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.
Ramos
Cristiane da Fonte
Cda F
Departamento de Anatomia, Unidade de Pesquisa Urogenital, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brasil. cristiane@pesquisador.cnpq.br
Lima
Sebastião Sérgio
SS
Rocha
Michael Luis Martins
ML
Lotufo
Bruna Messias
BM
Sampaio
Francisco José Barcelos
FJ
Barradas
Penha Cristina
PC
Tenório
Frank
F
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000737:chemistry; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D004958:Estradiol / Q000097:blood; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis*; D007031:Hypothalamus / Q000737:chemistry*; D007150:Immunohistochemistry; D007774:Lactation; D008297:Male; D044342:Malnutrition / Q000150:complications*; D008473:Median Eminence / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation / Q000502:physiology*; D014886:Weaning
D004044:Dietary Proteins; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol