Estrogen receptor mRNA alterations in the developing rat hippocampus

Area of Science:

• Neuroscience
• Developmental Biology
• Endocrinology

Background:

• Estrogen receptor (ER) protein levels are transiently elevated in the postnatal rat hippocampus.
• This suggests the hippocampus is sensitive to estrogenic influences during a critical period of sexual differentiation.

Purpose of the Study:

• To investigate if changes in ER gene expression explain the developmental pattern of hippocampal ER.
• To examine ER mRNA levels in the early postnatal and adult rat hippocampus.

Main Methods:

• Quantitative RNase protection assay.
• In situ hybridization histochemistry.

Main Results:

• Hippocampal ER mRNA levels peaked on postnatal day 4 (PND-4) and declined by PND-10.
• Adult male hippocampal ER mRNA levels were significantly lower than PND-4 levels.
• In situ hybridization showed high ER mRNA in CA3 pyramidal layer at PND-4, with minimal levels in adults.

Conclusions:

• The ontogeny of hippocampal ER is regulated by changes in ER gene expression.
• Specific neuronal populations in the hippocampus show dynamic ER gene expression during development.