title: Orchidectomy of middle-aged rats decreases liver deiodinase 1 and pituitary deiodinase 2 activity.
abstract: Endogenous androgens are involved in regulation of thyroid function and metabolism of thyroid hormones. As serum testosterone level progressively declines with age, this regulation may change. We tested how androgen deprivation, achieved by orchidectomy, affects thyroid homeostasis in middle-aged rats. Fifteen-month-old Wistar rats were orchidectomized (Orx) or sham-operated under ketamine anesthesia (15 mg/kg body weight). Five weeks after the surgery, animals were decapitated. Thyroids were used for histomorphometric and ultrastructural examinations and together with livers and pituitaries for real-time quantitative PCR and deiodinase (DIO) activity measurements. Serum testosterone, TSH, l-thyroxine (T(4)), and cholesterol (Chol) levels were determined. As expected, middle-aged control rats had lower (P<0.05) testosterone and T(4) compared with 3-month-old males. In the Orx middle-aged group, we detected diminished serum testosterone (P<0.05), no change in TSH and T(4) levels, and higher Chol level (P<0.05), in comparison with age-matched controls. Histomorphometric analysis of thyroid tissue revealed decreased relative volume densities of follicles and colloid (P<0.05). Relevant gene expressions and DIO1 enzyme activity were not changed in the thyroids of Orx rats. Liver Dio1 gene expression and DIO1 activity were decreased (P<0.05) in comparison with the control values. Pituitary levels of TSHβ, Dio1, and Dio2 mRNAs did not change, while DIO2 activity decreased (P<0.05). In conclusion, orchidectomy of middle-aged rats affected thyroid structure with no effect on serum T(4) and TSH. However, decreased liver DIO1 and pituitary DIO2 enzyme activities indicate compensatory-adaptive changes in local T(3) production.
authors.affiliation: Department of Cytology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Despot Stefan Boulevard, Belgrade, Serbia. brankasj@ibiss.bg.ac.rs
authors.forename: Branka
authors.initials: B
authors.lastname: Sosic-Jurjevic
authors.forename: Branko
authors.initials: B
authors.lastname: Filipovic
authors.forename: Kostja
authors.initials: K
authors.lastname: Renko
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ajdzanovic
authors.forename: Milica
authors.initials: M
authors.lastname: Manojlovic-Stojanoski
authors.forename: Verica
authors.initials: V
authors.lastname: Milosevic
authors.forename: Josef
authors.initials: J
authors.lastname: Köhrle
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D002784:Cholesterol / Q000097:blood; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D007453:Iodide Peroxidase / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000033:anatomy & histology / Q000201:enzymology*; D008297:Male; D009919:Orchiectomy; D010902:Pituitary Gland / Q000033:anatomy & histology / Q000201:enzymology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000097:blood; D013961:Thyroid Gland / Q000033:anatomy & histology / Q000201:enzymology; D013974:Thyroxine / Q000097:blood; D000097564:Iodothyronine Deiodinase Type II
chemical_list: D002784:Cholesterol; D007453:Iodide Peroxidase; D013739:Testosterone; D013974:Thyroxine; D000097564:Iodothyronine Deiodinase Type II; C109812:iodothyronine deiodinase type I