Fig. 15.

Male-female and estrogen-controlled sex differences in hedonics in rats. A: intact male rats licked more 0.025 and 0.05 M sucrose than intact females, and estradiol-treated ovariectomized females licked more than control, oil-treated females in 10-s palatability tests; neither sex difference was detected in tests of higher sucrose concentrations. Solid squares denote intact male rats, while open circles denote oil-treated ovariectomized females (OVX-OIL), and gray circles denote estradiol-treated ovariectomized females (OVX-EB). ^aSignificantly different from OVX-OIL. ^bSignificantly different from OVX-EB. B: overnight intake of 0.025 M sucrose in the same rats, expressed as ml/100 g body wt; abbreviations are the same as above. That males drank more independent of their greater size suggests that the hedonic difference shown in A controlled intake. In contrast, the effect of estradiol on palatability did not influence overnight intake. *Significantly different from both groups of ovariectomized females. A and B: Reprinted from Physiology and Behavior, Sex differences in behavioral taste responses to and ingestion of sucrose and NaCl solutions by rats, Kathleen S. Curtis, Linda M. Davis, Amy L. Johnson, Kelly L. Therrien, Robert J. Contreras, 80: 657–664, 2004; republished with permission from Elsevier; from Curtis et al. (152). C: intact rats tested during estrus (E/SAL, triangles) licked less 0.025 M sucrose solutions in 10-s palatability tests than rats tested during diestrus 2 (D2/SAL, circles). Intakes of 0.05–0.4 M sucrose solutions did not differ, suggesting that they were similarly palatable, and the effect obtained during the brief-access testing did not translate into an overnight effect (data not shown). ^aSignificantly different from diestrus, same sucrose concentration. Reprinted from Physiology and Behavior, vol. 86, Deann P. D. Atchley, Karen L. Weaver, and Lisa A. Eckel, Taste responses to dilute sucrose solutions are modulated by stage of the estrous cycle and fenfluramine treatment in female rats, 265–271, 2005, with permission from Elsevier; from Atchley et al. (23). D: estradiol failed to decrease 45-min sham intake of a 6.25% corn oil emulsion in ovariectomized rats, although estradiol significantly decreased real intake of the same solution; abbreviations are the same as in A. Rats received 2 μg estradiol benzoate or control injections once each 4th day and were tested on the day modeling estrus. *Significantly different from real intake in control rats. (Asarian L, Mangiaracina M, and Geary N, unpublished data).