Effects of central amygdaloid nucleus lesions on ingestion, taste reactivity, exploration and taste aversion.

Central amygdaloid nucleus lesions in rats had no effect on recovery of preoperative body weight and food consumption levels. The brain damaged rats also recovered preoperative levels of water consumption as rapidly as control rats but then developed a mild but persistent hypodipsia. The experimental rats also drank less than control rats when food deprived and showed marginally reliable decreases in 0.1% quinine solution consumption and latency to consume a novel food. There was no detectable lesion effect on 0.1% saccharin solution consumption, exploration of a novel environment or formation of a learned taste aversion. It is suggested that the central amygdaloid nucleus has a role in mediating the relationship between food and water intake and in some taste mediated consummatory behavior.     

Electroconvulsive shock effects on food and water intake as a function of prior deprivational state

Two experiments, each using approximately 30 male and 30 female hooded rats, examined the effects of electroconvulsive shock (ECS) on water intake as a function of the water deprivation state of the animal and food intake and body weight as a function of food deprivation state. In Experiment 1, half the animals were subjected to water deprivation prior to ECS or sham ECS, and the other half were watered ad lib; in Experiment 2, food deprivation was the pre-ECS manipulation. As predicted, ECS produced a decrease in water intake in the ad lib watered animals but not in the deprived ones. A similar treatment by deprivation interaction was not found for food intake or body weight. In the males, food intake was decreased for one day by the treatment but recovered to a normal level two days following ECS; however, such an effect of ECS on food intake did not occur in the females. Since food and water intake was not differentially affected by ECS and sham ECS in deprived animals, previous cautions regarding ECS effects on motivational states may not be germane to many studies using appetitive conditioning paradigms.     

Effect of treadmill exercise on food intake and body weight in lean and obese rats

Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.     

Influence of a monotonous food on body weight regulation in humans

Four human subjects were fed ad lib with a bland diet for a period of 3 weeks. Their body weight decreased by 3.13 kg during this period. It was observed that the shift of the palatability response to sucrose solutions induced by a gastric glucose load (alliesthesia) was not affected by such a reduction of body weight. This result was compared to a previous experiment showing a decreased alliesthesia after a body weight loss due to the restriction of a palatable diet. These results confirm the role of the palatability of the diet on the maintenance of a body weight level and provide evidence for an interaction between the two factors in determining the oral satiation process.     

Sucrose sham feeding decreases accumbens norepinephrine in the rat

Noradrenergic projections from the dorsomedial medulla reach the shell of the nucleus accumbens (NAcc), a structure implicated in both reward and feeding behavior. Despite this relationship, the effect of food reward on accumbens norepinephrine (NE) remains uninvestigated. In the course of assessing dopamine (DA) in the NAcc during sucrose ingestion [0.03, 0.1, and 0.3 M; Am. J. Physiol., Regul. Integr. Comp. Physiol., 286 (2004) R31], we also analyzed NE in the microdialysis samples from 14 ad-libitum-fed male rats. In contrast to DA, which increased with sucrose concentration (+20-47%) during sham feeding, in the same animals, NE levels were reduced (approximately -20%), regardless of sucrose concentration. These results demonstrate a novel relationship between accumbens DA and NE during orosensory stimulation with a preferred nutrient.     

CATs and HATs: the SLC7 family of amino acid transporters

The SLC7 family is divided into two subgroups, the cationic amino acid transporters (the CAT family, SLC7A1–4) and the glycoprotein-associated amino acid transporters (the gpaAT family, SLC7A5–11), also called light chains or catalytic chains of the hetero(di)meric amino acid transporters (HAT). The associated glycoproteins (heavy chains) 4F2hc (CD98) or rBAT (D2, NBAT) form the SLC3 family. Members of the CAT family transport essentially cationic amino acids by facilitated diffusion with differential trans-stimulation by intracellular substrates. In some cells, they may regulate the rate of NO synthesis by controlling the uptake of l-arginine as the substrate for nitric oxide synthase (NOS). The heterodimeric amino acid transporters are, in contrast, quite diverse in terms of substrate selectivity and function (mostly) as obligatory exchangers. Their selectivity ranges from large neutral amino acids (system L) to small neutral amino acids (ala, ser, cys-preferring, system asc), negatively charged amino acid (system x_c^–) and cationic amino acids plus neutral amino acids (system y⁺L and b^0,+-like). Cotransport of Na⁺ is observed only for the y⁺L transporters when they carry neutral amino acids. Mutations in b^0,+-like and y⁺L transporters lead to the hereditary diseases cystinuria and lysinuric protein intolerance (LPI), respectively.     

Influence of sympathectomy on body weight of rats given chow or supermarket diets

Rats that were neonatally sympathectomized with guanethidine (GUA) and given access to a four-component supermarket diet (SD) when either adolescent or adult gained weight at the same rate as controls. Adrenodemedullation (MDL) of adults, either alone or in combination with GUA treatment, also failed to influence the development of dietary obesity. Neonatal sympathectomy induced small changes in caloric consumption and diet preferences. These results question the notion that the sympathetic nervous system (SNS) is an essential contributor to the control of body weight and the development of dietary obesity.     

Potentiation by Acetylsalicylic Acid of Skin Weal Response to Compound 48/80 in ASA-Sensitive Asthmatics

The influence of acetylsalicylic acid (ASA) on skin response to intradermal injection of compound 48/80 and histamine was studied in order to determine whether ASA elicits any abnormalities also in the skin of asthmatics reacting with bronchoconstriction to ingestion of this drug.
The applied ASA dose (mean dose 150 mg) elicited bronchoconstriction in all 16 patients with asthma and ASA sensitivity (mean fall of FEV₁ 34%) and increased the weal response to compound 48/80 to about 51% (P>0.05) as compared with the response before the ASA-challenge, In asthmatic persons without ASA sensitivity a 150 mg ASA dose did not influence the skin response to any of the reagents. On the other hand, a 600 mg dose decreased skin response to histamine and compound 48/80 in persons without ASA intolerance, although the decrease was statistically significant only in the flare after compound 48/80 (P>0.05).
The authors believe that additional local defect is needed to reveal sensitivity to ASA in the skill of ASA-sensitive asthmatics, just as bronchial hyperreactivity is indispensible for revealing the action of ASA in the bronchi.     

The effects of subdiaphragmatic vagotomy on circadian corticosterone rhythmicity in rats with continuous or restricted food access

Plasma corticosteroid circadian periodicity was determined in three groups of individual adult male rats. Categories were: postsubdiaphragmatic vagotomy, sham-operated, and controls. Blood was sampled every 4 hours over a 48-hour period with ad lib feeding and after a 13-day period on daytime (0930–1330) restriction of food and water availability. Plasma corticosterone circadian periodicity was normal under ad lib conditions in control, sham-operated, and vagotomized animals. Under food-restricted conditions, both the sham-operated and vagotomized animals exhibited the 12-hour shift in the circadian peak of plasma corticosterone levels that we have previously described in normal animals under such conditions. There were no differences between groups in the total amount of food and water consumed or the percentage of nocturnal food intake on an ad lib feeding schedule. Both vagotomized and sham-operated animals manifested reductions in food intake under conditions of food restriction, although vagotomized consumed less than sham-operated animals. The present data indicate that an intact vagus nerve is not necessary for the establishment of circadian periodicity of plasma corticosterone levels or the shift in the periodicity of corticosteroid secretion produced by a restricted feeding regimen.