Full Papers

Effect of dehydroepiandrosterone on protein and fat digestibility, body protein and muscular composition in high-fat-diet-fed old rats

Fátima Pérez de Heredia^a1, David Cerezo^a1, Salvador Zamora^a1 and Marta Garaulet^a1 c1

^a1 Department of Physiology, University of Murcia, Paseo Rector Sabater s/n, Campus de Espinardo, 30100 Murcia, Spain

Abstract

The main objective of the present study was to examine the effects of dehydroepiandrosterone (DHEA) on the digestive efficiency of dietary protein and fat. Second, we analysed the specific changes in muscle composition induced by the hormone. DHEA was given in the diet (0·5 %, w/w) to 75-week-old, high-fat-fed Sprague–Dawley rats (n 11) for 13 weeks; age- and weight-matched rats fed on the same diet without DHEA supplementation were used as controls (n 10). To determine dietary protein and fat apparent digestibility coefficients, 1-week 24 h faecal depositions were collected. In parallel, urine N was assessed. These assays were performed twice, in the short term (2-week treatment) and in the long term (13-week treatment). Body and gastrocnemius muscle compositions were also analysed. The present results show that DHEA decreased energy intake, body weight, body fat, adipocyte size and number (P < 0·001). The feed efficiency ratio indicates that DHEA-treated rats were less efficient in transforming nutrients fed into their own biomass. Also, a short-term reduction in protein digestibility (P < 0·05) and in body-protein degradation (P < 0·01) was found in DHEA-treated rats, resulting in an increased content of body protein (P < 0·05). Gastrocnemius muscles were smaller, as a result of fat (P < 0·05) but not protein reduction. In conclusion, we confirm the slimming effect of DHEA and, for the first time, we demonstrate that DHEA has an effect at the digestive level. The anti-obesity properties of DHEA could be related to a reduction in protein digestibility in the short term and a protective effect on body protein with a selective mass loss from body fat.

(Received March 06 2006)

(Revised September 27 2006)

(Accepted October 04 2006)

Key Words:

• Dehydroepiandrosterone;
• Digestibility;
• Body protein;
• Gastrocnemius muscle;
• Obesity;
• High-fat diets

Correspondence:

^c1 *Corresponding author: Dr M. Garaulet, fax +34 968 36 39 63, email garaulet@um.es

Footnotes

Abbreviations: DHEA, dehydroepiandrosterone; DHEA-S, dehydroepiandrosterone sulfate; FER, feed efficiency ratio; NPU, net protein utilisation