A conditioned aversion to a novel milk solution was produced, and animals were then reexposed to milk while nondeprived (low conflict) or following a 72-hr food and water deprivation regimen (high conflict). No sex differences occurred if animals were nondeprived throughout testing. However, if deprived during the interval between conditioning and reexposure, sex differences in both behavior and adrenocortical responses occurred: (1) Presession corticoid levels of females were higher than those of males. (2) On the first reexposure day, females showed a suppression of plasma corticosterone below presession levels, while males maintained elevated or increased corticosterone levels. (3) On the second reexposure day, when no longer deprived, males showed a marked suppression of intake compared to females, and females subsequently recovered to pretoxicosis intake levels faster than males. (4) Gonadectomy eliminated these sex differences. While ovariectomized females continued to resemble intact females in both behavioral and hormonal responses, castrated males exhibited a corticoid suppression on the first reexposure day, and subsequently recovered to pretoxicosis intake levels at the same rate as females.
Bibliographical noteFunding Information:
This research was supported by funding from the C. F. Aaron Endowment Fund to Joanne Weinberg; HD-02881 from NICH&HD and Research Scientist Award MH-19936 from NIMH to Seymour Levine; Postdoctoral Training Grant MH-15147 to Megan Gunnar, Linda Brett, and Carol Gonzalez. The authors are grateful to Edna Lowe for assistance in testing animals, and Helen Hu for the corticosterone assay.
- Approach-avoidance conflict
- Conditioned taste aversion
- Pituitary-adrenal system
- Plasma corticosterone
- Sex differences