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Biomedical subjects

L L Bellinger

Publications and source records attributed to L L Bellinger.

At least 73 records · Page 4Linked to original sources
PubMed1983

Liver denervation does not modify feeding responses to metabolic challenges or hypertonic NaCl induced water consumption.

Following liver denervation (LD) food intake (FI) and body weights of the LD rats did not vary significantly from sham operated animals (S). Rats were injected intraperitoneally at 0800 hr (light/dark, 12:12, lights off 1230 hr) with saline (SAL), 2-deoxy-d-glucose (2DG): Experiment (EXP) 1, 250 and 400 mg/kg; EXP 2, 100 and 150 mg/kg and insulin: EXP 1, 6 and 12 IU/kg; EXP 2, 0.75 and 1.5 IU/kg. Both LD and S rats increased their FI similarly over SAL following 2DG and insulin. In EXP 1 rats were also injected with glucagon (G) (540 micrograms/kg) or SAL at 1330 hr. While this dose of G was later shown to cause hyperglycemia no suppression of FI was noted in either group. Later these rats were injected at 0800 hr with (10 ml/kg) SAL or hypertonic NaCl (0.25 M, 0.5 M and 1.0 M). The two highest doses elevated water intake of both groups comparably. In EXP 2 the ad lib chow fed rats were injected with G (540 and 800 micrograms/kg) or SAL prior to a one hour presentation of a milk diet at 0800 hr. In both groups, after G, meal size and length were significantly and similarly reduced. The data reveal no deficits in the LD rats' response to metabolic and hypertonic NaCl challenges and question what role, if any, liver glucoreceptors have on feeding behavior and liver osmotic receptors have on hypertonic NaCl induced water consumption.

Animals↗
PubMed1983

Naloxone suppression of food and water intake and cholecystokinin reduction of feeding is attenuated in weanling rats with dorsomedial hypothalamic lesions.

In Experiment 1, sham operated (SCON) and dorsomedial hypothalamic nuclei (DMN) lesioned (L) rats were given saline or naloxone (0.1, 1.0 or 2.0 mg/kg) just prior to the onset of the dark cycle, lights out. Compared to saline injections, naloxone at all doses suppressed the cumulative food intake of the SCON during the second and third hr of measurement. Naloxone was without significant effect on the food intake of DMNL rats. Similar results were obtained in Experiment 2, except that naloxone at 2.0 mg/kg significantly suppressed the DMNL rats' food intake by the fourth hr of measurement. Cumulative water intake of both groups was significantly suppressed by naloxone in both experiments but its effects appeared to be attenuated in the DMNL group. In a preliminary trial cholecystokinin octapeptide (3.0 and 6.0 micrograms/kg) given at the onset of the dark cycle significantly suppressed the food intake of the SCON group but had no significant effect on the DMNL rats. The possibility exists that the reduced food intake and lower body weight of DMNL rats may partially result from damage to an opioid system. The data also tentatively suggest that DMN may play a role in cholecystokinin-induced satiety.

Animals↗
PubMed1983

Aphagia and adipsia after kainic acid lesioning of the dorsomedial hypothalamic area.

Unlike rats which have electrolytic dorsomedial hypothalamic area lesions and are hypophagic and hypodipsic, the rats of the present study with dorsomedial hypothalamic area, kainic acid lesions (KAL) were postoperatively aphagic and adipsic. Subsequently, KAL rats rejected chow or a high-fat diet but ate a 30% sucrose-chow diet. Similarly the KAL rats were adipsic but drank a 30% sucrose solution. Slowly most of the KAL rats began to eat chow and drink tap water but remained hypophagic and hypodipsic. When tested for glucoprivic-induced feeding using 2-deoxy-D-glucose (200 or 400 mg/kg) the KAL rats, in contrast to the sham-operated controls, did not increase their food intake. During water deprivation the recovered KAL rats that would drink tap water ate, and following it they responded with an adequate increase in water consumption. During food deprivation the KAL rats, whether eating chow or sucrose-chow diet, drank, and subsequently the normally hypophagic rats actually ate more than the controls. Although the growth rate (linear and ponderal) of KAL rats was reduced compared with that of the controls, their body composition by indirect measurement was normal. The present data indicate that most of the dorsomedial hypothalamic syndrome results from damage to DMHA neurons and not to fibers of passage.

Animals↗
PubMed1982

Nutritional studies in the weanling rat with normophagic hypothalamic obesity.

Weanling male hypothalamic-obese Sprague-Dawley rats (VMNL) and sham-operated controls (CON) fed stock diet for 2 weeks postoperatively ate similar amounts, but VMNL laid down more fat and less body weight per calories. Three equicaloric diets of different macronutrient (MN) content each were fed for 21 days. Diet selection: VMNL selected more carbohydrate (CHO) diet and protein diet but similar amounts of fat diet; total caloric intake was comparable. Percent diet selection showed the identical pattern. MN intake: VMNL ingested more percent CHO, less percent protein and similar percent fat as CON. Refeeding after 2-day fast: both groups selected similar amounts of diets, but VMNL ingested less protein. High protein diet along (9 days): both groups increased caloric intake over previous regimens, weight gain and caloric intake were similar, but Lee Index was higher in VMNL. Stock diet (32 days): VMNL showed normal body weight gains but higher Lee Index despite hypophagia. They utilized calories similarly for body weight gains but more poorly for fat deposition than CON. After death several key plasma substrates were similar in both groups but epididymal fat pads were heavier in VMNL.

Adipose Tissue↗
PubMed1982

Water regulation in weanling hypodipsic dorsomedial hypothalamic-lesioned rats.

Weanling rats with dorsomedial hypothalamic nuclei lesions (DMN-L) are hypodipsic and hypophagic when compared to sham-operated rats. When tested for interdependence of food and water intake (WI) the DMN-L rats drank in the absence of food and ate in the absence of water. The data suggest DMN-L rats are not prandial drinkers. On testing for intracellular thirst (5.8 or 5.4% NaCl, 1 ml/100 g body wt), extracellular thirst [polyethylene glycol (PG), 25% wt/vol, 0.5 ml/35 g body wt], or a combination of both thirsts, the DMN-L rats responded as well or better than the control animals when the test data were expressed as a percentage of the rat's base-line WI. Both groups were more responsive to PG when tested in the light phase. When injected with angiotensin II (200 micrograms/100 g body wt) both groups responded similarly. Therefore, whereas the DMN-L rats were hypodipsic in comparison to controls, they respond as well or better than control animals when classical thirst testing procedures are utilized. It is suggested that DMN-L may have "reset" WI similarly to the previously proposed reset for body weight and food intake.

Angiotensin II↗
PubMed1982

Hypothalamic obesity in the weanling rat: dietary self-selection, actual macro-nutrient intake, caloric regulation and response to subsequent low palatability diet.

Weanling male Sprague-Dawley rats received bilateral electrolytic lesions in the ventromedial hypothalamic nuclei (VMNL rats); sham-operated rats served as controls. For 28 post-operative d all animals were fed three equicaloric [16.9 kJ/g (4.03 kcal)] diets with different amounts of macronutrients in each (HCD = high-carbohydrate diet, HFD = high-fat diet and HPD = high-protein diet). VMNL rats selected more than controls from HCD (P less than 0.05) and HFD (P less than 0.01) but similar amounts from the HPD. The total intake from all three diets was greater (P less than 0.001) than that of the controls, but in percent of total diet intakes, VMNL selected proportions comparable to the controls. In terms of macronutient intake, VMNL rats ingested more than controls from each (carbohydrate, P less than 0.001; fat, P less than 0.05; protein, P less than 0.01). Again, in percent of total macronutrient intake, they ingested proportions comparable to the controls. Lee Index (P less than 0.001) was greater and body weight gain/kJ (kcal) smaller (P less than 0.001) in VMNL rats than in controls. However, body weight gains were normal. For the following 14 d, one group of VMNL rats and one control group continued to self-select from the three diets while another VMNL and control group received lab chow [14.2 kJ/g (3.39 kcal)]. Analysis of variance showed a lesion effect for the Lee Index (P less than 0.001) and Lee Index gain /kJ(kcal) (P less than 0.01) but body weight gains and caloric intake were normal among the groups, ie the VMNL rats switched to chow decreased their caloric intake to control levels. On sacrifice, white and brown fat percent protein (P less than 0.001 for both), carcass lipid (P less than 0.001) and protein (P less than 0.01) and plasma insulin (P less than 0.001) showed lesion effects, but there were no differences among the groups in plasma glucose, glycerol, total protein and free-fatty acids. Availability of palatable diets immediately following VMN lesion placement in weanling rats will result in hyperphagia that after one month recedes to normophagia, whether the rats are fed palatable or less palatable diets. Availability of a less palatable diet (chow) following presentation of palatable diets will not result in diminished caloric intake, body weight, obesity and hyperinsulinemia.

Adipose Tissue↗
PubMed1981

Response of growth-retarded, hypophagic-hypodipsic rats with dorsomedial hypothalamic lesions to a diet in liquid and powder forms.

Weanling rats with dorsomedial hypothalamic lesions (DMNL rats) and sham-operated controls exhibited significantly reduced food intake and ponderal and linear growth during an 11-day post-operative period on lab chow. For 28 days, a synthetic liquid diet (Liquid) was fed to one DMNL and one control group; a second DMNL and control group received the same diet in a powder form (Powder). DMNL rats remained hypophagic on either diet but DMNL and control rats fed Liquid ate significantly more than their counterparts fed Powder. Total fluid intake pattern was identical to caloric intake. For 27 days all groups again received lab chow. They reverted to the caloric intake pattern shown during the 11-day post-operative period. Body weight gains paralleled the caloric and fluid intake patterns except that during the synthetic diet period the Liquid-fed controls outgained all other groups and that there was no difference between DMNL rats on Liquid and Powder. At sacrifice, plasma glucose, glycerol, free fatty acids and total protein were similar in all groups but carcass protein was higher in the DMNL rats formerly fed Liquid. DMNL rats behave in accordance with extensive previous data that led to the formulation of a "resetting" hypothesis.

Animals↗
PubMed1981

Further nutritional characterization of dorsomedial hypothalamic hypophagia in rats: diet consistency, finickiness, self-selection of diets, starvation and realimentation and "stress eating".

Young-mature male Sprague-Dawley rats received bilateral lesions in the dorsomedial hypothalamic nuclei (DMNL); sham-operated rats served as controls. After 30 days of a pelleted commercial laboratory diet, they received a powdered lab diet for 10 days. Both groups of rats reduced food intake for the duration of the test. Thus, although grossly hypophagic under ad libitum feeding conditions, DMNL do not impair adaptation to a diet of different consistency. Both DMNL and controls were significantly hypophagic when fed a quinine-adulterated powdered diet, but only on the first of a 9-day regimen. Thus, they show only transitory finickiness. During a 16-day self-selection test with three equicaloric diets with different amounts of the three macronutrients in each (HCD: high carbohydrate, HFD: high fat, and HPD: high protein diet), DMNL rats ate in absolute terms (g/day) the same amount of HCD, significantly less HFD and during two of seven measuring periods, significantly less HPD. However, their intake in percent of total consumption was similar to that of the controls., After a 48-hour fast, DMNL rats lost and regained body though these rats showed hypophagia during the 48-hour realimentation period, their efficiency of food utilization was similar to the controls. Thus, DMNL rats have not lost the capacity to regulate body weight and food intake after fast-induced weight loss. During eight tail pinch (TP) sessions (11 days), DMNL rats were hyperphagic and preferred HCD and HFD in comparison with controls. In their home cages (lab diet) DMNL rats were hypophagic and over 11 days showed a decline in food intake while the controls displayed an increase. In contrast to previous findings, the challenges of the present study unmasked some deficits in energy homeostasis in the DMNL rat.

Animals↗