Stereological Evaluation of the Seminiferous Tubules of Rats after Maternal Undernutrition during the Lactation Period

Perinatal malnutrition programs gene expression of leptin receptors isoforms in testis and prostate of adult rats

The aim of this paper was to evaluate if maternal malnutrition during lactation programs the expression of leptin receptor isoforms in the testes and prostate ventral lobe of adult rats. At delivery, Wistar rats were separated into 3 groups: control group (C) with free access to a standard laboratory diet containing 22% protein; protein-energy restricted group (PER) with free access to an isoenergy and protein-restricted diet containing 8% protein; and energy-restricted group (ER) receiving standard laboratory diet in restricted quantities, which were calculated according to the mean ingestion of the PER group. All animals were sacrificed at 90 days of age. Both PER and ER groups presented low body weight from the first days after birth, however, while the ER group reached the control weight around day 80, the body weight of PER group was significantly lower compared to controls until the day the animals were killed. In relation to tissue weight, only the relative testis weight of the ER group presented an alteration compared to the control group (p<0.03). There was also no alteration in the leptin serum levels among the groups. The main leptin receptors isoforms, OBRa and OBRb were significantly increased in the testis (OBRa: C=0.71±0.10; PER=1.14±0.17; ER=1.92±0.70, p<0.0007, OBRb: C=0.87±0.04; PER=1.20±0.05; ER=1.44±0.17, p<0.001) and prostate (OBRa: C=0.70±0.18; PER=1.30±0.14; ER=1.65±0.22, p<0.014, OBRb: C=0.77±0.14; PER=1.16±0.04; ER=1.30±0.13, p<0.027) of both malnourished groups. However, the testis OBRc (C=1.52±0.06; PER=1.35±0.23; ER=3.50±0.72, p<0.023) and OBRf (C=1.31±0.12; PER=1.66±0.27; ER=3.47±0.55, p<0.009) and prostate OBRc (C=0.48±0.13; ER=1.18±0.34, p<0.01) and OBRf (C=0.73±0.15; PER=0.99±0.11; ER=1.83±0.30, p<0.016) isoforms were significantly increased only in the ER group. The results presented here show for the first time that both testis and prostate leptin receptor isoforms gene expression are programmed by perinatal malnutrition. These data further stress the importance of monitoring maternal and neonatal status, as well as other pathophysiological situations, to combat the appearance of long-term diseases.

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

Gonadotropin-releasing hormone (GnRH) is the key hormone regulating reproduction. Its feedback regulation is exercised by estradiol. The early postnatal period is critical for sexual differentiation. 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 and estradiol serum concentrations of weaned pups. Six pregnant Wistar rats were separated into three groups at delivery with 6 pups each: control group (C) with free access to a standard diet containing 23% protein; protein energy restricted group (PER) with free access to an isoenergy and 8% protein diet; and an energy-restricted (ER) group receiving a standard diet in restricted quantities, which were calculated according to the mean ingestion of the PER group. At 21 days post partum, the animals were killed and the serum estradiol was evaluated by radioimmunoassay. Immunohistochemistry for GNRH was performed. The serum estradiol concentration was decreased in PER and ER groups compared with C (PER, 34%; ER, 19%;P < 0.01) and the staining of GNRH was restricted to arcuate nucleus and median eminence in the control group while in PER and ER stained processes aligned with the third ventricle wall (periventricular nucleus) were present. In conclusion, our data reinforce the concept that the maternal nutritional state during lactation is critical for sexual maturation since maternal malnutrition resulted in a neuron migration delay evidenced by an altered GnRH expression profile, probably a consequence of low estradiol serum levels.