[Effect of a Single Injection of Brain Derived Neurotrophic Factor into Midline Ventral Tegmental Area on Morphine...

Opiate reinforcement is considered as a stimulus inducing addiction, however underlying neurobiological mechanisms remain obscure. According to the literature, BDNF (brain-derived neurotrophic factor) in the lateral ventral tegmental area (VTA) could modulate morphine reinforcement, but the role of BDNF in the midline VTA has not been studied yet. The aim of the study was to investigate the effect of a single intra-mid- line VTA injection on the acquisition and expression of morphine conditioned place preference (CPP). CPP procedure was composed of eight conditioning sessions (one session per day): morphine (i.p., 10 mg/kg) and saline injections were paired to the compartments and counterbalanced.Recombinant human BDNF (0.75 ug) or phosphate-buffered saline (PBS) as a vehicle were injected once into the midline VTA one day before or after conditioning. According to the CPP test rats spent more time in the morphine-paired compartments a scompared to the saline-paired compartments (p < 0.05). After a single BDNF injection into the midline VTA be- fore conditioning, but not after conditioning, differences in time spent in morphine and saline-paired compartments did not reach significance (p > 0.05). Thus, taking into account limitations of the results, we sug- gest that BDNF in the midline VTA may block morphine reinforcement.