Regression analysis of relationship between liver weight and body weight after partial hepatectomy in rats

A method for evaluation of the initial weight of the liver is developed for calculating the regeneration coefficient after partial hepatectomy on the basis of linear regression analysis. Experiments on rats showed that the model reflecting the relationship between liver weight and body weight for calculation of regeneration coefficient after partial resection of the liver expressed by the equation P ₀=0.033×M can be used for screening of potential hepatoprotectors for quantitative evaluation of the regeneration processes. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 2, pp. 234–236, February, 2006     

The effects of estradiol on body weight and food intake in normal weight VMH-lesioned rats.

The effects of estradiol on food intake and body weight were examined in ovariectomized and VMH-lesioned, ovariectomized rats that were prevented from supranormal weight gain by food restriction. Estradiol injections that were effective in reducing weight in supranormal weight, ovariectomized rats had no effect on weight in normal weight, ovariectomized or VMH-lesioned, ovariectomized rats. Estradiol did not prevent hyperphagia and weight gain in VMH-lesioned, ovariectomized rats when they were provided with ad lib food.     

Influence of a diet rich in fish oil on blood pressure,body weight and cardiac hypertrophy in spontaneously hypertensive rats

Summary The effects of a diet rich in fish oil on arterial blood pressure, body weight, left ventricular weight and heart rate have been investigated in 8 month old spontaneously hypertensive male rats (SHR) as compared to age-matched hypertensive controls. A diet containing 10% fish oil decreased blood pressure by about 40 mmHg within 20 days of starting the experiment, and this effect persisted over the observation period of 80 days. Permitting the animals free access to food, the body weight of the diet group increased by 25%. The degree of hypertrophy as evaluated by relating left ventricular weight to tibial length was significantly reduced (10%) in the diet fed group. Heart rate was increased by 53%. The study demonstrates that a diet rich in fish oil can lower arterial blood pressure over several weeks without a recognizable loss in function despite a considerable increase in body weight. It can be assumed that a more marked regression of left ventricular hypertrophy is counteracted by a reflex increase in sympathetic efferentation to the heart.     

Effect of vitamin C deficiency and excess on the liver: a histopathological and biochemical study in guinea pigs fed normal or high cholesterol diet

When guinea pigs were kept on a restricted vitamin C intake of only 0.5 mg daily, their serum ascorbic acid fell to 0.16 +/- 0.06 mg/d1 in 16 weeks as compared to 0.73 +/- 0.11 in control. This was associated with significant increase in liver cholesterol and triglycerides. When they were simultaneously challenged with a high cholesterol load, this fat accumulation was markedly exaggerated. The weight of the liver now increased by almost two-and-half times. Liver cholesterol rose to 12.90 +/- 2.63 mg/gm as compared to 3.23 +/- 0.56 mg/gm with low vitamin C alone. Histopathology showed marked distension and vacuolation of hepatocytes, focal necrosis and fibroplasia. Administration of excess vitamin C (100 mg daily) significantly countered these changes. The vitamin C-lipid relationship has important clinical bearings and liver could be an important site of vitamin C action.     

Relationship between wheel running, feeding, drinking, and body weight in male rats

The amount of wheel running varies widely between rats. Wheel introduction and running also have profound effects on the animal's energy balance. We explored the effects of ad lib wheel access and running levels on feeding, drinking, and body weight in 30 young adult male rats with wheel access and in 30 rats without wheel access. The initial running period (Days 1-8) and a time of stable running [Days 29-32 (DEnd)] were analyzed using both between- and within-group approaches. Initially, wheel access suppressed feeding (by about 25% over the 8 days) but not drinking. There were no significant correlations between the amount of wheel running and the other behaviors. The degree of feeding suppression was also not correlated to the amount of running. When running had stabilized (animal ran from 841 to 13,124 wheel turns per day), food intake was increased by about 0.75 g per 1000 wheel turns. Running at this time correlated positively with feeding and drinking and negatively with body weight and weight gain. In animals without wheel access, feeding and drinking were positively correlated with weight and weight gain, but in animals with wheel access, these correlations were close to zero. Only early running predicted later levels of running but accounted for only 23% of the variance in running. Wheel access has profound but very different immediate and long-term effects on the rats' energy balance.     

The effect of liver denervation on meal patterns,body weight and body composition of rats

Neural liver glucoreceptors have been proposed as a primary controller of food intake (FI). Male Sprague-Dawley rats were either sham operated or liver denervated (LD). LD rats had all tissue cut between the liver and the esophagus, stomach and upper 1 cm of the duodenum. The hepatic artery and surrounding tissue were also removed. Finally the hepatic portal vein and the bile duct were stripped clean and the former phenol treated. Three days after surgery animals were placed in modules for continuous computer monitoring of feeding behavior. At no time after surgery did the daily food intake or body weight of the groups differ significantly. Meal size and frequency (light-dark distribution) were determined for 6 days and averaged. Neither parameter was altered by LD. During the next 6 months food intake and body weights of the groups did not differ significantly. At sacrifice, body composition was directly determined with no significant differences observed between LD and sham operated rats. LD were confirmed histologically. Monoamine histofluorescence of the livers of rats subjected to liver denervation revealed an absence of the normal fluorescence seen on small blood vessels in liver parenchyma of sham operated rats. The data do not support the concept that liver glucoreceptors are a major controller of FI.     

Effects of feeding urea and copper sulphate in different combinations on live body weight,carcass weight,percent weight to body weight of different organs and histopathological tissue changes in broilers

The study was carried out on a total of 100 broiler chicks divided into six equal groups at day 7 of age. Birds were fed copper sulphate and urea in different combinations for up to 37 days and then the birds of all the groups were fed plan feed for one week. The general signs were an increased water intake, ruffled feathering, watery droppings along with salivation in treatment groups. These signs were mild in groups fed low level of urea, while were severe in fed higher levels of these compounds together. Mild to moderate gross changes were observed in the birds of group B, C and D, while more pronounced changes were seen in birds of group E and F. In the latter groups, the liver was pale to yellowish and fragile. Kidneys were enlarged, swollen, congested and sometimes hemorrhagic. Histologically, mild cytoplasmic vacuolation and condensation/pyknosis or disappearance of the nucleus in the cells of the liver and kidney were the salient changes observed in the treatment groups, those were severe in birds fed higher levels of the two compounds. Changes in lungs were congestion and edema. Changes in the bursa of Fabricius were mild cytoplasmic vacuolation, cell depletion and chromatolysis. The live and carcass weights were lower in broilers fed higher levels of both copper and urea than the control group. The weights of kidney and heart were higher in birds fed higher levels of both of the compounds than the control group. It can be concluded from the present study that urea above 2% and copper sulphate above 1 gm in combination cause tissue damage, especially the liver and kidneys.     

Effects of a gastric implant on body weight and gastrointestinal hormones in cafeteria diet obese rats

In order to evaluate the effectiveness of a gastric implant in an animal model of dietary obesity, silicone implants (2.5 ml) were inserted into the stomachs of male rats maintained on a chow or "cafeteria" diet. At the time of implantation, the cafeteria fed rats weighed 14% more than chow fed controls. Overweight cafeteria fed animals lost weight in response to the gastric implant, whereas control chow fed animals did not. Both implant groups had significant increases in stomach weights in contrast to sham implant groups, but the increase was much less in the cafeteria diet group. The fasting plasma levels of the gastrointestinal hormones, gastrin and pancreatic polypeptide, and oxytocin (a marker of vagal afferent function) were measured by radioimmunoassay. Cafeteria fed sham or implanted animals had significantly higher fasting levels of plasma oxytocin and gastrin, and significantly lower plasma levels of pancreatic polypeptide than the chow fed groups. These studies demonstrate that the gastric implant has more effect on weight in overweight animals on a palatable mixed diet, perhaps related to both mechanical and neural factors.     

Neuroestrogenic control of feeding behavior and body weight in rats with kainic acid lesions of the lateral septal area

The role of the lateral septal area (LS) in the regulation of energy balance and the estrogenic control of feeding behavior in the female rat has been examined. Food intake (FI) and body weight (BWt) were measured daily following kainic acid (KA) LS lesions (KALS) to assess any regulatory changes in energy balance. In all animals KA lesions of the LS produced major cell loss in the LS; however the extent of damage was variable. Associated with KA lesions of the LS was the concurrent loss of CA3-CA4 cell groups in the hippocampus which was comparable for all the lesioned animals. The extent of septal damage was quantified morphometrically and correlated with changes in FI and BWt following estrogen treatment. The significant effects of the KALS lesions, relative to the control animals were: an increase in BWt which was statistically significant 22 days following brain surgery, an increase in daily FI which was significant by day 6 post surgery, an attenuation in the anorexic effects of estrogen on FI and BWt, and a significant decrease in the present days of vaginal estrus. Moreover, the anorexic effects of estrogen were significantly correlated with the extent of LS damage, but not the amount of hippocampal damage. The present study confirms that an increase in BWt is produced by KA lesions of the LS and further indicates that a sustained period of increased FI precedes the increase in BWt.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of very low calorie diet induced body weight loss with or without human pegylated recombinant leptin treatment on changes in ghrelin and adiponectin concentrations

The aim of the study was to investigate the effects of energy restriction with or without pegylated recombinant leptin (PEG-leptin) treatment on ghrelin, adiponectin, insulin and glucose concentrations. A randomized double-blind placebo-controlled trial was performed in 24 moderately overweight/obese men. PEG-leptin or placebo was administered weekly for 6 weeks, combined with a restricted energy intake of 2.1 MJ/d. At days 1, 25, and 46 a blood sample was taken and body-weight (BW) was measured. Days 1-25 was named phase 1, and days 25-46 phase 2. During phase 1 the rate of BW loss was significantly higher in the PEG-leptin compared to the placebo group (0.38+/-0.07 vs 0.32+/-0.06 kg/d, p<0.05). The rate of BW loss during phase 2 was 0.24+/-0.08 and 0.18+/-0.09 kg/d, respectively (p=0.07). In both groups the rate of BW loss during phase 1 was significantly higher than during phase 2 (p<0.001). Energy balance (EB) was significantly more negative during phase 1 than during phase 2 in both groups (p<0.0005). During phase 1 insulin, glucose and adiponectin decreased significantly in both groups. Adiponectin and ghrelin concentrations changed in the opposite direction between phase 1 and phase 2 (p<0.05). Initial BW loss due to a considerable negative EB induced decreased ghrelin, adiponectin, insulin and glucose levels. However, when EB became less negative and the rate of BW loss decreased, these changes were reversed for adiponectin and ghrelin. The PEG-leptin injections did not have an effect on the changes in insulin, glucose and adiponectin, but had an effect on the changes in ghrelin concentrations.     

Growth of the pig: changes in body weight and body fluid compartments.

Body weight and the rate of change in TBW, ECW, and ICW were measured in 252 anesthetized pigs during the first 12 weeks after birth. After TBW was measured with 3H2O, 55 of the pigs were killed and TBW measured by desiccation. 3H2O overestimated TBW by 6.5% of body weight and 4.9% of fat-free wet weight, compared to desiccation (P less than 0.001); mean figures for 3H2O were 78.6 +/- 1.02% of body weight, and for desiccation, 72.1 +/- 0.45%; on a FFWW basis, 88.6 +/- 0.94% for 3H2O, and 83.7 +/- 0.13% for desiccation. TBW decreased significantly from 85.0% of body weight at birth (1.5 dg) to 75% at 5 kg (day 28) at a rate of ---3.2% body wt/kg body wt (P less than 0.001 from a zero rate). After that the rate of decrease was not different from zero: --0.117% body wt/kg body wt. ECW decreased significantly from 48% at birth to 35% at day 28 at a rate of --3.802% body wt/kg body wt (P less than 0.001 from a zero rate), and after day 28 the rate of decrease was not different from zero (--0.149% body wt/kg body wt) through week 12. ICW decreased, but not significantly, at a rate of --0.099% body wt/kg body wt. The changes in the rate of decrease in TBW and ECW coincided with weaning, and it was speculated that there was a direct relationship between the two events.     

Chronic restraint or variable stresses differently affect the behavior, corticosterone secretion and body weight in rats

Organisms are constantly subjected to stressful stimuli that affect numerous physiological processes and activate the hypothalamo-pituitary-adrenal (HPA) axis, increasing the release of glucocorticoids. Exposure to chronic stress is known to alter basic mechanisms of the stress response. The purpose of the present study was to compare the effect of two different stress paradigms (chronic restraint or variable stress) on behavioral and corticosterone release to a subsequent exposure to stressors. Considering that the HPA axis might respond differently when it is challenged with a novel or a familiar stressor we investigated the changes in the corticosterone levels following the exposure to two stressors: restraint (familiar stress) or forced novelty (novel stress). The changes in the behavioral response were evaluated by measuring the locomotor response to a novel environment. In addition, we examined changes in body, adrenals, and thymus weights in response to the chronic paradigms. Our results showed that exposure to chronic variable stress increased basal plasma corticosterone levels and that both, chronic restraint and variable stresses, promote higher corticosterone levels in response to a novel environment, but not to a challenge restraint stress, as compared to the control (non-stressed) group. Exposure to chronic restraint leads to increased novelty-induced locomotor activity. Furthermore, only the exposure to variable stress reduced body weights. In conclusion, the present results provide additional evidence on how chronic stress affects the organism physiology and point to the importance of the chronic paradigm and challenge stress on the behavioral and hormonal adaptations induced by chronic stress.