Role of the interneurons in prefrontal-based attentional dysfunctions in nicotine addiction

The prefrontal cortex (PFC) plays a critical role in attentional processes in humans and animals. Neuroimaging studies have reported that cigarette smokers have reduced prefrontal cortex (PFC) function and impaired attention, suggesting that dysfunction in the PFC may underlie these attentional deficits. However, little is known about the PFC neuronal processes underlying attentional performance and their alterations following nicotine exposure. Here, we first assessed the long-term effects of nicotine intake escalation and withdrawal on attentional performance. Rats were trained in a 5-choice serial reaction time task (5-CSRTT), and then given access to a fixed or increasing dose of intravenous nicotine for self-administration, a differential procedure known to induce nicotine intake escalation and to alter PFC neuronal activity. Then, we assessed whether and to what extent these inhibitory deficits can be alleviated by manipulating the PFC activity, using a newly developed chemogenetic approach, to silence or activate the PFC interneurons (IN) during the 5-CSRTT. We found that chronic nicotine self-administration increases attention in both escalated (ES) and non-escalated (No-ES) rats, while withdrawal from nicotine intake escalation induces attentional deficits only in the ES group. Moreover, chemo-inhibition of PFC-IN after chronic nicotine self-administration induced attentional deficits in both groups, while it worsened attention only in the No-ES group during acute withdrawal. In contrast, the chemo-activation of the IN had no effect on attentional performances. Together, these results highlight the key role of the PFC-IN in attention and in their dysfunctions induced by nicotine intake escalation.