title: Androgen receptor CAG repeat polymorphism and hypothalamic-pituitary-gonadal function in Filipino young adult males.
abstract: OBJECTIVE
  Testosterone (T), the primary androgenic hormone in males, is stimulated through pulsatile secretion of LH and regulated through negative feedback inhibition at the hypothalamus and pituitary. The hypothalamic-pituitary-gonadal (HPG) axis also controls sperm production through the secretion of follicle-stimulating hormone (FSH). Negative feedback in the HPG axis is achieved in part through the binding of T to the androgen receptor (AR), which contains a highly variable trinucleotide repeat polymorphism (AR-CAGn). The number of repeats in the AR-CAGn inversely correlates with transcriptional activity of the AR. Thus, we predicted longer AR-CAGn to be associated with higher T, LH, and FSH levels.
  
  
  METHODS
  We examined the relationship between AR-CAGn and total plasma T, LH, and FSH, as well as "bioavailable" morning (AM-T) and evening (PM-T) testosterone in 722 young (21.5 ± 0.5 years) Filipino males.
  
  
  RESULTS
  There was no relationship between AR-CAGn and total T, AM-T, or LH (P > .25 for all). We did observe a marginally non-significant (P = .066) correlation between AR-CAGn and PM-T in the predicted direction, and a negative correlation between AR-CAGn and FSH (P = .005).
  
  
  CONCLUSIONS
  Our results both support and differ from previous findings in this area, and study parameters that differ between our study and others, such as participant age, sample time, and the role of other hormones should be considered when interpreting our findings. While our data point to a modest effect of AR-CAGn on HPG regulation at best, the AR-CAGn may still affect somatic traits by regulating androgenic activity at peripheral tissues.
authors.affiliation: Department of Anthropology, Northwestern University, Evanston, 60208, Illinois.
authors.forename: Calen P
authors.identifier: http://orcid.org/0000-0002-0550-7949
authors.initials: CP
authors.lastname: Ryan
authors.affiliation: Department of Anthropology, Northwestern University, Evanston, 60208, Illinois.|Institute for Policy Research, Northwestern University, Evanston, 60208, Illinois.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: McDade
authors.affiliation: Department of Anthropology, University of Notre Dame, South Bend, Indiana.
authors.forename: Lee T
authors.initials: LT
authors.lastname: Gettler
authors.affiliation: Department of Anthropology, University of Washington, Seattle, Washington.
authors.forename: Dan T A
authors.identifier: http://orcid.org/0000-0003-0812-1862
authors.initials: DT
authors.lastname: Eisenberg
authors.affiliation: Division of Endocrinology, Metabolism, and Molecular Medicine, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, 60611, Illinois.
authors.forename: Margarita
authors.initials: M
authors.lastname: Rzhetskaya
authors.affiliation: Department of Anthropology, Northwestern University, Evanston, 60208, Illinois.|Division of Endocrinology, Metabolism, and Molecular Medicine, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, 60611, Illinois.|Northwestern University Feinberg School of Medicine, Center for Genetic Medicine, Chicago, 60611, Illinois.
authors.forename: M Geoffey
authors.initials: MG
authors.lastname: Hayes
authors.affiliation: Department of Anthropology, Northwestern University, Evanston, 60208, Illinois.|Institute for Policy Research, Northwestern University, Evanston, 60208, Illinois.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Kuzawa
mesh_terms: D006066:Gonads / Q000502:physiology*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D010679:Philippines; D011110:Polymorphism, Genetic; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D018911:Trinucleotide Repeats; D055815:Young Adult
chemical_list: C410798:AR protein, human; D011944:Receptors, Androgen
keywords: HPG axis regulation; androgen receptor; follicle-stimulating hormone; short tandem repeats; testosterone