Melvin P. Enns

Contributions of age, sex and degree of fatness on preferences and magnitude estimations for sucrose in humans

Abstract Comparisons of magnitude estimate scaling for six suprathreshold concentrations (0.056–1.0 M) of sucrose by fifth graders, college students, and elderly persons revealed a steeper function for the children but no differences between the other two groups. Higher preferences were reported by males than by females for the sweeter concentrations and degree of fatness was inversely correlated with preference. These data suggest that deficits in sensory coding are not produced by old age and that important differences in sweet preference exist between human males and females.

Naloxone suppresses feeding and drinking but not wheel running in rats.

The effects of naloxone hydrochloride on food and water intake and number of wheel revolutions were measured in male rats. The administration of 10 mg/kg naloxone but not 1 mg/kg suppressed the 3-hr food and water intake in nondeprived rats. Naloxone injections (1 mg/kg or 10 mg/kg) were ineffective in altering the number of wheel revolutions in nondeprived or food deprived rats. These results support the interpretation that the suppressive effects of naloxone previously reported with deprived rats are evident in nondeprived rats and are specific to feeding and drinking.

The contributions of smell and taste to overall intensity: A model

A model is proposed to describe mathematically the integration of olfaction and gustation in producing the sensation of overall intensity or flavor. The basis of this additive model is the premise that the sensationof overall intensity is composed of the summation of the estimates of the intensities of smell and taste. However, since this summation has been consistently shown to be greater than the estimates of the intensity of flavor, the additive model is modified such that the psychophysical functions describing the magnitude estimates of smell and taste are “reduced” when used to predict the overall intensity or flavor. The model’s predictive capacity is demonstrated by the results of a test using the Two-Module Delivery System (Hornung & Enns, 1984) to present the odorant ethyl butyrate and the tastant sucrose. Using all combinations of distilled water and three concentrations of the odorant combined with distilled water and three concentrations of the tastant, subjects used the method of absolute magnitude estimation to scale the intensities of smell, taste, and flavor. Estimates of overall intensity (flavor) were predicted accurately from the intensity ratings given to smell and taste.

Oral glucose tolerance in bulimia

Bulimia, or binge-eating disorder, is an emerging public health problem, which has been thought by some clinicians to be related to hypoglycemic states. To test this hypothesis, the standard oral glucose tolerance test (OCTT) was done in normal weight bulimics and controls. Bulimics showed no ab- normality on the OCTT. There is no clear relationship between reactive hy- poglycemia and bulimia.

Interrelationships among activity, food intake and weight gain in genetically obese and lean Zucker rats

In Experiment 1, food deprivation resulting in a 30% reduction in body weight produced significant increases in wheel running in both obese and lean female Zucker rats. In Experiment 2, a new technique, food contingent activity (FR, VI), dramatically increased wheel running in both obese and lean female Zucker rats. This increase in activity was achieved primarily during the dark period. Regardless of changes in activity levels, food intake and body weight gain remained similar to controls. When food was again available ad lib, activity levels rapidly decreased for obese but not lean rats. These results indicate that behavioral interventions alone are not sufficient to correct the obesity of the genetically obese rat.