This research was supported by the National Institute on Alcohol Abuse and Alcoholism Grants AA08459, AA06420, and AA05457. This is Publication 11285-NP of The Scripps Research Institute.
Estrous Cycle Effects on Operant Responding for Ethanol in Female Rats
Article first published online: 30 MAY 2006
Alcoholism: Clinical and Experimental Research
Volume 22, Issue 7, pages 1564–1569, October 1998
How to Cite
Roberts, A. J., Smith, A. D., Weiss, F., Rivier, C. and Koob, G. F. (1998), Estrous Cycle Effects on Operant Responding for Ethanol in Female Rats. Alcoholism: Clinical and Experimental Research, 22: 1564–1569. doi: 10.1111/j.1530-0277.1998.tb03950.x
- Issue published online: 30 MAY 2006
- Article first published online: 30 MAY 2006
- Received for publication January 3, 1998; accepted June 8, 1998
- Operant Self-administration;
Human females have been reported to be uniquely sensitive to the deleterious effects of ethanol, thus it is important to study the characteristics of and mechanisms underlying alcohol consumption that may be specific to females. Models of ethanol self-administration in female rats that take into consideration the estrous cycle have the potential to provide important information concerning these characteristics and mechanisms. The purpose of this study was to explore the effect of the cycle on ethanol self-administration using a limited access operant paradigm. Female Wistar rats were trained to lever press for 10% ethanol versus water using a saccharin fading procedure. Responses were examined across the four phases of the estrous cycle. No effects of estrous cycle phase were observed when these rats were allowed to cycle freely. Subsequently, estrous phase effects were investigated in females whose cycles had been synchronized. Under this condition, an effect of estrous phase was present, with lower ethanol intake observed in estrus (and in some cases proestrus). Synchronized rats all showed at least one very clear 4-day estrous cycle, whereas free-running rats' cycles ranged from 3 to 5 days. Thus, it is more likely that synchronized rats were tested in the identical portion of each phase, when hormone levels were less variable. These results suggest that ethanol may be more reinforcing during diestrus than proestrus and estrus in female rats.