title: Sexual maturation modulates expression of nuclear receptor types in laser-captured single cells of the cichlid (Oreochromis niloticus) pituitary.
abstract: 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) alpha, beta, and gamma; androgen receptors (ARs) a and b; glucocorticoid receptors (GRs) 1, 2a, and 2b; and thyroid hormone receptors (TRs) alpha1, alpha2, and beta] in pituitary cells of immature (IM) and mature (M) male tilapia, Oreochromis niloticus. In the two reproductive stages, ACTH cells expressed only ERbeta, whereas all other pituitary cell types expressed ERalpha + beta, and a subpopulation coexpressed ARa, ARb, GR1, GR2b, and TRbeta but lacked ERgamma, GR2a, TRalpha1, and TRalpha2. 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 ERbeta, and TSH cells (IM 19.2% vs. M 0.0%) and MSH cells (IM 25.6% vs. M 0.0%) with ERalpha + TRbeta. A high percentage of FSH cells in IM males expressed ERbeta (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 ERalpha + beta 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.
authors.affiliation: School of Medicine and Health Sciences, Monash University, 46150 Bandar Sunway, Selangor, Malaysia.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitahashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Soga
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Ishwar
authors.initials: I
authors.lastname: Parhar
mesh_terms: D000818:Animals; D023681:Cichlids / Q000235:genetics*; D047628:Estrogen Receptor alpha / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics / Q000378:metabolism; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D005640:Follicle Stimulating Hormone / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006066:Gonads / Q000166:cytology / Q000378:metabolism; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007834:Lasers; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism; D011388:Prolactin / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D011960:Receptors, Estrogen / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012741:Sexual Maturation; D037021:Thyroid Hormone Receptors alpha / Q000235:genetics / Q000378:metabolism; D037042:Thyroid Hormone Receptors beta / Q000235:genetics / Q000378:metabolism; D013972:Thyrotropin / Q000235:genetics / Q000378:metabolism