J. A. F. Stevenson

Food Restriction and Lipogenesis in the Rat.

Summary 1. Using young male rats fed chow for only 2 hours daily, the increased lipogenesis in vitro and liver glycogen concentration reported by others has been confirmed. The phenomena have been demonstrated also in young male rats fed a purified, high carbohydrate diet for only 2 hours daily. 2. In contrast to the findings of Hollifield and Parson, young rats whose feeding time was restricted to 2 hours daily had a lower food intake and body weight gain than did ad libitum-fed controls whether provided with chow or the high carbohydrate diet. These “restricted” animals had slightly lower proportion of carcass fat and higher proportion of water and ash. 3. Adult male rats when provided with the high carbohydrate diet for only 2 hours daily, ate less than ad libitum-fed controls and failed to gain weight.

Effect of Exercise on Coronary Tree Size in the Rat

Using the vinyl acetate corrosion cast technique devised by Tepperman and Pearlman, it has been demonstrated that, in the rat, forced physical exercise (treadmill or swimming) causes an increase in apparent coronary tree size provided the exercise is not too strenuous or frequent.

Effects of ACTH and Corticosteroids in the Regulation of Food and Water Intake

Publisher Summary This chapter focuses on the effects of adrenocorticotropic hormone (ACTH) and corticosteroids in the regulation of food and water intake. The specific effects of ACTH and the adrenocortical hormones on food and water intake, however, remain unexplained. Clinical studies have often reported an increase in food intake of patients treated with adrenocortical hormones, but the issue has been clouded by the fact that the patients were frequently underweight to begin with, and the effect of the hormone on food intake was probably secondary to its effect on the general health and sense of well-being of the patient. In most of the experimental studies of the effect of the adrenocortical hormones on food intake and/or body weight changes in the intact animal, the administration of the exogenous hormone has inhibited weight gain or induced its loss. In the few quantitative experimental studies that have been made of the effect of the various glucocorticoids on food intake, the conclusion has been that these hormones, when administered exogenously, if anything, depress food intake.

MECHANISMS IN THE CONTROL OF FOOD AND WATER INTAKE

When asked to present a paper at the conference on neural regulation, I was given the title “Current assessment of the central mechanisms for the regulation of food and water intake.” I asked that the term “regulation” be changed to “control.” This request was based on the useful suggestion of Brobeck that a clear distinction be made between two concepts for which these two terms, control, and regulation, have been used interchangeably. Brobeck‘sl suggestion is that regulation be used to “denote the preservation of a relatively constant value by means of physiological mechanisms which include a specialized detector for the value or some function of it.” Examples of parameters regulated in the mammal are: blood pressure, body temperature, and the carbon dioxide tension of the blood. In contradistinction, the term “control” may be used to describe management of a rate of functioning. Heart rate, stroke volume, and peripheral resistance are all controlled to regulate the blood pressure. Similarly, the rate of heat production and the rate of heat loss are controlled to regulate body temperature. In the present instance, there is a control of food intake, as well as of heat loss and work output, to regulate the energy content of the body or some aspect of this content. Water intake and renal water loss are controlled to regulate the concentration and volume of water in the body. Controls are required to achieve a regulation. Whether or not one accepts this particular usage of these two terms, I think most investigators would agree that a distinction between the two concepts they represent is a useful one. One of the requirements in Brobeck’s definition of a physiological regulation is that there be specialized detectors for the value regulated or for some function of it. He points out that it may be incorrect to speak of a regulation of energy exchange “because we do not know the existence of any specialized cells capable of responding to changes in energy content or to any variable proportional to this content.” The latter part of this statement is open to question by the hypotheses that there are glucostatic, lipostatic and/or thermostatic controls of food intake which singly or together would measure variables proportional to the energy exchange or content of the body. In the case of the control of water intake the evidence for special detectors, osmoreceptors, and volume receptors, appears even more definitive; these provide information directly proportional to the concentration and volume of water in the body, the two values that appear to be regulated. The complete control systems for food and water intakes consist of detectors, situated centrally or peripherally, integrators, including modulator systems, and effectors. Some elements may be common to the two systems, for instance, those lor gastric distention which inhibit both food and water intake or those for osmotic

Sympathoadrenal System and Response of Heart to Acute Exchange Anemia

This report deals with a study of the relative roles that the sympathetic nervous system and adrenal medulla play in the cardiac responses to experimental anemia.

Diet and temperature effects on excretion of fat-mobilizing substances in rat urine.

Summary The effects have been investigated of 4 diets (high carbohydrate, high protein, high fat and high protein-high fat) and of environmental temperature (5-30°C) on urinary excretion of FMS IA (anorexi-genic) and FMS IB (fat-mobilizing) by the fasting rat. The greatest excretion of FMS IA and FMS IB was observed when the HP-HFD was fed prior to fasting; for FMS IB, the greatest total activity excreted per 24 hours was obtained after the diet highest in non-carbohydrate calories (HFD). Excretion of these materials increased with decreasing environmental temperature. A very marked increase in FMS IB excretion was observed between 10 and 15°C.