Influence of androgens on plasma concentrations of growth hormone in growing castrated and intact chickens.
Castrated chicks implanted with testosterone or 5 alpha-dihydrotestosterone (5 alpha-DHT) had circulating concentrations of the respective androgen similar to or less than in sham-operated chicks. In castrated chicks, 5 alpha-DHT or 19-nortestosterone (19-NorT) inhibited growth as indicated by body weight, while testosterone and 5 beta-dihydrotestosterone (5 beta-DHT) were without effect. In intact male or female chicks, growth was inhibited by either testosterone or 5 alpha-DHT but was unaffected by 5 beta-DHT or estradiol-17 beta. Plasma concentrations of luteinizing hormone (LH) were reduced in castrated chicks receiving implants of either testosterone or 19-NorT. Only the highest dose of 5 alpha-DHT depressed the circulating concentration of LH; lower doses of 5 alpha-DHT being without effect. During the first 6 weeks of growth, plasma concentrations of GH were unaffected by most steroid treatments (5 alpha-DHT, 5 beta-DHT, low doses of testosterone, estradiol-17 beta) in castrated or in intact male or in female chicks. Similarly, 19-NorT did not affect plasma concentrations of GH in castrated chicks. The high dose of testosterone, however, depressed plasma concentrations of GH in castrated chicks between 2 and 6 weeks of age. Between 8 and 12 weeks of age, all steroids tested, except 5 alpha-DHT, were without effect on plasma concentrations of GH. Plasma concentrations of GH were increased in 5 alpha-DHT-treated chickens. This effect was observed irrespective of dose of 5 alpha-DHT or whether the androgen was administered to castrated or to intact male or to female chicks.
Fennell
M J
MJ
Department of Animal Sciences, Rutgers, State University, New Brunswick, New Jersey 08903.
Johnson
A L
AL
Scanes
C G
CG
D000728:Androgens / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002645:Chickens / Q000097:blood*; D004343:Drug Implants; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009919:Orchiectomy
D000728:Androgens; D004343:Drug Implants; D007986:Luteinizing Hormone; D013006:Growth Hormone