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Biomedical subjects

R M Gold

Publications and source records attributed to R M Gold.

At least 37 records · Page 2Linked to original sources

Vagal mediation of hypothalamic obesity but not of supermarket dietary obesity.

In two independent experiments, complete subdiaphragmatic vagotomy did not prevent the development of the obesity that results from the addition of highly palatable foods to the diet of rats. The vagotomized animals exhibited only a 1-day delay in the onset of overeating, and this only when first exposed to the tasty diet. In independent tests of the functional completeness of the vagotomies, the vagotomized animals failed to overeat or gain excessive weight on a standard laboratory diet following bilaterally parasagittal hypothalamic knife cuts. Thus, hypothalamic knife-cut obesity requires the integrity of the vagus for its full expression, whereas dietary obesity does not.

Animals↗

Non-effect of Massachusetts cement kiln dust upon the food intake, body weight, or activity of female rats.

The addition of Georgia cement kiln dust to the diet of cattle or weanling male rats has been reported to increase body weight and feed efficiency. We attempted to replicate these effects by adding kiln dust to the Purina laboratory chow of adult female rats. Massachusetts cement kiln dust caused no significant change in food intake, weight gain, or activity. The kiln dust effect appears, therefore to depend upon (a) ingredients peculiar to Georgia kiln dust, (b) age (juveniles vs. adults), (c) sex and/or (d) deficiencies of the control diet.

Animals↗

Axon-sparing brain lesioning technique: the use of monosodium-L-glutamate and other amino acids.

Infusions of monosodium-L-glutamate into the rostral hypothalamus, believed to contain neurons mediating satiety, produced persistent hyperphagia and obesity, thus suggesting that a brain lesion had been produced. Similar infusions into the caudal hypothalamus, believed to contain unmyelinated axons of passage that mediate satiety, failed to alter food intake or body weight. Histological examination of the affected tissue confirmed the behavioral evidence that suggests that this technique spares axons but destroys cell bodies. Infusion of several other amino acids also damaged neurons while sparing axons of passage.

Amino Acids↗

Hypothalamic hyperphagia despite imposed diurnal or nocturnal feeding and drinking rhythms.

Rats normally do most of their eating at night. When ad lib fed rats are made hyperphagic with lesions or parasagittal hypothalamic knife cuts the increases in eating occur primarily during the day. This suggests that a disruption of circadian rhythms may mediate the overeating. However, when knife cut rats were food and water deprived all day excessive eating occurred at night. Similarly, when they were deprived all night overeating occurred during the day. Under both conditions od deprivation the food intakes and rapid weight gains of the ad lib fed knife cut group were defended. It was concluded that: (1) in hypothalamic hyperphagia either the excessive food intake or the excessive weight gain is defended when food and water are available only half of each day, and (2) disruption of nocturnal feeding and drinking rhythms is not the cause of hypothalamic hyperhagia.

Animals↗

Delayed hyperphagia and increased body length after hypothalamic knife cuts in weanling rats.

Four-week-old female rats received parasagittal hypothalamic knife cuts. Polydipsia began right surgery, but hyperphagia, obesity, and excessive nose-anal length did not begin until after the rats were 7-8 wk. old. The delayed onset appears to await some maturational event that is required for the expression of hypothalamic obesity. It appears likely that puberty is the critical maturational event.

Animals↗

Hypothalamic obesity: the myth of the ventromedial nucleus.

Lesions restricted to the ventromedial nucleus of the hypothalamus were neither necessary nor sufficient for, and did not contribute to, the production of hypothalamic obesity. Hypothalamic lesions and knife cuts that do produce obesity damage the nearby ventral noradrenergic bundle or its terminals.

Animals↗