Expression of sex-steroid receptors and steroidogenic enzymes in the carotid body of adult and newborn male rats

This study describes the localization and pattern of expression of estradiol and progesterone receptors as well as key enzymes for steroid synthesis (i.e. P450 side-chain-cleavage—P450scc, and P450 aromatase—P450Aro) in the carotid body (CB) and superior cervical ganglion (SCG) of adult, newborn and late fetal male rats, using immunohistochemistry, Western blot and real-time RT-PCR. Our results show a constitutive expression of the β estradiol receptor (Erβ) and the 80 kDa and 60 kDa progesterone receptors (PR-A and PR-C) isoforms in the CB, while in the SCG Erα, Erβ, PR-A and PR-C are expressed. While P450Aro staining was negative, P450scc staining was strong both in the SCG and CB. In late fetal and newborn rats, Erα was not detected in the CB or SCG, but a slight staining appeared for P450 aromatase in the CB, and to a lesser extent in SCG. P450scc was strongly expressed in CB and SCG of late fetal and newborn rats. We conclude that the carotid body shows a constitutive expression of Erβ and PR and may be able to synthesize steroids, including estradiol during late fetal life.