Involvement of NAPE-PLD and neuroplastic mediated mechanisms in the ventral prefrontal cortex in the anti-stress effects of sub-effective doses of cannabidiol and escitalopram

Author(s)

Franciele Franco Scarante

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2023-04-20

Examining board members

Alline Cristina de Campos; Fernando Morgan de Aguiar Correa; Nadja Schröder

• Advisor: Alline Cristina de Campos

Abstract

Chronic stress precipitates the symptoms of psychiatric disorders, including mood and anxiety disorders. Selective serotonin reuptake inhibitors (SSRIs) are often used for treating these stress-associated psychiatric disorders. However, a main limitation of SSRIs is their late-onset of action (only after 4-8 weeks of treatment). Previously, we have shown that the combination of escitalopram (ESC; 10mg/kg) with a sub effective dose of cannabidiol (CBD; 7.5mg/kg) accelerates the anxiolytic-like effects of the SSRI in mice submitted to a 10-day stress protocol. Here, we hypothesize that the anti-stress effect of ESC+CBD is dependent on the signaling mediated by lipid ligands of the Endocannabinoidome (ECBome), a system that seems to be a common target for ESC and CBD, in the ventromedial prefrontal cortex (vmPFC). To test this, C57Bl6 male mice (10-12weeks) received an intra-vmPFC injection of viral vectors directing the CRISPR-Cas9-mediated deletion of the enzyme NAPE-PLD or the enzyme DAGLα, which are involved in the synthesis of ECBoma ligands. After 15 days, mice were exposed to 10 days of chronic unpredictable stress (CUS) and treated for 7 days with vehicle or with ESC+CBD. The anxiolytic-like effect of ESC+CBD in the novelty-suppressed feeding (NSF) test was abolished in mice with induced deletion of NAPE-PLD, but not DAGLα, in the vmPFC. Furthermore, the combination of ESC+CBD, despite not altering the behavior of mice exposed to a 10-day stress protocol in the splash-test, induced anxiolytic-like effect in mice exposed to 21 days of stress and treated with the combinations of vehicle or ESC (10mg/kg) with Vehicle or CBD (7.5mg/kg) only in the last 7 days of the stress protocol. Moreover, stress decreased the expression of NAPE-PLD in the medial PFC and the treatment with ESC+CBD increased the expression of the enzyme while also increased the percentage of parvalbumin (PV) interneurons that expressed NAPE-PLD in the medial PFC. In addition, CUS increased the density of oligodendrocyte precursor cells (OPCs) and the survival of proliferating OPCs in the medial PFC. Our results indicate that ESC+CBD induce an anxiolytic-like effect after 7 days of treatment even in mice exposed to 3 weeks of stress. The anti-stress effects of ESC+CBD rely on the expression of NAPEPLD in the vmPFC and are characterized by plastic alterations in the PFC of stressed mice. (AU)

• FAPESP's process: 19/09178-3 - Involvement of endocannabinoid signaling and neuroplasticity within the prefrontal cortex in the behavioral effects of the combination cannabidiol and escitalpram in stressed mice
• Grantee: Franciele Franco Scarante
• Support Opportunities: Scholarships in Brazil - Doctorate