Effects of undernutrition on serum and testicular testosterone levels and sexual function in adult rats.

The aim of this study was to evaluate testosterone concentrations, sexual behavior, and androgen receptor protein level in the testes of rats submitted to protein- and energy-restricted diets during 30 days. Adult male Wistar rats were assigned to one of the following groups: (C) control, diet with 23% of protein; (PR) protein-restricted, diet with 8% of protein; (ER) energy-restricted, diet with 23% of protein in restricted quantities. Mount number, ejaculation latencies and copulatory efficiency were evaluated to determine sexual behavior. At the end of the experiment, the animals were sacrificed to determine serum and testicular testosterone concentrations as well as testicular androgen receptor protein level. Compared to the C group, the ER group presented a significant decrease in body (36%), testis (20%) and epididymis (14%) weights in serum (78%) and testicular (68%) testosterone concentrations as well as in copulatory efficiency (26%). On the other hand, the ER group presented a significant increase in mount number (114%) and ejaculatory latency (62%). The androgen receptor protein levels were significantly reduced in both PR and ER groups (41% and 74%, respectively). This is the first paper to demonstrate that the effect of undernutrition on reproduction is not related to reduced protein intake but caloric restriction. Also, in caloric restriction, there is a relationship between sex behavior, androgen receptors, and testosterone concentration.