Decrease of ventral tegmental area dopamine neuronal activity in nicotine withdrawal rats.

The present study was designed to examine the ventral tegmental area (VTA) dopamine neuronal activity in nicotine withdrawal rats by means of in vivo single-unit extracellular recordings. Animals were treated with nicotine base (6 mg/kg/day, s.c.) four times daily for 12 days. One day after the last nicotine administration, the firing rates of the VTA dopamine neurons were found to be significantly decreased. Following 2, 3, 5 and 10 days of nicotine withdrawal, however, the firing rates returned to the control levels. The number of spontaneously active dopamine cells was not altered at any time points. The results indicate that the VTA dopamine neuronal activity is reduced during the first day of nicotine withdrawal.