Effects of zinc deficiency on food intake and feeding patterns of rats

Abstract

1. The effects of alterations of the protein and zinc concentrations of a semi-synthetic diet on the food intake and dietary preferences of Zn-deficient and normal rats have beencompared.2. The voluntary food intake of Zn-deficient rats fell to 70% 96 of that of the controls. The day-to-day variation of intake increased markedly and was associated with a cyclical pattern of food consumption. When the food intake of deficient rats was slightly restricted the troughs of the cycles disappeared.3. Concurrent with the fall in food intake, Zn-deficient rats ceased to gain weight, but a similar change was found with pair-fed controls.4. Force-feeding Zn-deficient rats with 140 % of their voluntary intake rapidly induced signs of ill-health.5. Reduction of the protein content of the diet from 20 to 5 % resulted in an increased food intake and the disappearance of the cyclical pattern of intake. Growth, however, was not renewed.6. Zn-deficient rats responded to a Zn-supplemented diet within 1–2 h by an increased food intake.7. Zn-deficient rats were able to discriminate between diets containing 6 and I ppm Zn when both diets were offered simultaneously.8. The responses of Zn-deficient rats to Zn-containing diets did not occur if the diets did not contain protein.

The effect of growth hormone treatment on growth in zinc deficient rats

“…Rats given a zinc deficient diet will voluntarily restrict their food intake (Chesters and Quarterman, 1970;Chesters and Will, 1973). Day-to-day food intake varies and a cyclical pattern of eatinq develops (Chesters and Quarterman, 1970;Williams and Mills, 1970).…”

“…Day-to-day food intake varies and a cyclical pattern of eatinq develops (Chesters and Quarterman, 1970;Williams and Mills, 1970). This appears to he a necessary adaptation since force-feedinq of zinc-depleted rats with 140%…”

“…of their voluntary intake rapidly causes signs of ill health (Chesters and Quarterman, 1970). The reasoning behind the anorexia remains uncertain.…”

“…deficient animaIs remain nibblers (Chesters and Quarterman, 1970;Wallwork ~~, 1981). This altering of the frequency of food ingestion may result in differences in nutrient metabolism and body composition (Fabry and Braun, 1967;Leveille, 1972).…”

Differential Adaptations of the Hypothalamus-Pituitary-Thyroid Axis Between Food Restriction and Anorexia

“…In rodents, the most striking feature of experimental Zn deficiency is the cyclic feeding behavior that develops during Zn deprivation. Early studies report that this behavior is characterized by both a reduction of mean food intake, and periodic cyclic changes in daily food intake that disappear as soon as Zn is reintroduced in the diet (Chesters & Quarterman, 1970;Williams & Mills, 1970); an underlying alteration in hypothalamic galanin and NPY gene expression may be responsible for the altered feeding patterns in Zn deficient rats (Selvais et al, 1997).…”