Amphetamine Injection into the Nucleus Accumbens and Electrical Stimulation of the Ventral Tegmental Area in Rats After Novelty Test-Behavioral and Neurochemical Correlates.

Amphetamine abuse is a global health epidemic that is difficult to treat due to individual differences in response to environmental factors, including stress reactivity and anxiety levels, as well as individual neuronal differences, which may result in increased/decreased vulnerability to addiction. In the present study, we investigated whether the Wistar rats behavioral traits of high (HR) and low (LR) locomotor activity to novelty influence motivational behavior (induced feeding model; iFR by electrical stimulation of the ventral tegmental area; Es-VTA) supported by amphetamine injection into the nucleus accumbens shell (AcbSh) (HR(Amph), n = 5; LR(Amph), n = 5). A correlation was found between the novelty test's locomotor activity score and the frequency threshold percentage change (p < 0.001, Rs = -0.867). In HR(Amph), there was a shortening (-24.16%), while in LR(Amph), there was a lengthening (+51.84%) of iFR latency. Immunofluorescence studies showed differential neuronal density (activity of tyrosine hydroxylase, choline acetyltransferase, and cFos protein) in the selected brain structures in HR(Amph) and LR(Amph) animals as well as in comparison to a control group (HR(ACSF), n = 5; LR(ACSF), n = 5). These results contribute to expanding the state of knowledge of the behavioral and neuronal propensity to take drug abuse.