Localization of stereotaxic coordinates for the ventral tegmental area in early adolescent, mid-adolescent and adult rats.

The ventral tegmental area (VTA) is a brain region implicated in drug addiction and related behaviors; however, little research has been conducted examining the role of the VTA in these processes in adolescent rats. Understanding the development of the VTA is imperative for elucidating mechanisms mediating adolescent vulnerability to drug addiction. The purpose of the present study was to define stereotaxic coordinates for the VTA in developing rats. Early adolescent [postnatal day (PND) 28], mid-adolescent (PND 35), or adult male rats (PND 70) were surgically implanted with a guide cannula aimed at the VTA. Adult coordinates, (P: -3.5, L: +1.0, V: -8.5 mm from Bregma) were used as a baseline and guided localization of VTA coordinates for early and mid-adolescent rats. After recovery, dye was injected via a microdialysis probe and brains were removed, sliced, and stained for histological verification of cannula placement in the VTA. Data suggest VTA coordinates in adolescents differ significantly from adult rats. These findings imply that it is imperative to consider anatomical differences in the development of the VTA when comparing the neurochemical effects of abused drugs in adolescent and adult rats.