Effects of electrical stimulation of ventral tegmental area on morphine addiction in rat

Ventral tegmental area (VTA) is located in the mesencephalon and it is one of the main nuclei that play a major role in drug abuse or addiction. In this study we investigated the effect of electrical stimulation of the VTA on addiction to morphine. Intravenous self-administration was used to quantify the level of drug-dependence. Twenty-four Wistar rats were divided into three groups: 1) Sham or saline group that had surgery and received saline by self-administration. 2) Control or morphine group that had surgery and received morphine by self-administration. 3) Case or morphine + stimulation (25 μA; 100 Hz; 0.14 ms period; for 10 minutes) group that had surgery and received electrical stimulation 15 minutes before morphine self-administration. Addiction was seen only in the morphine group, and electrical stimulation of the VTA prevented the addiction. Electrical current stimulates all type of the neurons in the VTA. Since dopaminergic neurons comprise two-third of its neurons, VTA stimulation may cause the release of dopamine in the nucleus accumbence and produce rewards so that the animal needs no further rewards from morphine.