ERα agonists(Northeastern University)

This study aims to investigate how reproductive experience (RE) alters thermal preference and thermoregulation in female mice, with a focus on estrogen receptor alpha (ERα)-expressing neurons in the preoptic area (POA).

Thermal preference and body temperature were measured in female mice with and without RE, and virgin female mice with selective deletion of ERα from the POA (ERα^POA-KO). The number and activity of ERα-expressing POA neurons (ERα^POA) were assessed using immunohistochemistry and in vitro electrophysiology in response to temperature changes and ERα agonist.

We showed that female mice prefer a cooler environment starting from late pregnancy and persisting long term postpartum. Female mice with RE (>4 weeks post-weaning) displayed lower body temperature and a lower thermal preferred temperature, and lost preference for warm environments (30 °C) but preserved avoidance of cold environments (15 °C). This was associated with a significant decrease in the number of ERα^POA neurons. Importantly, virgin female ERα^POA-KO mice displayed lower thermal preferred temperature and impaired warm preference, mimicking RE mice. We further found that distinct ERα^POA subpopulations can be regulated by temperature changes with or without presynaptic blockers, and by ERα agonist. More importantly, RE decreased the number of warm-activated ERα^POA neurons and reduced the excitatory effects of warmth and estrogen-ERα signaling, while cold-activated ERα^POA neurons were slightly enhanced in female mice with RE.

Our results support that the thermosensing ability and estrogenic effects in ERα^POA neurons are regulated by reproductive experience, altering thermal preference.

Estrogen through its receptors, ERα and ERβ, regulate various aspects of spermatogenesis and male fertility. Because the sperm epigenome is an important contributing factor to male fertility, we evaluated the effects of estrogen signaling activation through the ERs on sperm DNA methylome in adult rats. Whole genome-bisulfite sequencing in caudal sperm DNA was performed. The differentially methylated CpG (DMC) sites were validated by pyrosequencing, and the expression of differentially methylated genes (DMGs) was evaluated in testis by quantitative RT-PCR. Activation of ERα signaling brought about large-scale changes in the sperm DNA methylome compared to ERβ. There were 28074 DMCs and 5189 DMGs obtained after ERα agonist 4,4′,4′′-(4-Propyl-[1H] pyrazole-1,3,5-triyl) (PPT) treatment, whereas 1492 DMCs and 336 DMGs for ERβ agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN). In genic regions, most of the DMCs were intronic, followed by promoter and upstream regions. DMCs were distributed around the transcription start site and in transcription factor-binding regions, implicating their plausible role in gene expression regulation. Genes important for spermatogenesis were identified and validated which showed a similar trend of differential methylation as obtained by whole genome-bisulfite sequencing. The expression of the DMGs was also found to be altered in the testis. There was a considerable overlap (14% to 50%) of PPT DMGs with the DMGs reported to be affected in clinical conditions of male infertility. This study highlights the role of ERs in shaping the sperm epigenome and that aberrant estrogen signaling could be a contributing factor in clinical conditions of male infertility.