SUMMARY Excitatory afferents to the nucleus accumbens (NAc) are thought to facilitate reward seeking by encoding reward-associated cues. Selective activation of different glutamatergic inputs to the NAc can produce divergent physiological and behavioral responses, but mechanistic explanations for these pathway-specific effects are lacking. Here, we compared the innervation patterns and synaptic properties of ventral hippocampus, basolateral amygdala, and prefrontal cortex input to the NAc. Ventral hippocampal input was found to be uniquely localized to the medial NAc shell, where it was predominant and selectively potentiated following cocaine exposure. In vivo, bidirectional optogenetic manipulations of this pathway attenuated and enhanced cocaine-induced locomotion. Challenging the idea that any of these inputs encode motivationally-neutral information, activation of each discrete pathway reinforced instrumental behaviors. Finally, direct optical activation of medium spiny neurons proved to be capable of supporting self-stimulation, demonstrating that behavioral reinforcement is an explicit consequence of strong excitatory drive to the NAc.

Antibodies are a key resource in biomedical research yet there are no community-accepted standards to rigorously characterize their quality. Here we develop a procedure to validate pre-existing antibodies. Human cell lines with high expression of a target, determined through a proteomics database, are modified with CRISPR/Cas9 to knockout (KO) the corresponding gene. Commercial antibodies against the target are purchased and tested by immunoblot comparing parental and KO. Validated antibodies are used to definitively identify the most highly expressing cell lines, new KOs are generated if needed, and the lines are screened by immunoprecipitation and immunofluorescence. Selected antibodies are used for more intensive procedures such as immunohistochemistry. The pipeline is easy to implement and scalable. Application to the major ALS disease gene C9ORF72 identified high-quality antibodies revealing C9ORF72 localization to phagosomes/lysosomes. Antibodies that do not recognize C9ORF72 have been used in highly cited papers, raising concern over previously reported C9ORF72 properties.

Previous studies have shown that effective antipsychotic medications attenuate reward, an effect that is generally attributed to their effectiveness at blocking the dopamine D2-like receptors. As blockade of the serotonin type 2a (5-HT2a) receptors is a common property of the newer antipsychotics, the present study compared the effect of haloperidol, clozapine, and M100907 (a selective 5-HT2a antagonist) and the combined effect of haloperidol and M100907 treatment on brain stimulation reward (BSR). Experiments were performed on male Sprague-Dawley rats trained to produce an operant response to obtain electrical stimulation in the lateral hypothalamus. Measures of reward threshold were determined in different groups of rats using the curve-shift method using fixed current intensity and variable frequency before and at different times after injection of haloperidol (0.01, 0.05, 0.1, and 0.25 mg/kg), clozapine (1, 7.5, 15, and 30 mg/kg), M100907 (0.033, 0.1, and 0.3 mg/kg), or their vehicle. The effect of M100907 (0.3 mg/kg) on the attenuation of BSR by a sub-and suprathreshold dose of haloperidol was studied in another group of rats. Clozapine produced a dose-orderly increase in reward threshold with a mean maximal increase of 50%; at high doses, clozapine induced cessation of responding in several animals at different time periods. Haloperidol induced a dose-dependent increase in reward threshold, with the mean maximal increase (75%) being observed at the highest dose; it also produced a dose-dependent reduction of maximum rates of responding. M100907 failed to alter reward at any of the doses tested and had no effect on the subthreshold dose (0.01 mg/kg) of haloperidol. But when combined with a suprathreshold dose of haloperidol, M100907 reduced the reward-attenuating effect of haloperidol. These results show that 5-HT2a receptors are unlikely to constitute a component of the reward-relevant pathway activated by lateral hypothalamic stimulation. However, blockade of 5-HT2a receptors may account for the relatively lower level of reward attenuation produced by clozapine, and predict that antipsychotic medications that have a high affinity for the 5-HT2a receptor may be less likely to induce dysphoria.