Effects of estradiol valerate on voluntary alcohol consumption, β-endorphin content and neuronal population in hypothalamic arcuate nucleus

The main goal of the present experiment was to study the voluntary consumption of alcohol before and after a single injection of estradiol valerate (EV); another goal was to assess β-endorphin (β-EP) neurons and β-EP peptide in hypothalamic arcuate nucleus 10 weeks after the injection of EV.Wistar female rats were injected either with a single 2.0 mg/rat injection of EV or with 0.2 ml of corn oil/rat (vehicle group). Two weeks before the injection and 10 weeks after it, every other day both groups were exposed to a free-choice alcohol drinking procedure. In weeks 4 and 5, the post-injection-consumption of alcohol was higher in the EV group than the vehicle group. In the EV group, food intake decreased and coincided with body weight lost in week 1 of post-EV injection. EV treated females showed significantly lower number of β-EP neurons than control group (reduction of 51.22%); however, β-EP content was similar in both groups, and they did not differ in the number of TSH and LHRH neurons. The present results suggest a positive relationship between high alcohol consumption and possible initial deficiency of β-endorphin content. The transient increase in alcohol consumption suggests a possible compensatory secretory effect of the surviving β-endorphinergic neurons, particularly when they are chronically stimulated with alcohol.