Figure 3.

Secretory pattern of LH in individual ewes showing the effect of a high dose of E₂BSA on the preovulatory-like surge of LH induced by E₂. In a preliminary study the magnitude of the LH surge in response to E₂ was determined; ewes were ranked based in the mean LH during the surge induced by E₂, then assigned to either a high (LH profiles in the left panel) or a low (LH profiles in the right panel) E₂-responsive group (n = 6 per group). Approximately one month later, ewes (n = 12) were given an im injection of 25 μg E₂ and then assigned alternatively within each responsive group, to receive an im injection of 60 mg E₂BSA (open squares) 8 h after injection of E₂ or saline solution (placebo; closed diamonds). The negative impact to E₂BSA on the massive release of LH induced by E₂ was more pronounced in ewes classified as highly responsive to E₂.