Effects of maternal undernutrition during lactation on aromatase, estrogen, and androgen receptors expression in rat testis at weaning

Abstract

The goal of this study was to evaluate the effects of maternal malnutrition during lactation on serum levels of testosterone and estradiol, testicular testosterone concentration, aromatase, testicular androgen (AR) and estrogen a (ERa) receptors expression in the pups at weaning. From parturition until weaning, Wistar rats were separated into three groups: (C) control group, with free access to a standard laboratory diet containing 23% protein; protein-energy restricted (PER) group, with free access to an isoenergy and protein-restricted diet containing 8% protein; and energy-restricted (ER) group, receiving standard laboratory diet in restricted quantities, which were calculated according to the mean ingestion of the PER group. All pups were killed at weaning, corresponding to 21 days post partum. Compared with the C group, body weights (CZ48G2 . 3 g; PERZ20G1 . 3 g; ERZ25 . 4G0 . 9 g; P!0 . 01) and testicular weights (CZ0 . 15G0 . 02 g, PERZ0 . 05G0 . 01 g, ERZ0 . 06G 0 . 02 g, P!0 . 001) of both PER and ER groups were lower.However, there was no significant difference in the testicular/body weight ratio in PER and ER groups compared with the C group. The testosterone serum concentration (ng/ml) was significantly higher in the PER group compared with ER and C groups (CZ0 . 09G0 . 012; PERZ0 . 45G0 . 04; ERZ0 . 15G0 . 03, P!0 . 01). Testicular testosterone concentration (CZ2 . 1G0 . 43; PERZ6 . 5G0 . 7; ERZ13G2 . 3, P!0 . 01) was increased in treated groups when compared with controls. The estradiol serum concentration (pg/ml) was lower in both dietary groups (CZ74G 4 . 6; PERZ49G3 . 2; ERZ60G5 . 5, P!0 . 01). The amounts of aromatase mRNA and ERa transcripts were significantly lower (P!0 . 05) in PER and ER groups; conversely AR (both mRNA and protein) was significantly enhanced (P!0 . 05) in treated animals. The nutritional state in early phases of development is important since we have demonstrated here that the maternal malnutrition during lactation leads to alterations in estradiol and testosterone serum concentrations, testicular testosterone concentration, AR and ERa expression together with a decrease of aromatase expression. All together, these changes of steroid status may be deleterious for future germ cell development and reproductive function of these male pups submitted to early malnutrition.

Maternal malnutrition during lactation alters gonadotropin-releasing hormone expression in the hypothalamus of weaned male rat pups

“…9,11 The reduction in body weight observed in this study is in agreement with past results showing that maternal malnutrition during lactation is associated with growth retardation. 9 The late embryonic/early postnatal period is critical for sexual differentiation in mice.…”

“…Weaned pups, whose mothers were malnourished during lactation, present low body weight, alterations in the testis structure, expression of aromatase, estrogen and androgen receptors in testis and in serum leptin levels. [9][10][11] Despite the fact that malnutrition-related reproductive suppression in rats is a well-documented phenomenon, we had no knowledge, until now, on how maternal malnutrition affects GnRH expression in the hypothalamus of weaned pups and its relation with estradiol serum concentrations.…”

Estrogens and male reproduction: a new concept

“…Moreover, it is now clear that not only P.II drives the aromatase gene in rat testis but two additional promoters, P.I.f (brain promoter) and a new one that we called P.I.Tr (testis rat; Silandre D, Delalande C, Carreau S, unpublished results), are involved. We have also demonstrated that the nutritional status of fetuses (43) and aging (Hamden K, Silandre D, Delalande C, El Feki A, Carreau S, unpublished results) can modulate aromatase gene expression in male rats. In mice it has been shown that aromatase expression is controlled by three different promoters, among them a testis-specific promoter (44).…”

Histomorphometric evaluation of the testicular parenchyma of rats submittedto protein restriction during intrauterine and postnatal life

“…According to Teixeira et al (2007), rats whose dams were submitted to protein restriction during lactation had an increase in serum and testicular testosterone. The authors suggested an adaptive mechanism of Leydig cells against the disorders caused by protein restriction.…”