Dampened motivation in schizophrenia: evidence from a novel effort-based decision-making task in social scenarios.

Apathy represents a significant manifestation of negative symptoms within individuals diagnosed with schizophrenia (SCZ) and exerts a profound impact on their social relationships. However, the specific implications of this motivational deficit in social scenarios have yet to be fully elucidated. The present study aimed to examine effort-based decision-making in social scenarios and its relation to apathy symptoms in SCZ patients. We initially recruited a group of 50 healthy participants (16 males) to assess the validity of the paradigm. Subsequently, we recruited 45 individuals diagnosed with SCZ (24 males) and 49 demographically-matched healthy controls (HC, 25 males) for the main study. The Mock Job Interview Task was developed to measure effort-based decision-making in social scenarios. The proportion of hard-task choice and a range of subjective ratings were obtained to examine potential between-group differences. SCZ patients were less likely than HC to choose the hard task with strict interviewers, and this group difference was significant when the hard-task reward value was medium and high. More severe apathy symptoms were significantly correlated with an overall reduced likelihood of making a hard-task choice. When dividing the jobs into two categories based on the levels of social engagement needed, SCZ patients were less willing to expend effort to pursue a potential offer for jobs requiring higher social engagement. Our findings indicated impaired effort-based decision-making in SCZ can be generalized from the monetary/nonsocial to a more ecologically social dimension. Our findings affirm the critical role of aberrant effort allocation on negative symptoms, and may facilitate the development of targeted clinical interventions.

Revisiting anticipatory hedonic processing in patients with schizophrenia: An examination between representation activation and maintenance.

BACKGROUND: Anticipatory anhedonia is one of the key deficits found in patients with schizophrenia (SCZ). However, the underlying mechanism of this deficit remains unclear. The present study examined whether representation activation and maintenance capacity influenced anticipatory experiences in SCZ patients. METHODS: We recruited 46 SCZ patients (26 males) and 45 matched healthy controls (24 males). The Reward Representation Activation and Maintenance (RRAM) Task was administrated to assess anticipatory experience and representation activation and maintenance capacity. RESULTS: SCZ patients exhibited lower subjective arousal than controls in anticipation of rewards with high probability when representation activation and maintenance were difficult to accomplish. SCZ patients also tended to reduce their button presses more than HC when they were required to maintain reward representation. CONCLUSIONS: Our findings suggest that representation activation and maintenance may partially account for anticipatory anhedonia observed in SCZ patients.

Zinc Supplementation, via GPR39, Upregulates PKCζ to Protect Intestinal Barrier Integrity in Caco-2 Cells Challenged by Salmonella enterica Serovar Typhimurium.

Background: Zinc has been shown to improve intestinal barrier function against Salmonella enterica serovar Typhimurium (S. typhimurium) infection, but the mechanisms involved in this process remain undefined.Objective: We aimed to explore the roles of G protein-coupled receptor (GPR)39 and protein kinase Cζ (PKCζ) in the regulation by zinc of intestinal barrier function.Methods: A Transwell Caco-2 monolayer was pretreated with 0, 50, or 100 µM Zn and then incubated with S. typhimurium for 0-6 h. Afterward, cells silenced by the small interfering RNA for GPR39 or PKCζ were pretreated with 100 µM Zn and incubated with S. typhimurium for 3 h. Finally, transepithelial electrical resistance (TEER), permeability, tight junction (TJ) proteins, and signaling molecules GPR39 and PKCζ were measured.Results: Compared with controls, S. typhimurium decreased TEER by 62.3-96.2% at 4-6 h (P < 0.001), increased (P < 0.001) permeability at 6 h, and downregulated (P < 0.05) TJ protein zonula occludens (ZO)-1 and occludin by 104-123%, as well as Toll-like receptor 2 and PKCζ by 35.1% and 75.2%, respectively. Compared with S. typhimurium-challenged cells, 50 and 100 µM Zn improved TEER by 26.3-60.9% at 4-6 h (P < 0.001) and decreased (P < 0.001) permeability and bacterial invasion at 6 h. A total of 100 µM Zn increased ZO-1, occludin, GPR39, and PKCζ 0.72- to 1.34-fold (P < 0.05); however, 50 µM Zn did not affect ZO-1 or occludin (P > 0.1). Silencing GPR39 decreased (P < 0.05) zinc-activated PKCζ and blocked (P < 0.05) the promotion of zinc on epithelial integrity. Furthermore, silencing PKCζ counteracted the protective effect of zinc on epithelial integrity but did not inhibit GPR39 (P = 0.138).Conclusion: We demonstrated that zinc upregulates PKCζ by activating GPR39 to enhance the abundance of ZO-1, thereby improving epithelial integrity in S. typhimurium-infected Caco-2 cells.