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Sexual differentiation of copulatory behaviour in the male chick requires gonadal steroids

N Sayag1, N Snapir, E Arnon

  • 1Department of Animal Science, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.

British Poultry Science
|July 1, 1991
PubMed

Insights

Embryonic exposure to antioestrogens and aromatase inhibitors suppressed male copulatory activity in chicks. This suggests that embryonic oestradiol is crucial for the normal development of male sexual behaviors.

Area of Science:

  • Endocrinology
  • Developmental Biology
  • Animal Behavior

Background:

  • Sexual behavior differentiation in birds is influenced by embryonic hormone exposure.
  • Oestradiol and testosterone are key steroid hormones regulating sexual development and behavior.

Purpose of the Study:

  • To investigate the role of embryonic oestradiol in the development of male copulatory activity (MCA) in young male chicks.
  • To determine the effects of antioestrogens, aromatase inhibitors, and androgen antagonists on embryonic development of MCA.

Main Methods:

  • Embryonic injections were administered to young male chicks with tamoxifen (TAM), CI-628 (antioestrogens), ATD (aromatase inhibitor), antibodies to oestradiol (E), flutamide (F, androgen antagonist), or antibodies to testosterone (T).
  • Male copulatory activity (MCA) was assessed in young male chicks.
  • Embryonic plasma luteinizing hormone (LH) levels were measured 24 and 48 hours after TAM injection.

Main Results:

  • Embryonic injections of TAM, CI-628, ATD, or anti-oestradiol antibodies significantly suppressed MCA.
  • Flutamide and anti-testosterone antibodies only slightly suppressed MCA.
  • TAM did not affect embryonic plasma LH levels.

Conclusions:

  • Embryonic oestradiol plays a critical role in the normal differentiation of male copulatory activity.
  • Androgens appear to have a less significant role in the embryonic programming of MCA compared to oestradiol.

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