Synthetic progestins and sweetness preference in intact female Sprague-Dawley rats

Intact Sprague-Dawley female rats were treated with 0.25 microgram or 1.25 micrograms ethinyl-estradiol (EE) in combination with one of 3 synthetic progestins: (5 micrograms) norethindrone, norethynodrel, or norgestrel. In Experiment 1 both dosages of EE in combination with the synthetic progestins suppressed sweetness preference, with a somewhat greater effect for the 1.25 micrograms EE dosage. Norgestrel in combination with EE produced the longest suppression of sweetness preference. In Experiment 2 progestins administered in the absence of EE showed no significant effect on sweetness preference. When 1.25 micrograms EE was administered singularly, a significant decline in sweetness preference occurred, but not as great a decline as in combination with a progestin.