Immunohistochemical localization of intracellular progesterone and glucocorticoid receptors in the rabbit lung

Abstract

We have determined the presence and distribution of intracellular progesterone receptors (PRs) and glucocorticoid receptors (GRs) in the lung of adult female rabbits using immunohistochemistry. The effects of ovariectomy and administration of oestradiol benzoate (10 micrograms for 3 consecutive days) upon PR and GR immunoreactivity were also studied. The results demonstrated the presence of both steroid hormone receptors in the female rabbit lung. PR and GR immunoreactivity was predominantly nuclear and located in alveolar epithelial cells and various interstitial cells such as polymorphonuclear leucocytes. Tissue distribution of both receptors was similar in all cases. Oestradiol treatment induced a marked increase in the number of PR immunoreactive cells compared with intact and ovariectomized female animals. Neither ovariectomy nor oestradiol treatment modified the number of GR immunoreactive cells. The presence and localization of intracellular PRs and GRs in several lung cell types suggest that they may play an important role in mediating the effects of progesterone and glucocorticoids in various physiological processes in the rabbit lung. The data also indicated an oestrogen regulation of PRs in the rabbit lung.

Changes in progesterone receptor mRNA content in the rabbit lung during early pregnancy and after sex steroid hormone treatment

“…Our results on the regulation of PR gene expression by sex steroid hormones assessed by PR mRNA content in the lung are in line with data obtained at the protein level by immunohistochemical examination (Camacho-Arroyo et al 1994). It has been reported that oestradiol treatment of ovariectomized rabbits increased the number of PR-immunoreactive cells in the lung as compared with that of ovariectomized animals treated with vehicle alone (Camacho-Arroyo et al 1994).…”

“…Interestingly, in the case of the uterus, no correlation was found between PR mRNA and PR protein content: on day 3 of pregnancy endometrial PR protein was not detectable in spite of the high PR mRNA content (Gutierrez-Sagal et al 1993). Although we observed a correlation between the effects of oestradiol on PR mRNA content and PR protein levels (Camacho-Arroyo et al 1994) in the lung, it is necessary to determine whether this correlation is maintained during early pregnancy in order to understand other aspects of PR gene expression regulation and the physiological meaning of PR changes in the lung during early pregnancy.…”

“…It has been reported that oestradiol treatment of ovariectomized rabbits increased the number of PR-immunoreactive cells in the lung as compared with that of ovariectomized animals treated with vehicle alone (Camacho-Arroyo et al 1994). There is a correlation between the effects of oestradiol on PR gene expression at both the mRNA and protein levels, suggesting that the changes in PR protein content in rabbit lung after sex steroid hormone treatment are the result of modifications at the transcriptional level.…”

“…PRs have been located by immunohistochemistry in several lung cell types such as alveolar epithelial cells, interstitial, endothelial and muscle cells (Camacho-Arroyo et al 1994). It was found that oestradiol treatment of ovariectomized rabbits increased the number of PR-immunoreactive cells in the lung compared with that in ovariectomized animals treated with vehicle (CamachoArroyo et al 1994).…”

Expression of retinoid receptors during rabbit lung development

“…Three RARs and three RXRs have been demonstrated in the developing human lung (Rajatapiti et al, 2005). Our results complete the list of nuclear receptors previously described to be expressed in the rabbit developing lung including pregnane X receptor (Savas et al, 2000), glucocorticoid receptor (GR) (Hummelink and Ballard, 1986), androgen receptor (Giannopoulos and Smith, 1982), thyroid receptor (TR) (Ballard et al, 1984), progesterone receptor (Camacho-Arroyo et al, 1994) and peroxisome proliferator activated receptor (Michael et al, 1997). In both humans (Rajatapiti et al, 2005) and rabbits, developing lungs express receptors TR, RAR, RXR and GR.…”