Estrogen receptor shapes the adolescent brain

Puberty is a period of profound change. Hormones like estrogen don’t only trigger physical development; they also influence how brain circuits for social and sexual behavior mature. Exactly how this works at the cellular level has been largely unclear until now.

A study published in eLife examined the hypothalamus of mice throughout adolescence. Using single-cell RNA sequencing, which maps gene activity in individual cells, the researchers tracked how gene expression changed in a brain region called the medial preoptic area. This region is critical for mating behavior and social interaction.

Estrogen receptor 1 as a switch

The findings point to a central role for estrogen receptor 1 (Esr1), a protein inside cells that responds to the hormone estrogen. When Esr1 was switched off in specific inhibitory neurons (GABAergic neurons), the maturation of behavioral patterns that normally develop during adolescence stalled. This applied to both male and female mice, though through distinct genetic pathways in each sex.

Notably, the same disruption did not occur when Esr1 was removed from excitatory neurons (glutamatergic neurons). The effect is therefore specific to the inhibitory cells in this brain region.

Relevance for hormones and brain aging

From a longevity perspective, this matters because estrogen signaling is not exclusive to puberty. The same hormone and receptor play a role later in life in cognitive function, mood regulation, and potentially in the pace of brain aging. How Esr1 activity in brain cells changes across the lifespan, and what that means for cognitive resilience in later life, is a natural next step from this research.

The study provides new detail on how sex-specific gene networks in the brain are organized and opens avenues for research into hormone-dependent vulnerabilities of the aging brain.

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