title: An investigation of the effectiveness of testosterone implants in combination with the prolactin inhibitor quinagolide in the suppression of spermatogenesis in men.
abstract: BACKGROUND
  Administration of testosterone inhibits gonadotrophin secretion and spermatogenesis in men but the degree of response is highly variable. This treatment also stimulates prolactin, itself a progonadal hormone in animals. This study investigated whether concomitant suppression of prolactin (PRL) with the non-ergot, dopamine receptor agonist quinagolide (Q), would enhance the efficacy of testosterone in its inhibition of spermatogenesis in healthy eugonadal men.
  
  
  METHODS
  A total of 46 men were randomized to three treatment groups: Group 1, T1200: 1200 mg testosterone implant plus daily oral placebo; Group 2, T1200 + Q: 1200 mg testosterone plus oral Q 75 microg/day; Group 3, T800 + Q: testosterone 800 mg plus oral Q 75 microg/day. After an initial pre-treatment period of 4 weeks, subjects were treated for 24 weeks followed by an 8-week recovery period.
  
  
  RESULTS
  The total numbers of subjects that achieved severe oligospermia (< or =10(6)/ml including azoospermia) from weeks 8-16 were 11/13 (85%), 11/12 (92%), 8/13 (61.5%) in the three groups respectively.
  
  
  CONCLUSIONS
  The results show that inhibition of PRL does not to confer additional efficacy in spermatogenic suppression in men. However, Q did not totally block PRL secretion in the subjects, possibly because testosterone replacement itself stimulated PRL by a direct action on the lactotroph, thus the effectiveness of dual inhibition of gonadotrophin and PRL could not be fully investigated.
authors.affiliation: MRC Human Reproductive Sciences Unit, The University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK.
authors.forename: W Morton
authors.initials: WM
authors.lastname: Hair
authors.forename: Frederick C W
authors.initials: FC
authors.lastname: Wu
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Lincoln
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000634:Aminoquinolines / Q000008:administration & dosage*; D000728:Androgens / Q000008:administration & dosage*; D018491:Dopamine Agonists / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D004357:Drug Synergism; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000037:antagonists & inhibitors / Q000097:blood; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000037:antagonists & inhibitors*; D013091:Spermatogenesis / Q000187:drug effects*; D013739:Testosterone / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D000634:Aminoquinolines; D000728:Androgens; D018491:Dopamine Agonists; D004343:Drug Implants; D013739:Testosterone; C046650:quinagolide; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone