Deep brain stimulation of the nucleus accumbens shell induces anti-obesity effects in obese rats with alteration of dopamine neurotransmission

The aim of this study was to assess the anti-obesity effects of nucleus accumbens shell (NAc-sh) deep brain stimulation (DBS) in diet-induced obese (DIO) and chow-fed (chow) rats. The influence of DBS on dopamine (DA) signaling in the NAc-sh was also evaluated. DIO and chow rats were subjected to DBS for 14 consecutive days. Food intake and weight gain were measured daily. The gene expression of the dopamine D1 and D2 receptors was evaluated by qPCR. In addition, the extracellular levels of DA and its metabolite, dihydroxyphenylacetic acid (DOPAC), were determined by microdialysis. We observed that chronic DBS induced significant reductions in total energy intake (596.0 ± 65.0 kcal vs. 1161.6 ± 22.2 kcal, p < 0.001) and weight gain (1.45 ± 0.57% vs. 9.64 ± 0.38%, p < 0.001) in DIO rats compared to sham-DIO rats. Up-regulated D2 receptor gene expression (2.43 ± 0.12 vs. 0.64 ± 0.04, p < 0.001) and increased DA levels (2.73 ± 0.15 pmol/mL vs. 0.62 ± 0.05 pmol/mL, p < 0.001) were observed in DIO rats compared to sham-DIO rats. DBS had no influence on food intake, weight gain, or DA neurotransmission in chow rats. Our results support an association of the anorexigenic effects of NAc-sh DBS with mesolimbic DA signaling and indicate that the positive alteration of DA function in DIO rats may be responsible for the different effects of DBS in DIO and chow rats.