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. Author manuscript; available in PMC: 2009 May 1.
Published in final edited form as: Horm Behav. 2008 Jan 10;53(5):673–692. doi: 10.1016/j.yhbeh.2007.12.013

Figure 5. GnRH and LH surges are absent in ovariectomized female rats treated with a PR antagonist.

Figure 5

Representative GnRH and LH release profiles of OVX, E2-primed rats (A) and OVX, E2-primed rats treated with ZK98299 (B). A, E2-priming stimulated significant increases in GnRH pulse amplitude commencing at approximately 1600 h, accompanied by a concomitant 3- to 5-fold increase in plasma LH. B, Treatment of E2-primed, OVX rats with ZK98299 prevented this E2-stimulated rise in both GnRH and LH release without affecting pulse frequency. Asterisks represent significant pulses as determined by the ULTRA pulse analysis program. (From Chappell et.al., 2000).