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Levodopa provides effective symptomatic treatment for Parkinson's disease. However, nonmotor symptoms are often insufficiently relieved, and its long-term use is complicated by motor fluctuations and dyskinesia. To clarify mechanisms of levodopa-induced dyskinesia and pharmacological interventions aimed at reducing dyskinetic symptoms, we have here characterized the neurophysiological activity patterns in sensorimotor and cognitive-limbic circuits in dyskinetic rats, comparing the effects of amantadine, pimavanserin, and the novel prospective antidyskinetic and antipsychotic treatment mesdopetam. Parallel recordings of local field potentials from 11 cortical and subcortical regions revealed suppression of narrowband gamma oscillations (NBGs) in sensorimotor structures by amantadine and mesdopetam in conjunction with alleviation of dyskinetic signs. Concomitant gamma oscillations in cognitive-limbic circuits were not directly linked to dyskinesia and were not affected by antidyskinetic treatments to the same extent, although treatment-induced reductions in functional coupling were observed in both sensorimotor and cognitive-limbic circuits, in parallel. In a broad frequency spectrum (1–200 Hz), mesdopetam treatment displayed greater similarities to pimavanserin than to amantadine. These findings point to the reduction of NBGs as a valuable biomarker for the characterization of antidyskinetic treatment effects and provide systems-level mechanistic insights into the antidyskinetic efficacy of mesdopetam, with potential additional benefits for the treatment of Parkinson's-related psychosis.

Background: Auditory hallucinations (which occur when the distinction between thoughts and perceptions is blurred) are common in psychotic disorders. The orbitofrontal cortex (OFC) may be implicated, because it receives multiple inputs, including sound and affective value via the amygdala, orchestrating complex emotional responses. We aimed to elucidate the circuit and neuromodulatory mechanisms that underlie the processing of emotionally salient auditory stimuli in the OFC — mechanisms that may be involved in auditory hallucinations. Methods: We identified the cortico-cortical connectivity conveying auditory information to the mouse OFC; its sensitivity to neuromodulators involved in psychosis and postpartum depression, such as dopamine and neurosteroids; and its sensitivity to sensory gating (defective in dysexecutive syndromes). Results: Retrograde tracers in OFC revealed input cells in all auditory cortices. Acoustic responses were abolished by pharmacological and chemogenetic inactivation of the above-identified pathway. Acoustic responses in the OFC were reduced by local dopaminergic agonists and neurosteroids. Noticeably, apomorphine action lasted longer in the OFC than in auditory areas, and its effect was modality-specific (augmentation for visual responses), whereas neurosteroid action was sex-specific. Finally, acoustic responses in the OFC reverberated to the auditory association cortex via feedback connections and displayed sensory gating, a phenomenon of local origin, given that it was not detectable in input auditory cortices. Limitations: Although our findings were for mice, connectivity and sensitivity to neuromodulation are conserved across mammals. Conclusion: The corticocortical loop from the auditory association cortex to the OFC is dramatically sensitive to dopamine and neurosteroids. This suggests a clinically testable circuit behind auditory hallucinations. The function of OFC input–output circuits can be studied in mice with targeted and clinically relevant mutations related to their response to emotionally salient sounds.

The signal transducer and activator of transcription 3 (STAT3) protein is a master regulator of most key hallmarks and enablers of cancer, including cell proliferation and the response to DNA damage. G-Quadruplex (G4) structures are four-stranded noncanonical DNA structures enriched at telomeres and oncogenes' promoters. In cancer cells, stabilization of G4 DNAs leads to replication stress and DNA damage accumulation and is therefore considered a promising target for oncotherapy. Here, we designed and synthesized novel quinazoline-based compounds that simultaneously and selectively affect these two well-recognized cancer targets, G4 DNA structures and the STAT3 protein. Using a combination of in vitro assays, NMR, and molecular dynamics simulations, we show that these small, uncharged compounds not only bind to the STAT3 protein but also stabilize G4 structures. In human cultured cells, the compounds inhibit phosphorylation-dependent activation of STAT3 without affecting the antiapoptotic factor STAT1 and cause increased formation of G4 structures, as revealed by the use of a G4 DNA-specific antibody. As a result, treated cells show slower DNA replication, DNA damage checkpoint activation, and an increased apoptotic rate. Importantly, cancer cells are more sensitive to these molecules compared to noncancerous cell lines. This is the first report of a promising class of compounds that not only targets the DNA damage cancer response machinery but also simultaneously inhibits the STAT3-induced cancer cell proliferation, demonstrating a novel approach in cancer therapy.