In utero protein restriction causes growth delay and alters sperm parameters in adult male rats

Abstract

Background: Recent studies have supported the concept of "fetal programming" which suggests that during the intrauterine development the fetus may be programmed to develop diseases in adulthood. The possible effects of in utero protein restriction on sexual development of rat male offspring were evaluated in the present study.

Methods: Pregnant Wistar rats were divided into two experimental groups: one group treated with standard chow (SC, n = 8, 17% protein) and the other group treated with hypoproteic chow (HC, n = 10, 6% protein) throughout gestation. After gestation the two experimental groups received standard chow. To evaluate the possible late reproductive effects of in utero protein restriction, the male offspring of both groups were assessed at different phases of sexual development: prepubertal (30 days old); peripubertal (60 days old); adult (90 days old). Student's t-test and Mann-Whitney test were utilized. Differences were considered significant when p < 0.05.

Results: We found that in utero protein restriction reduced the body weight of male pups on the first postnatal day and during the different sexual development phases (prepubertal, peripubertal and adult). During adulthood, Sertoli cell number, sperm motility and sperm counts in the testis and epididymal cauda were also reduced in HC. Furthermore, the numbers of sperm presenting morphological abnormalities and cytoplasmic drop retention were higher in HC.

Conclusions: In conclusion, in utero protein restriction, under these experimental conditions, causes growth delay and alters male reproductive-system programming in rats, suggesting impairment of sperm quality in adulthood.

Figure 1

Histopathological analysis of seminiferous epithelium. Rats at 30-day-old (A, B), 60-day-old (C, D), 90-day-old (E, F). Photomicrograph of testis sections from HP group (B, D, F) and SC group (A, C, E). H&E stain. 200x magnification. A, B: Note the presence of immature germ cells within the lumen (asterisks) and acidophilic cells (arrows). A-F: tubular lumen (lu), interstitial tissue (in), seminiferous epithelium (ep).

Figure 2

Sperm motility assessment. Sperm motility of 90-day-old animals from the standard chow group - SC and hypoproteic chow group - HC (n = 10 per group). Type A sperm (mobile with progressive trajectory), type B sperm (mobile with non-progressive trajectory), type C sperm (immobile). Values expressed as median and interquartile intervals, Mann-Whitney test, *p < 0.05.

Figure 3

Serum hormone levels and intratesticular testosterone concentration. Serum testosterone levels (A), intratesticular testosterone levels (B), serum LH levels (C) and serum FSH levels (D) of 90-day-old animals from the standard chow group - SC and hypoproteic chow group - HC. Values expressed as mean ± SEM. Mann-Whitney test.