Neuronal and Astrocytic Morphological Alterations Driven by Prolonged Exposure with Δ9-Tetrahydrocannabinol but Not Cannabidiol.

Elisa Landucci,Maria Grazia Giovannini,Daniele Lana,Domenico E Pellegrini-Giampietro,Costanza Mazzantini

doi:10.3390/toxics10020048

Abstract

Cannabis derivatives are largely used in the general population for recreational and medical purposes, with the highest prevalence among adolescents, but chronic use and abuse has raised medical concerns. We investigated the prolonged effects of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in organotypic hippocampal slices from P7 rats cultured for 2 weeks. Cell death in the CA1 subregion of slices was quantified by propidium iodide (PI) fluorescence, pre-synaptic and post-synaptic marker proteins were analysed by Western blotting and neurodegeneration and astrocytic alterations by NeuN and GFAP by immunofluorescence and confocal laser microscopy. The statistical significance of differences was analysed using ANOVA with a post hoc Dunnett w-test (PI fluorescence intensities and Western blots) or Newman–Keuls (immunohistochemistry data) for multiple comparisons. A probability value (P) of < 0.05 was considered significant. Prolonged (72 h) THC or CBD incubation did not induce cell death but caused modifications in the expression of synaptic proteins and morphological alterations in neurons and astrocytes. In particular, the expression of PSD95 was reduced following incubation for 72 h with THC and was increased following incubation with CBD. THC for 72 h caused disorganisation of CA1 stratum pyramidalis (SP) and complex morphological modifications in a significant number of pyramidal neurons and in astrocytes. Our results suggest that THC or CBD prolonged exposure induce different effects in the hippocampus. In particular, 72 h of THC exposure induced neuronal and glia alterations that must draw our attention to the effects that relatively prolonged use might cause, especially in adolescents.

Highlights

Cannabis has been widely used for thousands of years, both for recreational and medical purposes
We analysed the effects of cannabinoids; in particular, the slices were treated with THC and CBD and the Cornu Ammonis areas CA1 region was evaluated for damage using propidium iodide (PI) fluorescence (Figure 1B)
Quantitative analysis of hippocampal slices exposed for 24 h (Figure 1C) or 72 h (Figure 1D) to 1 μM THC or 10 μM CBD showed that these drugs did not induce injury in the CA1 region in this model compared with the exposure to maximal injury represented by 10 mM glutamate (24 h), which was used as a positive control (Figure 1B bottom left) [25,29]

Summary

Introduction

Cannabis has been widely used for thousands of years, both for recreational and medical purposes. In humans and animal experimental models, it has been shown that chronic exposure to THC during adolescence produces long-term behavioural alterations that share similarities with certain symptoms of psychiatric and neurodevelopmental disorders [7,8]. Chronic THC leads to sensitisation of animals when they are re-exposed to the drug after long periods without drug exposure [16]. These behavioural effects following prolonged exposure to THC and CBD, are not corroborated by functional electrophysiological synaptic plasticity experiments performed following prolonged incubation to cannabinoids

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Conclusion