Biomedical subjects

L L Bellush

Publications and source records attributed to L L Bellush.

24 records · Page 2Linked to original sources

PubMed1986

Dietary self-selection in diabetic rats: an overview.

The literature concerning dietary self-selection patterns of diabetic rats is reviewed and compared with new data. There is agreement among the various investigators as to the dietary choices observed following induction of diabetes, regardless of the diabetogenic treatment used. That is, moderately diabetic rats select a high fat, low carbohydrate diet, whereas more severely diabetic animals consume high protein, low carbohydrate diets with little change in fat consumption relative to nondiabetic controls. Even very midly diabetic rats reduce carbohydrate intake. Evaluation of metabolic status of diabetics suggests that with severe diabetes, the beneficial reduction of plasma glucose seen with consumption of a high fat diet may be offset by extreme elevations in ketone and triglyceride levels. Moreover, the hypothesis that diabetic rats are insensitive to carbohydrate calories seems weakened by evidence of reduced food intake following carbohydrate consumption either in solutions or as a gastric load. These findings are discussed in terms of "dietary wisdom" as first proposed by Richter.

Animals↗

PubMed1986

Effects of dietary protein and tyrosine on behavior of diabetic rats.

Streptozotocin-diabetic and nondiabetic control male rats were fed synthetic diets varying in macronutrient content (experiment 1) or diets with or without added tyrosine (experiments 2 and 3). All rats were evaluated for stereotyped behaviors after administration of apomorphine (1 mg/kg) and amphetamine (3 and 5 mg/kg). At the end of experiments 2 and 3, rates of tyrosine hydroxylation in hypothalamus, nucleus accumbens, and striatum were determined by measuring L-3,4-dihydroxyphenylalanine concentrations after decarboxylase inhibition. In experiment 3 the ratios of tyrosine to dopamine were also measured in striatum and nucleus accumbens. Diabetic rats fed a standard high-carbohydrate diet showed decreased stereotypy relative to controls. Neither systematic alterations of fat or protein content of the diet nor selective tyrosine enrichment affected this attenuation of stereotypy in diabetics. L-3,4-dihydroxyphenylalanine concentration in nucleus accumbens was increased by dietary tyrosine enrichment in experiment 2 but not in experiment 3. However, brain tyrosine levels were elevated in rats fed tyrosine-enriched diets. These results argue against a significant contribution of precursor elevation to catecholamine function and behavior in experimental diabetes.

Animal Feed↗

PubMed1985

Preference for high carbohydrate over various high fat diets by diabetic rats.

Streptozotocin-diabetic male rats were hyperphagic relative to nondiabetic controls when offered only high carbohydrate (CHO) laboratory chow. Diabetics and controls ate about the same amount of high fat diets made from 67% w/w chow and 33% either coconut oil (saturated) or safflower oil (unsaturated). However, when offered a simultaneous choice of high fat diets and chow, nondiabetics and low dose (35 mg/kg) streptozotocin-diabetics showed a preference for the high fat diet: in contrast the high dose (65 mg/kg) streptozotocin diabetics developed a preference for chow. When pairs of isocaloric synthetic diets were offered, diabetics again preferred low fat/high CHO to high fat/low CHO diets, but the actual intake of fat was not constant across different diet pairs. Nondiabetics also selected away from the high fat diets in these synthetic diet pairs, even when saccharin was added to the high fat diet in an attempt to equate its sweetness with that of the paired low fat-high CHO diet. Plasma ketone levels of diabetics during obligatory high fat diet consumption were negatively correlated with their subsequent preference for the fat diet over simultaneously-offered chow. These data show that strong dietary preferences do not develop for fat in diabetics and suggest that high fat diets do not have net beneficial postingestional effects in these rats.

Animals↗

PubMed1985

Metabolic and neurochemical correlates of glucoprivic feeding.

Various hypotheses are reviewed concerning the mechanisms of feeding induced by insulin or 2DG. New data are presented to show that elevated plasma ketone levels are not sufficient to suppress 2DG feeding, suggesting that nourishment of the brain either does not occur or is not sufficient to stop 2DG feeding. We find that both acetoacetate and hydroxybutyrate suppress spontaneous feeding. Another series of studies investigated the effects of 2DG and insulin on catecholamine turnover in several brain regions of animals that do (rat, mouse) or do not (hamster) eat in response to these stimuli. The effects of glucoprivic stimuli on NE turnover were minimal; however, 2DG did appear to inhibit DA turnover, especially in nucleus accumbens. Thus, brain NE does not seem specifically involved in glucoprivic feeding, data which are supported by a lack of additivity of feeding induced by 2DG and by clonidine. Finally, to resolve some of the disparate data concerning the effects of glucose infusion on insulin-induced feeding, we examined the time course for effects on feeding and for glucose tolerance. It appears that glucose strongly inhibits feeding only when it is utilized.

Animals↗

PubMed1985

Stereotyped behavior and diabetes mellitus in rats: reduced behavioral effects of amphetamine and apomorphine and reduced in vivo brain binding of [3H]spiroperidol.

Rats made diabetic with streptozotocin showed decreased stereotyped behaviors following administration of amphetamine or apomorphine. Spontaneous activity in an open field was lower in diabetics than in controls, but a low dose of apomorphine produced equivalent fractional decreases in activity in both groups. In vivo accumulation of amphetamine and apomorphine was generally similar in both groups: Reduced tissue access did not appear to be responsible for the decreased behavioral effects of these agents. The in vivo accumulation of spiroperidol in several brain regions was generally less in diabetics than in controls. These data are discussed in terms of altered catecholamine biochemistry and behavior in diabetics.

Animals↗

PubMed1985

Nycthemeral rhythms and sodium chloride appetite in rats.

Adrenalectomized rats maintained on a 12:12 light-dark cycle drank large amounts of 0.3 M NaCl solution during the night. They showed virtually no NaCl appetite during the day. As a result of their high day natriuresis, the adrenalectomized rats sustained a negative Na+ balance during the day about three times that of controls. This was offset by a correspondingly higher positive Na+ balance at night. In a second experiment in intact rats, the latency to exhibit NaCl appetite during polyethylene glycol-induced hypovolemia was shorter when the treatment was administered in the evening than in the morning. This again demonstrates a relative facilitation of NaCl intake at night and suggests a major nycthemeral interaction with putative physiological stimuli of NaCl appetite.

Adrenalectomy↗