Regulation of reproductive seasonality in the red deer hind: oestradiol-dependent and -independent influences on the patterns of LH concentrations

J Reprod Fertil. 1996 Mar;106(2):213-20. doi: 10.1530/jrf.0.1060213.

Abstract

The control of reproductive seasonality was studied in farmed adult red deer hinds that had been either ovariectomized or ovariectomized and oestradiol-treated (s.c. implants). The breeding season, delineated by progesterone secretion in intact hind herdmates, was characterized by high (mean 0.6, range 0.1-2.5 ng ml-1 plasma) LH concentrations in ovariectomized oestradiol-treated hinds. In contrast, during the non-breeding season plasma LH concentrations in these animals were significantly lower (mean 0.1, range 0-0.9 ng ml-1 plasma). LH secretion in ovariectomized untreated hinds also displayed a marked seasonal pattern, approximately the inverse of daily photoperiod (that is, a winter peak and summer trough). The pituitary LH response to 10 micrograms exogenous GnRH was also maximal during the breeding season in ovariectomized (mean 7.4, range 1.2-14.6 ng ml-1) and ovariectomized, oestradiol-treated (mean 16.4, range 1.4-32.3 ng ml-1) hinds. These results indicate that LH secretion in the hind is regulated by both steroid-dependent and -independent mechanisms.

MeSH terms

  • Animals
  • Deer / blood
  • Deer / physiology*
  • Estradiol / blood
  • Estradiol / pharmacology
  • Estradiol / physiology*
  • Female
  • Gonadotropin-Releasing Hormone / pharmacology
  • Luteinizing Hormone / blood
  • Luteinizing Hormone / metabolism*
  • Ovariectomy
  • Pituitary Gland / drug effects
  • Pituitary Gland / metabolism
  • Reproduction / physiology*
  • Seasons*

Substances

  • Gonadotropin-Releasing Hormone
  • Estradiol
  • Luteinizing Hormone