Fig. 4.

Plasma estradiol concentration during chronic, cyclic estradiol treatment. Plasma samples were taken in the 9th cycle of subcutaneous injection of 2 μg estradiol benzoate (EB) once each 4th day, at the middle of the light phase of day 2 (D2, arrow), which models diestrus 2 in intact rats. D4 of the treatment regimen modeled estrus based on maximally decreased eating behavior and increased sexual receptivity in progesterone-primed rats. Values below the detection threshold of our radioimmunoassay (30 pmol/l) are shown as 30 pmol/l. Reprinted from Hormones and Behavior, Cyclic estradiol treatment normalizes body weight and restores physiological patterns of spontaneous feeding and sexual receptivity in ovariectomized rats, 42: 461–471, 2002; republished with permission from Elsevier; from Asarian and Geary (15).