Hormonal regulation of androgen, estrogen receptor-α, and progesterone receptor expression in the adult male rabbit brain

Sex hormones regulate a broad range of brain functions beyond reproduction via specific receptors, whose expression can be modulated by hormones. However, the regulation of sex hormone receptors across different brain regions in male rabbits remains unknown. We investigated the effects of two hormone treatments in castrated male rabbits: testosterone propionate (TP) and dihydrotestosterone plus estradiol benzoate (DHT + EB), on androgen receptor (AR), estrogen receptor alpha (ERα), and progesterone receptor (PR) expression in the brain. Adult male New Zealand White rabbits were bilaterally castrated and daily treated with TP or DHT + EB for 16 days. One day after treatments (day 17), AR, ERα, and PR mRNA and protein levels were determined in the olfactory bulb, prefrontal cortex, hippocampus, preoptic area, hypothalamus, mesencephalon, and cerebellum using RT-qPCR and Western blot. AR mRNA levels increased with both treatments in the prefrontal cortex, preoptic area, and the hypothalamus following TP treatment. Notably, AR protein content increased across all regions after TP, and in the olfactory bulb, prefrontal cortex, preoptic area, and hypothalamus following DHT + EB. Both treatments reduced ERα mRNA in the olfactory bulb, hippocampus, preoptic area, hypothalamus, and mesencephalon; DHT + EB also decreased ERα mRNA in the cerebellum, while ERα protein content remained unchanged in all regions. TP and DHT + EB reduced PR mRNA expression in most regions, with DHT + EB showing broader effects. As with ERα, PR protein content showed no significant changes after treatments. These findings indicate that androgens and estrogens regulate AR, ERα, and PR expression, notably affecting AR protein content.