Estradiol valerate and alcohol intake: dose-response assessments.

BACKGROUND: An injection of estradiol valerate (EV) provides estradiol for a prolonged period. Recent research indicates that a single 2.0 mg injection of EV modifies a female rat's appetite for alcoholic beverages. This research extends the initial research by assessing 8 doses of EV (from .001 to 2.0 mg/female rat), as well assessing the effects of 2.0 mg EV in females with ovariectomies. RESULTS: With the administration of EV, there was a dose-related loss of bodyweight reaching the maximum loss, when it occurred, at about 4 days after injections. Subsequently, rats returned to gaining weight regularly. Of the doses tested, only the 2.0 mg dose produced a consistent increase in intake of ethanol during the time previous research indicated that the rats would show enhanced intakes. There was, however, a dose-related trend for smaller doses to enhance intakes. Rats with ovariectomies showed a similar pattern of effects, to intact rats, with the 2 mg dose. After extensive histories of intake of alcohol, both placebo and EV-treated females had estradiol levels below the average measured in females without a history of alcohol-intake. CONCLUSION: The data support the conclusion that pharmacological doses of estradiol can produce enduring changes that are manifest as an enhanced appetite for alcoholic beverages. The effect can occur among females without ovaries.

Estradiol increases consumption of a chocolate cake mix in female rats.

Female Sprague-Dawley rats were given an opportunity to eat chocolate cake mix (CCM) using a common brand of cake mix, while standard laboratory food was also available. They took large amounts of the CCM, often taking more than 20 g in 24 h. Some animals were given a single injection of 1 of 6 doses of estradiol valerate (ranging from 0.09 to 10.0 mg/kg) and others were given vehicle. Estradiol valerate provides for sustained release of estradiol. Those receiving estradiol ate more than those receiving vehicle at doses larger than 0.09 mg/kg. Further, with a dose of 10 mg/kg, greater intake among estradiol-treated females was apparent 2 months post-injection. Methodological issues of neophobia and conditioned avoidance were addressed in the study's design and may explain why increased intakes were observed here in contrast to the consensus that estradiol reduces food intake.

Estradiol valerate and intake of sweetened water.

Recently, it has been shown that female rats receiving very large doses (e.g., 2 mg) of estradiol valerate (EV) take considerably more alcoholic beverage than placebo controls. The question asked, with these procedures, is whether the enhanced appetite for alcoholic beverages was specific to those beverages or was a reflection of a general increase in appetite. Female rats were provided with various sweetened beverages. In one experiment, they were provided a palatable saccharin solution (0.25% solution) and a less palatable one (2% saccharin solution). EV treatment led to more intake of the palatable saccharin solution and reduced intake of the less palatable solution. EV induces changes leading to enhanced appetite for some ingesta (including palatable saccharin solutions and alcoholic beverages), but surely not all ingesta.

A pharmacological dose of estradiol can enhance appetites for alcoholic beverages.

Each of 30 female Sprague-Dawley rats were given 2 mg of estradiol valerate (EV), 30 others were given placebos. EV is a preparation that delivers estradiol for more than 12 days, but probably less than 20. Fifteen days later, the females had the opportunity to take sweetened alcoholic beverage 24 h a day across 25 days. Subsequently, they could self-administer other alcoholic beverages, including one of only alcohol and water. After a period of abstinence, rats had another opportunity to take sweetened alcoholic beverage (94 to 96 days after the single injection of EV). With every measurement, rats given EV consumed significantly more ethanol than controls. For example, mean of measurements representing daily intake for the fourth week of availability of palatable alcoholic beverage for placebo-treated=5.29 grams of ethanol per kilogram of bodyweight (g'E/kg); for EV-treated=8.13 g'E/kg; P=.003. The data support the conclusion that pharmacological doses of estradiol can induce marked, enduring changes in appetite for alcoholic beverages.

One injection of estradiol valerate induces dramatic changes in rats' intake of alcoholic beverages.

A series of experiments investigated the effects of a single injection of estradiol valerate (EV) on female rats' consumption of alcoholic beverages. EV provides sustained release of estradiol. Just after an injection of EV, rats' intake of a palatable alcoholic beverage, which had been taken regularly before, is reduced dramatically. Subsequently, rats' intake of alcoholic beverage returns to baseline levels. With continued opportunity to drink, rats take more ethanol than controls. When EV was given 15 and 31 days before the first opportunity to drink an alcoholic beverage, female rats markedly enhanced their intake of ethanol. Once enhanced intakes emerged, they were observed with different kinds of alcoholic beverages and endured for months.