Circadian rhythms of acid and bicarbonate efflux in fasting rat stomach

1991 ◽  
Vol 260 (4) ◽  
pp. G610-G614 ◽  
Author(s):  
K. R. Larsen ◽  
J. G. Moore ◽  
M. T. Dayton
Keyword(s):  
Circadian Rhythms ◽  
Test Solution ◽  
Circadian Rhythmicity ◽  
Sprague Dawley ◽  
Rat Stomach ◽  
Cosinor Analysis ◽  
Sprague Dawley Rats ◽  
Gastric Lumen ◽  
Sampling Times ◽  
Fasted Rats

One model of gastric ulcerogenesis implicates a disruption of complementary circadian rhythms between protective and destructive factors. The purpose of this study was to compare circadian rhythms in gastric production of H+ and HCO3- in fasted rats. Sprague-Dawley rats were acclimatized in sound-attenuating, light-proof chambers for 3 wk on a 12:12-h light-dark schedule. Eighteen-hour fasted rats were studied at each of eight sampling times. After anesthesia, the stomachs were cannulated and filled with test solution. Thirty-minute gastric samples were titrated for H+ or assayed for HCO3-. Cosinor analysis of the data showed significant (P less than 0.05) circadian rhythms for both H+ and HCO3-. Peak times were 22:45 HALO (hours after lights on) (4:45 A.M.) for H+ and 05:41 HALO (11:41 A.M.) for HCO3-. These data demonstrate that H+ and HCO3- secretion in the fasting rat gastric lumen follow circadian rhythms with different peak times. Theoretically, this may result in circadian rhythmicity of relative mucosal vulnerability to injury.

Circadian rhythm of serum and lymph apolipoprotein AIV in ad libitum-fed and fasted rats

1994 ◽  
Vol 267 (5) ◽  
pp. R1385-R1390 ◽  
Author(s):  
K. Fukagawa ◽  
H. M. Gou ◽  
R. Wolf ◽  
P. Tso
Keyword(s):  
Circadian Rhythm ◽  
Important Determinant ◽  
Lymph Flow ◽  
Right Atrial ◽  
Sprague Dawley ◽  
Mesenteric Lymph ◽  
Sprague Dawley Rats ◽  
Ad Libitum ◽  
Ad Libitum Feeding ◽  
Fasted Rats

The aim of the present study was to determine if there is a circadian rhythm in serum and lymph apolipoprotein (apo) AIV and what factors determine this rhythm. Male Sprague-Dawley rats with chronic right atrial catheter were housed in a room illuminated from 0600 to 1800. With ad libitum feeding, serum apo AIV concentration showed a circadian rhythm concomitant with the feeding pattern. In 24-h fasted rats, the serum apo AIV concentration maintained a circadian rhythm and was high during the dark. With mesenteric lymph diversion, serum apo AIV concentration diminished and the circadian rhythm was abolished. The lymph flow, lymph apo AIV, cholesterol, triacylglycerol, and phospholipid contents all exhibited the same circadian rhythm in fasting, with the levels higher in the dark. These circadian rhythms were abolished after bile diversion. In conclusion, serum apo AIV in ad libitum-fed and fasted rats exhibits a circadian rhythm governed by lymph apo AIV output. Furthermore, bile was an important determinant of the circadian rhythm of lymph flow, lymph apo AIV, triacylglycerol, cholesterol, and phospholipid output.

Range of entrainment of rat circadian rhythms to sinusoidal light-intensity cycles

2000 ◽  
Vol 278 (5) ◽  
pp. R1148-R1156 ◽  
Author(s):  
Setsuo Usui ◽  
Yasuro Takahashi ◽  
Terue Okazaki
Keyword(s):  
Circadian Rhythms ◽  
Light Intensity ◽  
Lower Limit ◽  
Phase Angle ◽  
Light Exposure ◽  
Sprague Dawley ◽  
Lighting Conditions ◽  
Behavioral Rhythm ◽  
Sprague Dawley Rats ◽  
Daily Cycles

The range of entrainment of the circadian behavioral rhythm was compared between two groups of Sprague-Dawley rats (each n = 10) exposed to daily cycles of rectangular light-dark alternation (LD) and sinusoidal fluctuations of light intensity (SINE), respectively. The maximum illuminance (20 lx), the minimum illuminance (0.01 lx), and the total amount of light exposure per cycle were the same under the two lighting conditions. The periods (Ts) of both lighting cycles were lengthened stepwise from 24 through 25, 26, 26.5, 27, 27.5, and 28 h to 28.5 h in experiment 1 and were shortened stepwise from 24 through 23.5, 23, and 22.5 h to 22 h in experiment 2. Each T cycle lasted for 30 cycles. In experiment 1, 60% of rats under the LD condition entrained up to T = 28.5 h, whereas 50% of rats under the SINE condition entrained up to T = 28.5 h. In experiment 2, no animal under the LD condition entrained to T < 23.5 h, whereas 40% of rats under the SINE condition entrained down to T = 23 h and 20% of rats remained to entrain down to T = 22 h cycles. The phase angle of entrainment was systematically changed, depending on T under both conditions. These results suggest that the lower limit of entrainment is expanded under the SINE condition compared with the LD condition.

Orexin A-induced feeding is augmented by caloric challenge

2005 ◽  
Vol 289 (2) ◽  
pp. R367-R372 ◽  
Author(s):  
A. J. Thorpe ◽  
J. A. Teske ◽  
C. M. Kotz
Keyword(s):  
Food Deprivation ◽  
Dose Response ◽  
Feeding Response ◽  
Sprague Dawley ◽  
Orexin A ◽  
Hypothalamic Area ◽  
Sprague Dawley Rats ◽  
Dose Response Study ◽  
Dose Dependent ◽  
Fasted Rats

Orexin neurons are stimulated by conditions that are glucoprivic, suggesting that orexin signaling may be increased during nutritional duress. We have previously shown that injection of orexin A (OxA) into the rostral lateral hypothalamic area (rLHa) robustly and dose-dependently increases feeding behavior. Thus we hypothesized that exogenous administration of orexin A would induce a greater feeding response after acute food deprivation or perceived caloric duress achieved through 2-deoxyglucose (2DG) administration. To test our hypothesis, male Sprague-Dawley rats implanted with internal guide cannulas directed to the rLHa were exposed to varying degrees of food deprivation (0, 3, 12, 24 h) and 2DG (200 mg/kg) before intra-rLHa OxA (500 pmol) infusion. We also performed a dose-response study using graded doses of OxA (0, 31.25, 125, and 500 pmol) in fed and 24-h fasted rats. OxA administration in conjunction with the highest level of prior food deprivation (24 h) resulted in the greatest feeding response (above baseline means; 0 h deprivation: 1.9 ± 0.6; 24 h deprivation: 4.4 ± 0.8; P = 0.0034) and showed a dose-dependent enhancement of feeding. Additionally, 2DG administration before OxA administration resulted in a significantly higher feeding response (above baseline means: 2DG = 1.8 ± 0.5; OxA = 1.8 ± 0.4; 2DG + OxA = 5.1 ± 0.6; P < 0.0001). These data support the hypothesis that orexin signaling may be important in modulating the feeding network under times of nutritional duress.

Mechanism of induction of mucosal ornithine decarboxylase by food

1986 ◽  
Vol 251 (3) ◽  
pp. G370-G374 ◽  
Author(s):  
K. Tabata ◽  
L. R. Johnson
Keyword(s):  
Enzyme Activity ◽  
Ornithine Decarboxylase ◽  
Fold Increase ◽  
Enzyme Activation ◽  
Gut Contents ◽  
Sprague Dawley ◽  
Direct Stimulation ◽  
Sprague Dawley Rats ◽  
Fasted Rats ◽  
Stimulation Of

Refeeding fasted rats dramatically increases ornithine decarboxylase (ODC) activity in the mucosa of the small intestine and colon. The agents responsible for that activation and pathways leading to activation, however, have not been identified. The current work examines whether stimulation of ODC activity is mediated humorally or directly and whether dietary amines might be in part responsible for activation. Male Sprague-Dawley rats were used 1 wk after they were surgically prepared with Thiry-Vella jejunal loops. Two hours after refeeding rats fasted for 48 h, ODC activity increased 40-fold in mucosa from the intact jejunum and 4-fold in the mucosa of the bypassed segments. The injection of intestinal contents (obtained from additional fed rats) into the bypassed loop caused a 10-fold increase in ODC activity in the loop measured 2 h later. Injection of gut contents, lyophilized to remove dietary amines, produced no change in enzyme activity. The addition of 400 mol dimethylamine to lyophilized gut contents restored enzyme activation to 80% of the previous level. These data allow the following conclusions: following a meal mucosal ODC is activated by both humoral and direct mechanisms, direct stimulation by dietary constituents appears to be the predominant mechanism involved, and dietary amines may be one of the agents involved in directly increasing enzyme activity.

Changes in regional vascular resistance and blood volume after hemorrhage in fed and fasted awake rats

1995 ◽  
Vol 78 (6) ◽  
pp. 2025-2032 ◽  
Author(s):  
D. N. Darlington ◽  
R. O. Jones ◽  
L. Marzella ◽  
D. S. Gann
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Bronchial Artery ◽  
Peripheral Resistance ◽  
Sprague Dawley ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Fasted Rats

To determine whether fasting alters the response of blood flow to hemorrhage, blood flow was measured by radiolabeled microspheres before and after a 20 ml.kg-1.3 min-1 hemorrhage in fed and fasted chronically cannulated male Sprague-Dawley rats. Restitution of blood volume, as determined by dilution of hematocrit, was attenuated in fasted rats, although the responses of arterial blood pressure, heart rate, cardiac output, and total peripheral resistance were not significantly different. Fasting only affected resting blood flow in the bronchial artery and fat and had no effect on resting vascular resistance in any organ studied. In both fed and fasted rats, hemorrhage led to a significant fall in blood flow to the stomach, small intestine, cecum, colon, spleen, pancreas, kidney, bronchial artery, thymus, and muscle and a rise in blood flow to the adrenals. However, fasting did not significantly alter the response of flow or vascular resistance to these organs. Fasting did alter the blood flow response to hemorrhage in bone, fat, and the hepatic artery. These results demonstrate that 24 h of fasting does not affect the responses of blood flow and vascular resistance to hemorrhage in most organs, even though restitution of blood volume is attenuated.

Feeding-entrained circadian rhythms in hypophysectomized rats with suprachiasmatic nucleus lesions

1999 ◽  
Vol 277 (5) ◽  
pp. R1376-R1384 ◽  
Author(s):  
Alec J. Davidson ◽  
Friedrich K. Stephan
Keyword(s):  
Circadian Rhythms ◽  
Food Access ◽  
Core Body Temperature ◽  
Pituitary Hormones ◽  
Sprague Dawley ◽  
Indirect Measure ◽  
Sprague Dawley Rats ◽  
Hypophysectomized Rats ◽  
Anticipatory Activity ◽  
Access To Food

Several pituitary hormones are important in the regulation of metabolism, and their release appears to be controlled by a circadian clock. Consequently, they may be involved in feeding-entrained circadian rhythms. Hypophysectomized (Hypox) and sham-operated male Sprague-Dawley rats had access to food for 4 h each day. Food-anticipatory activity (FAA) and core body temperature (Tb) were monitored. Both groups entrained to the daily meal with an increase in activity in the 4 h preceding meal access and quickly reentrained after an 8-h phase advance of food access. FAA was not disrupted in either group after suprachiasmatic lesions were added. Core Tb increased in the sham-operated subjects before mealtime, but Hypox rats failed to show this effect. Rather, Tb declined during anticipation and throughout the food access period. Respiratory quotient (RQ), an indirect measure of metabolic rate, was measured for 24 h in some subjects. Sham-operated rats showed a dramatic downturn in RQ 1 h before mealtime, whereas Hypox rats showed a steadily decreasing RQ throughout the day. The results show that the pituitary hormones are not necessary for FAA and that in Hypox rats the anticipatory rise in Tb and changes in RQ become dissociated from anticipatory behavior, indicating that these functions are separate outputs of the food-entrainable circadian oscillator.

scholarly journals Phyllanthus reticulatus Prevents Ethanol-Induced Gastric Ulcer via Downregulation of IL-8 and TNF-α Levels

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Hafsa Izhar ◽  
Arham Shabbir ◽  
Muhammad Shahzad ◽  
Aisha Mobashar ◽  
Syed Shoaib Ahmed
Keyword(s):  
Gastric Ulcer ◽  
Histopathological Examination ◽  
Ethyl Acetate Fraction ◽  
Sprague Dawley ◽  
Group Vi ◽  
Expression Levels ◽  
Sprague Dawley Rats ◽  
Tnf Α ◽  
Gastric Lumen ◽  
Pcr Method

The current study aimed to determine the protective effect of P. reticulatus on ethanol-induced gastric ulcer. For this purpose, thirty-six Sprague-Dawley rats were divided into six groups. The first group served as normal control, while, in other five groups, absolute ethanol was used to induce gastric ulcer. Group II served as a diseased group, while groups III, IV, and V were treated with methanol extract, ethyl acetate fraction, and n-hexane fraction, respectively, in a dose of 400 mg/kg bodyweight. Group VI was given omeprazole in a dose 20 mg/kg bodyweight. The stomachs were removed, ulcer score was evaluated, and histopathological examination of gastric lumen was conducted. Total acidity and pH values were determined in gastric juice. TNF-α and IL-8 mRNA expressions levels were determined using the reverse transcription real-time PCR method. The data indicated that P. reticulatus protected against gastric ulcer, which was evident by attenuation of ulcer score. The pretreatment with P. reticulatus raised the gastric pH and improved all evaluated histopathological parameters such as ulcer score, erosion score, hemorrhage score, fibrinoid necrosis score, inflammatory infiltrate score, and edema score. P. reticulatus significantly reduced mRNA expression levels of TNF-α and IL-8. In conclusion, P. reticulatus possess antiulcer property which might be attributed to downregulation of TNF-α and IL-8 expression levels.

Interruption of the rat circadian clock by short light-dark cycles

2003 ◽  
Vol 284 (5) ◽  
pp. R1255-R1259 ◽  
Author(s):  
Setsuo Usui ◽  
Terue Okazaki ◽  
Yoshiko Honda
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Circadian Clock ◽  
Constant Darkness ◽  
Sprague Dawley ◽  
Light Stimulation ◽  
Behavioral Rhythms ◽  
Light Pulses ◽  
Sprague Dawley Rats

Ninety male Sprague-Dawley rats were exposed to 1:1-h light-dark (LD1:1) cycles for 50–90 days, and then they were released into constant darkness (DD). During LD1:1 cycles, behavioral rhythms were gradually disintegrated, and circadian rhythms of locomotor activity, drinking, and urine 6-sulfatoxymelatonin excretion were eventually abolished. After release into DD, 44 (49%) rats showed arrhythmic behavior for >10 days. Seven (8%) animals that remained arrhythmic for >50 days in DD were exposed to brief light pulses or 12:12-h light-dark cycles, and then they restored their circadian rhythms. These results indicate that the circadian clock was stopped, at least functionally, by LD1:1 cycles and was restarted by subsequent light stimulation.

scholarly journals Effects of fasting on temporal variations in nephrotoxicity of gentamicin in rats.

1996 ◽  
Vol 40 (3) ◽  
pp. 670-676 ◽  
Author(s):  
D Beauchamp ◽  
P Collin ◽  
L Grenier ◽  
M LeBrun ◽  
M Couture ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Renal Toxicity ◽  
Temporal Variations ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Short Period ◽  
Ultrathin Sections ◽  
Sensitive Parameters ◽  
Beta Galactosidase ◽  
Fasted Rats

Evidence for temporal variations in the nephrotoxicity of low doses of aminoglycosides were recently shown by using specific and sensitive parameters of renal toxicity. The aim of the present study was to evaluate the effect of a short period of fasting on the temporal variations in the renal toxicity of gentamicin. Twenty-eight normally fed (i.e., food and water were available ad libitum throughout the experiment) female Sprague-Dawley rats (weight, 175 to 220 g) and 28 fasted rats (i.e., only water was available during a 12-h fast before and a 24-h fast after gentamicin injection) were used. The animals were synchronized on a 14-h light, 10-h dark cycle (lights on at 0600 h) for 1 week before gentamicin administration. In July 1993, each group of animals was treated with a single intraperitoneal injection of saline (NaCl, 0.9%) or gentamicin (150 mg/kg of body weight) at either the peak (1400 h) or the trough (0200 h) of the previously determined toxicity. On day 1, the 24-h urinary excretion of beta-galactosidase, N-acetyl-beta-D-glucosaminidase, and gamma-glutamyltransferase was significantly higher in normally fed animals treated with gentamicin at 1400 h than in their time-matched controls and in normally fed animals treated at 0200 h (P < 0.01), which had normal levels of these enzymes. By contrast, the urinary excretion of these enzymes was significantly higher in both groups of gentamicin-treated, fasted rats than in their time-matched control groups (P < 0.01), reaching levels similar to those measured in normally fed rats treated at 1400 h. The accumulation of gentamicin was significantly lower in the renal cortex of normally fed rats treated at 0200 h than in rats treated at 1400 h (P < 0.05), but this time-dependent difference was not found in fasted rats treated at 0200 and 1400 h. Immunogold labeling done on ultrathin sections and observed by electron microscopy showed a similar subcellular localization of gentamicin in normally fed and fasted rats treated at either 1400 or 0200 h. These results suggest that the feeding period is of crucial importance in the temporal variations of the nephrotoxicity of gentamicin in rats.

Ultrastructural Investigation of Spontaneous Pituitary Adenomas in Aging Sprague-Dawley Rats

1982 ◽  
Vol 40 ◽  
pp. 216-217
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Microscopic Study ◽  
Pituitary Adenomas ◽  
Wistar Rats ◽  
Microscopic Level ◽  
Sprague Dawley ◽  
Prolactin Cells ◽  
Light Microscopic Level ◽  
Ultrastructural Investigation ◽  
Sprague Dawley Rats ◽  
Long Evans

Investigation of the spontaneous pituitary adenomas in rat have been limited mainly to light microscopic study. Furth et al. (1973) described them as chromophobic, secreting prolactin. Kovacs et al. (1977) in an ul trastructural investigation of adenomas of old female Long-Evans rats, found that they were composed of prolactin cells. Berkvens et al. (1980) using immunocytochemistry at the light microscopic level, demonstrated that some spontaneous tumors of old Wistar rats could contain GH, TSH or ACTH as well as PRL.

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