Effects of Social Housing on Electrically Stimulated Dopamine Release in the Nucleus Accumbens Core and Shell in Female and Male Rats

Dopamine (DA) is a neurotransmitter that is important in the reward system and increased DA release is associated with rewarding properties of drugs. Highly addictive stimulants like methamphetamine (METH) increase DA release and block reuptake, causing the DA to stay in the synapse longer, enhancing its effects. Because the misuse of METH is increasing in the United States, it is important to investigate ways to protect against this highly addictive stimulant. Recent studies have shown that social support can be a protective factor against METH self-administration in females, but not males. Other studies using microdialysis have shown that socially housed females have lower DA release in the nucleus accumbens (NAc) compared to single housed females after treatment with METH. Additionally, researchers have shown that there are sex differences in stimulated DA release. The present study investigates whether social housing affects stimulated DA release after METH treatment. DA release in the NAc core and shell of socially housed and individually housed rats was measured using fast scan cyclic voltammetry (FSCV) with a chronic 16-channel carbon fiber electrode in the NAc. A stimulating electrode was aimed at the ventral tegmental area (VTA) to induce DA release in the NAc. The results showed that social housing enhances electrically stimulated DA release in males and that there was greater DA release in NAc core than shell in single males, but no difference in socially housed males. In females, social housing also enhanced ES DA release. In single females there was greater ES DA release in shell than in core. Additionally, in single housed females there was greater ES DA release over time, while the socially housed females had high ES DA release that remained stable over time. These results suggest that social housing protects females from sensitization, making single females more vulnerable to the addictive properties of METH.