Risky decision making involves the ability to weigh risks and rewards associated with different options to make adaptive choices. Previous work has established a necessary role for the basolateral amygdala (BLA) in mediating effective decision making under risk of punishment, but the mechanisms by which the BLA mediates this process are less clear. Because this form of decision making is profoundly sensitive to dopaminergic (DA) manipulations, we hypothesized that DA receptors in the BLA may be involved in risk-taking behavior. To test this hypothesis, male and female Long-Evans rats were trained in a decision-making task in which rats chose between a small, safe food reward and a larger food reward that was associated with a variable risk of footshock punishment. Once behavioral stability emerged, rats received intra-BLA infusions of ligands targeting distinct dopamine receptor subtypes prior to behavioral testing. Intra-BLA infusions of the dopamine D2 receptor (D2R) agonist quinpirole decreased risk taking in females at all doses, and this reduction in risk taking was accompanied by an increase in sensitivity to punishment. In males, decreased risk taking was only observed at the highest dose of quinpirole. In contrast, intra-BLA manipulations of dopamine D1 or D3 receptors (D1R and D3R, respectively) had no effect on risk taking. Considered together, these data suggest that differential D2R sensitivity in the BLA may contribute to the well-established sex differences in risk taking. Neither D1Rs nor D3Rs, however, appear to contribute to risky decision making in either sex.

01 Nov 2024·Harvard Review of Psychiatry

Cariprazine and Cognition in Patients with Schizophrenia and Bipolar Disorder: A Systematic Review

Review

Author: Scala, Mauro ; Álvarez-Mon, Miguel A. ; García-Fernández, Lorena ; Romero-Ferreiro, Carmen ; Romero-Ferreiro, Verónica ; Álvarez-Mon, Miguel A ; López, Estela Jiménez ; Santos, José Luis ; Rodriguez-Jimenez, Roberto ; Peñuelas-Calvo, Inmaculada

AbstractBackgroundCariprazine (CAR), an antipsychotic with partial agonism at the D3 receptor and higher affinity than dopamine, has shown significant procognitive effects in preclinical animal studies. This study systematically reviews CAR's effects on cognitive measures in patients with schizophrenia and bipolar disorder.MethodsTwo independent reviewers systematically searched PubMed, Web of Science, Scopus, and the Cochrane Library up to May 2024, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Additional studies were found by hand searching the references of included studies. Eligible studies were randomized controlled trials (RCTs) in English that assessed CAR's effects on cognition in patients with schizophrenia or bipolar disorder. Quality was assessed using the Jadad scale.ResultsOut of 139 reports, 5 studies (involving 6,104 patients with schizophrenia or bipolar disorder) were included. In schizophrenia, CAR showed better cognitive outcomes (mainly indirect measures) than placebo (PBO) in both early and late stages. It also outperformed risperidone and aripiprazole in attention-related cognitive tests. In bipolar disorder, CAR improved cognition compared to PBO (also using indirect measures). Most studies found the greatest cognitive benefits with low doses of CAR (1.5–3 mg/d).ConclusionsCAR improved cognitive measures compared to PBO and other D2 antagonists or partial agonists in RCTs, especially in patients with greater baseline impairment. Thus, CAR may be a promising option for enhancing cognition in schizophrenic and bipolar patients; though, more trials using specific cognitive assessment tools are needed.Systematic review registrationPROSPERO CRD42023485028

30 Oct 2024·Endocrinology

B2R-D2R Interaction in Prolactinomas and Nonfunctional Adenomas: Impact on Dopamine Resistance

Article

Author: Peña-Zanoni, Milagros ; Yaneff, Agustín ; Ciruela, Francisco ; Shayo, Carina ; Gironacci, Mariela M ; Abeledo-Machado, Alejandra ; Argerich, Josep ; Bornancini, Dana ; Vidal, Noemi ; García-Roca, Claudia ; Díaz-Torga, Graciela

AbstractProlactinomas, the most common pituitary-secreting adenomas, can be effectively treated with dopamine D2 receptor (D2R) agonists. However, a subset of them (∼20%) are resistant to dopamine-based therapies and require extirpation. The molecular mechanisms underlying their escape from dopaminergic regulation are not fully elucidated and may include alterations in D2R signaling. D2R can heteromerize with other G protein-coupled receptors, resulting in modulation of dopaminergic signaling. Because the bradykinin receptor type 2 (B2R) is overexpressed in prolactinomas, we interrogated whether this dopaminergic dysregulation observed in some prolactinomas may depend on a physical and functional interaction between D2R and B2R. The formation of B2R-D2R complexes in cultured cells transiently expressing both receptors was validated using NanoBiT technology. Interestingly, although D2R stimulation did not alter B2R-induced intracellular calcium mobilization, B2R stimulation abolished D2R signaling through modulation of cAMP. The existence of B2R-D2R complexes in pituitary adenomas biopsies was evaluated using an ALPHALisa approach. Importantly, B2R-D2R complexes were detected in human prolactinomas and nonfunctioning pituitary adenomas, but not in mixed (prolactin + growth hormone)-secreting adenomas. These results suggest that overexpression of B2R in resistant prolactinomas may promote the formation of B2R-D2R complexes, with B2R precluding D2R signaling, thus generating resistance to D2R agonists.

100 Deals associated with D2 receptor agonists (University of Toronto)

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Indication	Highest Phase	Country/Location	Organization	Date
Diagnostic agents	Preclinical	IN	University of Toronto	16 Jun 2005

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