Effect of high-dose liothyronine on semen quality and recovery following withdrawal in rabbits.
Endocrine aspects of the thyroid in the pituitary-thyroid-gonadal axis have been studied extensively, but few controlled studies have been conducted on sperm output in males with hyperthyroidism. The rabbit was used as a model to study the effects of hyperthyroidism induced with supraphysiologic doses of tri-iodothyronine (T(3)). Semen was collected from 18 sexually mature Dutch rabbits for 9 weeks before the experiment to standardize semen collection procedures, and to provide semen data to equalize treatment groups. Controls were continued on the same regimen for 18 weeks, whereas the treatment group received daily T(3) doses of 10 micro /kg per body weight for 5 weeks, followed by 13 weeks of recovery. Feed consumption was reduced precipitously during T(3) treatment, but it recovered rapidly following termination of T(3) administration. Gradual weight loss and recovery accompanied changes in feed consumption. Loss of libido was not detectable with treatment. Sperm output during 9 weeks following T(3) treatment was 46% of that collected during the standardization period. During the last 4 weeks, sperm output had recovered to 88% of pretreatment values, and subsequently, treated males had normal fertility. Histologic sections showed that the thyroid was inhibited by T(3) treatment and that spermatogenesis was moderately depressed. Both recovered by the termination of the experiment. These studies indicate that effects of induced hyperthyroidism on sperm production are transient.
Foote
Robert H
RH
Department of Animal Science, Cornell University, Ithaca, New York 14853, USA.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005298:Fertility / Q000187:drug effects; D007989:Libido / Q000187:drug effects; D008297:Male; D011817:Rabbits; D012661:Semen / Q000187:drug effects* / Q000502:physiology*; D013081:Sperm Motility / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects; D013961:Thyroid Gland / Q000187:drug effects; D020858:Tissue and Organ Harvesting; D014284:Triiodothyronine / Q000008:administration & dosage*
D014284:Triiodothyronine