Date of Award

Fall 1984

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

Abstract

The exact processes underlying dietary-induced thermogenesis (DIT) are unknown. Current research has suggested that DIT and non-shivering thermogenesis (NST) may share common thermoregulatory pathways. If that is so, variables that are known to affect DIT should also affect NST, and vice versa. It is known that exercise increases DIT, while cold-adaption increases NST.

This experiment examined the effects of cold- and exercise-adaption in male and female Sprague Dawley weanling rats. Cold-adaption consisted of 30 days of continuous exposure at 5 Centigrade. Graded exercise training was conducted daily on a treadmill for 40 continuous days.

Cold- and exercise-adaption had similar effects on a number of dependent variables. Most importantly, both groups had increases in aerobic capacity and cold tolerance. DIT and norepinephrine-induced thermogenesis (NE) were reduced indicating a conservation of energy. Both groups also had reductions in body weight which were primarily due to decreases in carcass fat.

There were two instances in which cold- and exercise-adaption had very different effects. Food intake was only slightly decreased in the exercise-adapted group, but increased dramatically in the cold-adapted group. Resting metabolic rate decreased in the exercise-adapted group, but increased dramatically in the cold-adapted group.

Cold- and exercise-adaption increased aerobic capacity and cold tolerance. In both cases DIT and NE were reduced. NST was increased in the cold- and probably in the exercise-adapted group. The magnitude of DIT and NE were primarily related to the nutritional status of the animal.

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