Nicotine Addiction Modulation in Rats

Rats were placed in a stereotaxic frame (David Kopf Instruments; Tujunga, CA, USA) and the LHA was targeted bilaterally using a 25-gauge needle (Hamilton; Reno, NV, USA) using the following stereotaxic coordinates: 2.85 mm posterior to the bregma, ±2 mm lateral to the midline and 8.1 mm ventral [6 (link)]. One µl at each injection site of AAV vectors (1 × 10⁹ genomic copies µL⁻¹) encoding null or Opkr1 short-hairpin RNAs [6 (link),18 (link)] were delivered at a rate of 200 nL min⁻¹ for 5 min. Fourteen days after AAV injection, an osmotic minipump flow moderator (Model 2002, Alzet, DURECT Corporation; Cupertino, CA, USA) containing a daily dose of 4 mg/ kg of nicotine (nicotine–hydrogen–tartrate salt, Sigma-Aldrich; St Louis, MO, USA) or saline was implanted subcutaneously. Food and body weight were measured for 14 days.