Sexual Maturation Modulates Expression of Nuclear Receptor Types in Laser-Captured Single Cells of the Cichlid (Oreochromis niloticus) Pituitary

• Published in: Endocrinology (Philadelphia) 2007-12, Vol.148 (12), p.5822-5830
• Main Authors: Kitahashi, Takashi, Ogawa, Satoshi, Soga, Tomoko, Sakuma, Yasuo, Parhar, Ishwar
• Format: Article
• Language: English
• Subjects: Adrenocorticotropic hormone; Androgen receptors; Animals; Biological and medical sciences; Cichlidae; Cichlids - genetics; Estrogen Receptor alpha - genetics; Estrogen Receptor beta - genetics; Estrogen Receptor beta - metabolism; Estrogen receptors; Estrogens; Fish Proteins - genetics; Fish Proteins - metabolism; Follicle Stimulating Hormone - genetics; Follicle Stimulating Hormone - metabolism; Follicle-stimulating hormone; Freshwater; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Glucocorticoid receptors; Glucocorticoids; Glycoproteins - genetics; Glycoproteins - metabolism; Gonads - cytology; Gonads - metabolism; Growth Hormone - genetics; Growth Hormone - metabolism; Growth hormones; Hormones; Immunohistochemistry; In Situ Hybridization; Lasers; Luteinizing hormone; Luteinizing Hormone - genetics; Luteinizing Hormone - metabolism; Male; Males; Molecular Sequence Data; Nuclear receptors; Oreochromis niloticus; Pituitary; Pituitary Gland - cytology; Pituitary Gland - metabolism; Pituitary Hormones - genetics; Pituitary Hormones - metabolism; Prolactin; Prolactin - genetics; Prolactin - metabolism; Real time; Receptors; Receptors, Androgen - genetics; Receptors, Cytoplasmic and Nuclear - genetics; Receptors, Estrogen - genetics; Reverse Transcriptase Polymerase Chain Reaction; Sexual Maturation; Steroids; Subpopulations; Thyroid; Thyroid gland; Thyroid hormone receptors; Thyroid Hormone Receptors alpha - genetics; Thyroid Hormone Receptors alpha - metabolism; Thyroid Hormone Receptors beta - genetics; Thyroid Hormone Receptors beta - metabolism; Thyroid hormones; Thyroid-stimulating hormone; Thyrotropin - genetics; Thyrotropin - metabolism; Tilapia; Vertebrates: endocrinology
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2007-0311

The role of steroid/thyroid hormones in the regulation of endocrine cells at the level of the pituitary has remained unclear. Therefore, using single-cell quantitative real-time PCR, we examined absolute amounts of transcripts for nuclear receptors [estrogen receptors (ERs) α, β, and γ; androgen receptors (ARs) a and b; glucocorticoid receptors (GRs) 1, 2a, and 2b; and thyroid hormone receptors (TRs) α1, α2, and β] in pituitary cells of immature (IM) and mature (M) male tilapia, Oreochromis niloticus. In the two reproductive stages, ACTH cells expressed only ERβ, whereas all other pituitary cell types expressed ERα + β, and a subpopulation coexpressed ARa, ARb, GR1, GR2b, and TRβ but lacked ERγ, GR2a, TRα1, and TRα2. IM males had high percentages of LH cells (IM 46.0% vs. M 10.0%), GH cells (IM 23.3% vs. M 7.9%), and prolactin cells (IM 68.8% vs. M 6.0%) with ERβ, and TSH cells (IM 19.2% vs. M 0.0%) and MSH cells (IM 25.6% vs. M 0.0%) with ERα + TRβ. A high percentage of FSH cells in IM males expressed ERβ (IM 46.9% vs. M 18.8%), and FSH cells in M males showed significantly high GR1 transcripts (IM 76.0 ± 5.0 vs. M 195.0 ± 10.7 copies per cell; P < 0.05), suggesting that FSH cells are regulated differently in the two reproductive stages. Coexpression of ERα + β in high percentages of cells of the GH family (GH, IM 43.8% vs. M 14.3%; prolactin, IM 8.3% vs. M 59.7%; somatolactin, IM 22.2% vs. M 42.2%) suggests that the expression of both ERs is important for functionality. Thus, differential coexpression of genes for nuclear receptors in subpopulations of pituitary cell types suggests multiple steroid/thyroid hormone regulatory pathways at the level of the pituitary during the two reproductive stages.