Effects of food deprivation on etonitazene consumption in rats

One group of free-feeding rats was given a 5 microgram/ml etonitazene HCl solution as their sole liquid. This group increased their drug intake by 100% when they were partially food-deprived during a 23-day period. Another group that remained food-satiated and received etonitazene for an equal number of days did not show similar increases in drug intake. However, this group drank greater volumes of the etonitazene solution than a food-satiated control group drank of water. These results are contrasted with a fourth group showing a 50% decrement in water intake during similar food-deprived conditions. The food-deprived group drinking etonitazene showed highly erratic drinking patterns compared to all the other groups. Daily liquid intake ranged from 30 to 250 ml in this group, and volumes oscillated from high to low on alternating days. When the food-deprived/food-satiated conditions were replicated in this experimental group, corresponding increases and decreases in drinking reliably occurred. However, during the second food-deprived phase, the large increases occurred almost immediately as contrasted with a gradual increase over 17 days during the first food-deprived phase. This would suggest a learning mechanism may be involved. Self-mutilation and other forms of stereotypy were noted only in food-deprived rats consuming etonitazene.