Transposition ◽  
Obese Rats

Blood flow to brown fat in lean and obese adrenalectomized Zucker rats

1986 ◽  
Vol 251 (5) ◽  
pp. R851-R858
Author(s):  
S. J. Wickler ◽  
B. A. Horwitz ◽  
J. S. Stern
Keyword(s):  
Blood Flow ◽  
Weight Gain ◽  
Brown Fat ◽  
Zucker Rats ◽  
Zucker Rat ◽  
Nonshivering Thermogenesis ◽  
Brown Adipose ◽  
Obese Rats

The Zucker obese rat is characterized by decreased capacity for diet-induced and for nonshivering thermogenesis. This decrease is due, in large part, to reduced thermogenesis in depots of brown adipose tissue, a major source of heat production in rats. Adrenalectomy retards the weight gain observed in the obese rats and also normalizes brown fat guanosine 5'-diphosphate (GDP) binding, an in vitro measure of brown fat thermogenic capacity. This study examined the effect of adrenalectomy on brown fat blood flow, an in vivo measure of the tissue's function, and on norepinephrine-induced O2 consumption (NST) of 11-wk-old obese (fa/fa) and lean (Fa/?) rats. Adrenalectomy had little effect on weight gain, NST, or norepinephrine-stimulated blood flow to brown fat in lean rats. However, adrenalectomy produced profound changes in the obese animals, preventing the weight gain normally occurring in the obese rats and normalizing both NST capacity and norepinephrine-stimulated blood flow to brown fat. These findings provide further support for the importance of brown fat thermogenesis and glucocorticoids in modulating the obesity of the Zucker rat.

scholarly journals Effect of grapefruit juice and sibutramine on body weight loss in obese rats

2015 ◽  
Vol 9 (8) ◽  
pp. 265-273 ◽  
Author(s):  
Farouk Hadir ◽  
S Mahmoud Sawsan ◽  
A El Sayeh Bahia ◽  
A Sharaf Ola
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Grapefruit Juice ◽  
Body Weight Loss ◽  
Obese Rats

scholarly journals Mechanism controlling sleep organization of the obese Zucker rats

1998 ◽  
Vol 84 (1) ◽  
pp. 253-256 ◽  
Author(s):  
David Megirian ◽  
Jacek Dmochowski ◽  
Gaspar A. Farkas
Keyword(s):  
Eye Movement ◽  
Rem Sleep ◽  
Nrem Sleep ◽  
Zucker Rats ◽  
Rapid Eye Movement ◽  
Zucker Rat ◽  
Obese Zucker Rat ◽  
Obese Rats ◽  
Obese Zucker Rats ◽  
The Mean

Megirian, David, Jacek Dmochowski, and Gaspar A. Farkas. Mechanism controlling sleep organization of the obese Zucker rat. J. Appl. Physiol. 84(1): 253–256, 1998.—We tested the hypothesis that the obese ( fa/fa) Zucker rat has a sleep organization that differs from that of lean Zucker rats. We used the polygraphic technique to identify and to quantify the distribution of the three main states of the rat: wakefulness (W), non-rapid-eye-movement (NREM), and rapid-eye-movement (REM) sleep states. Assessment of states was made with light present (1000–1600), at the rats thermoneutral temperature of 29°C. Obese rats, compared with lean ones, did not show significant differences in the total time spent in the three main states. Whereas the mean durations of W and REM states did not differ statistically, that of NREM did ( P = 0.046). However, in the obese rats, the frequencies of switching from NREM sleep to W, which increased, and from NREM to REM sleep, which decreased, were statistically significantly different ( P = 0.019). Frequency of switching from either REM or W state was not significantly different. We conclude that sleep organization differs between lean and obese Zucker rats and that it is due to a disparity in switching from NREM sleep to either W or REM sleep and the mean duration of NREM sleep.

scholarly journals Gene expression of lipid storage-related enzymes in adipose tissue of the genetically obese Zucker rat. Co-ordinated increase in transcriptional activity and potentiation by hyperinsulinaemia

1992 ◽  
Vol 281 (3) ◽  
pp. 607-611 ◽  
Author(s):  
I Dugail ◽  
A Quignard-Boulangé ◽  
X Le Liepvre ◽  
B Ardouin ◽  
M Lavau
Keyword(s):  
Adipose Tissue ◽  
Mrna Level ◽  
Lipid Storage ◽  
Zucker Rats ◽  
Transcriptional Level ◽  
Transcription Rate ◽  
Mrna Levels ◽  
Zucker Rat ◽  
Obese Zucker Rat ◽  
Obese Rats

The genetically obese Zucker rat displays excessive fat storage capacity which is due to a tissue-specific increase in the activities of a number of lipid storage-related enzymes in adipose tissue. The aim of this study was to investigate the molecular mechanism responsible for this phenomenon. Lean (Fa/fa) and obese (fa/fa) Zucker rats were studied during the early stages of adipose tissue overdevelopment, both before (at 16 days of age) and after (at 30 days of age) the emergence of hyperinsulinaemia, in order to delineate the effects of the fatty genotype independently of those of hyperinsulinaemia. Lipoprotein lipase (LPL), glycerophosphate dehydrogenase (GPDH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and malic enzyme (ME) mRNA levels in the adipose tissue of lean and obese rats were assessed by Northern blot analysis, and the relative transcription rates of the corresponding genes were compared in the two genotypes by a nuclear run-on assay. In normoinsulinaemic 16-day-old pre-obese rats, mRNA levels were increased over control values (LPL, 5-fold; ME, 2-fold; GAPDH, 3-fold), in close correlation with genotype-mediated differences in enzyme activities. Stimulation of the transcription rates of the ME and GAPDH genes was observed in obese rats, which could fully account for differences in steady-state mRNA levels. At this age, GPDH activity, mRNA level and transcription rate were similar in the two genotypes. In hyperinsulinaemic 30-day-old obese rats, a 6-7-fold increase in both mRNA and the transcription rate of GPDH emerged, together with an amplification of the genotype-mediated differences observed in younger animals (GAPDH, 6-fold; ME, 7.9-fold; LPL, 10-fold). These results demonstrate that the obese genotype exerts a co-ordinated control on the expression of these genes in adipose tissue, mainly at the transcriptional level. This genotype effect is greatly amplified by the development of hyperinsulinaemia.

Basal and glucoprivic-induced changes in extracellular GABA in the ventral hypothalamus of Zucker rats

1996 ◽  
Vol 271 (2) ◽  
pp. R388-R392 ◽  
Author(s):  
S. E. Specter ◽  
B. A. Horwitz ◽  
J. L. Beverly
Keyword(s):  
Food Intake ◽  
Brain Regions ◽  
Gabaergic System ◽  
Aminobutyric Acid ◽  
Zucker Rats ◽  
Gamma Aminobutyric Acid ◽  
Zucker Rat ◽  
Obese Rats ◽  
Before And After ◽  
Induced Changes

The diminished sensitivity of genetically obese (fa/ fa) Zucker rats to the glucoprivic agent 2-deoxy-D-glucose (2-DG) may involve impaired release of the neurotransmitter gamma-aminobutyric acid (GABA) in discrete regions of the hypothalamus. Extracellular GABA concentrations in the medial (MH) and lateral (LH) hypothalamus of lean (Fa/Fa) and age-matched obese (fa/fa) male Zucker rats before and after 2-DG (1.2 mmol/kg i.v.). Basal GABA concentrations were higher (P < 0.05) in the MH of obese vs. lean rats. No differences were noted in LH GABA levels between lean and obese rats or in baseline extracellular GABA levels between brain regions in lean rats. In lean rats, a characteristic bimodal increase in GABA concentrations was apparent in the MH, whereas GABA concentrations decreased in the LH during the 60 min after 2-DG. No changes in GABA concentrations in dialysate from the MH or LH of obese rats were observed after 2-DG. The alterations in basal activity and responsiveness to glucoprivic stimuli by GABAergic system in the MH of obese rats may reflect a defect in central glucostatic control of food intake and, ultimately, in the hypothesized autonomic imbalance in fa/fa Zucker rat.

scholarly journals Adipsin mRNA amounts are not decreased in the genetically obese Zucker rat

1989 ◽  
Vol 257 (3) ◽  
pp. 917-919 ◽  
Author(s):  
I Dugail ◽  
X Le Liepvre ◽  
A Quignard-Boulangé ◽  
J Pairault ◽  
M Lavau
Keyword(s):  
Gene Expression ◽  
High Fat Diet ◽  
Zucker Rats ◽  
Zucker Rat ◽  
Obese Mice ◽  
High Fat ◽  
Adult Rats ◽  
Obese Zucker Rat ◽  
Obese Rats ◽  
Obese Zucker Rats

Adipsin gene expression as assessed by mRNA amounts was examined in adipose tissue of genetically obese rats at the onset (16 days of age) or at later stages (30 and 60 days of age) of obesity. Amounts of mRNA were equivalent in obese and lean rats at 16 days of age. In adult rats, we observed a 2-fold decrease in adipsin mRNA in the obese rats compared with control lean rats, which was abolished by weaning the animals on a high-fat diet. Our data show that, in sharp contrast with genetically obese mice, adipsin mRNA is not suppressed in genetically obese Zucker rats.

scholarly journals Combined Deletion of Y1, Y2, and Y4 Receptors Prevents Hypothalamic Neuropeptide Y Overexpression-Induced Hyperinsulinemia despite Persistence of Hyperphagia and Obesity

Endocrinology ◽  
2006 ◽  
Vol 147 (11) ◽  
pp. 5094-5101 ◽  
Author(s):  
En-Ju D. Lin ◽  
Amanda Sainsbury ◽  
Nicola J. Lee ◽  
Dana Boey ◽  
Michelle Couzens ◽  
...  
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Neuropeptide Y ◽  
Energy Homeostasis ◽  
Viral Vector ◽  
Body Weight Gain ◽  
Hormonal Changes ◽  
Obesity Syndrome ◽  
Y Receptors

Neuropeptide Y (NPY) is a key regulator of energy homeostasis and is implicated in the development of obesity and type 2 diabetes. Whereas it is known that hypothalamic administration of exogenous NPY peptides leads to increased body weight gain, hyperphagia, and many hormonal and metabolic changes characteristic of an obesity syndrome, the Y receptor(s) mediating these effects is disputed and unclear. To investigate the role of different Y receptors in the NPY-induced obesity syndrome, we used recombinant adeno-associated viral vector to overexpress NPY in mice deficient of selective single or multiple Y receptors (including Y1, Y2, and Y4). Results from this study demonstrated that long-term hypothalamic overexpression of NPY lead to marked hyperphagia, hypogonadism, body weight gain, enhanced adipose tissue accumulation, hyperinsulinemia, and other hormonal changes characteristic of an obesity syndrome. NPY-induced hyperphagia, hypogonadism, and obesity syndrome persisted in all genotypes studied (Y1−/−, Y2−/−, Y2Y4−/−, and Y1Y2Y4−/− mice). However, triple deletion of Y1, Y2, and Y4 receptors prevented NPY-induced hyperinsulinemia. These findings suggest that Y1, Y2, and Y4 receptors under this condition are not crucially involved in NPY’s hyperphagic, hypogonadal, and obesogenic effects, but they are responsible for the central regulation of circulating insulin levels by NPY.

Leptin receptor-deficient obese Zucker rats reduce their food intake in response to hypobaric hypoxia

2006 ◽  
Vol 290 (3) ◽  
pp. E591-E597 ◽  
Author(s):  
Nadine Simler ◽  
Alexandra Grosfeld ◽  
André Peinnequin ◽  
Michèle Guerre-Millo ◽  
André-Xavier Bigard
Keyword(s):  
Gene Expression ◽  
Body Weight ◽  
Adipose Tissue ◽  
Food Intake ◽  
Hypobaric Hypoxia ◽  
Leptin Receptor ◽  
Zucker Rats ◽  
Hypoxia Exposure ◽  
Obese Rats ◽  
Hypothalamic Neuropeptides

Exposure to hypoxia induces anorexia in humans and rodents, but the role of leptin remains under discussion and that of orexigenic and anorexigenic hypothalamic neuropeptides remains unknown. The present study was designed to address this issue by using obese (Leprfa/Leprfa) Zucker rats, a rat model of genetic leptin receptor deficiency. Homozygous lean (LeprFA/LeprFA) and obese (Leprfa/Leprfa) rats were randomly assigned to two groups, either kept at ambient pressure or exposed to hypobaric hypoxia for 1, 2, or 4 days (barometric pressure, 505 hPa). Food intake and body weight were recorded throughout the experiment. The expression of leptin and vascular endothelial growth factor (VEGF) genes was studied in adipose tissue with real-time quantitative PCR and that of selected orexigenic and anorexigenic neuropeptides was measured in the hypothalamus. Lean and obese rats exhibited a similar hypophagia (38 and 67% of initial values at day 1, respectively, P < 0.01) and initial decrease in body weight during hypoxia exposure. Hypoxia led to increased plasma leptin levels only in obese rats. This resulted from increased leptin gene expression in adipose tissue in response to hypoxia, in association with enhanced VEGF gene expression. Increased hypothalamic neuropeptide Y levels in lean rats 2 days after hypoxia exposure contributed to accounting for the enhanced food consumption. No significant changes occurred in the expression of other hypothalamic neuropeptides involved in the control of food intake. This study demonstrates unequivocally that altitude-induced anorexia cannot be ascribed to anorectic signals triggered by enhanced leptin production or alterations of hypothalamic neuropeptides involved in anabolic or catabolic pathways.

scholarly journals Intact Leptin Receptor Signalling is not Required for the Sustained Weight Loss and Appetite Suppression Induced by Roux-en-Y Gastric Bypass Surgery

2021 ◽  
Author(s):  
Mohammed K. Hankir ◽  
Laura Rotzinger ◽  
Arno Nordbeck ◽  
Caroline Corteville ◽  
Annett Hoffmann ◽  
...  
Keyword(s):  
Weight Loss ◽  
Gastric Bypass ◽  
Body Weight ◽  
Food Intake ◽  
Glucose Tolerance ◽  
Leptin Receptor ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Sustained Weight Loss ◽  
Obese Rats

Leptin is the archetypal adipokine that promotes a negative whole-body energy balance largely through its action on brain leptin receptors. As such, the sustained weight loss and food intake suppression induced by Roux-en-Y gastric bypass (RYGB) surgery have been attributed to enhancement of endogenous leptin action. We formally revisited this idea in Zucker Fatty fa/fa rats, an established genetic model of leptin receptor deficiency, and carefully compared their body weight, food intake and oral glucose tolerance after RYGB with that of sham-operated fa/fa (obese) and sham-operated fa/+ (lean) rats. We found that RYGB rats sustainably lost body weight, which converged with that of lean rats and was 25.5 % lower than that of obese rats by the end of the 4 week study period. Correspondingly, daily food intake of RYGB rats was similar to that of lean rats from the second postoperative week, while it was always at least 33.9 % lower than that of obese rats. Further, oral glucose tolerance of RYGB rats was normalized at the forth postoperative week. These findings assert that leptin is not an essential mediator of the sustained weight loss and food intake suppression as well as the improved glycemic control induced by RYGB, and instead point to additional circulating and/or neural factors.

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