Showing papers by "John W. Erdman published in 2001"

Testosterone and Food Restriction Modulate Hepatic Lycopene Isomer Concentrations in Male F344 Rats

Abstract: We previously demonstrated that the castration of male rats profoundly increases hepatic lycopene compared with intact controls. Here we further characterized the role of testosterone in modulating hepatic lycopene accumulation and isomer patterns in male rats. Furthermore, because castration significantly decreases ad libitum food consumption, we investigated the influence of food restriction on lycopene metabolism. Forty male F344 rats 8 wk of age were randomly assigned to one of four treatments (n = 10/group): 1) intact, free access to food, 2) castration, free access to food, 3) castration plus testosterone implants, free access to food and 4) intact, 20% food restricted. All rats were fed an AIN-based diet with 0.25 g lycopene (as 10% water-soluble beadlets)/kg diet for 3 wk. Serum testosterone was 5.31 +/- 1.46 nmol/L in intact controls allowed free access to food, reduced in castrated animals (0.52 +/- 0.10, P < 0.0001 versus controls) and intact, food-restricted rats (1.53 +/- 0.49 nmol/L, P < 0.0001 versus controls) and greater (17.23 +/- 3.09 nmol/L) in castrated rats administered testosterone (P < 0.0001 versus controls). Castrated rats accumulated approximately twice as much liver lycopene (74.5 +/- 8.5 nmol/g; P < 0.01 versus controls) as intact rats allowed free access to food (39.5 +/- 5.0) despite 13% lower dietary lycopene intake (P < 0.001; 3.38 +/- 0.07 versus 3.95 +/- 0.06 mg lycopene/d). Testosterone replacement in castrated rats returned liver lycopene concentrations (32.5 +/- 5.5 nmol lycopene/g with 3.76 +/- 0.05 mg dietary lycopene/d) to those observed in intact rats. Food restriction resulted in a 20% decrease in lycopene intake but significantly increased liver lycopene by 68% (66.3 +/- 7.9 nmol lycopene/g with 3.38 +/- 0.00 mg lycopene/d) compared with controls and castrated rats administered testosterone. These results suggest that androgen depletion and 20% food restriction increase hepatic lycopene accumulation. We hypothesize an endocrine and dietary interaction, where higher androgen concentrations and greater energy intake may stimulate lycopene metabolism and degradation.

Nutrition: A Reservoir for Integrative Science

Abstract: In the last twenty years, powerful new molecular techniques were introduced that made it possible to advance knowledge in human biology using a reductionist approach. Now, the need for scientists to deal with complexity should drive a movement toward an integrationist approach to science. We propose that nutritional science is one of the best reservoirs for this approach. The American Society for Nutritional Sciences can play an important role by developing and delivering a cogent message that convinces the scientific establishment that nutrition fills this valuable niche. The society must develop a comprehensive strategy to develop our image as the reservoir for life sciences integration. Our efforts can start with our national meeting and publications, with the research initiatives for which we advocate, with our graduate training programs and with the public relations image we project for ourselves. Defining the image and future directions of nutrition as the discipline that can integrate scientific knowledge from the cell and molecule to the whole body and beyond to populations can be the most important task that our society undertakes. If we do not effectively meet this challenge, a golden opportunity will pass to others and nutritional scientists will be left to follow them.