title: Early-to-mid gestation fetal testosterone increases right hand 2D:4D finger length ratio in polycystic ovary syndrome-like monkeys.
abstract: A smaller length ratio for the second relative to the fourth finger (2D:4D) is repeatedly associated with fetal male-typical testosterone (T) and is implicated as a biomarker for a variety of traits and susceptibility to a number of diseases, but no experimental human studies have been performed. The present study utilizes the rhesus monkey, a close relative of humans, and employs discrete gestational exposure of female monkeys to fetal male-typical T levels for 15-35 days during early-to-mid (40-76 days; n = 7) or late (94-139 days; n = 7) gestation (term: 165 days) by daily subcutaneous injection of their dams with 10 mg T propionate. Such gestational exposures are known to enhance male-typical behavior. In this study, compared to control females (n = 19), only early-to-mid gestation T exposure virilizes female external genitalia while increasing 2D:4D ratio in the right hand (RH) by male-like elongation of RH2D. RH2D length and 2D:4D positively correlate with androgen-dependent anogenital distance (AG), and RH2D and AG positively correlate with duration of early-to-mid gestation T exposure. Male monkeys (n = 9) exhibit a sexually dimorphic 2D:4D in the right foot, but this trait is not emulated by early-to-mid or late gestation T exposed females. X-ray determined phalanx measurements indicate elongated finger and toe phalanx length in males, but no other phalanx-related differences. Discrete T exposure during early-to-mid gestation in female rhesus monkeys thus appears to increase RH2D:4D through right-side biased, non-skeletal tissue growth. As variation in timing and duration of gestational T exposure alter male-like dimensions of RH2D independently of RH4D, postnatal RH2D:4D provides a complex biomarker for fetal T exposure.
authors.affiliation: Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States of America. aabbott@primate.wisc.edu
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Abbott
authors.forename: Ricki J
authors.initials: RJ
authors.lastname: Colman
authors.forename: Ross
authors.initials: R
authors.lastname: Tiefenthaler
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Dumesic
authors.forename: David H
authors.initials: DH
authors.lastname: Abbott
mesh_terms: D000818:Animals; D004704:Endocrinology; D005260:Female; D005333:Fetus / Q000033:anatomy & histology / Q000187:drug effects*; D050278:Finger Phalanges / Q000033:anatomy & histology / Q000187:drug effects / Q000196:embryology; D005385:Fingers / Q000033:anatomy & histology* / Q000196:embryology*; D050823:Hand Joints / Q000033:anatomy & histology / Q000187:drug effects / Q000196:embryology; D008253:Macaca mulatta; D008297:Male; D011085:Polycystic Ovary Syndrome / Q000473:pathology* / Q000503:physiopathology; D011247:Pregnancy; D012098:Reproduction / Q000187:drug effects; D012727:Sex Characteristics; D013739:Testosterone / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D013739:Testosterone