Altered Signaling in CB1R-5-HT2AR Heteromers in Olfactory Neuroepithelium Cells of Schizophrenia Patients is Modulated by Cannabis Use

Abstract

Schizophrenia (SCZ) has been associated with serotonergic and endocannabinoid systems dysregulation, but difficulty in obtaining in vivo neurological tissue has limited its exploration. We investigated CB1R-5-HT2AR heteromer expression and functionality via intracellular pERK and cAMP quantification in olfactory neuroepithelium (ON) cells of SCZ patients non-cannabis users (SCZ/nc), and evaluated whether cannabis modulated these parameters in patients using cannabis (SCZ/c). Results were compared vs healthy controls non-cannabis users (HC/nc) and healthy controls cannabis users (HC/c). Further, antipsychotic effects on heteromer signaling were tested in vitro in HC/nc and HC/c. Results indicated that heteromer expression was enhanced in both SCZ groups vs HC/nc. Additionally, pooling all 4 groups together, heteromer expression correlated with worse attentional performance and more neurological soft signs (NSS), indicating that these changes may be useful markers for neurocognitive impairment. Remarkably, the previously reported signaling properties of CB1R-5-HT2AR heteromers in ON cells were absent, specifically in SCZ/nc treated with clozapine. These findings were mimicked in cells from HC/nc exposed to clozapine, suggesting a major role of this antipsychotic in altering the quaternary structure of the CB1R-5-HT2AR heteromer in SCZ/nc patients. In contrast, cells from SCZ/c showed enhanced heteromer functionality similar to HC/c. Our data highlight a molecular marker of the interaction between antipsychotic medication and cannabis use in SCZ with relevance for future studies evaluating its association with specific neuropsychiatric alterations.

A low repeated dose of Δ9-tetrahydrocannabinol affects memory performance through serotonergic signalling in mice

“…Specifically, enhanced expression of CB1R/5-HT2AR heterodimers was found in olfactory neuroepithelium cells of cannabis users (Galindo et al, 2018). Additionally, altered signalling in CB1R/5-HT2AR heterodimers also in olfactory neuroepithelium cells was reported in schizophrenia patients (Guinart et al, 2020) were a sensitized serotonergic responses are characteristic. However, further studies addressing the specific relevance of the CB1R/5-HT2AR heterodimers are key to better understand the cognitive deficits associated to repeated THC exposure.…”

“…The interactions between serotonin and cannabinoid receptors may be reciprocal since mice lacking CB1Rs showed a reduced number of head twitches caused by the 5-HT2R agonist, 2,5-Dimethoxy-4-iodoamphetamine (DOI) (Mato et al, 2007) as well as a dysregulation in serotonergic activity in the prefrontal cortex (Aso et al, 2009).In further support of this interaction, heterodimers of CB1R and 5-HT2AR have been described in both mice and humans (Viñals et al, 2015;Galindo et al, 2018). Enhanced expression of CB1R/5-HT2AR heterodimers has also been found in human cannabis users (Galindo et al, 2018), and enhanced levels and altered signalling of CB1R/5-HT2AR heterodimers was observed in olfactory neuroepithelium cells of schizophrenia patients (Guinart et al, 2020). In mice, the presence of CB1R/5-HT2AR heterodimer has been described in CA3 region of the hippocampus, the cortex, and the striatum.…”

“…In human studies, enhanced expression of CB1R/5-HT2AR heterodimer has been found in cannabis users (Galindo et al, 2018). In addition, enhanced levels and altered signalling of CB1R/5-HT2AR heterodimer was found in olfactory neuroepithelium cells of schizophrenia patients (Guinart et al, 2020). In mice, the presence of CB1R/5-HT2AR heterodimer has been described in CA3 region of the hippocampus, the cortex, and the striatum.…”

Cannabis Use Induces Distinctive Proteomic Alterations in Olfactory Neuroepithelial Cells of Schizophrenia Patients

“…In fact, in a synchrotron-based infrared spectroscopy study, significant differences in the protein spectra were reported in ON cells from SCZ cannabis users compared to non-users [26]. Additionally, we recently demonstrated that the functional signature of the CB 1 and serotonin 2A receptor (CB 1 -5HT 2A R) heteromer in ON cells is differentially regulated in SCZ patients depending on cannabis use [27].…”

“…ON samples were obtained by nasal brushing. Samples from the middle and upper turbinates were maintained in 250 µL of cold Dulbecco's Modified Eagle Medium/Ham F-12 (DMEM/F12) enriched with 10% FBS, 2% glutamine and 1% streptomycin-penicillin (GibcoBRL), as previously described [27]. At 80% confluence, cells were expanded using 0.25% trypsin (GibcoBRL) and replated in 75 cm 2 flasks.…”