Involvement of CB 1 and CB 2 receptors in neuroprotective effects of cannabinoids in experimental TDP-43 related frontotemporal dementia using male mice.

Background: The elevation of endocannabinoid levels through inhibiting their degradation afforded neuroprotection in CaMKIIα-TDP-43 mice, a conditional transgenic model of frontotemporal dementia. However, which cannabinoid receptors are mediating these benefits is still pending to be elucidated.
Methods: We have investigated the involvement of the CB ₁ and the CB ₂ receptor using chronic treatments with selective ligands in CaMKIIα-TDP-43 mice, analysis of their cognitive deterioration with the Novel Object Recognition test, and immunostaining for neuronal and glial markers in two areas of interest in frontotemporal dementia.
Results: Our results confirmed the therapeutic value of activating either the CB ₁ or the CB ₂ receptor, with improvements in the animal performance in the Novel Object Recognition test, preservation of pyramidal neurons, in particular in the medial prefrontal cortex, and attenuation of glial reactivity, in particular in the hippocampus. In addition, the activation of both CB ₁ and CB ₂ receptors reduced the elevated levels of TDP-43 in the medial prefrontal cortex of CaMKIIα-TDP-43 mice, an effect exerted by mechanisms that are currently under investigation.
Conclusions: These data reinforce the notion that the activation of CB ₁ and CB ₂ receptors may represent a promising therapy against TDP-43-induced neuropathology in frontotemporal dementia. Future studies will have to confirm these benefits, in particular with one of the selective CB ₂ agonists used here, which has been thoroughly characterized for clinical development.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: CGC, ISG, LGT, CRC, JFR and EdL declare that they have no conflicts of interest, whereas MBW, PD and UG are employees of the company F. Hoffmann-La Roche Ltd.
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