title: Prolonged hypothyroidism severely reduces ovarian follicular reserve in adult rats.
abstract: BACKGROUND
  There is substantial evidence both in humans and in animals that a prolonged reduction in plasma thyroid hormone concentration leads to reproductive problems, including disturbed folliculogenesis, impaired ovulation and fertilization rates, miscarriage and pregnancy complications. The objective of the present study is to examine the consequences of chronic hypothyroidism, induced in adulthood, for the size of the ovarian follicle pool. In order to investigate this, adult female rats were provided either a control or an iodide deficient diet in combination with perchlorate supplementation to inhibit iodide uptake by the thyroid. Sixteen weeks later animals were sacrificed. Blood was collected for hormone analyses and ovaries were evaluated histologically.
  
  
  RESULTS
  At the time of sacrifice, plasma thyroid-stimulating hormone concentrations were 20- to 40-fold increased, thyroxine concentrations were negligible while tri-iothyronin concentrations were decreased by 40% in the hypothyroid group, confirming that the animals were hypothyroid. Primordial, primary and preantral follicle numbers were significantly lower in the hypothyroid ovaries compared to the euthyroid controls, while a downward trend in antral follicle and corpora lutea numbers was observed. Surprisingly the percentage of atretic follicles was not significantly different between the two groups, suggesting that the reduced preantral and antral follicle numbers were presumably not the consequence of increased degeneration of these follicle types in the hypothyroid group. Plasma anti-Müllerian hormone (AMH) levels showed a significant correlation with the growing follicle population represented by the total ovarian number of primary, preantral and antral follicles, suggesting that also under hypothyroid conditions AMH can serve as a surrogate marker to assess the growing ovarian follicle population.
  
  
  CONCLUSIONS
  The induction of a chronic hypothyroid condition in adult female rats negatively affects the ovarian follicular reserve and the size of the growing follicle population, which may impact fertility.
authors.affiliation: Human and Animal Physiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.|College of Animal Science, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Meng
authors.affiliation: Human and Animal Physiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.|Institut für Experimentelle Endokrinologie, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
authors.forename: Eddy
authors.initials: E
authors.lastname: Rijntjes
authors.affiliation: Human and Animal Physiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.
authors.forename: Hans J M
authors.initials: HJ
authors.lastname: Swarts
authors.affiliation: Human and Animal Physiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: Keijer
authors.affiliation: Human and Animal Physiology, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands. katja.teerds@wur.nl.
authors.forename: Katja J
authors.initials: KJ
authors.lastname: Teerds
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000097:blood; D004195:Disease Models, Animal; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D007037:Hypothyroidism / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D006080:Ovarian Follicle / Q000473:pathology / Q000503:physiopathology*; D065851:Ovarian Reserve; D010053:Ovary / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D013963:Thyroid Hormones / Q000097:blood; D013972:Thyrotropin / Q000097:blood
chemical_list: D012739:Gonadal Steroid Hormones; D013963:Thyroid Hormones; D054304:Anti-Mullerian Hormone; D013972:Thyrotropin
keywords: AMH; Follicular atresia; Growing follicle population; Hypothyroidism; Ovary; Primordial follicle reserve